Entity

Time filter

Source Type


Saxena A.,Center for Fire Explosive and Environment Safety | Srivastava A.K.,Canadian Department of National Defence | Singh B.,Canadian Department of National Defence | Goyal A.,Solid State Physics Laboratory
Journal of Hazardous Materials | Year: 2012

Silica nanoparticles of diameter, 24-75nm and surface area, 875m 2/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. © 2011 Elsevier B.V.. Source


Saxena A.,Center for Fire Explosive and Environment Safety | Srivastava A.K.,Canadian Department of National Defence | Singh B.,Canadian Department of National Defence | Gupta A.K.,Canadian Department of National Defence | And 2 more authors.
Journal of Hazardous Materials | Year: 2010

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 2-30 nm with high surface area (375 m2/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 30 min 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. © 2009 Elsevier B.V. All rights reserved. Source


Roy P.K.,Center for Fire Explosive and Environment Safety | Singh P.,Delhi Technological University | Kumar D.,Delhi Technological University | Rajagopal C.,Center for Fire Explosive and Environment Safety
Journal of Applied Polymer Science | Year: 2010

This study is an attempt to investigate the effect of a representative pro-oxidant (manganese stearate) on the degradation behavior of 70 ± 5 μ thickness films of LDPE, LLDPE and their blends. Films were prepared by film blowing technique in the presence of varying quantities of manganese stearate (0.5-1% w/w) and subsequently subjected to accelerated degradative tests: xenon arc exposure and air-oven exposure (at 70°C). The physico-chemical changes induced as a result of aging were followed by monitoring the mechanical properties (Tensile strength and Elongation at break), carbonyl index (CI), morphology (SEM), melt flow index (MFI), oxygen content (Elemental analysis), and DSC crystallinity. The results indicate that the degradative effect of pro-oxidant is more pronounced in LDPE than LLDPE and blends, due to the presence of larger number of weak branches in the former. The degradation was also found to be proportional to the concentration of the pro-oxidant. Flynn-Wall-Ozawa iso-conversion technique was used to determine the kinetic parameters of degradation, which were used to determine the effect of the prooxidant on the theoretical lifetime of the polymer. © 2010 Wiley Periodicals, Inc. Source


Sharma P.K.,Center for Fire Explosive and Environment Safety | Patel B.P.,Indian Institute of Technology Delhi | Lal H.,Center for Fire Explosive and Environment Safety
Defence Science Journal | Year: 2016

The protective structures required for performing critical operations are vulnerable to the blast and shock loads of advanced weapons. A blast valve is an important component of such structures for ventilation during normal conditions and for protection from blast/ shock during explosion. In this paper, various aspects of blast valve design and related studies are briefly reviewed. The concept and effects of blast wave, blast impact, numerical modelling and deformation of circular plate (one of the critical components of blast valve) have been discussed. The merits and demerits of sensing mechanisms viz. remote and direct sensing are discussed. The leakage of blast pressure during finite closing period of the valve (one of the critical problems) and the shock tube as a major experimental facility for testing of blast valves are briefly discussed. © 2016, DESIDOC. Source


Bhatt A.,Center for Fire Explosive and Environment Safety | Rajagopal C.,Center for Fire Explosive and Environment Safety | Chopra R.,Center for Fire Explosive and Environment Safety | Gupta A.K.,Indian Institute of Technology Delhi
Journal of Environmental Chemical Engineering | Year: 2014

Heavy metal salts of Cr, Pb, Hg, Ni, Mn and Zn were stabilised in a cycloaliphatic epoxy resin as the immobilising material. The polymeric matrices were subjected to leaching studies as per ANSI/ANS-16.1-1986 leach test. The leachability index was found to be acceptable as per the test standard. The leach test data was used to develop an understanding of the leaching behaviour of the metal salts. The leaching rate was found to be dependent on the water penetration depth, the total leachable salt and leaching depth. Leaching depth was controlled by effective diffusivity and solubility of the salt. Salt leaching depth signifies the dissolution front, which progresses with time. A leach model based on diffusion controlled dissolution kinetics was developed to simulate the tests, which can be used to formulate standards for safe disposal. The leaching data was further correlated using the dimensionless time approach. The critical model parameters included effective unencapsulated salt concentration, salt leaching depth, porosity of matrix and effective diffusivity of salt. © 2014 Elsevier Ltd. Source

Discover hidden collaborations