The Adsorption and Chemistry of Tripropyl phosphate (TPP) into Microporous and Mesoporous NaX Zeolites
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The Adsorption and Chemistry of Tripropyl phosphate (TPP) into Microporous and Mesoporous NaX Zeolites Qingguo Meng1,* , David C. Doetschman1, Apostolos K. Rizos2, Min-Hong Lee1, Jürgen T. Schulte1, Apostolos Spyros2 , Charles W. Kanyi1 1
Department of Chemistry, State University of New York, Binghamton University, Vestal Parkway East, Binghamton, NY, 13902-6000, U.S.A 2 Department of Chemistry, University of Crete, PO Box 2208, 71003, Heraklion, Greece.
ABSTRACT Adsorption and chemistry of tripropylphosphate (TPP) in mesoporous NaX zeolite, which was templated by cationic templated polymer (polydiallyldimethylammonium chloride, PDADMAC) with two different length chains, was investigated. The structural properties of the zeolites were characterized by X-ray diffraction (XRD) and nitrogen adsorption analysis. The chemical activities of different zeolites toward the decomposition of TPP were determined with solid state 31 P NMR spectra. After exposure of zeolites to TPP was sufficient and equilibrium was reached, a stoichiometric amount of water was also adsorbed and hydrolysis was observed. The TPP decomposition yields in different NaX zeolites were compared. INTRODUCTION Organophosphates (OPs) refer broadly to a group of organic phosphorous (V) compounds that include neurotoxic pesticides or nerve agents, such as Sarin (O-isopropyl methylphosphonofluoridate). Restrictions on the use of pesticides have been recommended, in view of their adverse effects on public health in both chronic and acute poisoning. As a consequence, exploring efficient ways to decontaminate OPs, with minimal environmental impact, has become a global necessity. To date, numerous ways to degrade the OPs have been reported, such as electrochemical [1], catalytic oxidation [2], atmospheric pressure plasma [3], and photolytic [4] methods, etc. Lots of interests have been focused on hydrolysis method using fabrics [5], TiO2 [6], MgO [7], Al2O3 [8], ZnO [9], activated carbons [10], and mesoporous silica [11]. The most recent interests have been in the adsorption and reactive properties of OPs in zeolites. VX nerve agent has been reported to hydrolyze on NaY and AgY zeolites at room temperature, through the cleavage of the P-S bond [12]. Larsen et al.[13] have also reported the adsorption and thermal reaction of DMMP in nanocrystalline NaY zeolite. Nevertheless, the size limitation presented by the microporous NaX faujasite supercage was evident. Phosphonates with large ester groups or phosphorous substituents are likely to result in a drop-off in the adsorption and subsequent nucleophilic chemistry and there is a strong need to enlarge the pore size of the microporous zeolite in order to enhance adsorption. *
Corresponding author, Email: [email protected]
So in the present work, mesoporous NaX (MesoX), synthesized with an organic cationic polymer (polydiallyldimehylammonium chloride, PDADMAC) template with different molecular weights, were selected as the zeolite adsorbents. Trip
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