Organoclays for soil remediation: Adsorption of 2,4-dichlorophenol on organoclay/aquifer material mixtures studied under static and flow conditions

A column material containing organophilic clay particles was developed for soil remediation. 2,4-dichlorophenol adsorption on aquifer material with an effective particle diameter d<1 mm and various partially modified dioctadecyldimethylammoniummontmorillonite/aquifer material mixtures were studied under static and flow conditions. The 2,4-dichlorophenol adsorption on the aquifer material was negligible. On organoclay/aquifer material mixtures the adsorption capacity increased with increasing organoclay content and the adsorption isotherms could be fitted by the Freundlich equation. In columns filled with organoclay/ aquifer material mixtures, the 2,4-dichlorophenol retardation increased with increasing organoclay content up to 1% (w/w). Above 1.5-2.0% (w/w) the permeability of the column material decreased. The HYDRUS_1D model, which solves the convection-dispersion equation for solute transport, was used in a forward and inverse mode to simulate 2,4-dichlorophenol breakthrough in the columns. The simulations revealed that 2,4-dichlorophenol transport exhibited an additional kinetic effect not observed in the batch experiments. (C) 2006 Elsevier B.V. All rights reserved