Mechanism of Transfer of Hydrophobic Organic Compounds in Fine Disperse Systems during Their Electrokinetic Remediation

Abstract

A comprehensive study was conducted on the movement of a hydrophobic uncharged compound, o-chlorotoluene, in a model disperse system based on kaolin under the action of concentration gradients and an electric field, with and without the solubilizing solution of Triton X-100. The peculiarities of o-chlorotoluene transport were examined depending on the type of contamination—local (with the contaminated layer positioned between two pure layers of the dispersion) and uniform contamination of the entire dispersion. The impact of the electroosmotic flow character was considered (in a closed cell, with recirculating flow, or in an open cell, resulting in through-flow with diversion beyond the system) on the redistribution of o-chlorotoluene occurring during the treatment process is considered. In a closed cell, with local contamination of the dispersion, a symmetric distribution of o-chlorotoluene is formed, while preserving its initial amount. This is attributed to the electroosmotic flow and the counter hydrodynamic flows induced by it. In an open cell, even with the presence of narrow pores in the dispersion, the continuity of electroosmosis from the anode to the cathode is ensured, leading to the removal of o-chlorotoluene by the electroosmotic flow beyond the system. The efficiency of o-chlorotoluene removal depends on the type of contamination and the presence of a solubilizing agent. In the presence of Triton X-100, with local contamination of the dispersion, a decrease in the rate of o-chlorotoluene transport is observed compared to the treatment of the uniformly contaminated disperse system. Although the majority of the solubilized o-chlorotoluene, moving with the electroosmotic flow, is carried into the pre-electrode chamber, a portion of it enters the narrow space of pure kaolin or adsorbs onto the surface of its particles. In the absence of Triton X-100 solution, partial mechanical removal of the insolubilized o-chlorotoluene by the electroosmotic flow also occurs. Indicating that, its adsorption is partially reversible. This is related to the structure of kaolin, whose hydrophobic surface area, favorable for o-chlorotoluene adsorption under treatment conditions, is approximately 30–35%.