No full-text available
To read the full-text of this research,
you can request a copy directly from the authors.
Candle soot: Journey from a pollutant to a functional material
Abstract
Candle soot, traditionally considered as an unwanted source of air-pollution, has slowly been phased out by modern lighting techniques. However, a 2007 study by Liu and co-workers first brought to light the presence of fluorescent carbon nanoparticles (CNPs) in untreated candle-soot (CS). Subsequent studies revealed that these soot-generated CNPs can be refined and extracted for various applications including humidity sensing, trace element detection and biomedical to Li-ion batteries, supercapacitors, electrocatalysis and solar collector among others. There are over 100 published articles dealing with fabrication, extraction, treatment and application of CS derived CNPs. However, unlike traditional carbon-based nanostructures including graphene and fullerene, this field lacks the presence of a systematic endeavour to tap into the vast potential of candle-soot. Therefore, this article aims to present a focused review on the topic of CS derived CNPs and their potential applications. The paper starts with a brief introduction on the topic of candle-soot and its historic significance. This is followed by a description of the techniques used to extract, refine and functionalize these carbon particles. Thereafter the reported applications of candle-soot derived nanostructures and their comparative analysis with the current state-of-art are provided. Finally, a section discussing future scopes and challenges is presented followed by conclusions.
... Moreover, the inhalation of soot aerosol may cause lung cancer, permanent lung damage or cardiovascular diseases [7][8][9]. If the soot is intrinsically water repellent, a feature strongly dependent on the pyrolysis process and combustion source [10], it can be employed for the fabrication of nanostructured functional surfaces targeting different practical applications [11,12]. ...
... During this process, a pristine PAH molecule (e.g., naphthalene) is subjected to hydrogen abstraction and such a bond breaking produces acetylene, sequentially building-up and leading to the growth of solid-state species, including soot [32]. However, the soot is unevenly distributed within the candle flame and the region releasing hydrophobic particles is located just beneath the middle of the flame [12]. Below or above this narrow zone, the flame is non-sooting, due to the high content of wax vapor and oxygen, or consists toxic chemical compounds (e.g., benzo [a] pyrene) and hydrophilic soot, respectively. ...
... • low deposition rates of the candles and ethanol compared to rapeseed oil [12,[54][55][56] • the uniformity of soot monolayers depends on the flame region [35] • the thin flame front restricts the applicability of candles only to small and medium size objects in real life (e.g., microfluidic and lab-on-a-chip devices, piezoresonance sensors, filtration membranes) ...
The contemporary technological advancement of mankind is marked by several memorable industrial revolutions, encompassing the shift from hand-made production to more automatic processing via steam- and water power-based machines, followed by the emergence of telegraphs, railroad networks, gas/water supplies and sewage systems, and ending up with the invention of internet and home computers, along with the rise of nanotechnologies.
Nowadays, the nanotechnologies are considered as one of the masterpieces of science, since having the ability to manipulate the matter at atomic level opens literally endless possibilities to engineer new functional structures, materials and devices. Hence, many industrial sectors such as construction, shipbuilding, aviation, civil engineering, refrigeration and power, etc. may benefit in different ways from the novel concepts and insights into nano- and materials sciences, leading to the potential for developing high-performance products. The examples for such products include, but are not limited to, windows of residential and business buildings remaining completely dry and clean after rainfall (also known as “self-cleaning surfaces”), eternally sterile medical equipment exposed to non-sterile ambient environment, corrosion-free metal components, highly-efficient pervaporative membranes, aircraft and renewable energy systems passively protected (without the need of external energy source) from atmospheric/condensation icing, advanced and portable chemical and biological sensors or “smart” oil skimmers.
The aforementioned scientific innovations are based on precise physical and chemical modification of the solid surface-of-interest, converting it into extremely non-wettable (found in the literature as superhydrophobic if the involved liquid is water). Usually this happens by depositing a thin non-wettable film, possessing the required hydrophobic chemistry, on a solid surface with specific topography and hierarchical roughness (e.g., composed of micron- and nanosized asperities). To meet the stringent criteria for commercialization, however, any liquid-repellent coating has to balance between scalability (appropriateness for a large-scale manufacturing), applicability to objects with complex geometry and curvature, low cost, long-term mechanical durability and last of all, multifunctionality (if feasible, the coating must exhibit anti-corrosive, icephobic, anti-fouling and drag-reducing properties at once).
Having such a combination is tricky and one of the rare examples of coatings fulfilling the requirements, surprisingly, belongs to those made of carbon soot. Despite that, it is commonly accepted that the soot is a highly toxic substance and its accumulation in the troposphere is primarily responsible for the worrying climate changes. Therefore, the efforts worldwide are focused on industrial decarbonization and replacement of the internal combustion engines. Hence, the aspirations for converting the soot wastes into functional non-wettable products sound quite insane, but will be validated herein and will provide a basis for rethinking the current agenda.
The present doctoral dissertation summarizes the new knowledge accumulated within the last fifteen years of research, dedicated to the experimental study, design, characterization and optimization of a variety of superhydrophobic rapeseed oil-derived soot coatings. These soot patterns can suppress the ice formation and bacterial attachments on different solids, alleviate the two-factor freezing injury during cryopreservation of human spermatozoa and activate their motility, and could serve as an interfacial sensing nanomaterial benefiting the quantitative analysis of human semen and urine, as well as the tracking of freezing modes of water droplets.
... Candle soot is the carbon-rich black residue from burning a candle [24,25]. Several studies have demonstrated candle soot as a source of carbon nanoparticles with different optical, physical, and chemical properties [26][27][28]. ...
... Several studies have demonstrated candle soot as a source of carbon nanoparticles with different optical, physical, and chemical properties [26][27][28]. These carbon nanoparticles find use in various applications, including sensing, due to their many appealing properties, such as their nano-sized dimensions, high surface area, and electronic conductivity [24]. ...
... They quickly evaporate at room temperature and atmospheric pressure. As a result, individuals may be exposed to The carbon nanoparticles were synthesised following a simple and inexpensive method comprising the incomplete combustion of white paraffin wax candles [24]. Briefly, a ceramic mug was positioned about a centimetre above the burning white candles to collect the soot released from the flame. ...
In this work, we report on the synthesis of four morphologies of ZnO, namely, nanoparticles, nanorods, nanosheets, and nanoflowers, from a single precursor Zn(CH3COO)2·2H2O under different reaction conditions. The synthesised nanostructured materials were characterised using powder X-ray diffraction (XRD), Fourier transform infrared (FTIR) and Raman spectroscopy, UV–Vis, XPS analysis, transmission electron microscopy (TEM), scanning electron microscopy (SEM), and nitrogen sorption at 77 K. The XRD, FTIR, and Raman analyses did not reveal any significant differences among the nanostructures, but differences in the electronic properties were noted among the different morphologies. The TEM and SEM analyses confirmed the four different morphologies of the ZnO nanostructures. The textural characteristics revealed that the specific surface areas were different, being 1.3, 6.7, 12.7, and 26.8 m2/g for the nanoflowers, nanoparticles, nanorods, and nanosheets, respectively. The ZnO nanostructures were then mixed with carbon nanoparticles (CNPs) and cellulose acetate (CA) to make nanocomposites that were then used as sensing materials in solid-state sensors to detect methanol, ethanol, and isopropanol vapour at room temperature. The sensors’ responses were recorded in relative resistance. When detecting methanol, 6 out of 12 sensors were responsive, and the most sensitive sensor was the composite with a mass ratio of 1:1:1 of ZnO nanorods:CNPs:CA with a sensitivity of 0.7740 Ω ppm−1. Regarding the detection of ethanol vapour, 9 of the 12 sensors were responsive, and the 3:1:1 mass ratio with ZnO nanoparticles was the most sensitive at 4.3204 Ω ppm−1. Meanwhile, with isopropanol, 5 out of the 12 sensors were active and, with a sensitivity of 3.4539 Ω ppm−1, the ZnO nanoparticles in a 3:1:1 mass ratio were the most sensitive. Overall, the response of the sensors depended on the morphology of the nanostructured ZnO materials, the mass ratio of the sensing materials in the composites, and the type of analyte. The sensing mechanism was governed by the surface reaction on the sensing materials rather than pores hindering the analyte molecules from reaching the active site, since the pore size is larger than the kinetic diameter of the analyte molecules. Generally, the sensors responded well to the ethanol analyte, rather than methanol and isopropanol. This is due to ethanol molecules displaying a more enhanced electron-donating ability.
... Recently, considering the excessive carbon soot production, researchers have come out with solutions by utilizing it in various applications such as activated carbon [8,9]. Soot or known as an organic pollutant is produced from incomplete combustion of any carbon-based materials such as fossil fuels, woods, plants, wax, etc. Surprisingly, soot generated from paraffin wax candles contains high purity of carbon than other carbon soot sources [10]. It is made of heavy straight-chain hydrocarbons obtained from crude petroleum oil [11,12]. ...
... For this study, the inner flame or known as a yellow region has been chosen for particles collection. The inner flame was characterized as superhydrophobic and large agglomerates with particle diameter size 20-55 nm as reported in [10]. For the WS sample, the size particles are bigger than FS. ...
Carbon dioxide (CO2) is one of the greenhouse gasses that has various effects to the earth atmosphere. In recent years, carbon-based adsorbent used for CO2adsorption. To increase the adsorption of CO2, the surface treatment should affect the adsorption sites. However, the mechanism of the ethanol surface treatment was lack of study. Hence in this study, we investigate the effects of ethanol treatment on candle soot surface and adsorption performance. Briefly, the raw soot(FS) was collected directly from the inner flame. The collected soot was treated with aqueous ethanol and labelled as washed soot (WS). Both FS and WS were studied for the significant effect on its physical, chemical properties and adsorption capacities. FS and WS showed the agglomeration of particles (mean diameter >1). FS washed with ethanol significantly increased total pore volume (from 0.18 to 0.65 cm3/g) with almost the same surface area (from 111.01 to 113.54 m2/g). The CO2adsorption capacity was revealed that the maximum adsorption capacity obtained by FS was 68 mg/g and slightly increased after the pre-treatment (69 mg/g). Meanwhile, Freundlich isotherm modelfitted to the experimental data based on basis of the regression coefficient (R2) which are0.979 (FS) and 0.993 (WS). Based on the isotherm, after ethanol treatment particles suggesting heterogeneous surface with large number of CO2adsorption sites compared to non-treated soot.
... Carbon has been praised for its potential to form a wide variety of microscale and nanoscale structures (Luchnikov et al., 2022). Therefore, the past decades have witnessed remarkable advances in both the synthesis methods and the understanding of carbon nanoparticles' properties based on electrical and optical characterizations (De Falco et al., 2014, 2017Hagen et al., 2018;Mulay et al., 2019). Also, the interest in nanostructured films has increased more and more due to their potential applications in various industries, including optoelectronics, sensing, and energy harvesting (Akhtar et al., 2021;Benelmekki & Erbe, 2019;Kanakaraj & Sudakar, 2020;Minutolo et al., 2022;Saini et al., 2021;Sharma et al., 2019, pp. ...
... Numerous studies have focused on the electrical properties of carbon materials over the years, including graphite, coke, carbon fibers, and particularly carbon blacks (Llobet, 2013;Power et al., 2018;Saini et al., 2021). However, recently, thanks to their distinctive optical and electrical properties, soot nanoparticles also received considerable attention for various applications Mulay et al., 2019). To enhance certain properties, soot particles frequently undergo a post-processing treatment (Sharma et al., 2019, pp. ...
Carbon nanoparticles (CNPs) have received considerable attention due to their exceptional qualities andadaptability. Their unique physical and chemical characteristics make them extremely intriguing asmaterials for numerous high-potential applications, such as electronics and gas sensing. This studyfocused on producing carbon-based nanomaterial devices by deposition of flame-formed carbon nano-particles on a suitable substrate and investigating their gas-sensing properties. CNPs were produced in afuel-rich laminar premixed ethylene/air flame and the collected CNP film was morphologically andelectrically characterized. The electrical conductivity of the film was investigated as a function of ethanolconcentration and amount of deposited material. Notably, CNP films exhibited high sensitivity toambient ethanol gas concentrations, and rapid recovery times at room temperature, and showed asensitivity increasing with the amount of deposited material and the surface complexity. Our findingsdemonstrate the high potential of combustion-generated CNPs as building materials for low-cost andportable ethanol sensors.
... 38,39 The transition of CS from an industrial waste to a functional material is in line with the principle of green chemistry. 40 Nevertheless, there has been no attempt to utilize it as a photothermal agent to fuel a photo-driven actuator. CS is produced from incomplete combustion of wax and mainly composed of carbon nanoparticles, hydrocarbons, and carboxylic acids. ...
... CS is produced from incomplete combustion of wax and mainly composed of carbon nanoparticles, hydrocarbons, and carboxylic acids. 40 The polar functional groups in CS enable it to disperse thoroughly in polar solvents like alcohols, chloroform, and acetone. 41,42 Inspired by this feature, we also discovered that CS disperse well in polymer matrix, making it an ideal photothermal agent for LCE actuation. ...
In recent years, photoactive materials have attracted extensive interest in microrobots for their attractive abilities of untethered and tunable control with light. Conventional photo-oscillators based on Azo-containing liquid crystal network require complex surface alignment techniques and light sources with specific wavelengths and polarity, which limits their application in controlled autonomy. Here, we report a facile strategy to create self-oscillating microrobots powered and controlled by a wide spectrum of constant light. The oscillators are composed of a layer of candle soot (CS)-containing liquid crystal elastomer (LCE) attached to a layer of polydimethylsiloxane (PDMS). The strip-shaped oscillators with one end fixed can execute self-sustained oscillation through a self-shadowing mechanism. LCEs with CS as an excellent photo-absorber provides superior photothermal actuation, while PDMS with low viscoelasticity accelerates the actuation-recovery cycle of the oscillator. Our LCE composite photo-oscillators show tunable frequencies and amplitudes by structural and light intensity modulation, showing potential for autonomous soft robotic applications.
... The soot particles are synthesized by the incomplete combustion of hydrocarbons, resulting in functional groups such as -CH, -CO, and OH [31,32]. Unlike soot from diesel and coal combustion, which emits high levels of NOx and SOx, burning candles emit a small quantity of CO 2 and CO, with a comparatively low environmental impact [33][34][35]. Furthermore, Yang et al. demonstrated the roll-to-roll system for the continuous production of candle soot for large-scale production [36]. ...
Activated carbon holds a promising avenue in the context of energy storage because of its special attributes like high surface area, large pore volume, and ease of preparation. Herein, we synthesized the activated carbon from low‐cost candle soot and employed it as an electrode for supercapacitor application. Activation resulted in a high specific surface area of 1679 m² g⁻¹ The electrochemical properties of activated candle soot (ACS) and unactivated candle soot (CS) are evaluated in a three‐electrode setup using 1 M H2SO4 as an electrolyte. ACS and CS exhibited specific capacitance of 467 and 180 F g⁻¹ at a current density of 2 A g⁻¹, respectively. The improved electrochemical performance of ACS is attributed to an increase in surface area upon activation, which acts as a reservoir to accommodate a large number of electrolyte ions. Furthermore, two‐electrode studies of ACS symmetric cells revealed the extraordinary capacitance of 397 F g⁻¹ at 1 A g⁻¹. The ACS system retained a capacitance of 82% for 10,000 cycles at a high current density of 10 A g⁻¹. This system exhibited a specific energy of 19.8 Wh kg⁻¹ at a specific power of 574.8 W kg⁻¹. We performed density functional theory (DFT) simulations to validate the experimental observations and found that the quantum capacitance of ACS is greater than that of CS. Furthermore, the barrier energy for ionic diffusion across the surface of ACS is lower than that of CS, indicating improved mobility upon activation.
... In contrast, the PL spectrum of GQD (HA) shows two peaks; one at 426 nm is due to the emission from π-π* transitions of the graphene layer. The second peak at 527 nm is attributed to the functional groups present at the surface or the edges of the graphene layer [39]. This can be linked to the oxygen states created during the oxidative cutting process of the solvent, which contained a notable concentration of oxygen. ...
Carbon dots (CDs) are promising carbon-based nanomaterials with a wide range of applications. In this study, various synthetic strategies were used to prepare carbon dots from different precursor molecules, including citric acid, urea, and antibiotics. A facile method using the technique of carbonization was used to prepare luminescent carbon dots. In addition to that, a microwave-assisted method was utilized for synthesizing antibiotic-derived carbon dots, as well as for doping these carbon dots to enhance their crystallinity and narrow their emission peaks. The luminescent properties of the synthesized carbon dots differed based on the synthesis methods and precursors used. Comparative analysis of their antibacterial efficacy indicated that carbon dots derived from citric acid and urea were more effective in inhibiting bacterial growth compared to those based on antibiotics. However, the antibiotic-derived carbon dots exhibited a long-lasting antibacterial effect. Additionally, the impact of carbon dots on bacterial morphology and their subsequent size is examined, leading to the suggestion of developing non-antibiotic antibacterial agents to address the challenges posed by multidrug resistance (MDR).
... Energy-intensive methods are not necessary when employing techniques like free cooling, which make use of water or ambient air. By submerging servers in non-conductive fluids, liquid cooling reduces the need for substantial air cooling by enabling direct heat removal (Mulay et al., 2019). ...
The data-driven economy is transforming with data centers becoming a crucial business infrastructure. However, the increasing reliance on data centers is posing a threat to the environment. Climate change activists are focusing on reducing emissions from sectors like automotive, aviation, and energy. Data centers consume more electricity than the UK, accounting for 3% of global electricity supply and 2% of
... It has been reported that CS particles from the inner ame of the candle form aggregates which are compact and contain higher amount of organics due to incomplete combustion of the wax vapor. 30,34 The ame tip was avoided since the CS obtained from the ame tip is hydrophilic and oleophilic due to complete combustion that results in more oxygen and ash contents. During the deposition of CS, the copper mesh was moved back and forth within the inner ame to obtain a uniform layer of CS. ...
Superhydrophobic and superoleophilic meshes have gained considerable attention in oil/water separation in recent years. To fabricate such meshes, surface roughness features can be introduced, and the surface free energy can be lowered, preferably, by utilizing low cost, safe, and readily available materials. Herein, we report a novel approach for fabricating a superhydrophobic copper mesh using low-cost carbon nanoparticles embedded within surface micropatterns. To create the micropatterns, a femtosecond laser was employed. The fabricated mesh exhibited a water contact angle of 168.9° and a roll-off angle of only 5.9°. Additionally, the mesh was highly durable and effectively retained its superhydrophobicity during water jet impact and tape-peeling tests. After 50 cycles of the water jet impact test and 5 cycles of the tape-peeling test, the water contact angle reduced by only 0.3° and 2.3°, respectively. When tested for separating n-hexane/water mixtures, the mesh exhibited a separation efficiency of up to 98%. The separation efficiency remained essentially constant after 10 cycles of n-hexane/water separation. It was observed that the surface micropatterns played a significant role in achieving superhydrophobicity and imparting high durability to the mesh. Meshes lacking these laser-induced micropatterns showed higher wettability, lower durability, and decreased separation performance with repeated use.
... Energy-intensive methods are not necessary when employing techniques like free cooling, which make use of water or ambient air. By submerging servers in non-conductive fluids, liquid cooling reduces the need for substantial air cooling by enabling direct heat removal (Mulay et al., 2019). ...
The data-driven economy is transforming with data centers becoming a crucial business infrastructure. However, the increasing reliance on data centers is posing a threat to the environment. Climate change activists are focusing on reducing emissions from sectors like automotive, aviation, and energy. Data centers consume more electricity than the UK, accounting for 3% of global electricity supply and 2% of total greenhouse gas emissions. By 2040, digital data storage is projected to contribute to 14% of the world's emissions. The number of data centers worldwide has surged from 500,000 in 2012 to over 8 million, with energy consumption doubling every four years. The rise in internet penetration rates and the introduction of 5G technologies and IoT devices will further exacerbate the issue, increasing the demand for data processing.
... Therefore, it is crucial to investigate the thickness of the absorbing material to optimize transducer performance. Considering the linear relationship between the deposition thickness of CSNP and deposition time [21,37], we fabricated five sets of SMTC structures with a constant coupling ratio of 50%. The amplitude of the generated ultrasonic signal was studied by varying deposition time. ...
This study proposes a novel multipoint transducer system by utilizing the single-mode-multimode-thin-cladding fiber (SMTC) structure. This structure leverages the disparity in mode field diameter between the multimode fiber (MMF) and thin-cladding fiber (TCF) to generate high-amplitude ultrasonic signals safely and efficiently. The fabricated transducer exhibits signal amplitudes 2–3-fold higher compared to conventional laser-ultrasonic transducers. Simulation analysis investigates the impact of the length of the MMF and the diameter of the TCF on coupling efficiency. The coupling efficiency of individual transducer units can be accurately controlled by adjusting the length of the MMF. A three-point energy-balanced laser-ultrasonic transducer system was achieved, with improved energy conversion efficiencies, and the optimal thickness of candle soot nanoparticles (CSNPs) is experimentally determined. Additionally, we carried out experiments to compare the performance of the proposed SMTC-based transducer system under different material conditions using two different photoacoustic materials: graphite–epoxy resin and candle soot nanoparticle–polydimethylsiloxane (CSNP–PDMS) composite. CSNPs, as a cost-effective and easy-to-prepare composite material, exhibit higher photoacoustic conversion efficiency compared to graphite–epoxy resin. The proposed system demonstrates the potential for applications in non-destructive testing techniques.
... CS, as one kind of carbon black, is a zero-dimensional carbon nanomaterial composed of multi-carbon alkanes, which is compatible with nonpolar SEBS well and can be facilely produced by the incomplete combustion of candles [36,37]. Figure 1a shows the SEM image of CS particles, which present a loose and porous accumulation of nanoscale spherical particles with a mean size of 67 nm. ...
Nowadays, flexible resistive strain sensors attract growing attention owing to their various applications in the fields of electronic skin, human health detection, body motion, etc. Unfortunately, to date, the fabrication of a high-sensitivity soft sensor under a wide-range strain through a simple and cost-competitive approach is still a challenge. In this work, a facile polymer-surface-swelling-adhesion approach was developed to fabricate bilayer candle soot/poly (styrene-b-ethylene-butylene-b-styrene) elastic strain sensors, which obtained a high sensitivity performance at a wide range of strain. When the surface density of candle soot was 0.42 mg/cm2, the gauge factor (GF) values of the sensor were 113, 77, and 177 for various strain ranges of 0%–9%, 9%–60%, and 60%–100%, respectively. The sensor could detect tiny strains such as 0.1% and demonstrated a sensing time of 265 ms at 10% strain. Moreover, after 1000 cyclic loading-unloading at 30% strain, the relative resistance variations remain stable. The sensing mechanism was explained by the tunnel effect for low and medium strain ranges and contact resistance change for the high strain range. As a further step, respiration with a surgical mask, body motion, and road roughness were successfully monitored by using the sensor.
... The technological applications of soot, and in general of CNPs, have got significantly less attention from the scientific community than other well-known and thoroughly explored carbonbased nanomaterials such as fullerenes, carbon nanotubes, graphene, graphene oxides, and carbon-metal oxide composites [18][19][20]. Yet, soot has recently become increasingly common as a material for a variety of innovative uses [21], ranging from the production of hydrophobic coatings to their employment in a wide range of optical, electronic, and electrical devices, due to their chemical, structural, and morphological properties [3,[22][23][24]. ...
... Rapid technological advancements in various areas of our everyday lives have increased the demand for electrical energy and created a desire for new conductive materials that outperform traditional metals like copper [1]. As a result, carbon-based nanoparticles have become an alternative as a cost-effective and environmentally benign material with outstanding properties due to their intrinsic mechanical and electrical properties [2][3][4]. As a member of the carbonaceous group, candle soot is particularly interesting as it is an autothermic, one-step, fast and low-cost process. ...
The electrical properties of carbon-based materials have attracted significant interest due to their wide range of potential applications. This study investigated the effect of nitric acid treatment on the electrical conductivity of candle soot particle films. Electrospray deposition was used to deposit the candle soot dispersion on a solid substrate. The electrical conductivity of the films increased as the concentration of nitric acid increased, with the highest conductivity of 27.65 S cm À1 observed in the film treated with 5 M nitric acid. The increase in conductivity was attributed to the enhancement of interparticle bonding between soot particles after acid treatment. Functional groups such as carboxylic or nitro groups were observed in the films by Fourier transform infrared (FTIR) spectroscopy. Raman spectroscopy showed a broadening of the D bands, suggesting a defect in the crystalline structure due to the formation of functional groups on the soot structure. These results suggest that nitric acid treatment can be used to improve the electrical conductivity of candle soot particle films.
... The latter coatings were chosen as they have demonstrated high water repellency. 59,60 The submerged specimens were removed at time intervals of 15 min, 3 h, 6 h, 12 h, and 24 h to evaluate the wettability of sewage water (see Video S4, Supporting Information). In Figure 6c, uncoated T5-textured specimens reveal the retention of nonwetting properties for up to 24 h, except that a couple of droplets were pinned on the textured and untextured regions on the 12 and 24 h-submerged specimens. ...
Liquid-repellent surfaces are beneficial for improving corrosion resistance, anti-biofouling, anti-icing, and reducing material sticking in food, beverages, cosmetics, and medical industries. However, limited research data are available on fabricating sewage water-repellent surfaces, which should repel suspended organic/inorganic and biological matter in addition to water. Herein, we unveil the sewage water repellency and superhydrophobicity of magnetic silicone composites and poly(dimethylsiloxane) (PDMS). Hexagonally arranged microconical pillars (Wenzel roughness of 1.2–2.4) were printed via hot embossing and replica molding methodologies. High static contact angles of ∼160°, low contact angle hystereses of ∼5°, and low roll-off angles of ∼5° were achieved. At least 30 textured silicone composites were fabricated by successively hot embossing from a single custom-made and durable commercializable Ni–steel mold. All of them demonstrated excellent replication efficiency and retained superhydrophobicity and sewage water repellency as a function of embossing cycles. Furthermore, sewage water and deionized water droplets bounced off the silicone composite surface for a Weber number of up to 149, revealing a robust Cassie configuration. Furthermore, textured surfaces retained under-sewage water phobicity for up to 24 h, when submerged at 3 cm depth (0.3 kPa gauge pressure), wherein coated and untextured surfaces have failed just within 15 min, i.e., covered by a liquid film or sticky droplets. Also, textured surfaces inhibited the growth of the Escherichia coli bacterium, while a huge biofilm was observed on the untextured region. Briefly, this is the first demonstration of a one-step, upscalable, and facile hot embossing methodology to manufacture sewage water-repellent silicone composite and PDMS surfaces.
... [40] These soot particles displayed superhydrophobic and superoleophilic properties owing to their low surface energy hydrocarbon and methyl functional groups. [41,42] Although these soot particles showed remarkable properties, their poor adhesion and difficulty in recovery hinder the use of these particles for oil/water separation. One way to overcome these challenges could be depositing CS particles on paraffin wax, polydimethylsiloxane, methyltriethoxysilanebased surfaces or combining the same with a polymer solution before electrospinning to fabricate stable superhydrophobic surfaces. ...
... (2) PM and gaseous pollutants PM was only significantly negatively correlated with O 3 and positively correlated with other gaseous pollutants (SO 2 , NO 2 and CO). The Pearson correlation coefficients between PM with NO 2 , SO 2 and CO were either high or moderate (R > 0.5), indicating that they have a high degree of homology (e.g., fossil fuel combustion; (Mulay et al., 2019)). It has been pointed out that NO 2 , SO 2 and CO emissions are often accompanied by PM emissions (Ibe et al., 2020;Karimi & Shokrinezhad, 2020;Shen et al., 2020). ...
Currently, air quality has become central to global environmental policymaking. As a typical mountain megacity in the Cheng-Yu region, the air pollution in Chongqing is unique and sensitive. This study aims to comprehensively investigate the long-term annual, seasonal, and monthly variation characteristics of six major pollutants and seven meteorological parameters. The emission distribution of major pollutants is also discussed. The relationship between pollutants and the multi-scale meteorological conditions was explored. The results indicate that particulate matter (PM), SO2 and NO2 showed a “U-shaped” variation, while O3 showed an “inverted U-shaped” seasonal variation. Industrial emissions accounted for 81.84%, 58% and 80.10% of the total SO2, NOx and dust pollution emissions, respectively. The correlation between PM2.5 and PM10 was strong (R = 0.98). In addition, PM only showed a significant negative correlation with O3. On the contrary, PM showed a significant positive correlation with other gaseous pollutants (SO2, NO2, CO). O3 is only negatively correlated with relative humidity and atmospheric pressure. These findings provide an accurate and effective countermeasure for the coordinated management of air pollution in Cheng-Yu region and the formulation of the regional carbon peaking roadmap. Furthermore, it can improve the prediction accuracy of air pollution under multi-scale meteorological factors, promote effective emission reduction paths and policies in the region, and provide references for related epidemiological research.
Graphical abstract
... 673 Candle soot may exhibit superhydrophobic properties and has been recognized as a basis for applications in electrodes, sensors, and ultrasound transducers. 674 Ample research exists on carbon nanostructure formation from combustion and related inception mechanisms. These have in part been reviewed recently (2022) by Martin et al., who discuss different nanometer-sized carbonaceous species from combustion environments, namely fullerenes, graphene, and nanoparticles of about 1−6 nm size, and the pathways for their formation. ...
Combustion is a reactive oxidation process that releases energy bound in chemical compounds used as fuels─energy that is needed for power generation, transportation, heating, and industrial purposes. Because of greenhouse gas and local pollutant emissions associated with fossil fuels, combustion science and applications are challenged to abandon conventional pathways and to adapt toward the demand of future carbon neutrality. For the design of efficient, low-emission processes, understanding the details of the relevant chemical transformations is essential. Comprehensive knowledge gained from decades of fossil-fuel combustion research includes general principles for establishing and validating reaction mechanisms and process models, relying on both theory and experiments with a suite of analytic monitoring and sensing techniques. Such knowledge can be advantageously applied and extended to configure, analyze, and control new systems using different, nonfossil, potentially zero-carbon fuels. Understanding the impact of combustion and its links with chemistry needs some background. The introduction therefore combines information on exemplary cultural and technological achievements using combustion and on nature and effects of combustion emissions. Subsequently, the methodology of combustion chemistry research is described. A major part is devoted to fuels, followed by a discussion of selected combustion applications, illustrating the chemical information needed for the future.
... Herein, considering different light extinction effects, which included intrinsic absorption of carbon nanomaterials, multiple scattering of hollow microspheres, and anti-interfacial reflection of intermediate layer, we designed and prepared a sprayable ultrablack coating and analyzed the related light absorption mechanisms. This ultrablack coating can be applied to the parts with large area and/or complex curved surface by spray-coating method [40][41][42] only and then thermo-cured without the aid of any complicated equipment and harsh process conditions, and in principle, is more compatible with the current technological process, compared with the complicated techniques mentionedabove. The resulting coating exhibited excellent light reflection properties around 1% over a wide wavelength range from 400 to 2000 nm and approached 2% reflection in mid-infrared range of 2-20 μm, ensuring high-performance solar energy harvesting. ...
Although ultrablack surfaces are urgently needed in wide applications owing to their extremely low reflectance over a broadband wavelength, obtaining simultaneously the ultrablackness and mechanical robustness by simple process technique is still a great challenge. Herein, by decoupling different light extinction effects to different layers of coating, we design an ultrablack coating that is all-sprayable in whole process. This coating presents low reflectance over visible–mid-infrared (VIS–MIR) wavelength (av. R ≈ 1% in VIS), low multi-angle scattering (bidirectional reflection distribution function (BRDF) = 10⁻²–10⁻³ sr⁻¹), together with good substrate adhesion grade and self-cleaning ability, which are superior to most reported sprayable ultrablack surfaces. The light extinction effects of each layer are discussed. This method is also applicable in other material systems.
... As compared with extended periodic carbon surfaces, finite-sized aromatic carbon clusters are more common structural units in natural and industrial carbocatalysts (such as activated coke, carbon soot and carbon nanodots) [19][20][21][22]. Recent characterizations using advanced transmission electron microscopy and ionization-mass spectrometry have directly proved that the structural units in amorphous carbon materials are crystallites composed of finite-sized aromatic carbon clusters [23,24], some of which only contain several dozens of carbon atoms (Fig. S1). ...
Carbon-based catalytic oxidation widely exists in contamination control, energy conversion and chemical production, in which amorphous carbon containing heteroatom is commonly used carbocatalyst. Compared with crystalline carbon, small-sized aromatic carbon clusters in amorphous carbon exhibit edge and size effect for catalytic oxidation; however, the activity origin, especially accurate activity descriptor remains to be explored. Herein, using SO2 catalytic oxidation as the probe reaction, a combined computational and experimental investigation was conducted to reveal the activity origin of oxygen-doped amorphous carbon. By density functional theory calculations on various oxygen-doped carbon clusters, a site-specific descriptor considering dynamic electron transfer effect was proposed via combining Fukui function and Mulliken electronegativity, based on which the catalytic activity is found to be determined by both oxygen groups and edges. The configuration with cyclic ether embedded into K-region edge is predicted to own the highest activity with O2 activation and SO2 oxidation barrier as low as 35.4 and 89.3 kJ mol⁻¹. SO2 catalytic oxidation dynamic experiments using model amorphous carbocatalysts further validate the favorable role of ether and edges. This work demonstrates quantitative descriptor for O2 activation and catalytic oxidation on amorphous carbocatalyst, providing guidance for designing high-performance carbocatalyst considering size and edge effect.
... To assess the suitability of CSNP-PDMS composites in needle tracking during surgical interventions, a detailed characterisation of the mechanical and chemical properties, and biocompatibility of these composites should be undertaken. There should be further evaluation of the properties of CSNPs produced by using different candle waxes, wicks, and collection distances above the candle flame to examine their effects, if any, on the resulting composite [46]. The composite coated on the needle exterior is exposed directly to the imaged tissue during insertions and thus experiences a higher degree of abrasion from the tissue. ...
Ultrasound (US) image guidance is widely used for minimally invasive procedures, but the invasive medical devices (such as metallic needles), especially their tips, can be poorly visualised in US images, leading to significant complications. Photoacoustic (PA) imaging is promising for visualising invasive devices and peripheral tissue targets. Light-emitting diodes (LEDs) acting as PA excitation sources facilitate the clinical translation of PA imaging, but the image quality is degraded due to the low pulse energy leading to insufficient contrast with needles at deep locations. In this paper, photoacoustic visualisation of clinical needles was enhanced by elastomeric nanocomposite coatings with superficial and interstitial illumination. Candle soot nanoparticle-polydimethylsiloxane (CSNP-PDMS) composites with high optical absorption and large thermal expansion coefficients were applied onto the needle exterior and the end-face of an optical fibre placed in the needle lumen. The excitation light was delivered at the surface by LED arrays and through the embedded optical fibre by a pulsed diode laser to improve the visibility of the needle tip. The performance was validated using an ex-vivo tissue model. An LED-based PA/US imaging system was used for imaging the needle out-of-plane and in-plane insertions over approach angles of 20 deg to 55 deg. The CSNP-PDMS composite conferred substantial visual enhancements on both the needle shaft and the tip, with an average of 1.7- and 1.6-fold improvements in signal-to-noise ratios (SNRs), respectively. With the extended light field involving extracorporeal and interstitial illumination and the highly absorbing coatings, enhanced visualisation of the needle shaft and needle tip was achieved with PA imaging, which could be helpful in current US-guided minimally invasive surgeries.
Economic and eco-friendly superhydrophobic sponges were readily fabricated by coating a Candle Soot-Wax composite for efficient oil-water separation. For this, the candle soot was extracted from the combustion of a paraffin candle and deposited onto sponges using wax through a dip-coating process. This leads to the adhesion of candle soot and produces competent superhydrophobic sponges. It exhibits a water contact angle of >150° that informs remarkable surface superhydrophobicity. Also, its superiority was tested with several parameters, including thermal stability, pH tolerance, compression tolerance, chemical durability, reusability, etc., that offer satisfactory results besides validating its superhydrophobic nature. Furthermore, its superhydrophobic tolerance was tested for anti-wetting properties, cross-sectional cutting, pressing, paper peel test, and abrasion resistance. Therefore, it proved that this simple candle soot-wax coating technology has practical capabilities for coating large surfaces. This promising material can work as a distinct and economical oil-water separator, which will help to prevent massive environmental pollution caused by oil spills in water.
The integration of photothermal de‐icing and micro/nanostructured anti‐icing technologies into a surface is regarded as a promising solution to solve ice accretion aggravated. Unfortunately, light‐dependent heat effect and large‐scale production of micro/nano building still challenge the anti‐icing ability and applications for real‐world. Herein, a stick‐and‐play film embedded with bioinspired thermal‐management cells is developed. Inspired by the hollow framework of lotus seedpods, thermal‐management hydrophobic microcells (THMC) are designed by incorporating candle soot into insulating porous diatomite. Once embedding such microcells into PDMS substrate, the resulting THMC film delivers effective photothermal effect since the synergy of photothermal and insulation design. COMSOL simulations demonstrate thermal management effect of the “framework” and “photothermal seeds,” which causes increases in the heating rate by 20% and equilibrium temperature by 10%. Moreover, the self‐similarity structure of THMCs enable them to have durable hydrophobicity (148.7°) and photothermal effect (79.9 °C) even after repeated abrasions. When a stick‐and‐play functionality is imparted by designing adjustable milli‐suction cups, this THMC film could adhere effectively to various surfaces despite dry and humid conditions while maintaining efficient anti‐/de‐icing capabilities. This study provides a designing strategy of robust and efficient photothermal films constructed from THMC and finds flexible use for diverse surfaces.
The contribution of solar photovoltaics in electricity generation in 2020 reached up to 830,741 GWh and with concentrators 13,113 GWh. In 2022, solar photovoltaics captured nearly 60% (298.21 billion US$) share of global renewable energy investments. In India, nearly 2 Lakhs population have employment in the solar photovoltaic industry directly or indirectly. These reference data are enough to understand the importance of solar voltaic technology in modern-day life. In this chapter, we have outlined the history and development of solar cells with special attention to silicon heterojunction solar cells. We have mentioned the rise and some latest applications of graphene in silicon and other types of heterojunction solar cells. The electronic structure of pristine graphene severely restricts some of its electronic applications. Graphene Quantum Dots are fragmented nanostructures of graphene known for their excellent photoluminescent properties. The main objective of this chapter is to shed light on the synthesis techniques, properties, and applications of Graphene Quantum Dots in heterojunction solar cells.
Carbon-based conductive inks, with their low cost, ease of fabrication, and environmental friendliness, have a wide range of applications. In this study, we present the development of a candle-soot-based conductive ink through a simple and cost-effective synthesis process. The composite was formulated by incorporating candle-soot with PVDF-HFP polymer using DMF as a solvent. The study evaluates the performance of different amounts of carbon present in a candle-soot-polymer composite. The conductive ink was also filled in a ballpoint refill, circuits were drawn, and I–V responses were studied. The conductive films were thoroughly characterized using SEM, EDX, TGA, and IV characteristics. XRD and FTIR analyses were performed to assess the properties of the conductive film (CPC4) and candle-soot. Four distinct conductive ink formulations were synthesized by varying the percentage of candle-soot. I-V studies revealed that the electrical resistance of the composite films decreased with increasing candle-soot content. The results demonstrated excellent conductivity, enabling the fabrication of simple and functional conductive circuits on paper using the developed CPC4 ink. Candle-soot, as filler, exhibited promising results comparable to expensive conductive fillers such as graphene and multi-walled carbon nanotubes. The developed conductive ink shows promising performance in flexible electronic devices, offering a cost-effective and environmentally friendly alternative.
Carbon soot, traditionally considered a pollutant due to its harmful effects on human health and the environment, is now recognized as a valuable functional material. Carbon soot’s unique physical and chemical properties make it attractive for various applications, including energy storage, catalysis, electronics, water detoxification, and more. This review article covers the application of soot-derived carbon nanoparticles for water remediation. The article starts with discussing the soot formation mechanism, followed by a characterization of soot particles. Further, the application of carbon soot for oil–water separation and removal of contaminants from water are reviewed. The effect of various process parameters like pH, time of contact, and concentration are discussed. Further, the article discusses carbon soot particle’s limitations and future scope for water remediation. In conclusion, this review highlights the potential of carbon soot as a sustainable and cost-effective solution for water detoxification and presents an outlook for future research in this field. It also discusses the challenges and shortcomings of the work done till now in this area.
Novolac matrix composites are crucial due to their exceptional resistance to heat, chemicals, and mechanical stress. These advanced materials find applications in aerospace, electronics, and automotive industries, providing high-performance solutions for components requiring superior durability and reliability. In this context, the microstructure, thermal, phase, and mechanical properties of the composites obtained as a result of the recycling-oriented reinforcement of the waste candle-soot (CS) reinforcement at the rate of 1 wt% to the pure novolac (PN) and shaping with the hot press method were examined in detail at first time in the literature. While microstructural properties and fracture mechanisms were investigated by scanning electron microscopy (SEM), thermal properties were investigated by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The results obtained provided critical findings as the composite hardness, tensile strength, and flexural strength values were 3.28, 2.47, and 3.21 times higher than PN, respectively. CS-reinforced novolac composites made a significant contribution to the literature by introducing a novel and eco-friendly approach to enhance material properties. Their use as a filler material provided insights into sustainable novolac composites, offering potential applications in various industries, such as electronics and aerospace, with improved mechanical and thermal properties.
Wearable sweat sensor offers a promising means for noninvasive real‐time health monitoring, but the efficient collection and accurate analysis of sweat remains challenging. One of the obstacles is to precisely modulate the surface wettability of the microfluidics to achieve efficient sweat collection. Here a facile initiated chemical vapor deposition (iCVD) method is presented to grow and pattern polymer nanocone arrays with distinct superwettability on polydimethylsiloxane microfluidics, which facilitate highly efficient sweat transportation and collection. The nanoarray is synthesized by manipulating monomer supersaturation during iCVD to induce controlled nucleation and preferential vertical growth of fluorinated polymer. Subsequent selective vapor deposition of a conformal hydrogel nanolayer results in superhydrophilic nanoarray floor and walls within the microchannel that provide a large capillary force and a superhydrophobic ceiling that drastically reduces flow friction, enabling rapid sweat transport along varied flow directions. A carbon/hydrogel/enzyme nanocomposite electrode is then fabricated by sequential deposition of highly porous carbon nanoparticles and hydrogel nanocoating to achieve sensitive and stable sweat detection. Further encapsulation of the assembled sweatsensing patch with superhydrophobic nanoarray imparts self‐cleaning and water‐proof capability. Finally, the sweat sensing patch demonstrates selective and sensitive glucose and lactate detection during the on‐body test.
Electrowetting behaviour for carbon nanotubes (CNT) grown on stainless steel mesh was investigated. The effect of temperature, time, and applied bias voltage on the contact angle of water droplets was studied. The impact of temperature variation on contact angle was also performed for the temperature ranging from 25 to 70 °C. A decrement of contact angle by 68% was observed for the mentioned range indicating a transition from a hydrophobic to hydrophilic nature. A similar trend was observed on the application of electric potential to the CNT-modified stainless-steel mesh ranging from 0 to 8 V with a transition of contact angle from 146 to 30 deg respectively. A comparative analysis for the contact angle variation with time for CNT-coated mesh and uncoated mesh was performed for 180 min. It is observed that uncoated mesh shows a reduction in contact angle to 0 deg with time while the CNT coated mesh shows surplus hydrophobicity with a 2 deg decrement in the extent of time. CNT-modified mesh successfully absorbs 95% of rhodamine B (RB) dye and detergent from water in 10 cycles.
Biomass combustion provides energy needs for millions of people worldwide. However, soot accumulation on the combustors’ walls significantly reduces heat transfer efficiency. Herein, we demonstrate how microtextured surfaces minimize soot accumulation by enhancing soot oxidation. We investigate soot layers from the combustion of paraffin wax as a model for wood-based soot, and find that randomly microtextured glass obtained by sandblasting shows a 71% reduction in the time taken to oxidize 90% of surface soot coverage when compared to smooth glass at 530 °C. We also study grooved microtextures fabricated via laser ablation and find that grooves with widths between 15 and 50 µm enhance soot oxidation, while the expedited advantage is lost when the groove width is 85 µm. X-ray photoelectron spectroscopy validates the superior extent of soot removal on microtextures down to a sub-nanometer length-scale. The high density of sharp features such as peaks and edges on microtextures, and the conformality of the soot layer to the microtextures contribute to increased soot oxidation. We also demonstrate enhanced soot oxidation on microtextured stainless steel, the principal material of construction in biomass combustors. Microtextured surfaces that facilitate soot oxidation upon contact could significantly improve performance and longevity in various combustion applications.
Nagendra Singh, Sriram Krishnan, Samir Kumar Biswas Nano-scale laser beam size and its shape information are essential parameters in most optics-based precision measurements and nano-scale material processing. It is also quite challenging to measure nano-size optical beams accurately for both open experiments and at compact workplace of microscope due to various instrumental factors. Outside of the visible spectrum, usually wavelength-sensitive uorescence markers and composite materials are used to read the laser beam pro le. In this article, a cost-e ective carbon nano-particles (CNPs) lm has been developed from candle soot. Furthermore, the developed bio-carbon soot lm is encapsulated with optically transparent composite polymer on aqueous media to measure sub-micron size spot of a low-power laser. Field emission scanning electron microscopy, optical spectrum analysis, Fourier transform infrared spectroscopy, UV-visible spectroscopy, di erential scanning calorimetry and thermogravimetric analysis techniques have been performed to characterize the developed CNPs lm and optimized its functionality. The fabricated lm has been used to measure sub-micron laser beam size. Due to the wide absorption spectrum of the developed bio-CNPs lm, the sensitivity region for measurement lies within both visible and beyond the visible spectrum.
Wearable humidity sensors play an important role in human health monitoring. However, challenges persist in realizing high performance wearable humidity sensors with fast response and good stretchability and durability. Here we report wearable humidity sensors employing an ultrathin micro-nano hierarchical hydrogel-carbon nanocomposite. The nanocomposite is synthesized on polydimethylsiloxane (PDMS) films via a facile two-step solvent-free approach, which creates a hierarchical architecture consisting of periodic microscale wrinkles and vapor-deposited nanoporous hydrogel-candle-soot nanocoating. The hierarchical surface topography results in a significantly enlarged specific surface area (>107 times that of planar hydrogel), which along with the ultrathin hydrogel endow the sensor with high sensitivity and a fast response/recovery (13/0.48 s) over a wide humidity range (11-96%). Owing to the wrinkle structure and interpenetrating network between the hydrogel and PDMS, the sensor is stable and durable against repeated 180° bending, 100% strain, and even scratching. Furthermore, encapsulation of the sensor imparts excellent resistance to water, sweat, and bacteria without influencing its performance. The sensor is then successfully used to monitor different human respiratory behaviors and skin humidity in real time. The reported method is convenient and cost-effective, which could bring exciting new opportunities in the fabrication of next-generation wearable humidity sensors.
Intracellular delivery of bioactive macromolecules and functional materials plays a crucial role in fundamental biological research and clinical applications. Nondestructive and efficient harvesting of engineered cells is also required for some specific applications. In this work, we develop a multifunctional platform based on candle soot modified with copolymer brushes containing temperature-responsive poly(N-isopropylacrylamide) (PNIPAAm) and sugar-responsive phenylboronic acid (PBA) components. This platform possesses a high cell adhesion capacity due to the inherent hierarchical structure of candle soot and the formation of boronate ester bonds between the PBA groups and glycoproteins on the cell membrane. Under the irradiation of a near-infrared laser, the excellent light-to-heat conversion ability of candle soot enables the highly efficient delivery of macromolecules into diverse cells (including hard-to-transfect cells) attached to the surface via a photothermal-poration mechanism. Owing to the temperature-responsive properties of PNIPAAm and the sugar-responsive properties of PBA, the engineered cells could be harvested nondestructively from the platform by a mild treatment using a cold fructose solution. A proof-of-concept experiment demonstrates that fibroblasts attached to the surface could be transfected by a functional plasmid encoding basic fibroblast growth factor and then harvested efficiently and recultured with improved proliferation and migration ability. The whole delivery-harvesting process required less than 1 h, allowing the cells to be engineered without compromising their viability. This platform thus provides a widely applicable method for both the intracellular delivery of diverse macromolecules efficiently as well as harvesting engineered cells simply and safely, holding great potential for biomedical applications.
Developing sustainable, inexpensive material has been proposed as a promising catalyst. Herein, we report the synthesis of new hybrid material composed of carbon nanoparticles entrapped in iron vanadate. Thus obtained new material was characterized using SEM, PXRD, Raman and XPS.The catalytic potentiality of CNP/FeVO4 has been tested in the oxidation of biomass derived hydroxymethylfurfural (HMF) in an aqueous medium. An enhanced conversion of 5‐HMF to diformylfuran (DFF) is observed in the presence of CNP/FeVO4 than FeVO4 alone. The absence of expensive metals and using only water as a solvent, along with recyclability of catalyst make our catalytic method green and attractive.
Candle soot (CS) nanoparticles exhibit excellent superhydrophobic and superoleophilic properties, making them an ideal absorbent for separating oil and oil/water mixtures. Although their cost-effectiveness is attractive, the challenges associated with recovering soot nanoparticles after oil absorption and producing secondary pollutants have limited their attention. Our study demonstrates the synthesis of CS nanoparticles embedded polystyrene (PS) nanofibrous membranes with excellent stability, surface-to-volume ratios, and flexibility. CS-incorporated composite membrane with a rough surface showed a water contact angle (WCA) of 156° ± 1.5°, about 20% higher than the smooth pristine PS membrane. The CS-based composite membrane also demonstrated improved performance as an absorbent, owing to its hydrophobic characteristics linked with surface roughness when employed for separating oil from oil/water mixtures. Furthermore, when exposed to four different oils, the CS-based membrane displayed a higher absorption capacity (up to ≈120 g oil/g membrane) than the pristine membrane. Using a gravity-assisted continuous oil/water separation setup, we measured the oil permeate flux using nanofiber mats as a membrane. Compared to the original membrane, the modified membrane showed enhanced oil permeate flux of ~2873 ± 122 L m−2 h−1 and separation efficiency of over 99%.
Candle‐soot nanoparticles (CSNPs) have shown great promise for fabricating optical ultrasound (OpUS) transmitters. They have a facile, inexpensive synthesis whilst their unique, porous structure enables a fast heat diffusion rate which aids high‐frequency ultrasound generation necessary for high‐resolution clinical imaging. These composites have demonstrated high ultrasound generation performance showing clinically relevant detail, when applied as macroscale OpUS transmitters comprising both concave and planar surfaces, however, less research has been invested into the translation of this material's technology to fabricate fiber‐optic transmitters for image guidance of minimally invasive interventions. Here, are reported two fabrication methods of nanocomposites composed of CSNPs embedded within polydimethylsiloxane (PDMS) deposited onto fiber‐optic end‐faces using two different optimized fabrication methods: “All‐in‐One” and “Direct Deposition.” Both types of nanocomposite exhibit a smooth, black domed structure with a maximum dome thickness of 50 µm, broadband optical absorption (>98% between 500 and 1400 nm) and both nanocomposites generated high peak‐to‐peak ultrasound pressures (>3 MPa) and wide bandwidths (>29 MHz). Further, high‐resolution (<40 µm axial resolution) B‐mode ultrasound imaging of ex vivo lamb brain tissue demonstrating how CSNP‐PDMS OpUS transmitters can allow for high fidelity minimally invasive imaging of biological tissues is demonstrated. This article reports on two fabrication methods of nanocomposites composed of candle‐soot nanoparticles embedded within polydimethylsiloxane deposited onto fiber‐optic end‐faces using two different optimized fabrication methods: “All‐in‐One” and “Direct Deposition.” These demonstrate high‐resolution (<40 µm axial resolution) B‐mode ultrasound imaging of ex vivo lamb brain tissue.
Despite substantial advancements in development of artificially engineered superhydrophobic surfaces, durability and regenerative aspect of such surfaces remain elusive. Harsh working condition, especially extreme exposure to water or humidity deteriorates plastron property of superhydrophobic surfaces rendering them inappropriate for prolonged under water applications. We report a systematic approach for creating a durable superhydrophobic surface by first plasma-treating a fabricated porous nanochannel geometry on a silicon substrate followed by infusion-depletion of silicon oil and coating a layer of carbon derived from candle soot. The surface is capable of maintaining water contact angle (WCA) of nearly 160° and roll off angle (ROA) less than 5° after undergoing 20 different tests including mechanical (tap water jet up to 10.3ms-1, tape peeling test up to 12 cycles), chemical (saline and solvents immersion), thermal (high temperature exposure and condensation heat transfer), self-cleaning tests, organic compatibility (honey, soy sauce, chocolate syrup, all-purpose flour) and superoleophilic test, thus exhibiting potential real-world applications. The surface retains stable plastron with negligible change in WCA and ROA even after being under 10cm of water for 30 days, similar to respiration plastrons seen on some aquatic insects. Regenerative capability of the surface is demonstrated by restoring its superhydrophilicity from a forced degraded state.
We observed substantial enhancement in pyroelectric output with the help of candle soot coating on the surface of lead zirconate titanate (PZT). Candle soot of varying thicknesses was coated by directly exposing pyroelectric material to the candle flame. The open-circuit pyroelectric voltage and closed-circuit pyroelectric current were recorded while applying infrared heating across the uncoated and candle soot-coated samples for different heating and cooling cycles. In comparison to the uncoated sample, the maximum open-circuit voltage improves seven times for the candle soot-coated sample and electric current increases by eight times across a resistance of 10 Ω. Moreover, the harvested energy is enhanced by 50 times for candle soot-coated sample. Results indicate that candle soot coating is an effective and economic method to improve infrared sensing performance of pyroelectric materials.
To investigate the properties and structures of soot particles derived from candle combustion, two deposition routes were performed. In “Route-1,” the aerosol (soot) particles were collected by direct exposure of a substrate in a chamber with controlled airflows. In "Route-2,” deposited soot nanoparticles was transferred into suspension and subsequently, the deposition of particles on to the substrate was achieved by an electrospray. Raman spectral analysis has shown the difference of G-band intensity relative to D-band between hydrophobic and hydrophilic particle layers obtained from different collection regions of the candle flame. It also reveals the effect of airflows during the collection to the ratio of the D to G peak. Meanwhile, the Raman spectra of the particles seem invariant to the preparation methods of suspension and electrospray deposition process. From the curve gradient of spectroscopy (190–2500 nm) results, the electrospray-deposited particle layers (Route-2) show higher absorbance in the near-infrared region compared to direct-deposited particle layers (Route-1). This change in the spectrum may due to the change in morphology of nanoparticle layers formed by each route.
Highly transparent superhydrophobic hollow films (contact angle, 165.7° and sliding angle, 2.1°) have been prepared by using candle soot as a template, followed by methyltrimethoxysilane (MTMS) chemical vapor depostion (CVD) and calcination at 450 °C, without the addition of dibutyl tin laurate (DBTL). The influence of deposition time on the superhydrophobicity and transparency of the as-prepared films was discussed herein to get the optimum performance film. The film shows high transparency (transmittance close to 90%) when it was coated on a glass substrate. What is more, it shows good thermal stability and superior moisture resistance as well, retaining its superhydrophobicity after calcining up to 500 °C or even exposure to ambient conditions for 30 days. ²⁹Si NMR, XPS spectra and thermal analysis verify the existence of methyl groups linked with silicon matrix on film (low surface energy), while AFM and TEM analysis confirm the sub-100 nm roughness and hollow structure of the optimum film.
A facile technique to transform candle soots into nanoporous fibers via electrospinning of mixed solution of candle soots and polyvinylidene fluoride (PVDF) has been demonstrated for the first time. Due to insolubility of soot nanoparticles and good solubility of PVDF polymer in DMF/acetone solvents, the soot molecules are heterogeneously dispersed in the mixed solutions. The selection of an appropriate polymer concentration resulted in a good dispersion of the low-density soot nanoparticles which can be held for electrospinning. The electrospinning experiment shows that soot nanoparticles can be smoothly bonded with PVDF molecules to form nanoporous fibers. The unique superhydrophobic and superoleophilic properties of the as-prepared electrospun fibrous membrane were demonstrated by subjecting it to various aqueous liquids and oils. This work provides a simple way to transform low-density nanoparticles into high-performance nanoporous nanofibers, which should broaden the applications of electrospinning.
A facile synthesis method for highly stable carbon nanoparticle (CNP) dispersion in acetone by incomplete combustion of paraffin candle flame is presented. The synthesized CNP dispersion is the mixture of graphitic and amorphous carbon nanoparticles of the size range of 20–50 nm and manifested the mesoporosity with an average pore size of 7 nm and a BET surface area of 366 m²g⁻¹. As an application of this material, the carbon nanoparticle dispersion was spray coated (spray-based coating) on a glass surface to fabricate superhydrophobic (water contact angle > 150° and sliding angle < 10 °) surfaces. The spray coated surfaces were found to exhibit much improved water jet resistance and thermal stability up to 400 °C compared to the surfaces fabricated from direct candle flame soot deposition (candle-based coating). This study proved that water jet resistant and thermally stable superhydrophobic surfaces can be easily fabricated by simple spray coating of CNP dispersion gathered from incomplete combustion of paraffin candle flame and this technique can be used for different applications with the potential for the large scale fabrication.
Two proposed quartz fibrous filters with dissimilar solid volume fractions and thicknesses are investigated for their efficiency in removing soot aerosol particles from air. Soot particles are sourced from a candle burning in a chamber, and the tests involve 1.5 h of continuous loading of particles at three different flow rates: 4.5, 8.15 and 9.55 l/min. The fractional efficiency, morphology and pressure drop of both clean and loaded filters are studied using a scanning mobility particle sizer, scanning electron microscope and differential pressure gauge. Both filters have relatively similar levels of efficiency 93% for particle size (100–400 nm) at the lowest flow rate. At higher flow rates, the re-entrainment process effects the filtration efficiency of both filters. At the higher flow rate of 8.15 l/min, the filter with a higher solid volume fraction and thickness shows a higher pressure drop and an efficiency level of 95%. Increasing the flow rate to 9.55 l/min helps to pass the particles with diameters larger than 100 nm through two filters. This phenomenon decreases the fractional efficiency of both filters during the loading time.
We demonstrate a facile method termed candle soot coating (CSC) for fast developing latent fingermarks (LFMs) on various kinds of surfaces (glass, ceramic, metal, paper and adhesive tape). The CSC method can be considered as simple, fast, and low-cost as well as providing high contrast for LFM visualization in potential forensic applications.
The superhydrophobic sponges were fabricated through dip-coating candle soot (CS) and SiO2 nanoparticles on polyurethane (PU) sponges. The as-prepared sponges exhibited high absorption capacity for oils and organic solvents and the separation efficiencies of oil/water mixtures were all higher than 99.00%. In addition, the CS-SiO2-PU sponge with robust superhydrophobicity could selectively absorb oil from corrosive solutions, hot water (92 ± 2 °C), and ice/water mixtures at magnetic stirring. Furthermore, the as-prepared sponge connected with a vacuum system could remove oil from water continuously. Therefore, the CS-SiO2-PU sponge as a promising candidate can realize oil/water separation in harsh conditions.
Graphical Abstract
The CS-SiO2-PU sponges with robust superhydrophobicity toward harsh conditions could absorb oils from water quickly in a vacuum system.
Due to the different interfacial effects of oil and water, utilizing the special wettability of solid surfaces to design an oil and water separation process has been demonstrated to be an effective approach for oil/water separation. In this report, a simple process has been developed to fabricate special surface wettability mesh membranes. The carbon nanoparticles with diameters of 10 nm were first coated onto the surface of steel wires based on a candle soot coating process. These templates of carbon nanoparticles were then coated with a more stable layer of silica (SiO2) particles via a facile chemical vapor deposition route. After being modified by two separate methods, a superhydrophobic/superoleophilic membrane was obtained by the use of 1H,1H,2H,2H-perfluorooctyltrichlorosilane (PFOTS) and a oleophobic/superhydrophilic membrane was obtained by using poly(diallyldimethylammonium-perfluorooctanoate) (PDDA–PFO). Separation experiments show that these superhydrophobic/superoleophilic or oleophobic/superhydrophilic mesh membranes can be used to selectively separate oil/water with a high flux of more than 930 L m⁻² h⁻¹ and a collecting efficiency of over 97%. Furthermore, the repetitions of the separation experiments demonstrate that these superhydrophobic/superoleophilic or oleophobic/superhydrophilic mesh membranes are durable, stable and reusable, making them encouraging candidates for practical oil-polluted water treatment.
The Raman spectroscopic analysis of a rare wall decoration in a church belltower, depicting the initials of couples married there in circular roundels over some 230 years, since 1777, has been undertaken prior to their impending restoration. The spectral data indicate that the red pigment is exclusively haematite which has been applied to plaster which exhibits the signatures variously of calcite, gypsum, anhydrite, calcium phosphate and dolomitic limestone; evidence of amorphous carbon is attributed to the deposition of soot from candle illumination, which has been recorded in historical documentation. The presence of biosignatures attributed to carotenoids in several samples is evidence of biological colonisation and potential deterioration which requires special treatment in the restoration strategies. The blackened areas near the upper edges of the wall decoration indicate carbon deposition and organic contamination. The latest addition to the decoration accomplished in 2008 shows that haematite has been used over a calcite ground. In earlier dated specimens, the presence of limewash is evident, which has only been partially converted into calcite by aerial attack from carbon dioxide in moist conditions.
In order to improve the tribological properties of perfluoropolyethers (PFPE), fluorinated candle soot is adopted as the lubricant additive because of their special onion-like structure. The candle soot particles (CSP) are modified by 1H,1H,2H,2H-perfluorooctanol (CSP-PFHE nanoparticles), and after the fluorination, they exhibit good dispersivity in PFPE. The mixtures composed of CSP-PFHE nanoparticles and PFPE possess better tribological performance than neat PFPE under different test conditions including variable temperature, the irradiation of atomic oxygen and extreme pressure. The reason can be attributed to that the graphene layers are exfoliated from the surfaces of nanoparticles and adhere onto the steel surfaces to form the tribofilm, which can protect the sliding pairs surfaces from friction and severe wear. Meanwhile, the redundant nanoparticles act as the rolling bearing between the sliding surfaces to decrease the wear and some are packed into the corrosion pits generated by PFPE to prevent further erosion in the process of friction. At the end, the lubricating mechanism of CSP-PFHE nanoparticles as additives of PFPE is proposed based on the test results of scanning electron microscope, contact electrical resistance and X-ray photoelectron spectroscopy.
Graphical Abstract
Open image in new window
The fabrication of superhydrophobic coatings using a candle flame or rapeseed oil has become very attractive as a novel approach for synthesis of water repellent surfaces. Here, we report an improved, simplified and time-efficient method for the preparation of robust superhydrophobic carbon soot that does not require any additional stabilizers or chemical treatment. The soot's inherent stabilization is achieved using a specially-designed cone-shaped aluminum chimney, mounted over an ignited paper-based wick immersed in a rapeseed oil. Such configuration decreases the level of oxygen during the process of combustion; altering the ratio of chemical bonds in the soot. As a result, the fractal-like network of the carbon nanoparticles is converted into dense and fused carbon chains, rigidly coupled to the substrate surface. The modified carbon coating shows superb thermal sustainability and retains superhydrophobicity up to ∼300 °C. Furthermore, it demonstrates a low contact angle hysteresis of 0.7-1.2° accompanied by enhanced surface adhesion and mechanical durability under random water flows. In addition, the soot's deposition rate of ∼1.5 μm/s reduces the exposure time of the substrate to heat and consequently minimizes the thermal effects, allowing the creation of superhydrophobic coatings on materials with low thermal stability (e.g. wood or polyethylene).
A facile method was developed to prepare a superhydrophobic candle soot coating by burning candle and simple deposition on a low-density polyethylene substrate. The water contact angle and sliding angle of the as-prepared superhydrophobic candle soot coating were, respectively, 160 ± 2° and 1° under common condition. ESEM images showed that the superhydrophobic candle soot coating was comprised of many nanoparticles with the size range of about 30–50 nm. After condensation for 30 min, the average contact angle of the condensed water droplets was 150° ± 2°, showing excellent superhydrophobicity under condensation. The mechanism of the candle soot coating remaining superhydrophobicity under condensation was analyzed. This work is helpful for the design and preparation of superhydrophobic surface which can remain superhydrophobicity in future.
A method employing one kind of material both for the construction of rough morphology and the chemical modification is called self-modification by us, which has not been reported in fabricating superhydrophobic surfaces so far. In this paper, taking candle soot as an intermediate, we created rough, superhydrophilic and transparent surfaces on glass trough calcination of polydimethylsiloxane (PDMS) at 550. °C. Subsequently, a novel chemical vapour deposition (CVD) modification was conducted by heating PDMS at 330. °C in air to give the surfaces a water contact angle (WCA) of 170°. ±. 0.5° and a sliding angle (SA) of 0°. This CVD modification is expected to be a valuable way of modification because of its simple operation, low cost and short time consumption. Results indicate that the high temperature calcination and the moderate temperature CVD modification can drastically improve the stability of the surperhydrophobic surfaces through controlling the morphology and the surface chemical composition. The as-prepared glass surfaces are capable of bearing heavy rains, keeping the sight clear in the rain and being used at a high temperature (<400. °C) or in water. Besides, superhydrophobic fiberglass mesh was prepared and applied in oil-water separation.
Generation of high power laser ultrasound strongly demands the advanced materials with efficient laser energy absorption, fast thermal diffusion, and large thermoelastic expansion capabilities. In this study, candle soot nanoparticles-polydimethylsiloxane (CSNPs-PDMS) composite was investigated as the functional layer for an optoacoustic transducer with high-energy conversion efficiency. The mean diameter of the collected candle soot carbon
nanoparticles is about 45 nm, and the light absorption ratio at 532 nm wavelength is up to 96.24%. The prototyped CSNPs-PDMS nano-composite laser ultrasound transducer was characterized and compared with transducers using Cr-PDMS, carbon black (CB)-PDMS, and carbon nano-fiber (CNFs)-PDMS composites, respectively. Energy conversion coefficient and −6 dB frequency bandwidth of the CSNPs-PDMS composite laser ultrasound transducer were measured to be 4.41 × 10−3 and 21 MHz, respectively. The unprecedented laser ultrasound transduction performance using CSNPs-PDMS nano-composites is promising for a broad range of ultrasound therapy applications.
Nature provides an almost limitless supply of sources that inspire scientists to develop new materials with novel applications and less of an environmental impact. Recently, much attention has been focused on preparing natural-product-derived carbon dots (NCDs), because natural products have several advantages. First, natural products are renewable and have good biocompatibility. Second, natural products contain heteroatoms, which facilitate the fabrication of heteroatomdoped NCDs without the addition of an external heteroatom source. Finally, some natural products can be used to prepare NCDs in ways that are very green and simple relative to traditional methods for the preparation of carbon dots from manmade carbon sources. NCDs have shown tremendous potential in many fields, including biosensing, bioimaging, optoelectronics,
and photocatalysis. This Review addresses recent progress in the synthesis, properties, and applications of NCDs. The challenges and future direction of research on NCD-based materials in this booming field are also discussed.
Carbon nanoparticles (CNPs) are synthesized from candle soot and subjected to fractional isolation and characterization. Highly thermally stable (onset of degradation 697°C) and crystalline CNPs (size 20–25 nm) of superior purity were isolated by multistage separation and isolation process. In isolation process, various other fractions with sizes less and more than the size 20–25 nm were isolated and characterized. Nanolubricating fluid was prepared with purest fraction isolated and SAE 30 engine oil and its wear preventive property was evaluated. About 29% reduction in wear scar diameter with smoother wear scar morphology was observed, which exhibits good wear preventive property of nanolubricating fluid.
A general approach for controlled grafting of Polyaniline (PANI) chains from the surface of nano structured carbon materials following a 'grafting from' strategy through oxidative polymerization of aniline is reported. Fluorescent spherical carbon nano dots (CND) are obtained through HNO3 oxidation followed by size separation from easily available and cheap source like candle soot. Oxidative polymerization of aniline under dilute acid conditions is conducted in presence of CND tethered with mono amine group of N,N'-bis(4'-aminophenyl)-1,4-quinonediimine (APQD, in emaraldine state) (CNDT), as initiator. Appreciably lower oxidation potential of APQD compared to aniline directs growth of the PANI chains preferentially from these moieties acting as 'seeds'. Furthermore, the conditions are optimized to complete the entire polymerization within the duration of induction period (IP) for the oxidative polymerization of aniline under similar conditions to ensure grafting of PANI chains from CND surface only. The attachment of APQD moieties with CND surface and hence formation of PANI chains are confirmed by FTIR and XPS techniques. The covalently attached carbon nano dot/polyaniline shows a remarkably higher specific capacitance of 972 F/gm with 90% retention after 2000 cycles, in comparison of 482 F/g only for non covalently attached composite. The excellent electrochemical performance is attributed to the formation of nano structured composite material.
We observed large gain in pyroelectric voltage and current (when exposed to Infra red radiation) after candle soot coating on material's surfaces. A piezoelectric buzzer was selected to quantify the effect of candle soot on pyroelectric output. For a given temperature change, peak value of open circuit voltage was enhanced from 2 V to 8 V whereas electric current was boosted from 15nA to 95nA. A load capacitor was also connected through full wave rectifier. Energy storage in 10 µF load capacitor was increased 5nJ to 70nJ.
Carbon nanoparticles (CNPs) derived from candle soot were used to prepare an efficient electrode of a microbial fuel cell (MFC). The candle soot were deposited on an ultrafine stainless steel (SS) wire disk, and the SS disk-supported CNPs were directly used as the electrodes. The physico-electro-chemical characterization tests showed the prepared electrode materials to be hierarchically porous, graphitic, and mechanically and electrochemically stable. The polarization studies using linear sweep voltammetry analysis revealed the maximum open circuit potential, power and current densities of the fabricated MFC to be 0.68 ± 0.03 V, 1650 ± 50 mW/m² and 7135 ± 110 mA/m² respectively. The method of preparation for the soot-derived CNP-based electrode material is simple, cost-effective, reproducible, and scalable, and the fabricated MFC has potential for producing high bioenergy.
Oil water separation techniques have attracted more and more attention due to the increasing accidents of oil spills in marine transportation, food, and other industry fields. Oily waste water and water-cut oil are harmful to the ecological environment and human health. However, traditional separation methods posed low efficiency and high cost. So low cost, simple process and high efficiency separation materials are urgently needed. In this work, a low cost carbon nanoparticles acted as hydrophobic materials were used to modify rough copper mesh during the candle combustion. Surface morphology was observed by scanning electron microscope (SEM), and surface wettability was tested by contact angle (CA) meter.
Experimental results showed that water CA of the mesh after modification were above 150°, and oil CA is less than 5°, which showed good super-hydrophobicity and superoleophilicity. Additionally, the modified mesh also exhibited pronounced chemical stability, thermal stability, corrosion resistance, and oil/water separation properties with high oil flux (4378 Lm⁻² h⁻¹) and oil–water separation efficiency (>90%). Moreover, the modified mesh posed high separation efficiency and oil flux after 30 reused cycles. The modification process is short time consuming and low cost without any organic reagent and complicated chemical reaction. Therefore, it is believed that the facile fabrication proposed in this work may provide a novel strategy for oil water separation membrane and make the modified mesh a promising tool for application in oil-water separation.
We report a simple, inexpensive, rapid and one-step method for the fabrication of a stable and biocompatible superhydrophobic and superhemophobic surface. The proposed surface comprises candle soot particles embedded in a mixture of PDMS+n-hexane serving as the base material. The mechanism responsible for the superhydrophobic behavior of the surface is explained and the surface is characterized based on its morphology and elemental composition, wetting properties, mechanical and chemical stability and biocompatibility. The effect of %n-hexane in PDMS, the thickness of the PDMS+n-hexane layer (in terms of spin coating speed) and sooting time on the wetting property of the surface is studied. The proposed surface exhibits nanoscale surface asperities (average roughness of 187 nm), chemical compositions of soot particles, very high water and blood repellency along with excellent mechanical and chemical stability and excellent biocompatibility against blood sample and biological cells. The water contact angle and roll-off angle is measured as 160±1°and 2° respectively and blood contact angle is found to be 154±1° which indicate that the surface is superhydrophobic and superhemophobic. The proposed superhydrophobic and superhemophobic surface offers significantly improved (>40%) cell viability as compared to glass and PDMS surfaces.
Oil/water separation is of great importance for the treatment of oily wastewater, including immiscible light/heavy oil-water mixtures, oil-in-water or water-in-oil emulsions. Smart surfaces with responsive wettability have been received extensive attention especially in controllable oil/water separation. However, the traditional smart membranes with a switchable wettability between superhydrophobicity and superhydrophilicity are limited to certain responsive materials and continuous external stimulus, such as pH, electrical field, light irradiation, etc. Herein, candle soot coated mesh (CSM) with larger pore size and candle soot coated PVDF membrane (CSP) with smaller pore size with underwater superoleophobicity and underoil superhydrophobicity were successfully fabricated, which can be used for on-demand immiscible oil/water mixtures and surfactants-stabilized oil/water emulsion separation, respectively. Without any continuous external stimulus, the wettability of our membranes could be reversibly switched between underwater superoleophobicity and underoil superhydrophobicity simply by drying and washing alternately, thus achieving the effective and switchable oil/water separation with excellent separation efficiency. We believe that such smart materials will be a promising candidate for use in the removal of oil pollutant in the future.
The effects of unsaturation (including the C-C double bond's position in the alkyl chain) and the ester moiety in the fuel molecule on the morphology of soot particles in a laminar coflow diffusion flame are studied. The effects of the ester moiety are evaluated by comparing an n-decane flame with a biodiesel surrogate flame (composed of 50%/50% molar blend of n-decane and methyl octanoate). The effects of the unsaturation and the position of C-C double bond in the alkyl chain are analysed by comparing 1-decene, 5-decene and n-decane flames. Particles were collected thermophoretically on Transmission Electron Microscopy (TEM) carbon coated copper grids. TEM images are analysed to obtain parameters related to the size of the agglomerates such as radius of gyration, and morphological parameters such as fractal dimension and prefactor of the power-law relationship. The results show that the average primary particle diameter, the size of the agglomerates and the number of primary particles composing the agglomerates increase along the flame length to around two thirds of the flame length and then decrease as a consequence of oxidation becoming dominant over soot nucleation and growth. The fractal dimension of the agglomerates does not change significantly along the different pathlines of the flames. However, effects of the fuel chemical structure are clear. The lowest fractal dimensions are observed for the oxygenated fuel and the highest ones for the unsaturated fuels, with higher fractal dimension when the double bond is located at the edge of the molecule. The same trends are observed for agglomerate sizes: smallest agglomerates are observed for the oxygenated fuel and largest ones for the unsaturated fuels. This suggests that low soot-emitting fuels reduce their size as a consequence of oxidation while keeping their agglomeration skeletal structure.
In this work, a scalable and cost-effective approach was developed for the synthesis of magnetic carbon nano-onions (MCNOs) by using iron (III) acetylacetonate modified candle as the raw materials. The candle soot was collected from the burning candle and then subjected to calcination at 800 °C under N2 atmosphere. The obtained MCNOs were further applied as adsorbent for the removal of bisphenol A (BPA) from aqueous solutions. Adsorption of BPA onto the MCNOs was investigated with the influence of initial concentration of BPA, solution pH, and adsorption time. The results demonstrated the adsorption of BPA onto the MCNOs was almost not affected by pH in the range from 5–9. The adsorption isothermal and kinetic's data were better fitted by Langmuir isotherm and pseudo-second-order kinetic model, respectively. Moreover, the MCNOs are easily recycled by using and external magnet and regenerated by simply methanol washing. The results present here not only provide a novel synthetic approach toward low-cost nanocarbons but also revealed the great application potential of the MCNOs for the removal of endocrine disrupting compounds from aqueous solution.
Transparent coatings with self-cleaning properties are required for protection of outdoor optical devices. Highly transparent, fluorine-free superhydrophobic coatings of silica nanotubes (SNT) on glass substrates are fabricated by using poly(dimethylsiloxane) (PDMS) as the silica source and multi-walled carbon nanotubes (MWCNTs) as the sacrificial template, following by hydrophobization through chemical vapor deposition (CVD) of cured PDMS. The influence of surface topography from SNT on the transparency and superhydrophobicity of the coatings is investigated. High transparency and excellent superhydrophobicity of the surface can be achieved by changing the concentration of PDMS (CPDMS) for SNT coatings as well as the amount of the cured PDMS (APDMS) for hydrophobization. The optimum coating has an average transmittance higher than 83% in the visible-light range (400−780 nm), a water contact angle (CA) of 165° and a slide angle (SA) lower than 3°. When applied as protective cover, the glass substrate with superhydrophobic coating has little effect on the power generation efficiency of solar cells and has outstanding self-cleaning properties.
Any solid surface can spontaneously exhibit variational wettability toward liquids with varied surface tension (γ). However, this correspondence has seldom been proposed or used on an artificial superhydrophobic surface, which should be more remarkable and peculiar. Herein, we fabricated robust, transparent superhydrophobic surfaces, utilizing acid-catalyzed/base-catalyzed silica (AC-silica and BC-silica) particles combined with candle soot template for structural construction and CVD process for chemical modifi-cation. Three types of porous silica structures were devised, which present the distinctive surface-tension responsiveness in wettability. Interestingly, all types of surfaces (i.e. AC-silica, AC/BC-silica and BC-silica) show high repellence to the high-surface-tension liquid (γ > 35 mN/m) and small differences are observed. With the decreasing γ of the ethanol-water mixtures (γ < 35 mN/m), the static contact angles (SCAs) on all surfaces have an evident decline but the features of decrease are fairly different. As γ decreases, the SCA on the AC -silica surface descends gradually, but the extent of decline becomes larger when γ < 27.42 mN/m. However, the SCA on BC-silica surface decreases gradually except γ ~ 30.81 mN/m and the SCA undergoes a sharp decline at γ ~ 30.81 mN/m. The SCA on AC/BC-silica surface has a similar variation as the SCA on BC-silica surface, but lower rate of BC-silica particles, e.g., 1/16, 1/8, 1/1 (AC/BC), further diminishes the critical γ values (where a sharp SCA drop occurs) to 30.16, 29.56, 28.04 mN/m, respec-tively. The diversity is believed to be ascribed to the structure-induced selectivity of pore infiltration for liquid. The tunable responsiveness can be generalized to various classes of organic aqueous solutions including methanol, acetic acid, acetone and N, N-dimethylformamide. Benefiting from this, we can estimate organics concentration of an organic aqueous solution as well as its liquid surface tension by detecting its wettability on the all diverse superhydrophobic surfaces.
Soot volume fractions and soot temperatures have been measured for the first time on candle flames. Measurements on laminar steady flames were carried out using candles with wick diameters of 2, 3 and 4 mm. Wick length was varied between 4 and 10 mm. The shape of the candle flame was obtained from CH∗ spontaneous emissions. Measured flame heights show an increase with wick dimensions, approaching an asymptotic value for increasing wick lengths. Soot volume fractions were obtained from laser extinction measurements with the modulated absorption/emission (MAE) technique. A deconvolution technique and a regularization procedure were applied to the data. Radial profiles of soot volume fractions increase when varying the wick dimensions; this effect is produced by the greater amount of fuel released by the wick. Radially integrated soot volume fractions were also calculated, presenting a similar behavior to the soot volume fraction radial profiles. The peak integrated soot volume fraction was found at approximately half the flame height, independent of the wick dimensions and burning rates. Soot temperature was obtained from emission measurements at two different wavelengths considering the attenuation of the soot particles in the optical path length. A deconvolution and regularization procedure was carried out in order to obtain temperature profiles for different heights in the flame. The observed increase in soot production and soot temperature profiles was directly related to the higher burning rate experienced by the candle. The results show that peak integrated soot volume fractions are proportional to both the mass loss rates and the flame heights.
Carbon soot is one of the oldest materials known for its hydrophobic properties, robustness and availability, making them ideal material for use in various applications. The drawbacks however are the loose structural binding between constructing carbon nanoparticles and the amorphous nature of soot itself. In this paper, we present a facile chemical vapour deposition (CVD) method which maintains the soot template structural integrity and enables its modification into highly photoactive, self-cleaning titania fractal network. The results show that the small air pockets available on the surface combined with the salinization process produces TiO2 fractal network with superamphiphobic properties. Given the high surface area of the fractal network structure and titania’s well-known photocatalytic activity, the designed surfaces were assessed for their photocatalytic efficiency. The results showed that the soot template derived TiO2 films can offer enormous potential in many different applications where self-cleaning and/or high surface area and photoactive properties are required.
The counter electrode (CE), despite being as relevant as the photoanode in a quantum dot solar cell (QDSC), has hard-ly received the scientific attention it deserves. In this study, nine CEs: single walled carbon nanotubes (SWCNTs), tungsten oxide (WO3), poly(3,4-ethylenedioxythiophene) (PEDOT), copper sulfide (Cu2S), candle soot, functionalized multiwalled carbon nanotubes ( F- MWCNTs), reduced tungsten oxide (WO3-x), carbon fabric (C-Fabric), and C-Fabric/WO3-x were prepared by using low cost components and facile procedures. QDSCs were fabricated with a TiO2/CdS film which served as a common photoanode for all CEs. The power conversion efficiencies (PCEs) were: 2.02, 2.1, 2.79, 2.88, 2.95, 3.78, 3.66, 3.96, and 4.6 % respectively, and the incident photon to current conversion efficiency re-sponse was also found to complement the PCE response. Among all CEs employed here, the C-Fabric/WO3-x outper-forms all the other CEs, for the synergy between C-Fabric and WO3-x comes to the fore during cell operation. The (i) low sheet resistance of C-Fabric, and its? high surface area due to the mesh like morphology, enables high WO3-x load-ing during electrodeposition, and (ii) the good electrocatalytic activity of WO3-x, the very low overpotential and its high electrical conductivity that facilitate electron transfer to the electrolyte, are responsible for the superior PCE. WO3 based electrodes have not been used till date in QDSCs; the ease of fabrication of WO3 films, and their good chem-ical stability and scalability also favor their application to QDSCs. Futuristic possibilities for other novel composite CEs are also discussed. We anticipate this study to be useful for a well-rounded development of high performance QDSCs.
Recently, fabrication of hydrophobic materials with application in oil spill cleanup becomes a new research focus. Herein, we report the preparation of superhydrophobic and superoleophilic steel mesh covered with nanostructured organic film for oil and organic solvents collection from water surface. The superhydrophobic mesh was fabricated by a simple deposition of carbon soot (CS) nanospheres on the steel mesh using candle combustion flam, followed by vapour phase deposition of polypyrrole (ppy). Finally the surface was modified with stearic acid (SA). The topological structure and surface wettability of the prepared mesh were characterized by SEM, FT-IR, Raman spectra and contact angle measurements. The prepared hydrophobic mesh was shaped as a miniature boat which can float on water surface and absorbs various oils from water surface very fast. Additionally, the miniature boat could be reused for many times in the oil-water separating process without decreases of its separation ability. The results illustrate that the prepared hydrophobic mesh is, low cost and can be used for facile and rapid collection of oil and other organic solvent from water surface.
Carbon nanoparticles (C-dots) were prepared by refluxing the combustion soots of candles and corn stalk in nitric acid. The synthesized C-dots were characterized. The results showed a sharp increase in oxygen content and a sharp decrease in carbon content after oxidation. The C-dots had -OH and -CO2H groups introduced which made them hydrophilic. However, their difference was also obvious. The C-dots from candle soot had a 10-45 nm broad particle size distribution, and those from corn stalk soot had a 6-18 nm relatively small and narrow size distribution. The C-dots were mainly of sp 2 and sp 3 carbon structure different from the C-dots of diamond-like structure from candle soot. Interestingly, two kinds of C-dots all exhibited unique photoluminescent properties. The obtained C-dots have potential applications in a broad range of areas.
Super nonfouling surfaces resist protein adhesion and have a broad field of possible applications in implant technology, drug delivery, blood compatible materials, biosensors, and marine coatings. A promising route toward nonfouling surfaces involves liquid repelling architectures. The authors here show that soot-templated super-amphiphobic (SAP) surfaces prepared from fluorinated candle soot structures are super nonfouling. When exposed to bovine serum albumin or blood serum, x-ray photoelectron spectroscopy and time of flight secondary ion mass spectrometry analysis showed that less than 2 ng/cm2 of protein was adsorbed onto the SAP surfaces. Since a broad variety of substrate shapes can be coated by soot-templated SAP surfaces, those are a promising route toward biocompatible materials design.
Candle soot deposited from the candle flame was used as a catalyst support for an anode catalyst in a proton exchange membrane fuel cell. The results showed that Pt/soot hybrids prepared by magnetron sputtering of 5 nm platinum films on candle soot exhibit very high mass activity in the fuel cell, which is more than one order of magnitude higher than that for commercial catalyst. The elementary preparation, high surface-to-volume ratio, good conductivity and hydrophobicity make candle soot a promising type of the support for PEMFCs catalyst.
Based on the remarkable difference between the interactions of carbon nanoparticles (CNPs) oxide with single-stranded DNA (ssDNA) and double-stranded DNA (dsDNA), and the fact that fluorescence of DNA-stabilized silver nanoclusters (AgNCs) can be quenched by CNPs oxide, DNA-functionalized AgNCs were applied as label−free fluorescence probes and a novel fluorescence resonance energy transfer (FRET) sensor was successfully constructed for the detection of human immunodeficiency virus (HIV) DNA sequences. CNPs oxide were prepared with the oxidation of candle soot, hence it is simple, time-saving and low-cost. The strategy of dual AgNCs probes was applied to improve the detection sensitivity by using dual- probe capturing the same target DNA in a sandwich mode and as the fluorescence donor, and using CNPs oxide as the acceptor. In the presence of target DNA, a dsDNA hybrid forms, leading to the desorption of the ssDNA-AgNCs probes from CNPs oxide, and the recovering of fluorescence of the AgNCs in a HIV-DNA concentration-dependent manner. The results show that HIV-DNA can be detected in the range of 1 nM − 50 nM with a detection limit of 0.40 nM in aqueous buffer. The method is simple, rapid and sensitive with no need of labeled fluorescent probes, and moreover, the design of fluorescent dual-probe makes full use of the excellent fluorescence property of AgNCs and further improves the detection sensitivity.
Sootoid is a symphonic art created by collaboration between human, computer and flame of candle. While the major generative art pictures are drawn in a computer display, Sootoid creates a generative art drawing on a linen canvas by candle soot. Movement of candle is controlled by pre-programmed algorithm, making airflow and flickering of candle flame each time it moves to create unique soot line and color.
Based on a series of biochemical experiments for analysis and characterization, it is found that the uncharged C-dots have no effect on bacterial growth while the negatively charged and positively charged C-dots can induce bacteria apoptosis. For the positively charged C-dots, they can induce both bacteria apoptosis and bacteria death. These observations will provide new insights into bioapplications of carbon dots.
As a novel composite material for laser ultrasound transducer, candle soot nanoparticles polydimethylsiloxane (CSPs-PDMS) has been demonstrated to generate high frequency, broadband, and high-amplitude ultrasound waves. In this study, we investigated the mechanism of the high-optoacoustic conversion efficiency exhibited by the composite. A thermal-acoustic coupling model was proposed for analyzing the performance of the composite. The theoretical result matches well with the experimental observation. The acoustic beam profile was compared with Field II simulation results. The 4.41 × 10-3 energy conversion coefficient and 21 MHz - 6 dB frequency bandwidth of the composite suggest that CSPs-PDMS composites is promising for a broad range of ultrasound therapy and non-destructive testing applications.
Anthropogenic generated black carbon (BC) particulate matter as waste " pollutant soot " , contributed signifi cantly toward the degradation of air quality, global warming , and several health issues. Researchers used this pollutant BC as " free carbon precursor " for the synthesis of diff erent shaped nano-carbons with potential appli-cative prospects. Presently being use d as the fl uorescent probe for multicolored bio-imaging, sensing biomolecules and also used for water purifi cation purposes.
TiO2 thin films with developed structure were deposited by means of a hollow cathode plasma jet (HCPJ) in a DC regime with a supporting anode. The influence of the plasma temperature on the surface morphology and crystalline structure of the thin films under different deposition conditions was studied. Diagnostics of the thin films structure was carried out using XRD, SEM, EDX and TEM methods. One batch of samples was annealed at a temperature of 400 °C in atmospheric conditions as a comparison with the crystalline structure and morphology of unannealed samples. The presence of two crystalline polymorphs of rutile and anatase in the films was discussed. The vacuum system was improved for an extended deposition of non-conductive materials without terminating the discharge and cleaning of the deposition chamber. The aim of this investigation was to prepare the vacuum system for the fabrication of photo electrodes which are the main functional part in dye-sensitized solar cells. The test DSSCs (dye-sensitized solar cells) were prepared from low-cost materials (raspberry/hibiscus natural dye-sensitizers and candle soot counter electrode) in order to check the quality of the films, with a highest conversion efficiency η = 0.66% and a fill factor FF = 62%.
The electrochemical supercapacitor behaviour of bare, washed and nitric acid functionalized candle flame carbon soots were reported. Crystallinity and the morphology of the candle soots were recorded using X-ray diffraction analysis, scanning and transmission electron microscopy, respectively. The nitric acid functionalized candle soot showed an improved Brunauer–Emmett–Teller surface area of 137.93 from 87.495 m2 g−1 of washed candle soot. The presence of various functional groups in candle soots and the development of oxygen functionalities in the functionalized candle soot were examined through Fourier transform infrared spectroscopy and energy-dispersive X-ray analysis. Raman spectra showed the characteristic peaks corresponding to the D (diamond) and G (graphite) phase of carbon present in the candle soots. The electrochemical characterization was performed by cyclic voltammetry, galvanostatic charge/discharge test and impedance spectroscopy in 1 M H2SO4 electrolyte. The functionalized candle soot electrode showed an enhanced specific capacitance value of 187 F g−1 at 0.15 A g−1 discharge current density, which is much higher than that of bare and washed candle soot electrodes.
An experimental investigation of laminar smoke points of candle flames is presented. Adjustable wicks with diameters of 2-7.6 mm were used to measure smoke points in quiescent air for 13 different waxes. The measured smoke points varied from 36-89 mm and increased with wick diameter. Smoke points normalized to a wick diameter of 4 mm increased from consumer-grade waxes (candelilla, carnauba, beeswax, paraffin) to alkanes (hexatriacontane, tetracosane) to alcohols (octadecanol, docosanol, hexadecanol) to acids (stearic, palmitic, lauric, myristic). Within each wax family, a decrease in carbon number yielded an increased smoke point. Soot emission was not possible for any fuel when wick diameter was below 1.8 mm or when wick length was below 6 mm. The results suggest new ways of producing cleaner burning candles.
The coating characteristics of Pb-Co mixed metal oxide soot oxidation catalysts over a SiC foam filter were studied. The coating was done via incipient wetness impregnation of a slurry with Pb/Co weight ratio = 2. The coating was accomplished by 3 consecutive impregnation-drying-calcination cycles. After each cycle surface structure and composition were monitored by scanning electron microscope (SEM). SEM analysis revealed that the surface composition of Pb was high on the high porosity region and surface composition of Co was high on the low porosity region inside the filter. These overlayers were tested for their soot oxidation ability by depositing paraffin soot from a candle flame, thermally oxidizing, and collecting SEM pictures before and after oxidation. SEM pictures after soot deposition/oxidation cycles revealed that high amounts of Pb were necessary for efficient removal of soot. However, Pb composition of the surface decreased due to the evaporative loss of Pb.
Preparation, characterization and ion sensing property of water-dispersible fluorescent carbon nanoparticles (CNPs) is reported. These CNPs are prepared from inexpensive source (candle soot) with a water-based preparation without using organic solvent. Excitation-independent fluorescence behavior is a notable feature of these CNPs, which is found in limited reports in the literature. These CNPs exhibit selective dual metal ion (Hg2+ and Fe3+) recognition in aqueous media out of a large number of metal ions investigated. They also exhibit green fluorescence under UV light (365 nm) exposure, which disappears upon addition of Fe3+ and Hg2+. The fluorescence quenching due to the aggregation of CNPs in presence of Hg2+ and Fe3+ is supported by TEM and AFM studies. Detail studies on stability of CNPs, selectivity, interference, reversible binding of metal ion and optimum experimental conditions for sensing of metal ions were carried out. The detection limits for Hg2+ and Fe3+ (80 and 40 nM) and the range of concentration through which quantitative measurement can be done (160 to 2000 nM) are also determined. These CNPs have been used for quantitative estimation of Hg2+ and Fe3+ in aqueous media.
Data in the literature have been organized to give a detailed description of the chemical sequences leading to soot formation in a premixed laminar flame. Neutral free radical, polyacetylene, and polycyclic aromatic hydrocarbon mechanisms are not consistent with this description. However, when chemiions are assumed to be the precursor on which the free radicals, polyacetylenes, and polycyclic aromatic hydrocarbons repeatedly add in fast ion-molecule reactions, a mechanism can be developed which is consistent with experiment. This mechanism should be tested further by careful observations of both ion and neutral species (including free radical) profiles in flames and by developing a computer model of the process to compare with experiment.
In this article, we report a facile and inexpensive approach to synthesize fractal-like interconnected network of carbon nanoparticles from candle soot and its direct application as anode material for high-rate lithium ion batteries used for electric vehicles. At low charge/discharge rate (0.5C), an initial discharge capacity was found to be 1997 mAh/g with moderate 30% coulombic efficiency that increased to 91% after 10 cycles. More importantly, at very high charge/discharge rate (10C), reversible capacity was stabilized at 170 mAh/g even after 1000 cycles. This remarkable electrochemical performance may be ascribed to unique morphology of these hard carbon nanoparticles that reduces the diffusion length and also allows fast adsorption/desorption of Li ions on their surface.