An Innovative Approach to the Detoxification of Organophosphate Esters by Bifunctional Organoclays

摘要

Organoclays are clay minerals in which the inorganic cations are replaced by organic ones. Organoclays (OCs) may be used for pollution prevention and for remediation of the soil environment because of their excellent sorbing properties. A major drawback of this approach is that by sorbing a toxic material onto OC, one merely changes the environmental compartment in which the toxic material exists, and a second step is required to destroy or to detoxify it. In order to overcome this obstacle an innovative long chain OC, called bifunctional OC, was developed which is capable of sorbing and catalyzing the hydrolysis of several organophosphate pesticides. This bifunctional OC is based on a quaternary-ammonium long-chained OC that contains in addition to the quaternary ammonium headgroup , an alkylamine (-CH_2-CH_2-NH_2) as a second functional headgroup and that was capable of sorbing and catalyzing the hydrolysis of several organophosphate pesticides. Thus, for example it was found that half-life of methyl parathion (MP) in the presenceOf the bifunctional OC is about 4 days, while the half-life for the spontaneous hydrolysis of MP at the same pH (9.0) is 40 days. The explanation given for the enhanced reaction rates is that the incorporation of the substrate into the OC matrix facilitates a proximity effect, namely the substrate and the catalytically active amino group of the OC are brought closer to each other by the adsorption process.