Publications (9)28.74 Total impact
- [Show abstract] [Hide abstract] ABSTRACT: Ag–TiO2 nanoparticulate film was synthesized by dip coating followed by adsorption and photoreduction in UVA light, characterized by transmission electron microscopy, scanning electron microscopy, energy dispersive analysis of X-rays, glancing angle X-ray diffractometry and UV-Vis absorption spectrophotometry techniques. The data indicated the presence of TiO2 particles of anatase phase of size varying from 5–15 nm, Ag nanoparticles of size varying from 10–20 nm, and also indicated the added visible light activity in Ag–TiO2 nanoparticle films. Photocatalytic degradation of methyl parathion (O,O-dimethyl O-(4-nitrophenyl) phosphorothioate), a well known pesticide in aqueous solution was studied using Ag–TiO2 nanoparticulate film and the data was compared with TiO2 nanoparticulate film. Photocatalytic degradation reactions demonstrated pseudo first order behaviour. Methyl parathion was found to be degraded initially to paraoxon which further was degraded to p-nitrophenol, trimethyl ester of phosphoric acid, trimethyl ester of phosphothioic acid, and finally to phosphate ion. Minute amounts of carbon dioxide and acetaldehyde were also detected.
- [Show abstract] [Hide abstract] ABSTRACT: Mesoporous transition metal ion (Zr, Fe, Ru and Pt) doped TiO2 nanocatalysts were studied as materials for sunlight assisted photocatalytic degradation of sulfur mustard. Metal ion doped titania nanocatalysts exhibited better activity than undoped, and commercial titania nanocatalysts for the photocatalytic degradation of sulfur mustard in the presence of sunlight. Transition metal ion doped TiO2 nanocatalysts degraded 100% of sulfur mustard within 200–210 min. Whereas, it took 240 min for undoped TiO2 nanocatalyst, and 420 min for commercial TiO2 nanocatalyst to completely degrade sulfur mustard. The order of activity of nanocatalysts was observed to be zirconium doped titania nanocatalyst ∼ iron doped titania nanocatalyst > ruthenium doped titania nanocatalyst ∼ platinum doped titania nanocatalyst > undoped titania nanocatalyst > commercial titania nanocatalyst. These nanocatalysts degraded sulfur mustard to acetaldehyde, carbon dioxide, disulfide, sulfoxide and sulfone of sulfur mustard, chloro ethyl vinyl sulfide, chloro ethyl vinyl sulfoxide, etc., due to photocatalysis facilitated in the presence of sunlight. Enhanced visible light absorbance contributed to superior photocatalytic activity of metal ion doped titania nanocatalysts relative to other ones in the presence of sunlight.
- [Show abstract] [Hide abstract] ABSTRACT: ASZMT (Cu, Ag, Zn, Mo, TEDA impregnated) carbon was prepared by impregnation of active carbon with ammonical salts of Cu (II), Ag (I), Zn (II), Mo (VI) and TEDA using incipient wetness technique. Thereafter, ASZMT carbon was characterized using scanning electron microscopy, atomic absorption spectroscopy, thermogravimetry and surface characterization techniques. The ASZMT carbon was evaluated under dynamic conditions against carbon tetrachloride vapour that was used as a simulant for the persistent chemical warfare agents for testing breakthrough times of filter cartridges and canisters of gas masks in the National Approval Test of Respirators. The effect of carbon tetrachloride concentration, test flow rate, temperature and relative humidity on the breakthrough behaviour of the ASZMT carbon for CCl4 vapour has also been studied. The study clearly indicated that the ASZMT carbon provided adequate protection against carbon tetrachloride vapours. The breakthrough time decreased with the increase of the carbon tetrachloride concentration and flow rate. The variation in temperature and relative humidity did not significantly affect the breakthrough behaviour of ASZMT carbon at high vapour concentration of carbon tetrachloride whereas breakthrough time of ASZMT carbon reduced by an increase of relative humidity at low carbon tetrachloride vapour concentration.
- [Show abstract] [Hide abstract] ABSTRACT: Photocatalytic degradation of paraoxon-ethyl (o,o-diethyl o-(4-nitrophenyl) phosphate), a well known surrogate of chemical warfare agents, in aqueous solution was studied by using titania nanoparticulate film. Reaction followed pseudo first order behaviour. Photolytic degradation reaction of paraoxon-ethyl demonstrated relatively low rate with a value of rate constant of 2.5 x 10(-3) min(-1). Whereas, degradation reaction in the presence of titania nanoparticulate film and UV light displayed enhanced rate with a value of rate constant of 6.9 x 10(-3) min(-1) due to photocatalysis. Gas chromatography-mass spectrometry analysis showed the formation of p-nitrophenol, o,o-diethyl phosphonic acid, o-ethyl, diphosphonic acid, phosphoric acid, dimerized product of o,o-diethyl phosphonic acid, acetaldehyde, and carbon dioxide due to photocatalytic degradation of paraoxon-ethyl. It indicates that, photocatalytic degradation reaction begins with destruction of P-O-C bonds. Subsequently, P. C atoms were found to be oxidized gradually, and contributed to its photocatalytic degradation.
- [Show abstract] [Hide abstract] ABSTRACT: Present study investigates the potential of CuO nanoparticles calcined at different temperature for the decontamination of persistent chemical warfare agent sulphur mustard (HD) at room temperature (30 ± 2 °C). Nanoparticles were synthesized by precipitation method and characterized by using SEM, EDAX, XRD, and Raman Spectroscopy. Synthesized nanoparticles were tested as destructive adsorbents for the degradation of HD. Reactions were monitored by GC-FID technique and the reaction products characterized by GC-MS. It was observed that the rate of degradation of HD decreases with the increase in calcination temperature and there is a change in the percentage of product of HD degradation. GC-MS data indicated that the elimination product increases with increase in calcination temperature whereas the hydrolysis product decreases.
- [Show abstract] [Hide abstract] ABSTRACT: Mixed metal oxide nanocrystals of AP-Al(2)O(3), AP-Al(2)O(3)-Fe(2)O(3), AP-Al(2)O(3)-V(2)O(5) and AP-Al(2)O(3)-CuO have been prepared by aerogel process. XRD data of prepared materials revealed the formation of nanocrystals with a size range of 3-15 nm diameters. N(2) BET investigations on these materials revealed larger values of surface area ranging from 350 to 540 m(2)/g. Reactivity of these nanocrystalline materials against Yperite was examined by gas chromatography, gas chromatography-mass spectrometry and infrared spectroscopy techniques. AP-Al(2)O(3)-Fe(2)O(3), AP-Al(2)O(3)-V(2)O(5) and AP-Al(2)O(3)-CuO nanocrystals exhibited superior decontamination properties against Yperite than AP-Al(2)O(3). The reactions exhibited pseudo first order behaviour. 100% of Yperite was found to be decontaminated on Al(2)O(3)-Fe(2)O(3), Al(2)O(3)-V(2)O(5) and Al(2)O(3)-CuO where only 75% of the same was found to be decontaminated on AP-Al(2)O(3) within 40 h.
- [Show abstract] [Hide abstract] ABSTRACT: Studies on photocatalytic inactivation of spores of Bacillus anthracis have been carried out using nanosized titania materials and UVA light or sun light. Results demonstrated pseudo first order behaviour of spore inactivation kinetics. The value of kinetic rate constant increased from 0.4h(-1) to 1.4h(-1) indicating photocatalysis facilitated by addition of nanosized titania. Nanosized titania exhibited superior inactivation kinetics on par with large sized titania. The value of kinetic rate constant increased from 0.02 h(-1) to 0.26 h(-1) on reduction of size from 1000 nm to 16 nm depicting the enhanced rate of inactivation of Bacillus anthracis Sterne spores on the decrease of particle size.
- [Show abstract] [Hide abstract] ABSTRACT: Reactions of sulphur mustard and sarin were studied on the surface of V(1.02)O(2.98) nanotubes by gas chromatography and gas chromatography-mass spectrometry techniques. The V(1.02)O(2.98) nanotube samples were made by using hydrothermal method and characterized by scanning electron microscopy, nitrogen adsorption, X-ray diffractometry and thermogravimetry. Later, they were exposed to sulphur mustard and sarin separately at ambient temperature (30+/-2 degrees C). The data explored the formation of sulphoxide of sulphur mustard, thiodiglycol for sulphur mustard and isopropyl methyl phosphonic acid for sarin on V(1.02)O(2.98) nanotubes illustrating the role of oxidation and hydrolysis reactions in the decontamination.
- [Show abstract] [Hide abstract] ABSTRACT: Nanocrystalline zinc oxide materials were prepared by sol-gel method and were characterized by X-ray diffraction, scanning electron microscopy, thermogravimetry, nitrogen adsorption and infrared spectroscopy techniques. The data confirmed the formation of zinc oxide materials of zincite phase with an average crystallite size of approximately 55 nm. Obtained material was tested as destructive adsorbent for the decontamination of sarin and the reaction was followed by GC-NPD and GC-MS techniques. The reaction products were characterized by GC-MS and the data explored the role of hydrolysis reaction in the detoxification of sarin. Sarin was hydrolyzed to form surface bound non-toxic phosphonate on the surface of nano-zinc oxide. The data also revealed the values of rate constant and half-life to be 4.12h(-1) and 0.16 h in the initial stages of the reaction and 0.361 h(-1) and 1.9h at the final stages of the reaction for the decontamination reaction on nanocrystalline ZnO.