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Performance evaluation of Ferric oxide (Fe3O4) and Graphene nanoplatelet (GNP) nanoparticles in solar steam generation
Abstract
In the present work, the performance of water-based Fe3O4 (magnetite) nanofluid and graphene nanoplatelet (GNP) nanofluid in solar steam generation has been evaluated. For this purpose, a solar simulator, a beaker containing nanofluid, an electronic balance and temperature sensors were employed. In the first place, magnetite nanofluid with different mass fractions (0.01, 0.02 and 0.04 %) and GNP nanofluid with mass fractions of 0.001, 0.002 and 0.004% were separately exposed to solar illumination at intensity of 3.5 sun kW/m2. Then the most efficient concentration of magnetite nanofluid was mixed with different concentrations of GNP nanofluid and the photothermal conversion and solar evaporation behavior of the mixed nanofluid was studied. The results showed that adding the nanoparticles mentioned above to pure water, Highly increases the light absorption so that the solar vapor generation efficiency of magnetite nanofluid with concentration of 0.04 % mass weight and GNP nanofluid with the mass fraction of 0.004 % were 1.97 and 2.69 times as high as that of pure water. And the mixed nanofluid containing 0.01% mass weight of magnetite and 0.004% mass weight of GNP has a solar evaporation efficiency of 32.4% which is while the evaporation efficiency of pure water is 14.13%.
... Substantial efforts have been invested in exploring green technologies for clean water production. Solardriven water evaporation, which harnesses sunlight as a sustainable energy source, presents a viable strategy for addressing the issue of water scarcity while minimizing adverse environmental effects [8][9][10]. Nonetheless, the practical implementation of solar steam generation is hindered by the limited photothermal conversion efficiency, which is primarily attributed to the inadequate solar absorption of water and the heat losses associated with traditional bulk water heating methods [11,12]. ...
Developing a sustainable environment requires addressing primitive water scarcity and water contamination. Antibiotics such as oxytetracycline (OTC) may accumulate in the environment and in the human body, increasing the risks to the ecosystem. The treatment of polluted water and the production of potable water can be achieved in a variety of ways, including photodegradation, solar distillation, and filtration. Freshwater supplies can be increased by implementing energy-efficient technologies for the production of clean water. Solar water evaporation combined with photocatalytic degradation and sterilization offers a promising avenue for integration into the clean water and energy production fields. The present study reports the synthesis of a 3D solar steam generator comprised of BiVO4 and carbon nanotubes (CNT) nanocomposite decorated over a cigarette filter as the light-to-heat conversion layer for solar steam generation. The BiVO4@CNT-based 3D solar evaporator over the hydrophilic cellulosic fibers of the cigarette filter endowed excellent evaporation rates (2.36 kg m−2 h−1) under 1 kW m−2 solar irradiation, owing to its superior hydrophilicity and broadband solar absorption (96%) equipped with localized heating at microscale thermal confinement optimized by the minimum thermal conductivity of the overall system. Furthermore, the BiVO4@CNT composite exhibited a heightened photo activity up to 83% of the photodegradation of oxytetracycline (OTC) antibiotic due to the inhibition of charge recombination from the industrial effluents. This approach transforms the water-energy nexus into a synergistic bond that offers opportunities to meet expected demand, rather than being competitive.
... Ferrites nanoparticles (NPs) endow a wide range of solar absorption (200-2500 nm), chemical stability, and excellent adsorption capability towards various contaminants [24]. In this respect, negatively charged Fe 3 O 4 NPs manifest their enhanced photothermal conversion, magnetic adsorption, and regeneration potential are highly needed as compared to adsorbent materials for the purification of wastewater for industrial applications up to standard drinking water levels [25,26]. As a positively charged polymer, polypyrrole (PPy) also enhances the absorption capacity of metal oxides and their potential for regeneration. ...
Hybrid solar-driven interfacial evaporation (HSDIE) systems are promising solar technologies for simultaneous freshwater and power generation. However, lower efficiencies due to inevitable heat losses, salt accumulation, and volatile organic impurities are detrimental to the sustainability of solar evaporators that limit their practical applications. Herein, we report a highly charged solar evaporator for in-situ freshwater and power generation developed by a UV-induced deposition of Fe3O4@PPy nanospheres anchored on a self-floating cellulose evaporator. The endowment of synergic resistance of ammonium (NH4+) ions is significantly increased by optimizing the positive charge density of R-NH+ groups by the Donnan exclusion without sacrificing the evaporation rates (1.98 kg m-2 h-1) using Shahu Lake water / NH4Cl.H2O (25 wt%) slurry. The state-of-the-art investigations validate the long-term stability without any salt accumulation under natural conditions (mass change, 14.66 kg m-2 / 8 hrs). More importantly, in-situ thermoelectric power generation achieved power density (Pout ∼ 45.4 Wm-2, Iout∼ 101 mA) along with solar to electric conversion efficiency (γ = 2.27%) under 2kW m-2 solar irradiations. This work will further insight into further advancement in the multifunctional integration of solar evaporation technology concerning the water-energy nexus.
... Finally, the tests on the quality of condensed water showed that nanoparticles have no harmful effect on the quality of water. .Therefore (Taylor et al., 2011;Ghafurian et al. 2019;Hjerrild and Taylor, 2017 penetrates through the nanofluid. Moreover, the rate change of the absorbed energy with respect to depth is a function of the incident light intensity in addition to the extinction coefficient and depth which is shown in figure (2.s). ...
In the present study, the performance of water based-nanofluids containing four different types of carbon nanostructures for solar vapor generation has experimentally been investigated. The considered nanofluids are multi-walled carbon nanotube, single-walled carbon nanotube, graphene nanoplate and graphene oxide. Nanofluids with three nanoparticle mass concentrations of 0.001%, 0.002%, and 0.004% were prepared and their evaporation characteristics were investigated for solar radiation intensities in the range of 1.5 and 3.5 Suns. The results indicated that the multi-walled carbon nanotube nanofluid with a mass concentration of 0.004% provides the highest evaporation rate with the maximum total efficiency of 94% at 3.5 Suns. The total efficiencies for nanofluids containing the single-walled carbon nanotube, graphene nanoplate and graphene oxide at similar conditions and that of pure water, respectively, are about 91%, 90%, 81% and, 54%. Furthermore, it is observed that for the mass concentration of 0.004%, the evaporation rate with respect to water increases to about 72%, 63%, 58% and 36%, respectively, for the multi-walled carbon nanotube, the single-walled carbon nanotube, graphene nanoplate and graphene oxide nanofluids. As far as the sensible heat is concerned, graphene oxide shows the most considerable sensible heating efficiency at the mass concentration of 0.004% with the maximum fluid bulk temperature rise of 20.5 ͦ C, which is 40% higher than that of water. Finally, it was found that increasing the radiation intensity from 1.5 to 3.5 Suns improves the evaporation rate; however, the sensible heat efficiency is more influenced such that the evaporation efficiency declines. The quality of the produced water from a seawater sample is also examined and it was shown that it is well below the limitations of the drinking water standards.
In present paper, an experimental study using pinewood in solar steam generation is carried out. The unique properties of wood such as high porosity, hydrophilicity, lightness and low thermal conductivity have led to consider for localizing light on water surface and generating steam in this paper. At the first step, steam generated by water and the pinewood which can float on the water surface was compared. The results showed that the wood as a surface membrane can improve the evaporated mass, so that its evaporation rate increased to 26.3% of water. To enhance the light absorption via wood and evaporation rate, wood’s surface was carbonized with a metal plate in temperature 400°C. In addition, the optimum thickness and the effect of the duration of the carbonization process were tested. According to the results, the optimum thickness of carbonized wood and carbonized time were 10 mm and 150 s respectively. However, the using carbonated wood enhanced the evaporation rate about 1.86 times larger than water and allocated evaporation efficiency of 64.2 % to itself.
A نمونی سطح میاحت زیر نویس h آنتالپی fg فاز تغییر I نور تابش شدت چگالی í µí±̇ تبخیر نرخ عالئم یونانی η بازده 1-مضدمی مهم از یکی ،انرژی تامین روبی آن با همواره یر بشی کی یت اسی یائلی میی ترین .یت اسی بوده رو یال سی در ،اخیر های ذخایر کاهش با سوخت هم و فییلی های زییت مشکالت وسود دلیل بی چنین م از حاصل حیطی سوخت نوع این عنوان بی خورشیدی انرژی ،ها سایگیین انرژی منبع یک ، .اسییت گرفتی قرار بییییاری توسی مورد و دردسییترس ،پاک انرژی یک عنوان بی خورشیییدی انرژی تجدیدپذیر ، م ت ی ی س ر د ه د ا ف ت س ا ر د ی ی ال ا ب ل ی ی ن ا ت پ فتوولتائیک های ] 1 [ شیرین آب تامین ، ] 2 [ الب فا صفیی ت ، ] 3 [ ستریل ا ، نمودن پیشکی تجهییات ] 4 [ و خورشیدی گرمایش ] 5 [ دارد .
In the present paper, the steam generation performances of nanofluids containing titanium dioxide have experimentally been examined. For this purpose, a solar simulator with a xenon lamp as the radiation source, and a pyranometer as a light intensity measuring device are used. Then, the water based-nanofluids in five nanoparticle mass fractions of 0.001, 0.002, 0.004, 0.04, and 0.08 percent exposed to the light intensity of 3.5Suns (3.5 kW/m2) were investigated to compare their evaporation performances via water (H2O). Finally, the effects of the light intensity on the solar steam generation were examined. The results showed that the titanium dioxide nanostructures are more efficient to directly absorb the solar energy than the water; such that the maximum total evaporation efficiency of 77.4% and 54% were obtained at 3.5 kW.m-2 for nanofluid and water, respectively. Furthermore, it was found that light absorption increases as the nanofluid mass fraction increases. Also, increasing the light intensity from 1.5 to 3.5 kW.m-2 enhances the evaporation rate and the thermal efficiency, while it reduces the evaporation efficiency.
It is clear that access to economically renewable energy sources is essential for the development of a globally sustainable society. Developing sustainable energy technologies, especially solar energy, becomes extremely important in securing future energy. As an important source of renewable energy, solar power holds a great potential to be converted into other energy forms such as thermal, electric and chemical energy. In recent years, nanoscale particles were usually applied in the utilization of solar power because of its excellent properties such as large specific surface area. Most solar-assisted systems were established without considering the utilization of all the functions. Moreover, the nanoparticles used in these systems should be reused otherwise secondary pollution could happens. These issues severely limit the large-scale application of the solar technology. In this study, we developed a solar-assisted recyclable purification-evaporation system basing on magnetic Fe3O4 nanoparticles decorating with TiO2 nanoparticles (Fe3O4@TiO2), which could be separated from water by controlling the magnetic field strength. The TiO2 nanoparticles in Fe3O4@TiO2 enhance the ability to absorb solar energy, thus making it stronger than that of Fe3O4 nanoparticles. The recovery rate and efficiency could be controlled by adjusting the magnetic field strength and the magnetism property of Fe3O4@TiO2 nanoparticles. In a word, this system study provides an approach to not only significantly reduce the material consumption in the design of solar evaporators, but also to realize broad solar energy applications for water purification and vapor generation.
Solar steam generation, as a high efficient photo-thermal conversion pattern, has widespread applications, including in wastewater treatment, seawater desalination, and clean water production. However, the lower steam generation efficiency impedes its development. In present study, graphene with better thermal conductivity and light absorption was prepared successfully. Its stability in nanofluid was verified, implying the suitable for photo-thermal conversion. And it was found that the steam amount, evaporation rate and efficiency all increased with the increase of graphene concentrations in the solar steam generation experiment.
Technologies for solar steam generation with high performance can help solving critical societal issues such as water desalination or sterilization, especially in developing countries. Very recently, we have witnessed a rapidly growing interest in the scientific community proposing sunlight absorbers for direct conversion of liquid water into steam. While those solutions can possibly be of interest from the perspective of the involved novel materials, in this study we intend to demonstrate that efficient steam generation by solar source is mainly due to a combination of efficient solar absorption, capillary water feeding and narrow gap evaporation process, which can also be achieved through common materials. To this end, we report both numerical and experimental evidence that advanced nano-structured materials are not strictly necessary for performing sunlight driven water-to-vapor conversion at high efficiency (i.e. ≥85%) and relatively low optical concentration (≈10 suns). Coherently with the principles of frugal innovation, those results unveil that solar steam generation for desalination or sterilization purposes may be efficiently obtained by a clever selection and assembly of widespread and inexpensive materials.
In recent years, although many review articles have been presented about bioapplications of magnetic nanoparticles by some research groups with different expertise such as chemistry, biology, medicine, pharmacology, and materials science and engineering, the majority of these reviews are insufficiently comprehensive in all related topics like magnetic aspects of process. In the current review, it is attempted to carry out the inclusive surveys on importance of magnetic nanoparticles and especially magnetite ones and their required conditions for appropriate performance in bioapplications. The main attentions of this paper are focused on magnetic features which are less considered. Accordingly, the review contains essential magnetic properties and their measurement methods, synthesis techniques, surface modification processes, and applications of magnetic nanoparticles.
Molten salts are used as heat transfer fluids and for short-term heat energy storage in solar power plants. Experiments show that the specific heat capacity of the base salt may be significantly enhanced by adding small amounts of certain nanoparticles. This effect, which is technically interesting and economically important, is not yet understood. This paper presents a critical discussion of the existing attendant experimental literature and the phenomenological models put forward thus far. A common assumption, the existence of nanolayers surrounding the nanoparticles, which are thought to be the source of, in some cases, the large increase of a nanofluid’s specific heat capacity is criticized and a different model is proposed. The model assumes that the influence of the nanoparticles in the surrounding liquid is of long range. The attendant long-range interfacial layers may interact with each other upon increase of nanoparticle concentration. This can explain the specific heat maximum observed by different groups, for which no other theoretical explanation appears to exist.
Traditional solar–thermal receivers suffer from high surface temperatures, which increase heat losses to the surroundings. To improve performance, volumetric receivers based on nanoparticles suspended in liquid (nanofluids) have been studied as an approach to reduce surface losses by localizing high temperatures to the interior of the receiver. Here, we report measured vapor generation efficiencies of 69% at solar concentrations of 10 sun using graphitized carbon black, carbon black, and graphene suspended in water, representing a significant improvement in both transient and steady-state performance over previously reported results. To elucidate the vapor generation mechanism and validate our experimental results, we develop numerical and analytical heat transfer models that suggest that nanofluid heating and vapor generation occur due to classical global heating of the suspension fluid. This work demonstrates high nanofluid-assisted vapor generation efficiencies with potential applications in power generation, distillation, and sterilization.
During the operation of solar power towers there are occasions, commonly in the summer season, where some of the heliostats have to stop focusing at the central receiver, located at the top of the tower, because the maximum temperature that the receiver can withstand has been reached. The highest demands of cooling for air conditioning take place at these same occasions. In the present paper, we have analyzed the possibility of focusing the exceeding heliostats to the receiver increasing the mass flow rate of the heat transfer fluid over the nominal value and using the extra heat as a source of an absorption chiller. The chilled water would be used to cool buildings and offices, using a district cooling network. Using the extra heat of the solar power tower plant would greatly reduce the electricity usage.
In this work we have analyzed the case of a circular field of heliostats focusing at a circular receiver, such as the case of Gemasolar plant. We have quantified the thermal power that can be obtained from the unused heliostats, the cooling capacity of the absorption system as well as the heat losses through the insulated pipes that distribute the chilled water to the buildings of the network.
The lack of readily available sterilization processes for medicine and dentistry practices in the developing world is a major risk factor for the propagation of disease. Modern medical facilities in the developed world often use autoclave systems to sterilize medical instruments and equipment and process waste that could contain harmful contagions. Here, we show the use of broadband light-absorbing nanoparticles as solar photothermal heaters, which generate high-temperature steam for a standalone, efficient solar autoclave useful for sanitation of instruments or materials in resource-limited, remote locations. Sterilization was verified using a standard Geobacillus stearothermophilus-based biological indicator.
There is renewed interest in magnetic hyperthermia as a treatment modality for cancer, especially when it is combined with other more traditional therapeutic approaches, such as the co-delivery of anticancer drugs or photodynamic therapy.
The influence of bimagnetic nanoparticles (MNPs) combined with short external alternating magnetic field (AMF) exposure on the growth of subcutaneous mouse melanomas (B16-F10) was evaluated. Bimagnetic Fe/Fe3O4 core/shell nanoparticles were designed for cancer targeting after intratumoral or intravenous administration. Their inorganic center was protected against rapid biocorrosion by organic dopamine-oligoethylene glycol ligands. TCPP (4-tetracarboxyphenyl porphyrin) units were attached to the dopamine-oligoethylene glycol ligands.
The magnetic hyperthermia results obtained after intratumoral injection indicated that micromolar concentrations of iron given within the modified core-shell Fe/Fe3O4 nanoparticles caused a significant anti-tumor effect on murine B16-F10 melanoma with three short 10-minute AMF exposures. We also observed a decrease in tumor size after intravenous administration of the MNPs followed by three consecutive days of AMF exposure 24 hrs after the MNPs injection.
These results indicate that intratumoral administration of surface modified MNPs can attenuate mouse melanoma after AMF exposure. Moreover, we have found that after intravenous administration of micromolar concentrations, these MNPs are capable of causing an anti-tumor effect in a mouse melanoma model after only a short AMF exposure time. This is a clear improvement to state of the art.
Multidrug resistance (MDR) is a major obstacle to cancer chemotherapy. We evaluated the effect of daunorubicin (DNR)-loaded magnetic nanoparticles of Fe3O4 (MNPs-Fe3O4) on K562-n/VCR cells in vivo. K562-n and its MDR counterpart K562-n/VCR cell were inoculated into nude mice subcutaneously. The mice were randomly divided into four groups: group A received normal saline, group B received DNR, group C received MNPs-Fe3O4, and group D received DNR-loaded MNPs-Fe3O4. For K562-n/VCR tumor, the weight was markedly lower in group D than that in groups A, B, and C. The transcriptions of Mdr-1 and Bcl-2 gene were significantly lower in group D than those in groups A, B, and C. The expression of Bcl-2 was lower in group D than those in groups A, B, and C, but there was no difference in the expression of P-glycoprotein. The transcriptions and expressions of Bax and caspase-3 in group D were increased significantly when compared with groups A, B, and C. In conclusion, DNR-loaded MNPs-Fe3O4 can overcome MDR in vivo.
In the present study, the performance of water based-nanofluids containing four different types of carbon nanostructures for solar vapor generation has experimentally been investigated. The considered nanofluids are multi-walled carbon nanotube, single-walled carbon nanotube, graphene nanoplate and graphene oxide. Nanofluids with three nanoparticle mass concentrations of 0.001%, 0.002%, and 0.004% were prepared and their evaporation characteristics were investigated for solar radiation intensities in the range of 1.5 and 3.5 Suns. The results indicated that the multi-walled carbon nanotube nanofluid with a mass concentration of 0.004% provides the highest evaporation rate with the maximum total efficiency of 94% at 3.5 Suns. The total efficiencies for nanofluids containing the single-walled carbon nanotube, graphene nanoplate and graphene oxide at similar conditions and that of pure water, respectively, are about 91%, 90%, 81% and, 54%. Furthermore, it is observed that for the mass concentration of 0.004%, the evaporation rate with respect to water increases to about 72%, 63%, 58% and 36%, respectively, for the multi-walled carbon nanotube, the single-walled carbon nanotube, graphene nanoplate and graphene oxide nanofluids. As far as the sensible heat is concerned, graphene oxide shows the most considerable sensible heating efficiency at the mass concentration of 0.004% with the maximum fluid bulk temperature rise of 20.5 ͦ C, which is 40% higher than that of water. Finally, it was found that increasing the radiation intensity from 1.5 to 3.5 Suns improves the evaporation rate; however, the sensible heat efficiency is more influenced such that the evaporation efficiency declines. The quality of the produced water from a seawater sample is also examined and it was shown that it is well below the limitations of the drinking water standards.
In the present paper, the performance of the graphene oxide in the solar steam generation has experimentally been examined. For this purpose, a setup was built for measuring the evaporation rate, which consists of a solar simulator with a xenon lamp as a radiation source, a pyranometer for light intensity measuring, and a sensory system for measuring the temperature and the weight. Then, the nanofluid with three nanoparticle mass concentrations of 0.001, 0.002, and 0.004% was prepared and exposed to the light intensity of 3.5 Suns (3.5 kW m−2). Finally, the effects of the light intensity variations on the solar steam generation were studied at the steady and transition conditions. The results showed that the examined carbon nanostructure is efficiently capable of direct solar energy harvesting, such that a maximum total efficiency of 78.9% at 3.5 Suns can be obtained, while the corresponding value for the case of pure water is about 54%. Furthermore, it was found that increasing the light intensity from 1.5 to 3.5 Suns enhances the evaporation flux rate, yet, reduces the evaporation efficiency.
Recently, nanofluids have been proposed as an innovative method in the direct absorption of solar energy for the steam generation applications. In the present paper, the performance of the nanofluids on the solar fresh water production has experimentally been investigated. In this regards, two types of multi-wall carbon nanotubes functionalized by carboxyl and hydroxyl groups have been examined at very low nanoparticle mass fractions of 0.0005, 0.001, and 0.002%. Then, the effects of the solar power density, supplied by a solar simulator, on the solar steam generation have been studied in the steady and transition conditions. The obtained results established the capability of the employed carbon nanostructures in the efficient direct absorption of solar energy and production of the fresh water. As a result, the maximum evaporation efficiencies of 26.79% and 34.63% were achieved under the radiation of 3.2kW/m2 using the modified carbon nanotubes with carboxyl and hydroxyl groups, respectively. Furthermore, it was found that the amount of fresh water production increases with increasing the nanoparticles concentrations. The intensification of solar irradiation also led to an increase in the sensible thermal efficiency, which became more considerable by adding the nanoparticles.
You can find the abstract in the attached file.
Vaporisation (evaporation and boiling) through direct absorption solar collectors (DASCs) has recently drawn significant attention. Many studies suggested that plasmonic nanoparticles, such as gold nanoparticles, can significantly enhance the photo-thermal conversion efficiency of DASCs. However, there is still a lack of comparative studies of the feasibility of using gold nanoparticles for solar applications. This study performed well-controlled experiments for two different categorised particles, i.e., gold and carbon black suspended in water, and assessed their performance in terms of evaporation rate, materials cost and energy consumption. The results show that gold nanofluids are not feasible for solar evaporation applications, where the cost of producing 1 g/s vapour is ∼300 folds higher than that produced by carbon black nanofluids. This infeasibility is mainly due to the high cost and the low absorbance of gold comparing to carbon black nanoparticles. Moreover, this work reveals that with the increase of nanoparticle concentration or incident solar radiation, more energy is trapped in a small volume of the nanofluid near the interface, resulting in a local higher temperature and a higher evaporation rate. For efficient steam production, future optimisation of the system should consider concentrating more solar energy at the interface to maximize the energy consumed for evaporation.
The present study aimed to recognize the optimized configuration of Multiple Effect Desalination with Thermal Vapor Compression (METVC) and Reverse Osmosis (RO) desalination (METVC+RO) and gas turbine cycle. To achieve this goal, first, a comprehensive model was developed for different parts of the cycle; then, economical status of the system was evaluated using a thermoeconomic method. At first, six configuration for METVC+RO desalination were considered while in the sixth configuration. Two approaches were considered in the optimization study. In the first approach, the water production of METVC plants was fixed at 70000 m3/day and the capacity of RO was considered as 50%, 75% and 100% of METVC capacity. In the second approach, the water production of METVC plant was not fixed but the total production rate of METVC+RO plants were given. This issue was considered in order to achieve a comprehensive conclusion and analyze the effect of water production rate of each desalination (METVC+RO) on the economical and thermodynamic aspects of the hybrid systems. Thus, thirty-six optimization processes must be performed that it was expected that a comprehensive assessment of system can be achieved using these two approaches.
Decontamination of waste water is one of the most practical techniques to tackle the worldwide clean water shortage. In recent times, solar steam based decontamination of contaminated water has been attested as a potential sustainable strategy to get clean water using renewable resources. Herein, we report the utilization of Carbon fabric and Titanium Nanorods on Carbon Fabric for solar steam based water purification techniques. The performance of Carbon Fabric was tested under different conditions and the results proved that Carbon Fabric has excellent light to heat conversion capabilities in both real and ideal conditions. Owing to the excellent performance of Carbon Fabric, it was used for purification of different types of contaminated water. About 99.9% of salt and 87% of organic contaminants were removed from saline water and organic waste water respectively, using a simple low cost carbon fabric based homemade prototype. We also present the application of Titanium Nanorods on carbon fabric for the efficient removal of dye molecules like Rhodamine B from contaminated water using solar driven interfacial steam generation mechanism.
Steam production has a wide range of applications such as seawater desalination, waste sterilization, and power generation. The utilization of solar energy for this purpose has attracted much attention due to its inexhaustibility and pollution-free nature. Here, direct solar steam generation at low-concentrated solar power using plasmonic nanofluids containing gold nanoparticles (Au NPs) was investigated experimentally. The key factors required for highly efficient solar steam generation, including Au NP concentration and solar power intensity, were studied in a simulated solar system by measuring the water weight loss and system temperature change. The best evaporation performance was obtained using a plasmonic nanofluid containing 178 ppm of Au NPs under 10 sun (1 sun = 1 kW m⁻²) illumination intensity, and the total efficiency reached 65%. However, the total efficiency of pure water was only 16%, which means that the plasmonic nanofluids reached a ∼300% enhancement in efficiency. Higher solar power led to a higher evaporation rate, higher specific vapor productivity (SVP), and higher Au NP concentrations resulted in better evaporation performance. Localized solar heating at the fluid-air interface was shown to contribute more to solar steam generation than to bulk fluid heating. Furthermore, the model of photothermal heating of plasmonic nanoparticle was established and the numerical results demonstrated the photothermal conversion process of plasmonic NPs from the light absorption to the heat dissipation into the bulk fluid.
Solar power, as an important source of renewable energy during the recent years, holds a great potential to produce vapor. Solar-assisted evaporation systems usually rely on the concentration of nanofluids and the intensity of solar illumination. However, the nanofluids used in these systems can cause secondary pollution. These issues severely limit large-scale application of the solar evaporation technology. In this study, we developed a solar thermal evaporation system based on carbon nanotubes (CNTs) decorated with magnetic Fe3O4 nanoparticles (Fe3O4@CNT), which could be separated from water under the action of a magnetic force. The two components (with different ratios) of these Fe3O4@CNT differed in their magnetic and thermal properties. A high evaporation efficiency (60.3%) was obtained with a 0.5 g/L Fe3O4@CNT nanofluid under a solar illumination power of 10 sun (1 sun = 1 kW·m⁻²), which was achieved by heating the nanofluid locally rather than by increasing the temperature in bulk. A thermal receiver efficiency of 88.7% was obtained with a 0.5 g/L Fe3O4@CNT nanofluid under a solar illumination power of 1 sun achieved by a bulk temperature increase. The Fe3O4@CNT nanoparticles could be separated from water at a rate faster than that of the Fe3O4 nanoparticles. The recovery rate of the Fe3O4 nanoparticles and Fe3O4@CNT ranged from 97.9% to 98.7%. The Fe3O4 nanoparticles in Fe3O4@CNT enhance their ability to absorb the solar energy, thus making it higher than that of CNTs. The recovery rate and efficiency could be controlled by adjusting the magnetic field strength and the ratio of Fe3O4 and CNTs. Thus, this system study provides an approach to not only significantly reduce the material consumption in the design of solar evaporators, but also to realize broad solar energy applications such as seawater desalination and vapor generation.
Research in collection and conversion of solar energy has attracted an increasing interest because of the fact that conventional energy resources are becoming increasingly exhausted. For this reason, Ag@TiO2 core–shell nanoparticles (NPs) with great absorptivity in the visible region were synthesized in this work. Subsequently, an experimental study on photo-thermal performances including steam generation and solar energy capture in a thermal receiver containing the Ag@TiO2 NPs-based nanofluids was conducted. The effects of the NP concentration as well as the optical concentration were taken into consideration. The results showed that the nanofluids can be used for direct steam generation with a short period of solar irradiation time, even at the illumination intensity of 1 sun (1 sun = 1 kW/m²). An evaporation efficiency of 53.6% can be achieved when the NP concentration is only 200 ppm owing to the surface plasmon resonance of the NPs. In addition, it is found that the nanofluid with a lower NP concentration has a higher temperature rise during illumination. Our findings also showed that the absorbed solar energy is transferred preferentially into latent heat enthalpy and consumed for steam generation instead of heating the nanofluids.
Solar vapor generation enabled by nanoparticles is a green, efficient and direct approach to utilize solar energy. In this work, nanocomposites of graphene oxide (GO) and gold (Au) nanoparticles were prepared to generate solar steam under sunlight irradiation. The changes on steam pressure, mass loss and temperature of water were used to study the solar photothermal properties of GO-Au nanocomposites in water, which demonstrated that the synergistic interaction between GO nanosheets and Au nanoparticles played an active role in the photothermal effect of the nanocomposites. Trace of Au nanoparticles (15.6 wt‰) in the GO nanofluids could significantly improve the efficiency of solar vapor generation. More interestingly, the morphology and color of GO-Au nanofluids varied with irradiation times under sunlight, and our results suggested that GO sheets were reduced to graphene sheets. This process of photothermal deoxygenation of GO provides an available solution for preparing graphene sheets under ambient conditions without any reductions, and the solar steam generation method can enable potential applications like sterilization of waste, seawater desalination, and disinfection.
Traditional solar-energy collection systems experience high thermal losses because of the high surface temperature of the absorber. Nanofluid developments have led to extensive studies on their suitability for direct absorption as solar-energy collectors. A potential approach for solar steam generation via nanoparticle absorption of solar light and its conversion to thermal energy for water evaporation has been introduced recently. Direct solar vapor generation enabled by carbon-nanotube nanofluids was investigated experimentally in the present work. The effects of solar-power density and carbon-nanotube concentration on solar steam-generation performance are discussed. The evaporation rate increases with an increase in solar power and carbon-nanotube concentration. A high evaporation efficiency (46.8%) was obtained with a 19.04 × 10⁻⁴ vol.% carbon-nanotube nanofluid under a solar illumination power of 10 Sun (1 Sun = 1 kW m⁻²). A high evaporation rate was achieved by localized heating of the nanofluid rather than by a bulk temperature increase, which provides a mechanism for low-temperature solar vapor generation and exhibits broad solar-energy applications such as seawater desalination, waste sterilization and power generation.
This work investigated experimentally the photothermal conversion efficiency (PTE) of gold nanofluids in a cylindrical tube under natural solar irradiation conditions, which was also compared with a developed 3-D numerical model. The PTE of gold nanofluids was found to be much higher than that of pure water, and increased non-linearly with the nanoparticle concentration, reaching 76.0% at a concentration of 5.8 ppm. Significant non-uniform temperature distribution was identified both experimentally and numerically, and a large uncertainty can be produced in the PTE calculation by using only one-point temperature measurement. A mathematical model was also established to calculate the solar absorption efficiency without knowing the temperature field within the nanofluids, which can be used to predict the theoretical PTE for nanofluids based on their optical properties only.
Floatable low-density millimetre-sized hollow carbon beads were prepared by a phase inversion method, and they were used to promote water evaporation under simulated sunlight. Hollow carbon beads with 1.5 mm diameter achieved an evaporation rate of 1.28 L m−2 h−1 that was around 237% of the rate attained without carbon beads when 714 g m−2 (0.5 g) of carbon beads were present. This significant enhancement of water evaporation rate is owing to the dramatic increase of the water surface temperature, which is brought about by the light-absorbing property of the floating hollow carbon beads. In addition, a good recyclability was also demonstrated. In general, these millimetre-sized hollow carbon beads accelerate the water evaporation process, making the collection and recycle process easier to suit the practical application.
Presents a rigorous analysis of the laws of Beer and Lambert. Keywords (Audience): Upper-Division UndergraduateKeywords (Domain): Physical ChemistryKeywords (Subject): Chemometrics
Concentrated solar power plants (CSPs) are gaining increasing interest, mostly as parabolic trough collectors (PTC) or solar tower collectors (STC). Notwithstanding CSP benefits, the daily and monthly variation of the solar irradiation flux is a main drawback. Despite the approximate match between hours of the day where solar radiation and energy demand peak, CSPs experience short term variations on cloudy days and cannot provide energy during night hours unless incorporating thermal energy storage (TES) and/or backup systems (BS) to operate continuously. To determine the optimum design and operation of the CSP throughout the year, whilst defining the required TES and/or BS, an accurate estimation of the daily solar irradiation is needed. Local solar irradiation data are mostly only available as monthly averages, and a predictive conversion into hourly data and direct irradiation is needed to provide a more accurate input into the CSP design. The paper (i) briefly reviews CSP technologies and STC advantages; (ii) presents a methodology to predict hourly beam (direct) irradiation from available monthly averages, based upon combined previous literature findings and available meteorological data; (iii) illustrates predictions for different selected STC locations; and finally (iv) describes the use of the predictions in simulating the required plant configuration of an optimum STC. The methodology and results demonstrate the potential of CSPs in general, whilst also defining the design background of STC plants.
AbstractA novel and efficient method to produce water dispersible superparamagnetic Fe3O4 nanoparticles is described. Nanoparticles prepared by non‐hydrolytic organic phase methods are subsequently functionalized with (3‐glycidyloxypropyl)trimethoxysilane, a linker that prevents aggregation and is available for subsequent coupling reactions with a wide range of polymers and biomolecules. Ring opening coupling reactions were used to coat the epoxy‐functionalized magnetite nanoparticles with aminated polymers (polyetheramines) or small molecules (arginine). The resulting nanoparticles, with hydrodynamic size of 13 nm, are found to be very stable over extended periods in water or PBS due to the presence of a dense stabilizer layer covalently anchored to the surface. Exceptionally high spin‐lattice relaxivity, r 1, values of 17 s−1 mM−1, and low r 2/r 1 ratios of 3.3–3.8 were exhibited in the clinical MRI frequency range, irrespective of the molecule selected for nanoparticle stabilization. As a result the dispersions are excellent candidates for incorporation into multi‐functional assemblies or for use as positive contrast agent for MRI.
Fe3O4 magnetic nanoparticles with different average sizes were synthesized and structural characterizations showed that the three kinds of nanoparticles had different sizes, i.e., an average particle size of 8 nm, 12 nm and 35 nm was observed for the nanoparticles prepared with the co-precipitation method, the co-precipitation combining a surface decoration process, and the polyol process, respectively. The synthesized Fe3O4 nanoparticles with different mean particle sizes were used for treating the wastewater contaminated with the metal ions, such as Ni(II), Cu(II), Cd(II) and Cr(VI). It is found that the adsorption capacity of Fe3O4 particles increased with decreasing the particle size or increasing the surface area. Various factors influencing the adsorption of metal ions, e.g., pH, temperature, amount of adsorbent, and contacting time were investigated to optimize the operation condition for the use of Fe3O4 nanoparticles with an average size of 8 nm. The obtained results indicated that the mechanism was strongly influenced by the pH and temperature of wastewater. The maximum adsorption occurred at pH 4.0 under room temperature (20 °C) and the adsorption capacity of Fe3O4 nanoparticles was as high as 35.46 mg/g, which is almost 7 times higher than that of the coarse particles.
Precise localization of exogenously delivered stem cells is critical to our understanding of their reparative response. Our current inability to determine the exact location of small numbers of cells may hinder optimal development of these cells for clinical use. We describe a method using magnetic resonance imaging to track and localize small numbers of stem cells following transplantation. Endothelial progenitor cells (EPC) were labeled with monocrystalline iron oxide nanoparticles (MIONs) which neither adversely altered their viability nor their ability to migrate in vitro and allowed successful detection of limited numbers of these cells in muscle. MION-labeled stem cells were also injected into the vitreous cavity of mice undergoing the model of choroidal neovascularization, laser rupture of Bruch's membrane. Migration of the MION-labeled cells from the injection site towards the laser burns was visualized by MRI. In conclusion, MION labeling of EPC provides a non-invasive means to define the location of small numbers of these cells. Localization of these cells following injection is critical to their optimization for therapy.
Drug–nanoparticle conjugates: The anticancer drug camptothecin (CPT) was covalently linked at the surface of ultrasmall superparamagnetic iron oxide nanoparticles (USPIOs) via a linker, allowing drug release by cellular esterases. Nanoparticles were hierarchically built to achieve magnetically-enhanced drug delivery to human cancer cells and antiproliferative activity.
The linking of therapeutic drugs to ultrasmall superparamagnetic iron oxide nanoparticles (USPIOs) allowing intracellular release of the active drug via cell-specific mechanisms would achieve tumor-selective magnetically-enhanced drug delivery. To validate this concept, we covalently attached the anticancer drug camptothecin (CPT) to biocompatible USPIOs (iron oxide core, 9–10 nm; hydrodynamic diameter, 52 nm) coated with polyvinylalcohol/polyvinylamine (PVA/aminoPVA). A bifunctional, end-differentiated dicarboxylic acid linker allowed the attachment of CPT to the aminoPVA as a biologically labile ester substrate for cellular esterases at one end, and as an amide at the other end. These CPT–USPIO conjugates exhibited antiproliferative activity in vitro against human melanoma cells. The intracellular localization of CPT–USPIOs was confirmed by transmission electron microscopy (iron oxide core), suggesting localization in lipid vesicles, and by fluorescence microscopy (CPT). An external static magnetic field applied during exposure increased melanoma cell uptake of the CPT–USPIOs.
Accessible Graphene Aerogel for Efficient Harvesting Solar Energy
- Y Fu
- G Wang
- T Mei
- T Li
Fu Y, Wang G, Mei T, Li T (2017) Accessible
Graphene Aerogel for Efficient Harvesting Solar
Energy. ACS Sustain Chem ENG. 5(6): 4665-4671.
Experimental study and economic evaluation of various techniques for increasing fresh water production in a cascade solar water desalination unit
- M Vafaie
- M Barzgarnezhad
- A Arbabi
- E Shakib
- M M Ghafurian
Vafaie M, Barzgarnezhad M, Arbabi A, Shakib E,
Ghafurian MM (2018) Experimental study and
economic evaluation of various techniques for
increasing fresh water production in a cascade
solar water desalination unit. Articles in Press,
Amirkabir Journal of Mechanical Engineering,
Accepted Manuscript, Available Online from 22
Nov. 2018.