Sangeeta Sahu; Madhurima Pandey; Shilpa Sharma
Abstract
Cadmium is biopersistant. Significant concentration of cadmium is released in the environment by various industrial activities worldwide. Therefore, removal of cadmium from waste water is now receiving greater attention from researcher various techniques for cadmium metal removal from industrial effluents ...
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Cadmium is biopersistant. Significant concentration of cadmium is released in the environment by various industrial activities worldwide. Therefore, removal of cadmium from waste water is now receiving greater attention from researcher various techniques for cadmium metal removal from industrial effluents has been developed. These techniques are: chemical precipitation, chemical reduction, ion exchange, evaporation, membrane processes, and adsorption. Each method has its own advantages and disadvantages among these techniques; adsorption of cadmium metal by using various materials was proved to be a very effective method. Moreover, research is needed to find the commercial and practical utility of low-cost adsorbents.From the current review, adsorption seems to be t he best alternative, help to develop new metal remediation technology and to study the scientific advances of recent years in this area.
Geitu Yirga; H C Ananda Murthy; Eshetu Bekele
Abstract
Humic acid modified magnetite nanoparticles (HA-Fe3O4 NPs) were synthesized by co-precipitation method by varying the precursor magnetite to HA ratio of 10:1 and 20:1. The synthesized NPs were characterized by FTIR, XRD, SEM-EDX and UV-Vis DR Techniques. The appearance of C=O vibration at 1390 cm -1 ...
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Humic acid modified magnetite nanoparticles (HA-Fe3O4 NPs) were synthesized by co-precipitation method by varying the precursor magnetite to HA ratio of 10:1 and 20:1. The synthesized NPs were characterized by FTIR, XRD, SEM-EDX and UV-Vis DR Techniques. The appearance of C=O vibration at 1390 cm -1 confirms positive interaction of carboxylate anion of HA and Fe3O4. The XRD pattern and SEM image shows bare Fe3O4 and HA-Fe3O4 (10:1 and 20:1) exhibit cubic spinel structure and the spherical shape morphology, respectively. The crystallite sizes of NPs were found to be 11.50 nm, 9.17 nm and 12.65 nm for bare, 10:1 and 20:1 Fe3O4-NPs, respectively. The adsorption capacity for the dye was found to increase with increase in contact time, adsorbent dose and initial pH of the solution. The result was best fitted to pseudo 2 nd order kinetics model and Langmuir isotherm model. The methylene blue (MB) removal efficiency of bare, 10:1 and 20:1 Fe3O4-NPs from aqueous solutions was recorded to be 95.8%, 99.4%, and 97.6%, respectively. The study confirms the greater efficiency of HA-Fe3O4 NPs compared to bare Fe3O4 for the removal of MB dye. The MB removal efficiency of HA-Fe3O4 NPs was found to be proportional to amount of adsorbed HA. Copyright © VBRI Press.
Sneha Chawla; Himani Uppal; Mohit Yadav; Dinesh Singh; Nahar Singh
Abstract
The present work has been envisaged to develop an efficient process for adsorptive decontamination of Brilliant green (BG) dye from waste water at room temperature. In recent past, various natural as well as advanced materials and composites have been reported to remove dyes from water. But these materials ...
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The present work has been envisaged to develop an efficient process for adsorptive decontamination of Brilliant green (BG) dye from waste water at room temperature. In recent past, various natural as well as advanced materials and composites have been reported to remove dyes from water. But these materials have certain limitations like time consumption, lower adsorption capacity and residual toxicity etc. To overcome these limitations, zinc peroxide-charcoal composite (ZnO2-C) has been synthesized by wet chemical route. The proposed composite efficiently decontaminates BG from waste water within 25 minute in wide pH range (2-9). The spectral and microscopic studies have been done for ZnO2-C composite before and after adsorption of BG to know the adsorption behavior of proposed material. Various parameters like pH, adsorbent dose, contact time and dye concentration were optimized by the batch sorption experiment to determine maximum adsorption capacity of ZnO2-C. The adsorption capacity of the composite was found to be 156.1 mg g -1 which is better than several other adsorbents cited in literature in recent past. The experimental adsorption data follows second order kinetics and Freundlich adsorption isotherm.
David J. Henry
Abstract
Stabilisation and modulation of nanocluster reactivity are key elements for the development of these materials as versatile and selective catalysts. This study presents a preliminary investigation of the interaction of ligands with a gallium nanocluster (Ga13). The amphoteric nature of Ga13 means that ...
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Stabilisation and modulation of nanocluster reactivity are key elements for the development of these materials as versatile and selective catalysts. This study presents a preliminary investigation of the interaction of ligands with a gallium nanocluster (Ga13). The amphoteric nature of Ga13 means that both a Lewis base (NH3) and a Lewis acid (BH3) strongly adsorb to the surface of the cluster. More importantly, ligand coordination modifies the electronic structure of the cluster, leading to an enhancement of reactivity. In particular, NH3 coordination was found to lower the energy barrier for H2 chemisorption by 10% and BH3 coordination led to reduction of the barrier by 20%. These results demonstrate the potential for ligand coordination as a means of accelerating reactions on cluster surfaces.
Himani Uppal; Nijhuma Kayal; Sneha Chawla; S. Swarupa Tripathy; Sonali Gupta; Rajni Singh; Bharti Sharma; Nahar Singh
Abstract
A new hydrothermal approach has been investigated for synthesis of alumina which has been utilized for decontamination of trivalent and hexavalent chromium (Cr) as well as microbes from water. The heat treatment of aluminum nitrate and sucrose forms single phase g-alumina compact of 318 m 2 /g surface ...
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A new hydrothermal approach has been investigated for synthesis of alumina which has been utilized for decontamination of trivalent and hexavalent chromium (Cr) as well as microbes from water. The heat treatment of aluminum nitrate and sucrose forms single phase g-alumina compact of 318 m 2 /g surface area at 1100 °C. The carbon particles present in aluminum nitrate- sucrose system get oxidized as carbon dioxide. The removal efficiency of synthesized alumina has been compared with commercial alumina and studied as a function of pH, time and adsorbent dose. Interestingly, synthesized alumina have better removal efficiency than commercial one. The adsorption data was best fitted to Langmuir isotherm suggesting monolayer adsorption. The adsorption capacity of the proposed material was found to be 11.76 mg g -1 and 11.9 mg g -1 for Cr (III and VI) respectively, which is better than several inorganic materials reported. The proposed alumina also inhibits growth of several bacteria like Bacillus cereus, Bacillus subtilis, Bacillus licheniformis, Staphylococcus aureus, Streptococcus pyogene, Pseudomonas aeruginosa, Klebsiella pneumoniae, Serratia marcescens, Salmonella typhimurium and Proteus hauseri upto 98%. The adsorption experiments were carried out in triplicate to get reproducible results. All experimental data for Cr removal has been reported with 95% confidence level (K=2).
M. Vinuth; H. S. Bhojya Naik; M. M. Mahadev Swamy; B.M. Vinoda; R. Viswanath; H. Gururaj
Abstract
Herein we reported the malachite green dye removal by Fe(III)−Mt through adsorption process under ambient conditions. The amount of MG dye removal by Fe(III)–Montmorillonite(Fe(III)–Mt) was estimated from its optical density at lmax = 617 nm using UV-Vis spectrophotometer. The MG dye ...
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Herein we reported the malachite green dye removal by Fe(III)−Mt through adsorption process under ambient conditions. The amount of MG dye removal by Fe(III)–Montmorillonite(Fe(III)–Mt) was estimated from its optical density at lmax = 617 nm using UV-Vis spectrophotometer. The MG dye removal was found to be rapid at basic pH and increased further with temperature up to 50°C. At pH 7 & 8, a complete reduction (100%) was observed within 5 min and 7 min, whereas at pH 4 & 5, it took 10 min &15 min respectively. The time taken for complete reduction at 0°C, RT (30°C) and 50°C were 10, 7 and 5 min respectively. The removal followed by adsorption of dye molecules on the spent clay mineral was evident from FESEM/EDX analysis. More importantly, Fe(III)–Mt could be separated and retrieved easily after the reaction by centrifugation from the degraded MG dye solution. The experimental results of MG dye removal from Fe(III)–Mt follows the pseudo first order kinetics. We believe that Fe(III)–Mt could be the efficient and suitable material to augment the real filed applications. This study provides a new avenue to gain in-depth insight to the applications of Fe(III)–Mt as an effective clay mineral for remediation of dye effluents. Overall Fe(III)–Mt bears the capability for environmental remediation in relation to the dye pollution.
Vandana Singh; Tulika Malviya; Sneha Joshi; Angela Singh; Devendra N. Tripathi
Abstract
Poly(acrylamide) has been efficiently grafted onto Cassia fistula seed gum using ceric ammonium sulphate/sodium disulphite redox system. The conditions for obtaining optimum % grafting (208 %) and % efficiency (92 %) are: acrylamide = 0.16 M, ceric ammonium sulphate = 0.026 M, sodium disulphite = 0.050 ...
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Poly(acrylamide) has been efficiently grafted onto Cassia fistula seed gum using ceric ammonium sulphate/sodium disulphite redox system. The conditions for obtaining optimum % grafting (208 %) and % efficiency (92 %) are: acrylamide = 0.16 M, ceric ammonium sulphate = 0.026 M, sodium disulphite = 0.050 M, Cassia fistula seed gum = 25 mL (0.4 % (w/v)), and temperature = 40 ± 0.2 ºC. Cassia fistula-graft-poly(acrylamide) (CF-g-PAM) was characterized using FTIR and SEM studies. CF-g-PAM could very efficiently capture “Reactive Blue (RBH5G)” dye from its aqueous solution. The copolymer did not dissolve even under highly acidic pH conditions and was able to remove 99.4 % dye from 100 mg L -1 dye solution under the optimized conditions (pH= 2, rpm = 150, adsorbent dose = 30 mg, temperature = 40 ºC, and contact time = 4 h). The adsorption equilibrium data are better explained by Freundlich isotherm, which indicated the presence of heterogeneous adsorption surface sites at CF-g-PAM. Langmuir adsorption isotherm, indicated significantly high Qmax (500 mg g -1 ) for the adsorption. The dye adsorption followed a pseudo second order kinetics (k’ = 5.3 x 10 -3 g. mg -1 min -1 ), indicating chemisorption of the dye is taking place. The kinetic study also supported the intervention of some boundary layer control. The results revealed that ceric ammonium sulphate/and sodium disulphite redox system is an efficient system for grafting poly(acrylamide) onto Cassia fistula seed gum and CF-g-PAM behaved as an efficacious adsorbent for Reactive Blue H5G dye. In future, the material may be explored for the adsorption of other anionic azo dyes and may be developed as the proficient dye adsorbent.
Pankaj Srivastava; Subhra Dhar; Neeraj K Jaiswal
Abstract
We investigate Ag atom bonding to zigzag graphene ribbons and properties of these systems to increase the understanding of spin transport. Results concerning the total energies preferred binding sites, equilibrium distances, and electronic character for Ag adatoms on ZGNR are predicted in this study. ...
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We investigate Ag atom bonding to zigzag graphene ribbons and properties of these systems to increase the understanding of spin transport. Results concerning the total energies preferred binding sites, equilibrium distances, and electronic character for Ag adatoms on ZGNR are predicted in this study. The study also provides insight into the diffusion kinetics of adsorbed Ag atoms on zigzag edged graphene nanoribbons. The ribbons considered in the present work have an antiferromagnetic ground state and undergoes transition from semiconducting to half-metallic on spin polarization. DOS profiles of Ag-adsorbed ZGNR at the bridge site reveals low DOS across the Fermi level ensuring its semiconducting character, validated from the unpolarized spin calculations. Though nonlinear at biases less than 1V in the FM and AFM calculations, the spin current of atop adsorbed ribbon increases rapidly with the increase of the bias voltage beyond 1V.
Abstract
Guar gum-graft-poly(vinylacetate) (GG-g-PVA) has been synthesized and evaluated for Hg(II) removal from synthetic Hg(II) solution. The optimum performance GG-g-PVA sample (G1) was synthesized using 0.25 g guar gum, 1.0 × 10 -2 M K2S2O8, 2.3 × 10-2 M ascorbic acid, 0.46 M vinyl acetate (VA), ...
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Guar gum-graft-poly(vinylacetate) (GG-g-PVA) has been synthesized and evaluated for Hg(II) removal from synthetic Hg(II) solution. The optimum performance GG-g-PVA sample (G1) was synthesized using 0.25 g guar gum, 1.0 × 10 -2 M K2S2O8, 2.3 × 10-2 M ascorbic acid, 0.46 M vinyl acetate (VA), total reaction volume 25 mL, grafting time 1 h, and reaction temperature 35±0.5 °C. G1 has been extensively characterized using FTIR, SEM, TGA, and DSC studies. pH drift experiments have shown that G1 has pHzpc of 2.8 and it was most efficient in removing Hg(II) at pH 6. The kinetic studies indicated that the removal involved chemisorption in the rate determining step and the sorption equilibrium was attained in 4 h. High Qmax (100 mg g -1 ) of the copolymer indicated its suitability as a versatile and sustainable adsorbent for exceptionally high mercury recovery.
Aida Mohammadi; Abolghasem Ataie; Saeed Sheibani
Abstract
Barium hexaferrite (BaFe12O19) magnetic nano-powder was prepared by co-precipitation method. The effectiveness of different chemical synthesis variables such as solvent and mechanical milling on the adsorption efficiency of barium hexaferrite nano-particles to remove Cr (VI) ions from aqueous solutions ...
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Barium hexaferrite (BaFe12O19) magnetic nano-powder was prepared by co-precipitation method. The effectiveness of different chemical synthesis variables such as solvent and mechanical milling on the adsorption efficiency of barium hexaferrite nano-particles to remove Cr (VI) ions from aqueous solutions was examined. Structural, magnetic, and adsorption properties of the powders are investigated by different techniques. X-ray diffraction analysis revealed that barium hexaferrite formed at a relatively low temperature of 700?C in the sample prepared with a mixture of water/alcohol as a solvent. The FESEM and VSM studies confirmed that all samples had a plate like structure with a particle size in the range of 87-145 nm and high magnetic properties. It was demonstrated that nanometer barium hexaferrite was produced to be an operative adsorbent for removal of Cr (VI) ions from solutions. Different Cr (VI) adsorption experiments were carried out by controlling effective adsorption factors. It was revealed that the sample calcined at a temperature of 700°C and then milled for 5 h (owing themaximum surface area 13 m2/g) showed the highest removal efficiency of 99.5% at pH 3.0, amount of nano adsorbent 1.5 g, initial chromium concentration 133 mg/l, and contact time 1 h. FTIR analysis showed that due to the existence of Cr-O stretching band on the surface of nano-particles, the electrostatic reaction between Cr (VI) ions and nano-adsorbent is possible. The adsorption data were best fitted with the pseudo-second-order kinetic model. Also, the equilibrium adsorption capacity of Cr (VI) calculated from adsorption experiments was found to be 13.25 mg/g. Adsorption studies indicated that the potential use of barium hexaferrite nano-adsorbents for the removal of the other heavy metal ions without sacrificing adsorption capacity can be practical.
Deepak Kumar; R. P. Tandon ;Partap K Chaudhury; Poornendu Chaturvedi; Abhilasha Chouksey
Abstract
The recovery of single wall nanotube (SWNT) based gas sensors have been investigated in the presence of Ultraviolet (UV) light at ambient conditions by real time monitoring. The rate of recovery is same for low concentration upto 5 ppm, but decreases with increase in concentration of NO2. It is observed ...
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The recovery of single wall nanotube (SWNT) based gas sensors have been investigated in the presence of Ultraviolet (UV) light at ambient conditions by real time monitoring. The rate of recovery is same for low concentration upto 5 ppm, but decreases with increase in concentration of NO2. It is observed that the response of thick film resistor (CNT-TFR) remains 7.5 and 25.4 % with multiple exposures of 5 ppm and 20 ppm NO2 concentration, respectively. But the recovery rate decreases with multiple exposures. Both the response and recovery rate changes in case of micro resistor (CNT-µR). To study the significant effect of absorbed O2 in recovery behavior, the analyte is exposed to gas sensor with and without regeneration in the presence of UV light. The gas sensor response increases 1.5 times but it does not recover to its base line when regenerated in the presence of UV light.
Y. P. Tsai; J. C. Yang; P. C. Chuang; C. C. Chou; J. W. Lin
Abstract
This study used multi-walled carbon nanotubes (MWCNTs), TiO2 and their mixture (TiO2/CNT) to remove humic acids (HA) in water. The thermodynamic parameters with respect to the adsorption of MWCNTs, including free energy of adsorption (ΔG 0 ), enthalpy (ΔH 0 ), and entropy (ΔS 0 ) changes, ...
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This study used multi-walled carbon nanotubes (MWCNTs), TiO2 and their mixture (TiO2/CNT) to remove humic acids (HA) in water. The thermodynamic parameters with respect to the adsorption of MWCNTs, including free energy of adsorption (ΔG 0 ), enthalpy (ΔH 0 ), and entropy (ΔS 0 ) changes, are further calculated in the study. The ΔH 0 data showed the adsorption of HA onto MWCNTs is an endothermic physisorption. The ΔG 0 data indicates the adsorption of HA onto MWCNTs was spontaneous and thermodynamically favorable. Photocatalytic experiments showed 60 mgl -1 of HAs were completely degraded and mineralized as CO2 after 5 h UV irradiation by 0.8 gl -1 of TiO2, indicating the efficiency of TiO2 for the removal of HA is better than CNTs. The experiments of TiO2/CNT indicated the photocatalytic efficiency of TiO2 in the presence of CNTs was not improved, even worse than TiO2 alone. However, the photocatalytic efficiency of TiO2/CNT mixture became better than TiO2 alone due to the supply of oxygen by aeration, ascribing to the reason that the provided oxygen might be adsorbed on the surface of CNTs and accept e- as well as form •O2 - , which also leads to the formation of •OH - in the system.
Vandana Singh; Angela Singh; Devendra Singh; Jadveer Singh; Arvind K Pandey; Tulika Malviya
Abstract
In present communication we report on the kinetic and isotherm studies on Hg(II) removal using our recently reported material, the millimeter sized hollow titania spheres (TSP). The mesoporous spheres with high surface area (11.75 m 2 /g) and bimodal pore size distribution were fabricated by a facile ...
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In present communication we report on the kinetic and isotherm studies on Hg(II) removal using our recently reported material, the millimeter sized hollow titania spheres (TSP). The mesoporous spheres with high surface area (11.75 m 2 /g) and bimodal pore size distribution were fabricated by a facile sol-gel approach using alginate-guar gum hybrid beads as the structure directing agent. In order to investigate the utility of TSP for Hg(II) adsorption, the batch adsorption experiments were conducted at various pH values (2–7), initial Hg(II) concentrations (50–300 mg/L), and TSP doses (20-100 mg) at 150 rpm, and 30 °C temperature. The spheres exhibited good capacity to adsorb Hg(II) in wide pH range (pH 3 to pH 7). It was possible to remove >95 % Hg(II) from 100 mg/L synthetic Hg(II) solution at pH 5, and 50 mg TSP dose in 10 h. The adsorption equilibrium data were better fitted to Langmuir model at low temperatures while Freundlich model become favored as the temperature was increased to 40 ºC. Langmuir adsorption isotherm study indicated that the monolayer adsorption capacity of TSP was 62.5 mg/g 62.5 mg/g 78.7 mg/g and 100 mg/g at 10, 20, 30, and 40 ºC respectively, which suggested good Hg(II) adsorption capacity of TSP. The calculated RL values evidenced the feasibility of the adsorption. Adsorption kinetic data well accorded with pseudo-second order kinetic model with the rate constant k, equal to 2.5 x 10 -4 g/mg.min 1.99 x 10 -4 g/mg.min and 0.28 x 10 -4 g/mg.min at 100, 150 and 200 mg/mL initial Hg (II) concentrations, indicating chemisorption taking place in the rate determining step. At high initial Hg(II) concentration (200 mg/mL), the adsorption was exclusively controlled by intraparticle diffusion. The study revealed the suitability of TSP for the mercury removal from wastewater.
Asha H. Gedam; Rajendra S. Dongre; Amit K. Bansiwal
Abstract
The adsorption of poisonous lead (II) from aqueous solution using graphite doped chitosan composite as an adsorbent has been carried out. The characterizations of graphite doped chitosan composite were studied by using instrumental techniques like X-ray diffraction, Fourier Transform Infrared Spectroscopy ...
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The adsorption of poisonous lead (II) from aqueous solution using graphite doped chitosan composite as an adsorbent has been carried out. The characterizations of graphite doped chitosan composite were studied by using instrumental techniques like X-ray diffraction, Fourier Transform Infrared Spectroscopy and Scanning Electron Microscopy. The XRD study showed the crystalline nature of synthesized graphite doped chitosan composite with sharp and symmetric peaks. SEM morphology showed wide range of porosity that could achieve high lead (II) sorption. FTIR investigation evidenced that the presence of C=O and –OH functionalities participated in lead (II) adsorption from aqueous solution. The influence of pH, contact time, dose of adsorbent and initial metal ion concentration on removal of lead (II) was investigated. The adsorption efficiency was found to be pH dependent and the maximum 98% lead (II) removal observed at optimum pH 6. Results showed that the maximum adsorbent capacity was at dosage of 1g/L and equilibrium time achieved at 120 min. Equilibrium adsorption experiments were studied at room temperature and data obtained fitted to Langmuir and Freundlich adsorption isotherm. Langmuir model had higher R 2 values of 0.943 with sorption capacity of 6.711 mg of adsorbate/g of adsorbent which fitted the equilibrium adsorption process more than the Freundlich model. The adsorption kinetics was analyzed using pseudo first order, pseudo-second order and intraparticle diffusion models. Experimental data better fitted with pseudo second order kinetics model. The results illustrated that graphite doped chitosan composite has the potential to remove lead (II) ions from aqueous solution.
Jyoti Tyagi;Rita Kakkar
Abstract
This review focuses on the applications of graphene, and the effects of doping and functionalization on its properties. Though known for several years, the potential applications of graphene in various fields have only been recently realized. Remarkable research is going on in the various application ...
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This review focuses on the applications of graphene, and the effects of doping and functionalization on its properties. Though known for several years, the potential applications of graphene in various fields have only been recently realized. Remarkable research is going on in the various application based fields of graphene, such as in hydrogen storage, Li batteries, catalysis and many more. Its use as a sensor to detect various species at the molecular level is fascinating. Also, on account of its 2D structure, graphene has found promising applications in several adsorption phenomena. Various adsorption studies have been done on the graphene surface resulting in the chemisorption of the chemical species. This review focuses on the application of graphene for removal of hazardous substances, such as heavy metal ions and drug metabolites, from waste waters. Another class of substances, known as disinfection by-products (DBPs), formed during the disinfection of drinking water using chlorine, ozone, chloramines and chlorine dioxide as disinfectants, and the use of graphene for their removal, is also discussed. Use of graphene based materials as chemical and biosensors and its applications in various other fields is also briefly discussed.
Neha Sharma;Rita Kakkar
Abstract
Chemical warfare agents (CWA) have been used in the World Wars and in terrorist attacks, and hence there is an urgent need to find means of their decontamination. Metal oxides offer a rapid means of their disposal, since they contain reactive Lewis acid and basic sites, on which adsorption of the CWA, ...
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Chemical warfare agents (CWA) have been used in the World Wars and in terrorist attacks, and hence there is an urgent need to find means of their decontamination. Metal oxides offer a rapid means of their disposal, since they contain reactive Lewis acid and basic sites, on which adsorption of the CWA, and subsequent hydrolysis, can take place. Destructive adsorption of CWA on metal oxides yields non-toxic products. Nanoscale metal oxides display enhanced reactive properties toward warfare agents due to their high surface area, large number of highly reactive edges, corner defect sites, unusual lattice planes and high surface to volume ratio. Both experimental and theoretical studies have established that decomposition of nerve agents is facilitated on nanoscale Al2O3, MgO, CaO, TiO2, ZnO and small edge and corner clay mineral fragments. Compared to sulfur mustard, nerve agents are more potent. We first briefly describe their mode of action. Many experimental and theoretical studies have been performed to study their decomposition on various metal oxide surfaces, such as MgO, CaO, Al2O3, TiO2, V2O5, and clay minerals. The results of these studies are reviewed here. Photochemical degradation on TiO2 nanosurfaces has also yielded promising results. Because of the toxicity and risk involved, experimental studies have been mostly confined to the benign simulants, whereas theoretical studies have attempted to compare the real agents with their mimics. These studies establish a qualitative correlation between the G-agents and their simulant DMMP, and, hence, decomposition on metal oxide surfaces can be analyzed by observing the surface chemistry of DMMP on a wide variety of metal oxide surfaces. This review attempts to compile the literature concerning CWA and their simulants.
Nandita Maiti; ;Tulsi Mukherjee; Sudhir Kapoor; and Tulsi Mukherjee
Abstract
Surface-enhanced Raman scattering (SERS) spectroscopy is one of the most sensitive tools for the detection of molecules adsorbed on nanometer-sized roughened metal surfaces. Additionally, SERS combines high sensitivity with the observation of vibrational spectra of the adsorbate, giving complete information ...
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Surface-enhanced Raman scattering (SERS) spectroscopy is one of the most sensitive tools for the detection of molecules adsorbed on nanometer-sized roughened metal surfaces. Additionally, SERS combines high sensitivity with the observation of vibrational spectra of the adsorbate, giving complete information on the molecular structure of the system under investigation. In this paper, good SERS substrates in the form of silver-coated films with an average size of ~16 nm particles were produced by reducing silver nitrate by neat formamide. SERS was then applied for the trace-level detection of chlorogenic acid (CGA) adsorbed over these silver-coated films. SERS spectra with good signal-to-noise (S/N) ratio, was achieved for the identification and characterization of CGA down to 10 -9 M concentration.
Saksham Srivastava
Abstract
This is a scientific review defining the technical feasibility of surface oxidized carbon nanotubes (CNTs) for sorption of divalent metal ions (Cd 2+ , Cu 2+ , Ni 2+ , Pb 2+ , Zn 2+ ) from aqueous solution. By conducting the detailed literature review it was found that the adsorption capacities of CNTs ...
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This is a scientific review defining the technical feasibility of surface oxidized carbon nanotubes (CNTs) for sorption of divalent metal ions (Cd 2+ , Cu 2+ , Ni 2+ , Pb 2+ , Zn 2+ ) from aqueous solution. By conducting the detailed literature review it was found that the adsorption capacities of CNTs remarkably increased after conducting their surface oxidization with NaOCl, HNO3 and KMnO4 solutions. Unlike many microporous adsorbents, CNTs possess ï
Hong-zhen Li; Zhao-xiang Wang; Dong-hua Jing; Xiang-he Kong; Ke-zhu Yan
Abstract
The formation of two-dimensional crystalline film of n-pentadecane (C15H32) on a flat substrate with attractive forces similar to that of the metals or graphite substrate is investigated with molecular dynamics simulation. By controlling the deposition rate of the molecules, we observed the behavior ...
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The formation of two-dimensional crystalline film of n-pentadecane (C15H32) on a flat substrate with attractive forces similar to that of the metals or graphite substrate is investigated with molecular dynamics simulation. By controlling the deposition rate of the molecules, we observed the behavior in adsorption and conformational change of single molecule and the growing process of the n-pentadecane film. Two distinct sub-processes are recognized in the formation of the crystalline film, the formation of the molecular clusters and the coalescence of the molecular clusters. It is found that the conformational changes are gentle when only or few molecules are deposited on the substrate. However, this change becomes drastic as more molecules are gathered together. The accelerated conformational variation is attributed to the no-bonding molecular interaction.
Neha Gupta; Atul K. Kushwaha;M.C. Chattopadhyaya
Abstract
The Hydroxyapatite/Zeolite (HApZ) composite were synthesized by precipitation method and used as an adsorbent for the removal of cobalt ions from the aqueous solution. The materials were characterized by scanning electron microscope (SEM) and Fourier transform infrared (FTIR) spectroscopy. It has been ...
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The Hydroxyapatite/Zeolite (HApZ) composite were synthesized by precipitation method and used as an adsorbent for the removal of cobalt ions from the aqueous solution. The materials were characterized by scanning electron microscope (SEM) and Fourier transform infrared (FTIR) spectroscopy. It has been observed that there was slight enhancement in the % removal of cobalt ions from aqueous solution by HApZ (63%) than HAp (58%) and zeolite (47%). Batch experiments were performed to observe the effect of pH, adsorbent dose, contact time and initial cobalt (II) concentration. Kinetic study shows that the adsorption process follow pseudo-second order kinetic model. Equilibrium data were well fitted to Langmuir and Freundlich isotherm model.
Ajit Kumar Sharma;Ajay Kumar Mishra
Abstract
In this study, we have synthesized chitosan-grafted-styrene (Ch-g-sty) without any radical initiator or catalyst using microwave (MW) irradiation. Ch-g-sty was synthesized with 187% grafting using 80 % MW power in 40 second at (styrene) 0.13 M, (Chitosan) 0.1 g/25 mL. On the other hand, under similar ...
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In this study, we have synthesized chitosan-grafted-styrene (Ch-g-sty) without any radical initiator or catalyst using microwave (MW) irradiation. Ch-g-sty was synthesized with 187% grafting using 80 % MW power in 40 second at (styrene) 0.13 M, (Chitosan) 0.1 g/25 mL. On the other hand, under similar condition of concentration of styrene and chitosan, 148% grafting was observed with potassium persulphate (K2S2O8)/ascorbic acid as redox initiator and atmospheric oxygen as co-catalyst in 1 h using conventional method at 35 o C. Microwave synthesized Ch-g-sty copolymer was characterized by Fourier transform-Infrared (FTIR) spectroscopy, thermo gravimetric analysis (TGA), X-ray diffraction (XRD) measurement and scanning electron microscopy (SEM). Maximum grafting was optimized by varying the microwave power, exposure time and styrene/chitosan concentration. Ch-g-sty copolymer was found to be more efficient for Cr(VI) removal as compare to conventionally and parent chitosan in aqueous solution. Sorption of Cr(VI) was depending upon pH and concentration, with pH=3 being the optimum value. The equilibrium data followed the Langmuir isotherm model with maximum capacities of 526.3 mg/g, 312.5 mg/g and 166.7 mg/g for Ch-g-sty copolymer, conventional (thermostatic water bath) method and parent chitosan respectively.
Ajit Kumar Sharma;Ajay Kumar Mishra
Abstract
In this study, we have synthesized chitosan-grafted-styrene (Ch-g-sty) without any radical initiator or catalyst using microwave (MW) irradiation. Ch-g-sty was synthesized with 187% grafting using 80 % MW power in 40 second at (styrene) 0.13 M, (Chitosan) 0.1 g/25 mL. On the other hand, under similar ...
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In this study, we have synthesized chitosan-grafted-styrene (Ch-g-sty) without any radical initiator or catalyst using microwave (MW) irradiation. Ch-g-sty was synthesized with 187% grafting using 80 % MW power in 40 second at (styrene) 0.13 M, (Chitosan) 0.1 g/25 mL. On the other hand, under similar condition of concentration of styrene and chitosan, 148% grafting was observed with potassium persulphate (K2S2O8)/ascorbic acid as redox initiator and atmospheric oxygen as co-catalyst in 1 h using conventional method at 35 o C. Microwave synthesized Ch-g-sty copolymer was characterized by Fourier transform-Infrared (FTIR) spectroscopy, thermo gravimetric analysis (TGA), X-ray diffraction (XRD) measurement and scanning electron microscopy (SEM). Maximum grafting was optimized by varying the microwave power, exposure time and styrene/chitosan concentration. Ch-g-sty copolymer was found to be more efficient for Cr(VI) removal as compare to conventionally and parent chitosan in aqueous solution. Sorption of Cr(VI) was depending upon pH and concentration, with pH=3 being the optimum value. The equilibrium data followed the Langmuir isotherm model with maximum capacities of 526.3 mg/g, 312.5 mg/g and 166.7 mg/g for Ch-g-sty copolymer, conventional (thermostatic water bath) method and parent chitosan respectively.
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