Electrokinetic Remediation of Pentachlorophenol Contaminated Clay Soil

Abstract

This paper presents a bench-scale experimental study performed to investigate the remediation of low permeable soil contaminated with pentachlorophenol (PCP) using the electrokinetic technique. A total of six electrokinetic tests were performed using kaolin soil spiked with 100 mg/kg of PCP. The first three tests were performed with an applied voltage gradient of 1 VDC/cm, where each test employed one of the three different flushing solutions: deionized water, electrolyte, or buffered electrolyte. The other three tests were performed using the same electrolyte solution, but each employed voltage gradient of 2 VDC/cm under constant and periodic application modes and constant voltage gradient with electrode liquid recirculation. The results of this study showed that PCP can be degraded in an electrokinetic system due to the direct electrochemical reduction process at the electrodes. The degradation of PCP ranged from 52% to about 78% depending on the conditions present. As the applied voltage gradient across the PCP-contaminated soil increased, the electroosmotic flow and PCP migration toward the cathode increased, resulting in higher PCP degradation by the direct reduction process. In the tests with electrolyte flushing solution, PCP degradation was about 58% and 65% under the applied voltage gradients of 1 and 2 VDC/cm, respectively. The mode of application of voltage potential across the PCP-contaminated soil showed noticeable effect on the system pH and electroosmotic flow and hence the PCP degradation. The highest PCP degradation (i.e., 78%) was in the test with constant 2 VDC/cm voltage gradient and recirculation application. Overall, this study demonstrated that electrokinetic technology has the potential to remediate PCP-contaminated clay soils by the direct reductive process. The electroosmatic flow as well as degree of PCP degradation during electrokinetics depend on the applied potential gradient and properties of the aqueous phase such as pH, ionic strength, and presence of carbonates.

Enhanced Electrokinetic Remediation of Hydrophobic Organics Contaminated Soils by the Combination of Non-Ionic and Ionic Surfactants

“…. ) was critical to maintain a high electroosmotic flow and achieved a satisfactory removal [24,27,28]. Furthermore, the interaction of surfactants with soil may clearly reduce the effectiveness of the electrokinetic treatment.…”

An assessment of the effectiveness and impact of electrokinetic remediation for pyrene-contaminated soil

“…Electrokinetic remediation is an effective technology for the remediation of organic contaminated soil (Alcántara et al, 2008(Alcántara et al, , 2012Pazos et al, 2010;Reddy et al, 2011). Electrochemical oxidation, an important component process of electrokinetic remediation, has been suggested as an effective pathway to remove organic pollutants from soil (Rahner et al, 2002;Andreottola and Ferrarese, 2008;Istrate et al, 2011).…”

Advances in Electrokinetic Remediation for the Removal of Organic Contaminants in Soils

“…Periodic voltage application consists of a cycle of continuous voltage application followed by a period of "down time" where the voltage was not applied was found to allow time for the mass transfer, or the diffusion of the contaminant from the soil matrix, to occur and also polarize the soil particles. Several laboratory studies have demonstrated such desirable electro-osmotic flow behavior in a consistent manner, but field demonstration projects are needed to validate these results under scale-up field conditions [29,30]. …”