A column test for leaching of organochlorines from soil by amphiphilic nonionic nanopolymers

Abstract

Amphiphilic nonionic cross-linked nanopolymers (NPs) were synthesized to examine removal of five organochlorines (OCs), namely lindane, heptachlor, aldrin, dieldrin, endrin, and DDT, from a range of Thai agricultural soils. The synthesized NP particles had polarity characteristics similar to those of nonionic surfactant micelles and were largely in the size range of 55–155 nm. This work aimed to determine the optimal conditions for leaching of OC contaminated soil with NPs and also to investigate the role and influence of soil properties on this leaching. An investigation of the concentrations of aqueous dispersions of these particles found that a concentration of 10 g L−1. was found most effective in leaching the OCs from a column of spiked soil. The optimal contact time that allowed a NP dispersion and spiked soil to reach equilibrium was 48 h. The results indicated influencing factors for OC removal and soil remediation were properties both of the soil and the compounds themselves. Soil organic carbon (SOC) content and soil texture played an important role on the sorption as well as compound hydrophobicity expressed as log KOW values. The removal efficiency was found to be in the range of 85.2–92.8 % for all soil samples and in the order of DDT < aldrin < heptachlor < dieldrin < endrin < lindane regardless of soil type. This order is inversely related to the log KOC values of these compounds. For OC compounds with a similar molecular structure, removal efficiency was related to molecular weight (MW).