Accelerated hydrolysis of industrial organophosphates in water and soil using sodium perborate

Accelerated alkaline hydrolysis of organophosphates (OP) in sodium perborate (NaBO3) solutions has been previously demonstrated with OP pesticides and OP warfare agents. The feasibility of an aqueous decontamination and an ex situ soil washing technique utilizing this reaction for the hydrolysis of isomers of tricresylphosphate (TCP), triphenylphosphate (TPP), and other industrial Ops was investigated. The hydrolysis half-lives (t(1/2)) of these compounds were studied in aqueous NaBO3 solutions and in laboratory-scale slurries of OP spiked soil and water. Hydrolysis rates of the aryl OPs and of a trialkylthiophosphate (DEF) were enhanced 10-100 x over basic hydrolysis. These compounds demonstrated t(1/2)s in NaBO3 solutions in the range of 4-90 min. Alkyl Ops, with the exception of DEF, were not hydrolyzed appreciably either in the presence of NaBO3 or under basic conditions. Hydrolysis of aryl OPs in soil slurries was considerably slower. Data from 17-day degradation studies best fit a non-linear two parameter function developed to describe desorption kinetic studies. Addition of the surfactant Triton X-100 did not enhance degradation rates in the slurry. This reaction may be useful for direct detoxification of OP aqueous wastes, and has the potential for remediation of soil-bound OP contamination. (C) 1999 Elsevier Science Ltd. All rights reserved.