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Copper Coated Silica Nanoparticles for Odor Removal
Abstract
Copper species coated silica nanoparticles (CuOXS) were synthesized for odor removal application. Coating with copper increased the capacity of silica nanoparticles for eliminating a model odor-ethyl mercaptan. Surface area, pore size distribution, and electron paramagnetic resonance spectroscopy analyses indicated that, at lower copper concentrations, copper species preferentially adsorb in 20 Å pores of silica. These copper species in a dispersed state are effective in catalytic removal of ethyl mercaptan. The best performance of copper-coated silica nanoparticles was achieved at a copper concentration of 3 wt %, at which all 20 Å nanopores were filled with isolated copper species. At higher copper loading, copper species are present as clusters on silica surfaces, which were found to be less effective in removing ethyl mercaptan. Gas chromatography experiments were carried out to verify catalytic conversion of ethyl mercaptan to diethyl disulfide by CuOXS particles. The present study suggests that the nature of the copper species and their site of adsorption, as well as state of dispersion, are important parameters to be considered for catalytic removal of sulfur-containing compounds. These parameters are critical for designing high-performance catalytic copper-coated silica nanoparticles for applications such as deodorization, removal of sulfur compounds from crude oil, hydrogenation, and antimicrobial activity.
... sewage/waste water treatment and sanitary landfill activity) will bring about this disagreeable odor [2]. Common approaches for controlling malodor gas include catalytic destruction [3][4][5][6][7][8][9][10][11][12][13][14][15][16], absorption [1,[17][18][19][20][21][22], non-thermal plasma purification method [23], and biological method [24]. Among the processes, catalytic destruction has been paid the most attention because it is a final disposal and energy saving process [25,26]. ...
... CH 3 SH was employed as a model odor. Copper doping results in the formation of two different copper species depending on the concentration of the copper ions [19]. However, the efficacy of these copper species in ligand formation with water and therefore odor removal is not reported. ...
... The result of CH 3 SH removal in the gas phase is presented in Fig. 1. Although pure mesoporous silica has minor absorption capacity of CH 3 SH [19], C/S-0 is ineffective in removing lowconcentrated CH 3 SH. For C/S-1$10, there is an abruptly increase of absorption capacity when compared with C/S-0. ...
... For instance, at ambient temp the breakthrough time was achieved at 131 min while at 100 °C was achieved at 1 study conducted by [69] using MnO2 for methyl mercaptan removal, indicated creasing temperature led to a higher rate of methyl mercaptan decomposition in thyl disulfide (DMDS), which aligns with our observations of increased sulfur co tion in the breakthrough experiments as the temperature increases. A similar tr noted in a study by [70] which used MOF-199 (a copper-based metal-organic fram to remove methyl and ethyl mercaptan removal. Figure 14 compares the breakthrough times for methyl mercaptan remov both Select HP and UL-Best catalyst at different temperatures. ...
... A study conducted by [69] using MnO 2 for methyl mercaptan removal, indicated that increasing temperature led to a higher rate of methyl mercaptan decomposition into dimethyl disulfide (DMDS), which aligns with our observations of increased sulfur concentration in the breakthrough experiments as the temperature increases. A similar trend was noted in a study by [70] which used MOF-199 (a copper-based metal-organic framework) to remove methyl and ethyl mercaptan removal. Figure 14 compares the breakthrough times for methyl mercaptan removal using both Select HP and UL-Best catalyst at different temperatures. ...
Methyl mercaptan is a sulfur-based chemical found as a co-product in produced natural gas and it causes corrosion in pipelines, storage tanks, catalysts, and solid adsorption beds. To improve the quality of methane produced, researchers have studied the use of metal oxides and aluminum silicates as catalysts for removing mercaptan. However, there are restrictive limitations on the efficiency of metal oxides or aluminum silicates as adsorbents for this application. Therefore, this study investigated the performance of these materials in a fixed-bed reactor with simulated natural gas streams under various operating conditions. The testing procedure includes a detailed assessment of the adsorbent/catalysts by several techniques, such as Braeuer–Emmett–Teller (BET), Scanning Electron Microscope (SEM), Energy-Dispersive X-ray Spectrometry (EDS), and X-ray Photoelectron Spectroscopy. The results revealed that metal oxides such as copper, manganese, and zinc performed well in methyl mercaptan elimination. The addition of manganese, copper, and zinc oxides to the aluminum silicate surface resulted in a sulfur capacity of 1226 mg S/g of catalyst. These findings provide critical insights for the development of catalysts that combine metal oxides to increase adsorption while reducing the production of byproducts like dimethyl sulfide (DMS) and dimethyl disulfide (DMDS) during methyl mercaptan removal.
... This behavior may be also linked to the formation of disulfides. A study by [75] confirmed the conversion of ethyl mercaptan to diethyl disulfide at 150 °C. Our results align with this observation, disulfide was present at 150 °C experiment but not at ambient temperature. ...
Methyl Mercaptan is a sulfur-based chemical found as a co-product in produced natural gas and causes corrosion in pipelines, storage tanks, catalysts, and solid adsorption beds. To improve the quality of methane produced, researchers studied the use of metal oxides and aluminum silicates as catalysts for removing mercaptan. However, there are restricted limitations on the efficiency of metal oxides or aluminum silicates as adsorbents for this particular application. Therefore, this study investigated the performance of these materials in a fixed-bed reactor with simulated natural gas streams under various operating conditions. The testing procedure includes a detailed assessment of the adsorbent/catalysts by several techniques, such as Braeuer-Emmett-Teller (BET), Scanning Electron Microscope (SEM), Energy-Dispersive X-ray Spectrometry (EDS), and X-ray Photoelectron Spectroscopy. The result revealed that metal oxides such as copper, manganese, and zinc performed well in methyl mercaptan elimination. The addition of manganese, copper, and zinc oxides to the aluminum silicate surface resulted in a sulfur capacity of 1226 mg S/g of catalyst. These findings provide critical insights for the development of catalysts that combine metal oxides to increase adsorption while reducing the production of byproducts like dimethyl sulfide (DMS) and dimethyl disulfide (DMDS) during methyl mercaptan removal.
... The CuPs incorporated onto nano-silica also showed an inhibitory effect on the growth of microorganisms. They were also used to remove the odor of mercaptans [28]. The CuPs immobilized onto the surface of SiO 2 spheres did not aggregate and showed good antimicrobial properties against colonies of Escherichia coli, Staphylococcus aureus, and Candida albicans when the concentration of SiO 2 @Cu was higher than 500 µg/mL [29]. ...
Literature reviews have described the applications of silver, copper, and zinc ions and metallic particles of Cu, Ti, and Zn oxides, which have been found to be useful antimicrobial reagents for the biofunctionalization of various materials and their surfaces. For this purpose, compositions of water dispersions containing emulsions of synthetic copolymers based on acrylic and vinyl monomers, polysaccharides (hydroxyethyl cellulose and starch), and various additives with wetting and stabilizing properties were used. Many stable water dispersions of different chemical compositions containing bioactive chemical compounds (copper silicate hydrate, titanium dioxide, and zinc oxide (and other auxiliary substances)) were developed. They were used for the preparation of thin hybrid coatings having good antimicrobial properties against Gram-negative bacteria (Escherichia coli), Gram-positive bacteria (Staphylococcus aureus), and yeast fungus (Candida albicans). Polyester (PES) and polylactide (PLA) nonwovens were modified using the dip-coating method, while PES and cotton fabrics were biofunctionalized by means of dip-coating and coating methods. The antimicrobial (antibacterial and antifungal) properties of the textile materials (nonwovens and fabrics) biofunctionalized with the above-mentioned bioactive agents exhibiting antimicrobial properties (CuSiO3, TiO2, ZnO, or ZnO∙SiO2) were strongly dependent on the agents’ content in the water dispersions. The PES and PLA nonwovens, modified on the surface with water compositions containing copper silicate hydrate, showed good antibacterial properties against the Gram-negative bacteria Escherichia coli, even at a content of 1 wt.% CuSiO3∙xH2O, and against the Gram-positive bacteria Staphylococcus aureus, at the content of at least 5 wt.% CuSiO3∙xH2O. The bacterial growth reduction factor (R) was greater than 99% for most of the samples tested. Good antifungal properties against the fungus Candida albicans were found for the PES and PLA nonwoven fabrics modified with dispersions containing 5–7 wt.% CuSiO3∙xH2O and 4.2–5.0 wt.% TiO2. The addition of TiO2 led to a significant improvement in the antifungal properties of the PES and PLA nonwovens modified in this way. For the samples of PES WIFP-270 and FS F-5 nonwovens, modified with water dispersions containing 5.0 wt.% CuSiO3∙xH2O and 4.2–5.0 wt.% TiO2, the growth reduction factor for the fungus Candida albicans (R) reached values in the range of 80.9–98.0%. These new biofunctionalized polymeric nonwoven textile materials can find practical applications in the manufacture of filters for hospital air-conditioning systems and for the automotive industry, as well as in air purification devices. Moreover, similar antimicrobial modification of fabrics with the dip-coating or coating methods can be applied, for example, in the fabrication of fungi- and mold-resistant garden furniture.
... As these influences in a straight line regulate the request of Cu NPs and valuation of the toxicity of Cu NPs in humans, it is extremely significant to regulate the release of Cu 2+ from Cu NPs and rise the steadiness of Cu NPs. To solve these difficulties, numerous substances have been chosen as the carriers of copper, such as zeolite [38], montmorillonite [39], titanium dioxide [40], activated carbon fiber [41], phosphate glass fiber [42] and silicon dioxide [43]. These substances might stabilize Cu NPs or regulate the release of Cu 2+ , and partially improve the antibacterial activity and steadiness of Cu NPs. ...
Graphene oxide (GO) is a complicated composite which can be synthesized from graphite or other carbon sources by a simple top-down method. Graphene is a two-dimensional carbon sheets which can be oxidized to synthesis its oxide structure. The graphene oxide sheets can be functionalized in order to be used actively in different areas. The graphene oxide nanocomposite materials have attracted researches and scientists’ attention due to their wade applications from electrochemical industry to drug delivery. In this novel work the authors have synthesized graphene oxide films and then functionalized with an amino acid, Lysine, and Cu in order to synthesize the Lysine-Cu-Graphene oxide combination. The novelty of this investigation is the authors have functionalized graphene oxide with l-lysine as an amino acid at diverse temperature. Also, this product is environmentally friendly product since it is soluble in aqueous medium and can be applied as an active antibacterial material. After the synthesizing process, the obtained materials had been characterized using different techniques such as Fourier-transform infrared spectroscopy (FTIR) to confirm the success of the functional reaction. Ultra violet visible (UV–Vis) spectroscopy, atomic force microscopy (AFM), X-ray diffraction (XRD), and thermal gravimetric (TG) analysis, were also utilized to approve the covalent attachment of Lysine and also to show the improvement in the thermal stability of GO.
... The CuPs incorporated onto nanosilica also showed the inhibitory effect on the growth of microorganisms. They were also used to remove the odor of mercaptans [28]. The CuPs immobilized onto the surface of SiO2 spheres did not aggregate and showed good antimicrobial properties against colonies of Escherichia coli, Staphylococcus aureus and Candida albicans, when the concentration of SiO2@Cu was higher than 500 µg/ml [29]. ...
Many stable water dispersions of various chemical compositions containing bioactive chemical compounds: copper silicate, titanium dioxide and zinc oxide (and other auxiliary substances) were developed and fabricated - they were used for preparation of thin hybrid coatings having very good antimicrobial properties against gram negative bacteria (Escherichia coli), gram positive bacteria (Staphylococcus aureus) and yeast fungus (Candida albicans). Polyester (PES) nonwovens were modified by dip-coating, and PES and cotton fabrics - by dip-coating and coating methods.
... Nanotechnology is becoming an increasingly important aspect of our lives, being included in the food industry [1], electronics [2][3][4], medicine [5], and textiles [6,7]. It has been noted nanoparticles have not only small size but also unique physical, chemical, and biological characteristics that do not occur in the macro-material. ...
Generation of gold and silver nanoparticles by laser ablation in water without the addition of surfactants is very attractive due to the purity of such nanoparticles. However, such nanoparticles face the problem of long-term stability, which severely limits their applicability. Here, we demonstrate the generation of hybrid gold-silver nanoparticles using the laser ablation of thin-film composites on a glass substrate in water, and compare with the laser fabrication of nanoparticles by using bulk targets of silver and gold. Thin-film method allows the formation of stable hybrid Au-Ag nanoparticles in distilled water without any stabilizers and additional ligands with an opportunity to regulate the nanoparticle composition using different metal ratios, layer order, and thickness of films. The stability and optical properties of the hybrid nanoparticles depend on the used laser pulse energy. This study demonstrates that the thin film method produces nanoparticles with higher stability compared to the bulk target method. These outcomes are encouraging for the creation of better-performing, stable, and clean nanoparticles that can be used in a variety of applications in biomedicine, sensors, integrated circuits, filters, batteries, covid-19 tests, solar cells, dual-energy mammography (DEM), computed tomography (CT), and other components of optical and electronic devices.
... This inevitably requires the development of new materials along with the associated deposition and/or processing methods. To bridge this gap, nanomaterials, heterogeneous composite materials with embedded nanoparticles [4,5], and 2D materials [6,7] are stepping in and providing the required functionalities and properties that have so far been elusive using other means, including antimicrobial properties, hydrophobic properties, catalytic performance, handling of odors, controlled drug release, and response to external stimuli via electrical, color, or physiological signals without spoiling their durability. The conventional materials used in textiles could be replaced by the nonwoven nanofibrous materials deposited by the electrospinning technique [8], together with their further post-processing for gaining extra functionalities [9]. ...
Textiles, originally made from natural fiber materials, have thousands of years of history [...]
... Furthermore, slight dosages of copper (safe, proficient, and adequate doses) could be applied to prevent the propagation of harmful microbial lineage. Thus, nanocrystalline materials had excellent antibacterial characteristics and bactericidal impacts against numerous types of pathogenic bacterial (Singh et al., 2010). Consequently, the incredibly crystalline nanoporous alumino-copper silicate is established by secure sol-gel procedures to obliterate pathogenic organisms and to act as a disinfecting compound in wastewater and ingestion water treatment (El Nahrawy et al., 2019b). ...
The morphological and dielectric properties of bioactive sol-gel alumino-copper silicate nanoporous are characterised. It is characterised by sharp diffraction peaks confirming the high crystallinity. Alumino-copper silicate was utilised as a disinfecting agent for wastewater disinfection. The growth inhibitory effect of alumino-copper silicate sanitiser was investigated against various categories of microbial pathogens. Toxicity assay of fabricated alumino-copper silicate nanoporous was measured. The acquired results disclosed that target pathogenic microbes in the raw wastewater sample were inactivated when subjected to 100 mg/L of fabricated alumino-copper silicate. Likewise, results could not discover any deleterious and poisonous influences for the Vibrio fischeri bacterium and HEp-2 cell line of such nanostructures subsequently, it will be safe for use in water treatment. This investigation, therefore, recommends that the prepared alumino-copper silicate could be considered a future substitute marvellous and sustained-active disinfectant for the production of pathogenic free treated wastewater for recycling in many different applications.
... Furthermore, slight dosages of copper (safe, proficient, and adequate doses) could be applied to prevent the propagation of harmful microbial lineage. Thus, nanocrystalline materials had excellent antibacterial characteristics and bactericidal impacts against numerous types of pathogenic bacterial (Singh et al., 2010). Consequently, the incredibly crystalline nanoporous alumino-copper silicate is established by secure sol-gel procedures to obliterate pathogenic organisms and to act as a disinfecting compound in wastewater and ingestion water treatment (El Nahrawy et al., 2019b). ...
The morphological and dielectric properties of bioactive sol-gel alumino-copper silicate nanoporous are characterised. It is characterised by sharp diffraction peaks confirming the high crystallinity. Alumino-copper silicate was utilised as a disinfecting agent for wastewater disinfection. The growth inhibitory effect of alumino-copper silicate sanitiser was investigated against various categories of microbial pathogens. Toxicity assay of fabricated alumino-copper silicate nanoporous was measured. The acquired results disclosed that target pathogenic microbes in the raw wastewater sample were inactivated when subjected to 100 mg/L of fabricated alumino-copper silicate. Likewise, results could not discover any deleterious and poisonous influences for the Vibrio fischeri bacterium and HEp-2 cell line of such nanostructures subsequently, it will be safe for use in water treatment. This investigation, therefore, recommends that the prepared alumino-copper silicate could be considered a future substitute marvellous and sustained-active disinfectant for the production of pathogenic free treated wastewater for recycling in many different applications.
... Figure 9 represents the β-pinene epoxide isomerization over Fe/MCM-41 catalyst. MCM-41 is a mesoporous material with pores in 2D and hexagonally arranged (Moreira, Dias, and Correia 2016;Singh et al. 2010;Kruk et al. 2000;Barthomeuf 1996) that facilites the location of Fe sites which act as acid sites. With the change of the solvent, selectivity is modified; solvent does not change the catalyst acidity but could affect the thermodynamics and kinetics of the formation of both myrtanal and perillyl alcohol, decreasing the activation energy of the steps of perillyl alcohol production using a polarbasic solvent and faciliting the dipolar interactions. ...
In this work, a critical review of the state of the art about the solvent influence on the performance of metal catalysts in the hydrogenation of carbonyl compounds, specifically unsaturated aldehydes, ketones and ketoesters, is carried out.
... To avoid the cytotoxic effects of CuNPs in humans, it is crucial to increase the CuNPs' stability and to control the Cu 2+ release. To realize these goals, different substances were conjugated as copper carriers, such as titanium oxide (Sunada et al., 2003), silicon dioxide (Kim et al., 2006;Singh et al., 2010), activated carbon fiber (Byeon et al., 2007), zeolite (Top and Ülkü, 2004), phosphate glass fiber (Abou Neel et al., 2005), and montmorillonite (Hu and Xia, 2006). To improve the longterm antibacterial activity and water solubility of CuNPs, polyl-lysine/reduced graphene oxide/copper nanoparticles (PLL-rGO-CuNPs) were produced in which PLL-rGO served as a carrier of CuNPs that were anchored on the rGO surface. ...
Bacterial infections represent nowadays the major reason of biomaterials implant failure, however, most of the available implantable materials do not hold antimicrobial properties, thus requiring antibiotic therapy once the infection occurs. The fast raising of antibiotic-resistant pathogens is making this approach as not more effective, leading to the only solution of device removal and causing devastating consequences for patients. Accordingly, there is a large research about alternative strategies based on the employment of materials holding intrinsic antibacterial properties in order to prevent infections. Between these new strategies, new technologies involving the use of carbon-based materials such as carbon nanotubes, fullerene, graphene and diamond-like carbon shown very promising results. In particular, graphene- and graphene-derived materials (GMs) demonstrated a broad range antibacterial activity toward bacteria, fungi and viruses. These antibacterial activities are attributed mainly to the direct physicochemical interaction between GMs and bacteria that cause a deadly deterioration of cellular components, principally proteins, lipids, and nucleic acids. In fact, GMs hold a high affinity to the membrane proteoglycans where they accumulate leading to membrane damages; similarly, after internalization they can interact with bacteria RNA/DNA hydrogen groups interrupting the replicative stage. Moreover, GMs can indirectly determine bacterial death by activating the inflammatory cascade due to active species generation after entering in the physiological environment. On the opposite, despite these bacteria-targeted activities, GMs have been successfully employed as pro-regenerative materials to favor tissue healing for different tissue engineering purposes. Taken into account these GMs biological properties, this review aims at explaining the antibacterial mechanisms underlying graphene as a promising material applicable in biomedical devices.
... Although cenosphere is a non-conducting ceramic, electrical conductivity may be imparted to it by the coating of pure metals such as copper and silver on its surface (Shukla et al. 2002). Several studies regarding coating of copper on some materials like silica nanoparticles (Singh et al. 2010), silicon nanowires (Chen et al. 2011), silica-based particles (Palza, Delgado, and Curotto 2015), iron (Coleman and Foba 1989), mica (Deonath and Rohatgi 1981) etc., have been reported in the literature. However, the coating methods are expensive and no literature reports the usage of copper-coated substrates as a cathode in batteries. ...
Fly-ash is a by-product of various thermal power plants. The utilization of fly-ash is a big concern in the current scenario as its production rate is much higher than its consumption rate. Cenosphere is one of the most value-added fractions of coal fly-ash. It has a hollow spherical structure and can be applied in many industrial applications, due to its superior properties, such as low bulk density, good thermal resistance, high strength, etc. The present work deals with the usage of fly-ash cenosphere to develop the paper battery and electrochemical battery. The study demonstrates the process of chemical deposition of Cu-ion on cenosphere by electro-less plating technique using silver-nitrate as an activator. Subsequently, metal-ion-coated cenosphere is used for developing the paper battery and electrochemical battery; testing is done by measuring the open circuit voltage (OCV) and by analyzing the discharge curves of battery. The present work analyzes various factors and characteristics affecting the performance of developed batteries.
The objective of present work is to explore the applications of low-cost materials like cenosphere, ordinary paper, cotton-balls and aluminum powder for developing thinner batteries like paper battery. The results confirm that the copper-ion-coated cenosphere can be successfully applied for developing electrochemical battery.
... SiO 2 NPs served as a substrate for the continuous deposition of copper. Nanoporous silica doped with copper nanocrystallites displayed antibacterial properties and had bactericidal effects on many pathogenic bacterial species (Singh et al. 2010). Therefore, the nanoporous CAS was synthesized via a green method to eradicate pathogenic microbes and to use as a disinfectant in drinking water and wastewater treatment. ...
We used a green sol–gel synthesis method to fabricate a novel nanoporous copper aluminosilicate (CAS) material. Nanoporous
CAS was characterized using X-ray powder diffraction (XRD), field emission transmission and scanning electron microscopies
(FE-TEM/FE-SEM), Fourier transform infrared (FTIR) spectroscopy, and optical analyses. The CAS was also evaluated for use
as a promising disinfectant for the inactivation of waterborne pathogens. The antimicrobial action and minimum inhibitory
concentration (MIC) of this CAS disinfectant were determined against eight microorganisms (Escherichia coli, Salmonella
enterica, Pseudomonas aeruginosa, Listeria monocytogenes, Staphylococcus aureus, Enterococcus faecalis, Candida albicans,
and Aspergillus niger). An antimicrobial susceptibility testing of CAS was measured. Results of disc diffusion method pointed
out that the diameters of the zone using well diffusion were wider than disc diffusion methods, and the findings also showed that
the MIC of the CAS disinfectant against E. coli, S. enterica, and P. aeruginosa was 100 mg/L within 20 min of contact time.
Meanwhile, the MIC of the CAS disinfectant was 100 mg/L within 40 min of contact time for the other strains. The efficacy of
antimicrobial action (100%) reached within 20 to 40 min against all tested microbes. Herein, the antimicrobial susceptibility
testing of CAS disinfectant showed no toxicity for human and bacterial cells. It can be concluded that nanoporous CAS is a
promising, economically, and worthy weapon for water disinfection.
... SiO 2 NPs served as a substrate for the continuous deposition of copper. Nanoporous silica doped with copper nanocrystallites displayed antibacterial properties and had bactericidal effects on many pathogenic bacterial species (Singh et al. 2010). Therefore, the nanoporous CAS was synthesized via a green method to eradicate pathogenic microbes and to use as a disinfectant in drinking water and wastewater treatment. ...
We used a green sol–gel synthesis method to fabricate a novel nanoporous copper aluminosilicate (CAS) material. Nanoporous
CAS was characterized using X-ray powder diffraction (XRD), field emission transmission and scanning electron microscopies
(FE-TEM/FE-SEM), Fourier transform infrared (FTIR) spectroscopy, and optical analyses. The CAS was also evaluated for use
as a promising disinfectant for the inactivation of waterborne pathogens. The antimicrobial action and minimum inhibitory
concentration (MIC) of this CAS disinfectant were determined against eight microorganisms (Escherichia coli, Salmonella
enterica, Pseudomonas aeruginosa, Listeria monocytogenes, Staphylococcus aureus, Enterococcus faecalis, Candida albicans,
and Aspergillus niger). An antimicrobial susceptibility testing of CAS was measured. Results of disc diffusion method pointed
out that the diameters of the zone using well diffusion were wider than disc diffusion methods, and the findings also showed that
the MIC of the CAS disinfectant against E. coli, S. enterica, and P. aeruginosa was 100 mg/L within 20 min of contact time.
Meanwhile, the MIC of the CAS disinfectant was 100 mg/L within 40 min of contact time for the other strains. The efficacy of
antimicrobial action (100%) reached within 20 to 40 min against all tested microbes. Herein, the antimicrobial susceptibility
testing of CAS disinfectant showed no toxicity for human and bacterial cells. It can be concluded that nanoporous CAS is a
promising, economically, and worthy weapon for water disinfection.
... Copper NPs homogeneously formed on the surface of SiO 2 nanoparticles did not undergo aggregation and exhibited excellent antibacterial activity with respect to multiple microorganisms. Nanosilica modified on the surface with copper particles exhibited antibacterial properties, and was used to remove the odour of mercaptans and sulfur compounds from petroleum [40]. ...
A biofunctionalization of nonwoven fabrics was carried out with 0.1 - 4 wt.% of copper silicate. Polypropylene (PP), polyethylene (PE) and biodegradable polymers [poly(lactic acid) (PLA), polyhydroxyalkanoates (PHA)] or their mixtures were used as polymer components. Mostly liquid oligomers of ethylene glycol (PEG) or copolymers of ethylene oxide and propylene oxide (2.5 - 5 wt.%) were applied as plasticizers. New composite nonwovens containing CuSiO3 were prepared by the melt-blown technique [1]. They showed very good antibacterial and antifungal properties against colonies of gram-negative bacteria (Escherichia coli), gram-positive bacteria (Staphylococcus aureus) and a yeast fungus (Candida albicans). Nonwovens containing ≥ 0.5 wt.% of CuSiO3 can be used, e.g. as hygienic and bioactive filter materials in air-conditioning systems. The application of PLA and PHA affects the ability of these hybrid nonwovens to biologically decompose. DSC analysis indicated that the incorporation of additives in PLA and PP nonwovens significantly affected their melting and crystallization processes. © 2016, Institute of Biopolymers and Chemical Fibres. All rights reserved.
... Metal nanoparticles supported on metal oxides and carbon surfaces are the basis for many catalysts of importance in energy technologies, pollution prevention, and environmental cleanup [2]. From the different kinds of supported metal nanoparticles, those having copper are highlighted due to their wide range of applications, especially in catalysts [3][4][5][6][7][8][9][10]. Dispersed copper catalysts have been of great interest in several reactions from steam reforming to biosensing applications [11]. ...
... Other protocols based on wet-chemical methods were also reported, for example, polyol reduction [226,227], hydrothermal synthesis [228], microwave heating in the presence [229,230] or absence of stabilizers (e.g., CS or starch) [231], or UV photoreduction [232]. ...
The antimicrobial properties of metals such as silver and copper have been known for centuries whereas the use of nanostructures and nanotechnology in antimicrobial strategies is an emerging area of research. Recently, the confluence of nanotechnology and the search for new agents in the fight against microbes with multi-drug resistance has brought metals in the form of nanoparticles (NPs) to the fore as potential antimicrobial agents. NPs have unique and well-defined physical and chemical properties that can be manipulated for desired applications, and the antimicrobial efficacy of metallic NPs is highly dependent on their large surface area to volume ratio. In this chapter, we review the properties of a range of metal and metal oxide NPs, such as those derived from copper, silver, zinc, and so on, along with different strategies for their development. In addition, we describe potential applications of NPs as antimicrobials in areas such as medical devices, the food industry, and textile fabrics.
... In previous studies, antimicrobial effects by which several clay minerals acted were notably explained as follows: (1) interaction phenomena between organic molecules 23 (e.g., humic acid), inorganic ions, and microorganisms; (2) the formation of C−O−Na−Si complexes on the surfaces of bacterial cell walls; 24,25 (3) drug loadings of modified clays; 26,27 (4) particle size of clay minerals; 28,29 and (5) the antimicrobial activity was the synergistic effect of the amount of drug released, surface charge, and particle size of organo-clay minerals. 2 As is well-known, DTP is an organic antibacterial agent, and is dangerous to living organisms. ...
In order to extend the antibacterial time of quaternary phosphonium salt in bacteria, palygorskite (PGS) is used as the carrier of dodecyl triphenyl phosphonium bromide (DTP), and a DTP-PGS hybrid is prepared. Antibacterial performance of this novel hybrid is investigated for both Gram-positive and Gram-negative bacteria. The results show that the DTP could be absorbed on the surface of PGS which had bacteria-adsorbed capability. The DTP-PGS hybrid, combining the advantages of PGS and DTP, display specific-targeting capability, long-term antibacterial activity and lower cytotoxicity, suggesting the great potential application as PGS-based antibacterial powder.
Particulate and surfactant systems are an integral part either in processing or product lines in essentially every major industry, including Energy and Minerals, Pharmaceutical, Agriculture & Food, Microelectronics, Healthcare, Cosmetics, Consumer Products, and Analytical Instrumentation & Services. In most applications, product and process specifications depend on the synergistic or competitive interactions between the particles and reagent schemes. The primary goal of our research efforts has been to generate the structure-property-performance correlations-based knowledge and technology platforms for industry to develop more sustainable products and processes. Engineering the physicochemical/mechanical properties of surfaces, particles, and self-assembling surfactant systems enables their enhanced performance in industrial applications. Specifically, understanding and control of the nano and atomic-scale forces between particles and synthesis of functionalized particles form the foundation for targeted contributions in biomedical, advanced materials and minerals, sensor, and coating technologies. A synoptic overview of selected projects is presented in this review. Additional details can be found in the topic-specific references listed at the end of this manuscript.
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Cosmetics, preparations repeatedly applied directly to the human skin, mucous membranes, hair and nails, should be safe for health, however, recently there has been increasing concern about their safety. Unfortunately, using these products in some cases is related to the occurrence of unfavourable effects resulting from intentional or the accidental presence of chemical substances, including toxic metals. Heavy metals such as lead, mercury, cadmium, arsenic and nickel, as well as aluminium, classified as a light metal, are detected in various types of cosmetics (colour cosmetics, face and body care products, hair cosmetics, herbal cosmetics, etc.). In addition, necessary, but harmful when they occur in excessive amounts, elements such as copper, iron, chromium and cobalt are also present in cosmetic products. Metals occurring in cosmetics may undergo retention and act directly in the skin or be absorbed through the skin into the blood, accumulate in the body and exert toxic effects in various organs. Some cases of topical (mainly allergic contact dermatitis) and systemic effects owing to exposure to metals present in cosmetics have been reported. Literature data show that in commercially available cosmetics toxic metals may be present in amounts creating a danger to human health. Thus, the present review article focused on the problems related to the presence of heavy metals and aluminium in cosmetics, including their sources, concentrations and law regulations as well as danger for the health of these products users. Owing to the growing usage of cosmetics it is necessary to pay special attention to these problems. Copyright © 2015 John Wiley & Sons, Ltd.
Copyright © 2015 John Wiley & Sons, Ltd.
This Chapter reports on the advances in 2010 in the field of nanoparticles.
Ultrasmall copper nanoparticles (1.6 nm) on silica catalysts were successfully prepared via an in situ self-assembled core–shell precursor route. XRD, SEM-EDS and chemisorption results showed that only fatty acids with carbon chain length > 2 carbon atoms could effectively promote the dispersion of copper on silica. XPS results showed that non-stoichiometric copper butyrate was formed when butyric acid was used as a capping agent, and this non-stoichiometric compound of copper butyrate self-assembles into a shell structure outside the core of copper nitrate species. The in situ self-assembled core–shell structure could effectively prevent the copper particles from agglomeration. The catalytic performances of as-prepared 10% Cu/SiO2 catalysts enhanced with fatty acids with carbon chain length > 2 carbon atoms exhibited good activities for water–gas shift reaction due to the high proportion of defect sites, highly dispersed Cu particles and/or isolated Cu atom sites.
Zinc ferrite supported on porous carbon (ZFPC) was prepared by thermal conversion of a mixture of ferric nitrate, zinc chloride, and novolac resin and was used as a catalyst for the catalytic oxidation of mercaptan under alkali-free conditions. ZFPC exhibited a high butyl mercaptan removal efficiency (222.29 mg/g), fast catalytic degradation rate, stable catalytic activity, and outstanding regenerative ability. It is believed that the effective butyl mercaptan removal was achieved by the synergism between adsorption of porous carbon and catalysis of zinc ferrite. The mechanism of catalytic oxidation of mercaptan into disulfides by ZFPC was further discussed based on the contrast experiment. The results indicated that oxidation of mercaptan in the presence of ZFPC followed the Merox process, in which Zn(II) acted as basic sites and Fe(III) acted as oxidation sites.
The present study describes the synthesis, characterization, and catalytic activity of Cu(II) containing nanosilica triazine dendrimer (Cu(II)-TD@nSiO(2)). The prepared catalyst was characterized by FT-IR, TGA, elemental analysis, UV-vis, FE-SEM, TEM, XPS and ICP-OES techniques. The Cu(II)-TD@nSiO(2) has been used as an efficient catalyst for the preparation of various benzimidazoles, benzothiazoles, symmetrical bis-benzimidazoles and bis-benzothiazoles under mild conditions. For the first time, we report the synthesis of an unsymmetrical bis-benzimidazole and also a compound containing both benzimidazole and benzothiazole moieties, indicating the efficiency of this catalytic system. The present method offers advantages of excellent yields, short reaction times and simple work-up. Also, the catalyst can be easily recycled and reused several times, which makes this method attractive, economic and environmentallybenign.
Antimicrobial properties of copper (Cu) and silver (Ag) ions have been widely studied. Hundreds of nanotech based consumer products are now available in the market which uses antimicrobial Ag nanoparticles. Cu and Cu alloy based touch surfaces are shown to be effective in controlling bacterial infection. In this study, we will present our research on synthesis and characterization of sol-gel silica nanoparticle/nanogel materials loaded with antimicrobial Cu and Ag. Structure/morphology and antimicrobial properties of the silica nanoparticle/nanogel delivery system with and without containing the active agent (Cu or Ag) will be discussed. We have tested antimicrobial properties of these materials against both gram-negative (E. Coli) and gram-positive (B. Subtilis) bacteria. Our results on Cu nanomaterials showed improved antibacterial efficacy of Cu loaded silica nanomaterial over its Cu source while the concentration of metallic Cu remained the same. Several materials characterization techniques were used to understand structure-property relationship using Cu loaded silica nanoparticle/nanogel nanomaterial.
In order to improve the water-solubility and long-term antibacterial activity of copper nanoparticles (CuNPs), a poly-l-lysine-modified reduced graphene oxide (PLL-rGO) was used as the carrier of CuNPs, and a poly-l-lysine/reduced graphene oxide/copper nanoparticles (PLL-rGO-CuNPs) hybrid was prepared by anchoring the CuNPs on the reduced graphene oxide surface. The novel PLL-rGO-CuNPs hybrid was characterized and the antibacterial activity of it on gram-negative Escherichia coli and Gram-positive Staphylococcus aureus was tested. Such a hybrid showed additively antibacterial activity, and the CuNPs on PLL-rGO were more stable than those on polyvinyl pyrrolidone, resulting in long-term additively antibacterial effect. Meanwhile, this hybrid showed excellent water-solubility, suggesting great potential application in microbial control.
Luciferase is a powerful tool in bioanalysis. Several well-established methods employ luciferases, particularly firefly and Renilla luciferases, as reporter genes or biosensors in environmental, biomedical and biochemical research. These techniques have interesting features for the analyst such as sensitivity, specificity and reduced assay time. Nanochemistry and Nanotechnology are disciplines that are gaining much attention and evolving rapidly. They allow the development of custom-made nanomaterials with the desired properties, starting from conventional bulk materials. Recently, the coupling of nanomaterials such as carbon nanotubes, mesoporous silica nanoparticles, metallic nanoparticles and quantum dots with luciferases led to new or improved methodologies for analyte quantification and enhanced gene delivery strategies. One of the principal scopes is to modulate or alter luciferase's bioluminescence emission, either by stabilizing it or tuning it to longer wavelengths. This chapter aims to present state-of-art articles regarding new methods based on the coupling of luciferases to nanomaterials, along with a brief introduction to Nanoscience.
We report synthesis of a novel core-shell silica based antimicrobial nanoparticles where the silica shell has been engineered to accommodate copper (Cu). Synthesis of the core-shell Cu-silica nanoparticle (C-S CuSiO2NP) involves preparation of base-hydrolyzed Stöber silica "seed" particles first, followed by the acid-catalyzed seeded growth of the Cu-silica shell layer around the core. The Scanning Electron Microscopy (SEM) and the Transmission Electron Microscopy (TEM) measured the seed particle size to be -380 nm and the shell thickness to be -35 nm. The SEM particle characterization confirms formation of highly monodispersed particles with smooth surface morphology. Characterization of particle size distribution in solution by Dynamic Light Scattering (DLS) technique was fairly consistent with the electron microscopy results. Loading of Cu to nanoparticles was confirmed by the SEM-Energy Dispersive X-Ray Spectroscopy (EDS) and Atomic Absorption Spectroscopy (AAS). The Cu loading was estimated to be 0.098 microg of metallic copper per mg of C-S CuSiO2NP material by the AAS technique. Antibacterial efficacy of C-S CuSiO2NP was evaluated against E. coli and B. subtilis using Cu hydroxide ("Insoluble" Cu compound, sub-micron size particles) as positive control and silica "seed" particles (without Cu loading) as negative control. Bacterial growth in solution was measured against different concentrations of C-S CuSiO2NP to determine the Minimum Inhibitory Concentration (MIC) value. The estimated MIC values were 2.4 microg metallic Cu/mL for both E. coli and B. subtilis. Bac-light fluorescence microscopy based assay was used to count relative population of the live and dead bacteria cells. Antibacterial study clearly shows that C-S CuSiO2NP is more effective than insoluble Cu hydroxide particles at equivalent metallic Cu concentration, suggesting improvement of Cu bioavailability (i.e., more soluble Cu) in C-SCuSiO2NP material due to its core-shell design.
Wastewater treatment plant odors are caused by compounds such as hydrogen sulfide (H2S), methyl mercaptans, and carbonyl sulfide (COS). One of the most efficient odor control processes is activated carbon adsorption; however, very few studies have been conducted on COS adsorption. COS is not only an odor causing compound but is also listed in the Clean Air Act as a hazardous air pollutant. Objectives of this study were to determine the following: (1) the adsorption capacity of 3 different carbons for COS removal; (2) the impact of relative humidity (RH) on COS adsorption; (3) the extent of competitive adsorption of COS in the presence of H2S; and (4) whether ammonia injection would increase COS adsorption capacity. Vapor phase react (VPR; reactivated), BPL (bituminous coal-based), and Centaur (physically modified to enhance H2S adsorption) carbons manufactured by Calgon Carbon Corp. were tested in three laboratory-scale columns, 6 in. in depth and 1 in. in diameter. Inlet COS concentrations varied from 35 to 49 ppmv (86-120 mg/m3). RHs of 17%, 30%, 50%, and 90% were tested. For competitive adsorption studies, H2S was tested at 60 ppmv, with COS at 30 ppmv. COS, RH, H2S, and ammonia concentrations were measured using an International Sensor Technology Model IQ-350 solid state sensor, Cole-Parmer humidity stick, Interscan Corp. 1000 series portable analyzer, and Drager Accuro ammonia sensor, respectively. It was found that the adsorption capacity of Centaur carbon for COS was higher than the other two carbons, regardless of RH. As humidity increased, the percentage of decrease in adsorption capacity of Centaur carbon, however, was greater than the other two carbons. The carbon adsorption capacity for COS decreased in proportion to the percentage of H2S in the gas stream. More adsorption sites appear to be available to H2S, a smaller molecule. Ammonia, which has been found to increase H2S adsorption capacity, did not increase the capacity for COS.
The electron spin resonance of Mn(H2O)2+6 and of Cu(H2O)2+6 ions was used to investigate the mobility and the freezing properties of water adsorbed on silica gel samples with pore diameters of 4, 6, 20, and 100 nm. The lineshape analysis of the esr spectra shows that the first two or three layers of water molecules are strongly immobilized even at room temperature, while at least the first ten layers from the surface do not freeze at any low temperature. Beyond this limit, the water seems to behave like normal water.
Odors from New York City's sewage treatment plants are controlled by activated carbon housed in 44 large towers, each holding about 11 tons of carbon. The carbons are impregnated with NaOH or with KOH, or are unimpregnated but continuously injected with ammonia gas.
A study is now under way in our laboratory to monitor the progressive exhaustion of these carbon beds and to predict their useful lifetimes. The monitoring tests include a measure of the residual breakthrough capacity of the carbon for hydrogen sulfide, and an estimate of the remaining capacity for physical adsorption of other gases. For the caustic-impregnated carbons, the tests include a measure of the actual life-extension that can be realized by the retrofit of ammonia injection without interrupting the operation of the carbon vessels. A procedure to predict the results of in situ regeneration is described.
Charlotte-Mecklenburg Utilities (Utilities) has received increasingly frequent complaints about odors at the Six-Mile Creek Pump Station force main discharge, downstream throughout the gravity system to McAlpine Creek Water Reclamation Facility (WRF), and at the WRF. Utilities is committed to adding odor control at these facilities. The primary objective of the caustic slugging operation was to provide an immediate short-term solution to reduce odors and eliminate complaints in the Ballantyne neighborhood through which the wastewater discharged from the pump station force main flows by gravity. A secondary objective was to provide data that would assist in developing a long-term solution for odor control in that area of the collection system. The objective was to be achieved by passing a slug of caustic (sodium hydroxide) down the force main to kill the bacteria that produce odorous sulfides. Modifications to pumping cycles were also planned as part of the operation. The caustic slugging only provided reduced hydrogen sulfide (H2S) levels for 4 days before the levels returned to pre-treatment levels. Modifying the pump cycle to a longer run time appeared to provide longer results.
Pure SiO2 having a MCM-41 structure was modified by the introduction of 1 mmol/g of Al, Zr, W, B, or P. The parent silica and the modified materials were used to support a dispersed cupric oxide. The distribution, properties and thermal stability of the catalytic Cu2+-active sites were examined by ESR and IR spectroscopy and by measuring the activity in a test reaction of ethane oxidation. Modification of the parent silica MCM-41 influences drastically the stabilization of isolated Cu2+-species. Al-MCM-41 provides the most disperse (70–80%) and thermally stable state of the cupric phase. However, no simple correlation exists between the total number of surface Cu2+-sites and the catalytic activity. The specific catalytic activity (per one Cu2+-active site accessible to the reactants) depends strongly on the structure of the localized site. Isolated Cu2+-sites grafted to Al-MCM-41 show relatively high activity for the sample calcined at 520 °C. Thermal treatment at 650–750 °C causes a sharp loss of specific Cu2+ catalytic activity of Cu/Al-MCM-41 (as is also the case with CuH-ZSM-5). The less disperse cupric phase in non-modified MCM-41 demonstrates a higher specific catalytic activity.
The role of the bis(μ-oxo)dicopper core, i.e., [Cu2(μ-O)2]2+, in the decomposition of NO and N2O by the Cu-ZSM-5 zeolite has been studied with combined operando UV–vis monitoring of the catalyst and on-line GC analysis. An optical fiber was mounted on the outer surface of the quartz wall of the plug-flow reactor and collected the UV–vis diffuse reflectance spectra under true catalytic conditions. Measurement under transient reaction conditions indicated that [Cu2(μ-O)2]2+ is formed by O abstraction of N2O, which is an intermediate in the NO decomposition. This conversion of N2O to N2 and O2 is strongly retarded below 673 K. Above 673 K, the produced [Cu2(μ-O)2]2+ fulfills the role of O2 release, guaranteeing the self-reduction of the catalytic site. Studying the NO decomposition as a function of the O2 content in the feed strongly suggested that O2 release from [Cu2(μ-O)2]2+ is rate limiting in the NO decomposition at 773 K.
The hydrogenation of 1,3-cyclooctadiene and the CO-NO reaction have been studied on Cu/TiO{sub 2} catalysts, with reference to the effects of the preparation method and of the reductive pretreatments of the samples. In the hydrogenation of 1,3-cyclooctadiene at 433 K, a marked difference in activity is observed between catalysts prepared by a chemisorption-hydrolysis method (C) and those prepared by wet impregnation, the former showing turnover numbers about 100 times greater than the latter. This large difference in activity is ascribed to differences in the morphology of the copper species present at the surfaces of the two different kinds of catalysts: there are three-dimensional stepped small particles of Cu in the first case (C), very efficient in hydrogen dissociation, whereas there are isolated copper sites embedded in the reduced support in the second case (1), very much less active toward hydrogen dissociation. In the CO-NO reaction, C samples show a decrease in the activity on increasing the catalyst prereduction temperature, while an opposite behavior is observed on I samples. For this reaction the rate determining step is NO dissociation; the interpretation of the apparently conflicting data is that NO dissociation occurs efficiently on copper sites on mildly reduced C catalysts exposing three-dimensional copper particles and also on reduced titania sites formed in the high-temperature reductive treatments on I catalysts. 19 refs., 7 figs., 2 tabs.
Three 8 wt% copper catalysts supported on SiO{sub 2} and on two SiO{sub 2}/TiO{sub 2} powders with different TiO{sub 2} content have been prepared by a chemisorption-hydrolysis method. Transmission electron microscopy indicated that after calcination the three catalysts contain supported particles which are small and quite homogeneous in size (mean diameter, d{sub m} = 3.0 nm). These particles slightly increase in size after reduction in H{sub 2} up to 773 K (d{sub m} = 3.5 nm). On the basis of the diffuse reflectance UV-Vis-NIR spectra CuO and Cu{sub 2}O were found to be present after calcination, while the electronic spectra were dominated by the features due to metallic Cu particles already after a mild reduction in H{sub 2} at 523 K. FTIR spectra of CO adsorbed onto the three catalysts reduced at 523 K appeared very similar. By a spectral fitting procedure, four different carbonylic species were evidenced, three assigned to carbonylic adducts on different types of microfacets exposed at the surface of three-dimensional Cu particles and one related to CO molecules adsorbed on plate-like two-dimensional copper particles. By increasing the reduction temperature an overall decrease in intensity of the bands due to CO adsorbed on copper supported on silica-titania carriers was observed, probably because of the formation of titanium suboxides that can cover a fraction of the copper sites. Furthermore, the CO-O{sub 2} and CO-NO reactions were studied by FTIR spectroscopy of the adsorbed species and quadrupole mass analysis of the gas phase over the catalysts. This allows the elucidation of the nature of the surface sites involved in the activation of these molecules and the nature of the intermediates present at the surface of the catalysts during the reactions. The role played in these reactions by the uncoordinated copper surface atoms exposed at the surface of the two different types of Cu particles will be discussed.
Wastewater treatment plant odors are caused by compounds such as hydrogen sulfide (H{sub 2}S), methyl mercaptans, and carbonyl sulfide (COS). One of the most efficient odor control processes is activated carbon adsorption; however, very few studies have been conducted on COS adsorption. COS is not only an odor causing compound but is also listed in the Clean Air Act as a hazardous air pollutant. Objectives of this study were to determine the following: (1) the adsorption capacity of 3 different carbons for COS removal; (2) the impact of relative humidity (RH) on COS adsorption; (3) the extent of competitive adsorption of COS in the presence of H{sub 2}S; and (4) whether ammonia injection would increase COS adsorption capacity. Vapor phase react (VPR; reactivated), BPL (bituminous coal-based), and Centaur (physically modified to enhance H{sub 2}S adsorption) carbons manufactured by Calgon Carbon Corp. were tested in three laboratory-scale columns. It was found that the adsorption capacity of Centaur carbon for COS was higher than the other two carbons, regardless of RH. As humidity increased, the percentage of decrease in adsorption capacity of Centaur carbon, however, was greater than the other two carbons. The carbon adsorption capacity for COS decreased in proportion to the percentage of H{sub 2}S in the gas stream. More adsorption sites appear to be available to H{sub 2}S, a smaller molecule. Ammonia, which has been found to increase H{sub 2}S adsorption capacity, did not increase the capacity for COS.
Radial copper concentration profiles from alumina pellets impregnated with aqueous solutions of copper(II) chloride are presented. Temperature programmed reduction and electron spin resonance measurements indicate the presence of at least two differently immobilized species. Copper ions which are reduced at temperatures between 350 and 400°C are assigned to immobilization by strong adsorption. The species which are reduced at lower temperatures (210 – 240°C) are predominantly formed during drying by precipitation from the liquid enclosed in the pore volume. The influence of impregnation time and concentration of the impregnant solution on the distribution of these two species is discussed. A precipitation step subsequent to impregnation leads to changes in the radial profiles and to prevalence of the copper ions reducible at low temperatures.
Cotton fabric with a deodorizing function is prepared by mordant dyeing with direct dyes containing copper ions and copper(II) nitrate. The effects of pre- and after-mordant ings and after-treatment with copper(II) nitrate are examined for C.I. Direct Violet 47 and C.I. Direct Black 112. The copper ion uptake of cotton dyed with pre- and after mordantings is about 1/10 the value for wool samples. The elimination of ethyl mercaptan from air by the mordant dyed fabrics is measured in a Teddler bag. Untreated cotton fabric shows no deodorizing ability, but each of the pre-mordanted, dyed, after-mordanted, and after-treated fabrics shows a considerable deodorizing ability. The effects of after mordanting and after-treatment are particularly notable, implying that they are caused by dye-copper ion complexes.
Copper-exchanged zeolites, Beta and ZSM-5, were studied using variable-temperature electron paramagnetic resonance (EPR) spectroscopy to probe changes in the local environment of the Cu2+centers when samples were dehydrated and heated in flowing helium or under reagent flow. Hydrated samples of Cu-ZSM-5 and Cu-Beta exhibited EPR spectra consistent with EPR signals previously assigned to Cu2+in distorted octahedral coordination. EPR spectra of dehydrated Cu-Beta and Cu-ZSM-5 showed the presence of coordination environments that were similar to EPR signals previously assigned to Cu2+in distorted square pyramidal and distorted square planar environments. An empirical model is presented that correlatesg∥andA∥for a series of copper-exchanged zeolites and model compounds and provides additional insight into the coordination environment of Cu2+in copper-exchanged zeolites. The empirical model links a number of past EPR studies on different copper-exchanged zeolites and provides an explanation for the observed trends in EPR parameters related to the charge at the copper center. The EPR spectra for dehydrated Cu-ZSM-5 and Cu-Beta samples exhibited a temperature dependence. The EPR spectrum of Cu-ZSM-5 and Cu-Beta recorded at 673 K showed an increase ing∥and a decrease inA∥when compared with the EPR spectrum recorded at room temperature. These changes in spectral parameters are attributed to changes in the electronic environment of the Cu2+species through modification of the coordination environment.
Supported copper particles are widely used in heterogeneous catalysis. Influence of supports of different nature on the Cu particles formation is studied by the methods of UV–Vis spectroscopy of diffuse reflectance, XRD and electron microscopy. Different states of supported copper have been identified by UV–Vis spectroscopy: absorption bands at 250 (Cu+), 320–370 and 400–440 (charge transfer bands of O–Cu–O and Cu–O–Cu complexes), 520–580 (Cun plasmon resonance) and 620–850 nm (d–d transitions in Cu2+ ions). The size of Cu clusters and Cun/Cunδ+ ratio strongly depends on the support nature.
Detailed X-band EPR studies on 1.0 mol% copper oxide doped silica gels, oven dried as well as calcined at various temperatures up to 1000 °C have been carried out in the temperature range 10.4–300 K. Spin Hamiltonian and line-width parameters are determined by computer simulation of the observed spectra. Important information derived on the dynamics of the porous structure of Cu-doped silica gel in the light of the EPR parameters is as follows: (i) Three kinds of Cu2+ species (including one Cu-pair) are present in the 100 °C oven dried silica gel. (ii) Two kinds of slow rotating isolated Cu2+ species (one Cu2+ pair) occur in the 400 °C calcined sample at room temperature. The Cu-pair species agglomerate at low temperatures (⩽200 K) to form CuO clusters which remain undetected apparently because of their large line-width. (iii) Only one kind of Cu-species is detected in the 700 °C calcined silica glass at all measuring temperatures. The Cu2+-pair/CuO cluster spectrum is absent. (iv) The isotropic EPR spectrum due to rapidly rotating Cu2+-species occurring in very large pores of silica glass calcined at 800 °C has been obtained at room temperature. (v) Pore collapse starts at 900 °C, and results in the observance of a very broad EPR line (∼5000 Oe) for 900 and 1000 °C calcined samples. This shows that the pore collapse and the formation of superparamagnetic nano-sized CuO particles in the silica glass matrix take place simultaneously.
Orientation and charge transfer upon adsorption of ethanethiol on Cu(111) surface at 85 K has been investigated by S K-edge near edge X-ray absorption fine structure (NEXAFS) and X-ray photoelectron spectroscopy (XPS) techniques. Exposure-dependent S K-edge NEXAFS identified the monolayer saturation at ∼0.8 L exposure. Polarization-dependent NEXAFS spectra of submonolayer ethanethiol shows that S–C bond is tilted 37±7° from the surface. Temperature-dependent NEXAFS spectra shows that ethyl thiolate starts breaking at 300–350 K and atomic sulfur creates. A significant amount of charge transfer (1.4 electrons) from copper to ethanethiol molecules has measured by S 1s XPS technique.
A brief review of the chemistry of copper and thiols is given and a contrast is made to the behavior of copper-containing adsorbents used for the desulfurization of liquid hydrocarbon streams that are routinely treated in refinery processes. A study was made of the chemistry between copper adsorbents and model liquid feed streams containing mercaptans. It was found that sulfur capacity can be quite high, greater than 8% by weight, and is dependent on the dispersion of the copper oxide on the adsorbent. In addition, it is shown that bulk copper is involved in the adsorption of mercaptans, as there is significantly more sulfur than there is copper on the surface. At a temperature of approximately 150°C, very well formed lamellar crystals of copper(I) thiolate are formed, which indicates that the copper migrates from the surface of the catalyst to expose bulk copper for further reaction. When the temperature is raised to 190°C, there is evidence that the copper(I) butanethiolate decomposes to copper(I) sulfide. Reaction mechanisms are proposed for the process of desulfurization of liquid hydrocarbon streams containing mercaptans when using a copper-containing adsorbent.
A series of novel Cu-incorporated mesoporous materials (CMMs) with molar ratios of Cu/Si ranging from 1/200 to 1/20 were synthesized by sol–gel method using glutaric acid as template. The materials were characterized by powder X-ray diffraction (XRD), N2 adsorption, diffuse reflectance UV–vis spectroscopy and transmission electron microscopy (TEM). The results indicate that the CMMs have a three-dimensional (3D) worm-like mesoporous structure with a surface area between 600 and 800m2g−1 and the copper ions are incorporated into the matrix with octahedral environment. The catalytic activity of these CMMs in the phenol hydroxylation using H2O2 as oxidant is comparable to that of TS-1. Effects of Cu/Si molar ratio in the catalyst and the influence of various reaction parameters on the catalytic activity were investigated in detail and the optimized reaction condition was acquired.
A complex oxide of Cu2(OH)PO4 has been successfully synthesized by the hydrothermal method, and its structure was investigated by X-ray analysis. It crystallizes in the orthorhombic space group of Pnnm with a=8.058(2), b=8.393(2), and c=5.889(2) Å. Furthermore, the sample was characterized by thermal analysis (DTA and TG), and these results indicated that the sample was stable below 650°C. After calcination at 850°C, Cu2(OH)PO4 was dehydrated to form Cu4O(PO4)2. The sample isotherm for N2 showed that there wre no micropores or mesopores, and the surface area was only at 1.4 m2/g when the particle size of the sample was 150 μm. Moreover, when this sample was used as a catalyst for phenol hydroxylation by H2O2, the catalytic data showed high activity, which was comparable to that of TS-1. Various factors that influence this catalytic reaction, such as the solvent, reaction temperature, reaction time, catalyst size, catalyst amount, molar ratio of phenol to H2O2, and mode of H2O2 addition, were investigated intensively. Additionally, this catalytic reaction was characterized by electron spin resonance (ESR), and it was found that on the Cu2(OH)PO4 catalyst hydroxyl radicals possibly resulting from Cu2+ and H2O2 were important intermediates for formation of catechol and hydroquinone from hydroxylation phenol.
Because effluents to atmosphere from sewage treatment typically include hydrogen sulfide (H2S) among other malodors, and because H2S is a light gas, it is commonly assumed that unmodified (“virgin”) activated carbon, which acts largely by physical adsorption, is inadequate for such applications. Instead, caustic-impregnated and other modified carbons have been used in the U.S.A., Europe, and Israel for odor control where H2S is an expected airborne component.
Our laboratory and full-scale comparative studies question this assumption and practice, and strongly support the advantages of virgin over impregnated or other special carbons for control of H2S as well as for general odor removal. In this report, we suggest that biofiltration in the carbon bed helps achieve such favorable outcomes.
Methyl mercaptan (CH3SH) is a representative odorous pollutant from various odor emission sources such as sewage and municipal solid wastes. This study confirms that CH3SH in a synthetic foul gas can be effectively decomposed by UV-C (<280 nm) photolysis using germicidal lamps, but is resistant to destruction under UV-A (365 nm) irradiation using black-light lamps. This study also demonstrates that CH3SH in foul gas can be successfully degraded by photocatalytic oxidation under UV-A irradiation using TiO2-based photocatalysts. In this study, two new catalysts, NH4+-modified TiO2 (NH4+-TiO2) and SO42--modified TiO2 (SO42--TiO2), were prepared by a precipitate-refluxing method and a hydrothermal method, respectively. These two catalysts as well as the commercially available catalyst Degussa P25 (P25-TiO2) were used for the photocatalytic degradation of CH3SH. It was found that the NH4+-TiO2 catalyst achieved a better performance than P25-TiO2, whereas SO42--TiO2 demonstrated a poorer performance. The high photocatalytic activity of NH4+-TiO2 for CH3SH degradation results from its basic characteristics and the presence of an ammonium (NH4+) group on the NH4+-TiO2 catalyst surface. The photocatalytic degradation of CH3SH was further studied using the P25-TiO2 catalyst under different experimental conditions. The experimental results showed that catalyst loading, relative humidity, and initial concentration could influence the efficiency of CH3SH photocatalytic degradation significantly. It was found that a catalyst loading of 3.93 mg cm-2 and a relative humidity of 43% are two essential factors for achieving the best performance under these experimental conditions. This work provides new insights into the removal of a sulfur-containing organic substance (CH3SH) from the gas phase by both photolysis and photocatalytic oxidation processes.
Thiols can be selectively removed and recovered from a hydrocarbon stream by a heterogeneous reaction with oxides and hydroxides of Pb, Hg(II), and Ba. Alkanethiols of lengths n-C6, n-C8, and n-C12 were found to react with powdered metal oxides to form stable thiolates that are solid at room temperature and insoluble in aqueous and organic solvents. The reaction converts the solid oxide phase into a solid thiolate phase, removing ions from the surface of the oxide, allowing the reaction to reach completion. The thiolates can be removed from the feed stream by filtration. Once separated, the metal and the original thiols can be recovered by extraction with a dilute acid, yielding a metal salt in the aqueous phase and a hydrophobic layer of thiol. The choice of reactive metal oxides may be predicted from simple thermodynamic considerations.
A series of Ni(II) complexes containing polyamines and 1, 2, or 3 labile aqua ligands ([Ni(en)(dien)(H2O)]2+, [Ni(en)2(H2O)2]2+, [Ni(dien)(H2O)3]2+) were selectively adsorbed on the same silica support. In all cases, saturation coverages derived from adsorption isotherms were far below one physical monolayer and UV−visible and EXAFS spectroscopy suggested adsorption by grafting on specific surface sites. The density of adsorption sites was different for all three complexes, suggesting that molecular recognition phenomena, probably implying interactional complementarity between surface and adsorbate, are operative in the adsorption mechanism.
The Cu2+ ion doped silica gel matrices in monolithic shape were prepared by hydrolysis and condensation of tetraethyl orthosilicate
(TEOS). The absorption, transmittance and fluorescence spectra of the gel matrices heat treated at different temperatures
were monitored. The loss of water and hydroxyl group from silica network changes the optical properties of the Cu2+ ions in the host, noted by the change in colour of monolith and spectral characteristics. The pronounced blue shift observed
(700–900 nm to 600–850 nm) for the broad band of the absorption spectra of the samples heated up to 700°C is attributed to
the ligand field splitting and partial removal of hydroxyl group from the silica matrices. The results indicate broadband
filtering effects of the samples in the wavelength region 400–600 nm. Absorption and fluorescence spectra of the glass matrices
heated to 1000°C confirms the conversion of Cu2+ ion to Cu+ ion.
Alumina-supported CuCl2, the basic catalyst for ethylene oxychlorination, has been investigated 1 hour after preparation by UV-vis spectroscopy, a solubility test, EPR, EXAFS, and XRD in a wide range (0.25-9.0 wt%) of Cu concentration. We have evidenced that, at low Cu content, the formation of a surface aluminate species takes place, where isolated Cu(II) ions occupy octahedral vacancies of the alumina surface, having (within experimental errors) five oxygen ligands at 1.92±0.02 Ã
. The chlorine released by copper chloride during its interaction with alumina gives >Al-Cl species. The formation of this surface copper aluminate stops at 0.95 wt% Cu/100 m2; at higher Cu concentrations excess copper chloride precipitates directly from solution during the drying step, forming an amorphous CuCl2·2H2O phase, overlapping progressively the surface aluminate. A slow hydrolysis, giving traces of paratacamite, an insoluble Cu hydroxochloride, also occurs. A room temperature dehydration process up to 10-3 Torr i
DOI: 10.1016/j.apcata.2005.02.025 A series of cerium ion-doped titanium dioxide (Ce³⁺-TiO₂) catalysts with special 4 ƒ electron configuration was prepared by a sol–gel process and characterized by Brunauer-Emmett-Teller method, X-ray diffraction, X-ray photoelectron spectroscopy (XPS), UV–vis diffuse reflectance spectroscopy (DRS), and also photoluminescence (PL) emission spectroscopy. The photocatalytic activity of Ce³⁺-TiO₂catalysts was evaluated in the 2-mercaptobenzothiazole (MBT) degradation in aqueous suspension under UV or visible light illumination. The experimental results demonstrated that the overall photocatalytic activity of Ce³⁺-TiO₂catalysts in MBT degradation was signigicantly enhanced due to higher adsorption capacity and better separation of electron-hole pairs. The experimental results verified that both the adsorption equilibrium constant (Kₐ) and the saturated adsorption amount (Ꮁ[sub max]) increased with the increase of cerium ion content. The results of XPS analysis showed that the Ti³⁺, Ce³⁺, and Ce⁴⁺ ions reside in the Ce³⁺-TiO₂catalysts. The results of DRS analysis indicated that the Ce³⁺-TiO₂ catalysts had significant optical absorption in the visible region between 400 and 500 nm because electrons could be excited from the valence band of TiO₂or ground state of cerium oxides to Ce 4 ƒ level. In the meantime, the dependence of the electron-hole pair separation on cerium ion content was investigated by the PL analysis. It was found that the separation efficiency of electron-hole pairs increased with the increase of cerium ion content at first and then decreased when the cerium ion content exceeded its optimal value. It is proposed that the formation of two sub-energy levels (defect level and Ce 4 ƒ level) in Ce³⁺-TiO₂might be a critical reason to eliminate the recombination of electron-hole pairs and to enhance the photocatalytic activity. Author name used in this publication: F. B. Li Author name used in this publication: X. Z. Li
For present purposes, a protein-bound metal site consists of one or more metal ions and all protein side chain and exogenous bridging and terminal ligands that define the first coordination sphere of each metal ion. Such sites can be classified into five basic types with the indicated functions: (1) structural -- configuration (in part) of protein tertiary and/or quaternary structure; (2) storage -- uptake, binding, and release of metals in soluble form: (3) electron transfer -- uptake, release, and storage of electrons; (4) dioxygen binding -- metal-Oâ coordination and decoordination; and (5) catalytic -- substrate binding, activation, and turnover. The authors present here a classification and structure/function analysis of native metal sites based on these functions, where 5 is an extensive class subdivided by the type of reaction catalyzed. Within this purview, coverage of the various site types is extensive, but not exhaustive. The purpose of this exposition is to present examples of all types of sites and to relate, insofar as is currently feasible, the structure and function of selected types. The authors largely confine their considerations to the sites themselves, with due recognition that these site features are coupled to protein structure at all levels. In the next section, the coordination chemistry of metalloprotein sites and the unique properties of a protein as a ligand are briefly summarized. Structure/function relationships are systematically explored and tabulations of structurally defined sites presented. Finally, future directions in bioinorganic research in the context of metal site chemistry are considered. 620 refs.
In this paper, adsorption characteristics of methyl mercaptan on virgin activated carbon and copper chloride impregnated activated carbons were studied by using a dynamic adsorption method in a fixed bed. The activated carbons were characterized by nitrogen adsorption, XRD, TGA and solubility tests. The impregnation of copper chloride on the activated carbon significantly enhanced the adsorption capacity of methyl mercaptan, despite a notable decrease in microporosity. It is likely that copper chloride may act as adsorption site for methyl mercaptan. Copper chloride on the activated carbon in a range of 3-20 wt% Cu content was present mostly in the amorphous form of CuCl(2), according to the results of the solubility, XRD and TGA tests. Starting at 10 wt% in Cu loading, the adsorption capacity for methyl mercaptan decreases gradually. It is likely that a decrease in the degree of copper chloride dispersion and an accessibility of small pores may lead to the decrease in the adsorption capacity of the activated carbon for methyl mercaptan.
EasySpin, a computational package for spectral simulation and analysis in EPR, is described. It is based on Matlab, a commercial technical computation software. EasySpin provides extensive EPR-related functionality, ranging from elementary spin physics to data analysis. In addition, it provides routines for the simulation of liquid- and solid-state EPR and ENDOR spectra. These simulation functions are built on a series of novel algorithms that enhance scope, speed and accuracy of spectral simulations. Spin systems with an arbitrary number of electron and nuclear spins are supported. The structure of the toolbox as well as the theoretical background underlying its simulation functionality are presented, and some illustrative examples are given.
Copper catalysts prepared by chemisorption-hydrolysis technique over silica (Cu/Si) and silica-alumina (Cu/SiAl) supports were studied to understand the role of the support on the nature and surface properties of the copper species stabilized on their surfaces. The morphological and surface properties of the copper phases have been characterized by complementary techniques, such as HRTEM, EXAFS-XANES, EPR, XPS, and FTIR. For the FTIR investigation, molecular probes (CO and NO) were also adsorbed on the surfaces to test the reactivity of the copper species. Moreover, the catalytic performances of the two catalysts have been compared in the HC-SCR reaction (NO reduction by C(2)H(4)) performed in highly oxidant conditions. The superior activity and selectivity of the supported silica-alumina catalyst with respect to that supported on silica could be related with the different nature of the copper species stabilized on the two supports, as emerged from the results obtained from the spectroscopic investigations. Small and well-dispersed CuO particles were present on silica, whereas isolated copper ions predominated on silica-alumina, likely in regions rich in alumina that made some exchangeable sites available, as indicated by FTIR spectra of adsorbed CO. The less positive global charge of copper species on Cu/SiAl than in Cu/Si has been confirmed by EPR, XPS, and EXAFS-XANES analyses.
Cu deposition on the surface of spherical SiO2 nanoparticles was studied to achieve the hybrid structure of Cu-SiO2 nanocomposite. SiO2 nanoparticles served as seeds for continuous Cu metal deposition. The chemical structure and morphology were studied with X-ray photoelectron spectroscopy (XPS), scanning electron microscope energy dispersive X-ray (SEM-EDX), and a transmission electron microscope (TEM). The antibacterial properties of the Cu-SiO2 nanocomposite were examined with disk diffusion assays. The homogeneously formed Cu nanoparticles on the surface of SiO2 nanoparticles without aggregation of Cu nanoparticles showed excellent antibacterial ability.
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