Advanced Catalytic Technologies for Improved Global Security

Abstract

The abatement of toxic chemical warfare agents (CWA) is conventionally achieved via stoichiometric reactions using strong oxidants with high environmental impact and/or via thermal degradation. The international Project NanoContraChem, in the framework of NATO Science for Peace and Security Programme, aims at obtaining innovative nanostructured inorganic materials for the catalytic decontamination of CWA. In the first year of activity, a class of heterogeneous catalysts has been designed to transform selectively and under mild conditions toxic organosulfur chemical agents in non-noxious products with reduced environmental impact. Nb(V)-containing saponite clay was identified as an optimal catalyst for the CWA oxidative abatement. The conventional synthetic protocol used to obtain saponite materials was modified to allow the insertion of Nb(V) ions within the inorganic framework of the clay, thus obtaining a bi-functional catalyst with strong oxidizing and acid properties. The catalytic performance of these clays was evaluated in the oxidation reaction of (2-chloroethyl)ethylsulfide (CEES), simulant of sulfur mustard (blistering CWA), with aqueous hydrogen peroxide. Remarkable activity and outstanding selectivity to the related sulfoxide were obtained, at room temperature and ambient pressure. The new class of Nb(V)-containing clays have been tested for acute and chronic toxicity with bioluminescent bacteria, Photobacterium leiognathii Sh1. A study of biocidal properties of saponite materials (both containing and non-containing Nb sites) has been carried out by means of bioluminescence inhibition tests. None of the solids have shown significant detrimental effects on the bacteria. These results suggest thus the possibility to use these Nb-saponite catalysts as environmentally-safe tools for the decontamination and abatement of CWA.