G.K. Prasad

Nanocrystalline zinc oxide for the decontamination of sarin.

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.

Photocatalytic inactivation of Bacillus anthracis by titania nanomaterials

Photocatalytic inactivation of Bacillus anthracis was studied by using titania nanomaterials and UVA light. Experimental data clearly indicated that, time of exposure, quantity of catalyst, intensity of light, particle size and Sunlight affected the inactivation. It also demonstrated the pseudo-first order behavior of inactivation kinetics and pointed out the enhanced rate of inactivation in the presence of nano-titania existing as a mixture of anatase and rutile phases. The values of rate constant were found to increase when the quantity of catalyst and intensity of UVA light were increased. Nanosized titania exhibited better inactivation properties than the bulk sized titania materials. Sunlight in the presence of nano-titania (mixture of anatase and rutile phases) displayed better photocatalytic bactericidal activity of B. anthracis than sole treatment of Sunlight.

Effect of calcinations temperature of CuO nanoparticle on the kinetics of decontamination and decontamination products of sulphur mustard.

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.

Reactions of sulphur mustard and sarin on V1.02O2.98 nanotubes

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.

Photocatalytic inactivation of spores of Bacillus anthracis using titania nanomaterials.

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.

N-doped, S-doped TiO2 nanocatalysts: synthesis, characterization and photocatalytic activity in the presence of sunlight

N doped and S doped nano TiO2 catalysts were synthesized by a sol–gel process followed by hydrothermal treatment at low temperature and tested for catalytic activity by natural sunlight photocatalytic degradation of a toxic chemical warfare agent. It is observed that sulfate groups were anchored on the surface of titania upon doping, and also create active surface oxygen vacancies, both of which are responsible for sunlight absorption and the promotion of electrons to the conduction band. The formation of a superoxide radical (O2˙−) and hydroxyl radicals may be mainly responsible for the photodegradation of sulfur mustard under sunlight.

The reaction of thiodiglycol on metal-impregnated carbon

Abstract In order to investigate the reactive removal of persistent chemical warfare (CW) gases, active carbons, grade 80 CTC, and active carbon impregnated with cobalt(II), chromium(VI), nickel (II), cadmium(II) or copper(II) salts were saturated at room temperature with the vapours of thiodiglycol (TDG), a hydrolysis product of sulphur mustard. The carbons exposed to TDG were subjected to thermogravimetric analysis (TGA). The thermograms indicated the reactions of metal salts with the adsorbate, as was confirmed by GC-MS after extracting the reaction products from TDG-exposed carbon impregnated with a mixture of chromium(VI) salt and sodium hydroxide. The extractants used were dichloromethane and methanol. 1,4-Oxathiane and 1,4-oxathiane,4-oxide were the reaction products on Cr(VI) plus NaOH impregnated carbon.The reaction mechanisms are also proposed.

Synthesis, characterization and photocatalytic activity of Ag–TiO2 nanoparticulate film

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.

Decontamination of Yperite using mesoporous mixed metal oxide nanocrystals.

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.

Solvent-free synthesis of polyhydroquinoline derivatives employing mesoporous vanadium ion doped titania nanoparticles as a robust heterogeneous catalyst via the Hantzsch reaction

Mesoporous vanadium ion doped titania nanoparticles (V–TiO2) were used as a reusable and robust heterogeneous catalyst for one-pot four component synthesis of polyhydroquinoline derivatives via the esteemed Hantzsch reaction using arylaldehyde, β-ketoester, dimedone and ammonium acetate at 80 °C under solvent-free conditions as a multi-component synthesis. On the other hand, the catalytic activity of V–TiO2 was compared with undoped commercial titania nanocatalyst. This protocol was successfully pertinent to a wide range of structurally diverse arylaldehydes with β-ketoester, dimedone and ammonium acetate to afford the corresponding polyhydroquinoline derivatives. Operational simplicity, short reaction time and satisfactory yields are the key features of this protocol. The catalyst could easily be recycled and reused without observable decrease in catalytic activity.