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Abstract: Metal oxide nanoparticles such as silica, alumina, magnesium oxide and calcium oxide were synthesized using sol–gel process followed by super critical drying. In order to increase reactivity, nanoparticles were loaded with zero valent iron. Nanoparticles were then characterized for their surface area, porosity, particle size, surface morphology, compositions, thermal stability, etc. Nanoparticles showed particle diameter in the range of 5–60nm, surface area 23–673m2/g and microporous–mesoporous characteristics. Adsorption of nitrobenzene on prepared nanoparticles was performed in closed glass chamber and the kinetics parameters such as equilibration constant, equilibration capacity, diffusional exponent and adsorbate–adsorbent interaction constant have been determined using linear driving force and Fickian diffusion model. Zero valent iron loaded silica nanoparticles showed maximum adsorption potential (1155mg/g) and considerable ratio for adsorption capacity to surface area (3.14mg/m2) among impregnated systems. [Copyright &y& Elsevier]

Abstract: Silica nanoparticles of diameter, 24–75nm and surface area, 875m2/g were synthesized using aero-gel route. Thereafter, nanoparticles were impregnated with reactive chemicals, and used as reactive adsorbent to study the removal of toxic nerve and blister chemical warfare agents and their simulants from solutions. Trichloroisocyanuric acid impregnated silica nanoparticles showed the best performance and indicated physisorption followed by chemisorption/degradation of toxicants. This indicated their suitability as universal decontaminant for nerve and blister agents. This system showed a decrease in t 1/2 from 1210 to 2.8min for the removal of king of chemical warfare agents, i.e., sulphur mustard. Hydrolysis, dehydrohalogenation and oxidation reactions were found to be the route of degradation of toxicants over impregnated silica nanoparticles. [Copyright &y& Elsevier]

Abstract: Nanoparticles of AP-Al2O3 (aero-gel produced alumina) have been produced by an alkoxide based synthesis involving aluminum powder, methanol, toluene and water. Thus produced alumina nanoparticles were characterized and the data indicated the formation of nanoparticles of alumina in the size range of 2–30nm with high surface area (375m2/g). Thereafter, these nanoparticles were impregnated with reactive chemicals. Adsorptive removal kinetics for DEClP (diethylchlorophosphate) and GB (isopropylmethylphosphonofluoridate, sarin) was monitored by GC–FID (gas chromatograph coupled with flame ionization detector) technique and found to be following pseudo first order reaction kinetics. Among impregnated AP-Al2O3 nanoparticles based sorbent systems AP-Al2O3 impregnated with 9-molybdo-3-vanadophosphoric acid (10%, w/w) was found to be the most reactive with least half-life values of 7 and 30min for the removal of DEClP and GB, respectively, whereas unimpregnated AP-Al2O3 nanoparticles showed the best adsorption potential among all studied systems. In addition to this, hydrolysis reaction {identified using GC/MS (gas chromatograph coupled with mass spectrometer) technique} was found to be the route of degradation of DEClP and GB on impregnated alumina nanoparticles. [Copyright &y& Elsevier]

Abstract: Alumina nanoparticles in the size range of 2–30nm and surface area 375m2/g were synthesized using aerogel route and then characterized using N2–BET, SEM, TEM, XRD, FTIR and TGA techniques. Thereafter, these were impregnated with reactive chemicals and tested for their potential by conducting studies on kinetics of adsorption of 2-chloroethylethylsulphide (2-CEES) under static conditions. Kinetics was studied using linear driving force and Fickian diffusion model. The kinetics parameters such as equilibration constant, equilibration capacity, diffusional exponent and adsorbate–adsorbent interaction constant were also determined. AP-Al2O3 with 10% impregnation of MoVPA (V3) and NaOH showed the maximum (574mg/g) and minimum (88mg/g) uptake of 2-CEES among impregnated systems respectively. All impregnated systems except NaOH impregnation showed the values of diffusional exponent to be <0.5, indicated the diffusion mechanism to be Fickian, whereas AP-Al2O3 with and without NaOH impregnation showed the diffusional mechanism to be anomalous. Hydrolysis and dehydrohalogenation reactions (identified using GC/MS technique) were found to be the route of degradation of 2-CEES. [Copyright &y& Elsevier]

Abstract: Activated carbon based palladium impregnated catalyst (Pd/C) was prepared for the reactive removal of carbon monoxide (CO) gas under ambient air conditions. For this, active carbon of 1250m2/g surface area was impregnated with palladium salt to get Pd/C catalyst, containing palladium from 4.0 to 8.0% (w/w). Catalytic efficiency of the catalyst against CO gas was determined under dynamic conditions by passing CO–air mixture to the fixed bed of the Pd/C catalyst. Results indicated that Pd/C catalyst was continuously adsorbing and actively removing CO gas during the course of the palladium catalyzed reaction, i.e., CO+1/2 O2 →CO2 and was found capable of providing excellent protection against CO gas. Moisture content (humidity) of inlet CO–air mixture indicated it to be an important factor affecting the CO removal efficiency of the catalyst, as an increase in humidity after the CO breakthrough resulted in to the activation of the catalyst due to the generation of hydroxyl groups and enhanced protection by the regeneration of the catalyst. Study indicated that Pd/C catalyst works as a catalytic converter, i.e., the continuous conversion of CO to CO2 using atmospheric oxygen and moisture. In order to determine the shelf life, the Pd/C catalyst was also evaluated for its performance after accelerated ageing at 70°C and 50% relative humidity (RH) for 3.75 and 7.5 months. The catalyst was found to be working efficiently for 3.75 months but after 7.5 months it could not provide 100% protection against CO gas, however, the same catalyst started giving 100% protection after regeneration. Hence, studies indicated the Pd/C catalyst to be a promising catalyst for the reactive removal of CO gas in enclosed spaces/compartments, coal mines, fire accidents and for getting the protection for longer duration under ambient air conditions. [Copyright &y& Elsevier]

The article presents a study examining the kinetics of adsorption of 2-chloroethylethyl sulfide (2-CEES) and sulfur mustard (HD) on silica nanoparticles that were impregnated with reactive chemicals. The effectiveness of the chemicals against HD is noted, as well as the static conditions under which the kinetics of adsorption of 2-CEES and HD were studied. Linear driving force and Fickian diffusion models were used for the examination, noting that the study determined kinetic parameters including equilibration constant, equilibration capacity, and diffusional exponent.

Abstract: High surface area (887.3m2/g) silica nanoparticles were synthesized using aerogel route and thereafter, characterized by N2-Brunauer–Emmet–Teller (BET), SEM and TEM techniques. The data indicated the formation of nanoparticles of silica in the size range of 24–75nm with mesoporous characteristics. Later, these were impregnated with reactive chemicals such as N-chloro compounds, oxaziridines, polyoxometalates, etc., which have already been proven to be effective against sulphur mustard (HD). Thus, developed novel mesoporous reactive sorbents were tested for their self-decontaminating feature by conducting studies on kinetics of adsorptive removal of HD from solution. Trichloroisocyanuric acid impregnated silica nanoparticles (10%, w/w)-based system was found to be the best with least half-life value (t 1/2 =2.8min) among prepared systems to remove and detoxify HD into nontoxic degradation products. Hydrolysis, dehydrohalogenation and oxidation reactions were found to be the route of degradation of HD over prepared sorbents. The study also inferred that 10% loading of impregnants over high surface area and low density silica nanoparticles enhances the rate of reaction kinetics and seems to be useful in the field of heterogeneous reaction kinetics. [Copyright &y& Elsevier]

Abstract: Nanoparticles of AP–Al2O3 (aerogel produced alumina) have been produced by an alkoxide based synthesis involving aluminum powder, methanol, toluene and water. Thus produced alumina nanoparticles were characterized by N2-BET, scanning electron microscopy, transmission electron microscopy, X-ray diffraction, Fourier transformed infra-red spectroscopy and thermogravimetry techniques. The data indicated the formation of nanoparticles of alumina in the size range of 2–30nm with high surface area (375m2/g) and microporous–mesoporous characteristics. Thereafter, these nanoparticles were impregnated with polyoxometalates and other reactive chemicals, which have already proven to be effective against sulphur mustard (HD). Adsorptive removal kinetics for HD was monitored by GC–FID (gas chromatograph coupled with flame ionization detector) technique and found to be following pseudo first order reaction kinetics. Among polyoxometalates impregnated alumina nanoparticles based novel mesoporous reactive sorbent systems AP–Al2O3 impregnated with 9-molybdo-3-vanadophosphoric acid (10%, w/w) was found to be the most reactive with least half life value (214min). In addition to this, degradation products of sulphur mustard on prepared mesoporous reactive sorbents were identified using GC/MS technique. Hydrolysis, dehydrohalogenation and oxidation reactions were found to be the route of degradation of sulphur mustard. [Copyright &y& Elsevier]

Abstract: Bis-2-chloroethyl sulphide (sulphur mustard or HD) is an extremely toxic and persistent chemical warfare agent. For in situ degradation of HD and its analogues (simulants), i.e., dibutyl sulphide (DBS) and ethyl 2-hydroxyethyl sulphide (HEES), different carbon systems such as 11-molybdo-1-vanadophosphoric acid impregnated carbon (V1/C), ruthenium chloride impregnated carbon (Ru/C) and combination of these two (V1/Ru/C) were prepared. These carbons were characterized for cumulative micropore volume and surface area by N2 BET. The kinetics of the in situ degradation of HD and its simulants were studied and found to be following the first order kinetics. Kinetic rate constants and t 1/2 values were determined. Products were characterized using NMR, IR and GC–MS. Reaction products were found to be sulphoxide and sulphone. The combined system, i.e., 11-molybdo-1-vanadophosphoric acid plus ruthenium chloride (V1/Ru/C) was found to be best for in-situ degradation of HD and its simulants. In-situ degradation by polyoxometalate based system was found to be stoichiometry based while Ru/C oxidized HD in presence of chemisorbed oxygen. In combined system of V1/Ru/C ruthenium worked as a catalyst and polyoxometalate acted as a source of oxygen. Effect of moisture was also studied in combined system. Rate of degradation of HD was found to be increasing with increased percentage of moisture content. [Copyright &y& Elsevier]

Abstract: Whetlerite carbon, which is in use in nuclear, biological and chemical filtration systems can degrade highly volatile chemical warfare gases such as phosgene, cyanogen chloride, hydrogen cyanide, etc. Degradation of vesicants such as sulphur mustard (HD) over whetlerite has not been extensively studied, except that the probability of some hydrolysis has been reported. In order to investigate the latter and incorporate HD degradation capability to the filter adsorbent, indigenous whetlerite carbon containing sodium hydroxide was further impregnated with various in situ degradation capable impregnants. The prepared adsorbent materials (impregnated modified whetlerite systems) were studied for in situ degradation of HD at ambient temperature. Degradation kinetics monitored by GC/FID was found to be pseudo-first-order. Kinetic rate constant and half-life values of degradation were calculated. Hemimustard, thiodiglycol, 1,4-oxathiane, sulphoxide and vinyl-2-chloroethyl sulphide were found to be the degradation products with modified whetlerite (MWh) and modified whetlerite impregnated with 11-molybdo-1-vanadophosphoric acid (MWh/V1) systems indicating that oxidative, hydrolytic and dehydrohalogenation decompositions are responsible for HD degradation. Effect of moisture on HD degradation was also studied on MWh and MWh/V1 systems, indicating that the rate of degradation increases with increasing moisture content. [Copyright &y& Elsevier]