Effect of Cosolvents on Toxaphene Aqueous Solubility

Environmental Context. Remediation of sites contaminated by chlorinated organic compounds is a significant priority. Toxaphene was widely used as a pesticide until its ban by the USA Environmental Protection Agency, but its prevalence in the environment continues to make it a significant priority pollutant. The present research examined the effectiveness of the cosolvents methanol, ethanol, isopropanol, and propanol in increasing toxaphene solubility in water for easier removal in potential field remediation applications. Cosolvents were found to increase toxaphene solubility in water nearly a thousand-fold, and show they can greatly increase the efficiency of removing toxaphene from contaminated soil with water flushing.

Abstract. Remediation of sites contaminated by chlorinated organic compounds is a significant priority in the environmental field. Toxaphene was widely used as a pesticide until it was banned by USA Environmental Protection Agency, but its prevalence in the environment continues to make it a significant priority pollutant. The present research examined the effectiveness of the cosolvents methanol, ethanol, isopropanol, and propanol in increasing toxaphene aqueous solubility for potential in situ flushing application. Aqueous solubility of toxaphene was found to increase as a function of cosolvent fraction increase in solution. Cosolvency powers for methanol, ethanol, isopropanol, and propanol were determined to be 3.43, 3.64, 3.51, and 3.91 respectively. Experimentally derived data were found to compare favourably to theoretically derived data from established log–linear models, including the modified Universal Quasichemical Functional Group Activity Coefficient model. Solubility of toxaphene in water was also noted to increase with an increase in the number of carbon atoms of the cosolvents in solution, and branched cosolvents solubilized less toxaphene than straight-chained alcohols of equivalent length, and mass. Potential applications of the present research include chemical and environmental remediation of sites or aquifers contaminated not only with toxaphene, but also potentially other pesticides and complex hazardous chemicals.