Journal of Hazardous Materials 175 (2010) 795–801 Contents lists available at ScienceDirect Journal of Hazardous Materials journal homepage: www.elsevier.com/locate/jhazmat Kinetics of adsorptive removal of DEClP and GB on impregnated Al 2 O 3 nanoparticles Amit Saxena a , Avanish K. Srivastava b , Beer Singh b,∗ , Arvind K. Gupta b , Malladi V.S. Suryanarayana b , Pratibha Pandey b a Centre for Fire Explosive & Environment Safety, Timarpur, Delhi 110054, India b PD Division, Defence R & D Establishment, Jhansi Road, Gwalior 474002, MP, India article info Article history: Received 11 September 2009 Received in revised form 20 October 2009 Accepted 20 October 2009 Available online 30 October 2009 Keywords: Metal oxide nanoparticles Impregnation Sorption kinetics Degradation Diethylchlorophosphate (DEClP) Sarin (GB, isopropylmethylphosphonofluoridate) abstract Nanoparticles of AP-Al 2 O 3 (aero-gel produced alumina) have been produced by an alkoxide based syn- thesis 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 m 2 /g). Thereafter, these nanoparticles were impregnated with reactive chemicals. Adsorptive removal kinetics for DEClP (diethylchlorophosphate) and GB (isopropy- lmethylphosphonofluoridate, 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-Al 2 O 3 nanoparticles based sorbent systems AP-Al 2 O 3 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-Al 2 O 3 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. 1. Introduction Use of chemical warfare agents (CWAs) to produce physical immobilization in war is known from early ages. Therefore, the protection against these CWAs is important and can be achieved by degrading/removing them permanently from the contaminated area. The current technologies for the removal/degradation of CWAs involve the use of adsorbents, i.e., impregnated carbon [1] and corrosive chemical solutions [2]. The latter cannot be effec- tively used for decontamination of CWAs available as gases in the contaminated zone. Activated carbon suffers from the fact that it does not destroy persistent CWAs but merely holds them by adsorp- tion forces (physisorption). One of the important ways to solve the current problem and achieve protection against these CWAs is to utilize suitable material, which can perform the function of both physisorption (physical adsorption) followed by chemisorp- tion, i.e., chemical degradation of these toxicants. Highly porous multifunctional nanoparticles have attracted enormous attention in recent years because of unique physical and ∗ Corresponding author. Fax: +91 0751 2341148. E-mail addresses: amsa888@rediffmail.com (A. Saxena), beerbs5@rediffmail.com (B. Singh). chemical properties such as larger surface area, reactive surface, corner defects and unusual lattice planes [3]. These materials are typically obtained via soft chemistry by sol–gel approach [3–7], which is the most common and widely used “bottom-up” wet chemical method. Utamapanya et al. [5] in 1991 described the mod- ified hypercritical drying process for the preparation of inorganic metal oxide nanoparticles by sol–gel process utilizing aero-gel route. Remarkable contributions have been made by Klabunde [3–7], Kansas State University, USA for the preparation, character- ization and application of metal oxide nanoparticles alone and in association with other oxides. Nanocrystals of AP-Al 2 O 3 (aero-gel produced alumina nanoparticles) are currently under considera- tion as reactive adsorbents for the removal and decontamination of chemical warfare agents [8–11]. A series of solid sorbent mate- rials, including alumina (Al 2 O 3 ) and silica (SiO 2 ) have been studied as sorbents for SO 2 and 2-chloroethyl ethyl sulphide [9]. Bermudez has discussed the quantum-chemical and computational study of environmental effects in the adsorption of DMMP, sarin, and VX on -Al 2 O 3 [10,11]. As literature suggests that single metal oxide nanoparticles show promising results, but these nano-adsorbents can further be modified for second generation nano-adsorbents by load- ing/impregnating with reactive compounds [1,12–15]. In our previous study [16,17] we have also discussed impregnated Al 2 O 3 0304-3894/$ – see front matter © 2009 Elsevier B.V. All rights reserved. doi:10.1016/j.jhazmat.2009.10.078