Treatment of Trichloroethylene by Adsorption and Persulfate Oxidation in Batch Studies

For remediation of trichloroethylene (TCE) contaminated groundwater, activated carbon (AC) has been used to adsorb and reduce the TCE concentration and to manage contaminant migration. Additionally, AC may also act as all activator of the electron-transfer mediator in activating persulfate anion (S2O82-) to generate sulfate radical (SO4-center dot) for contaminant destruction. The objective of the present research was to examine the combined use of AC and persulfate to treat TCE. The degradation of persulfate in the presence of AC follows a first-order kinetic behavior, and the faster persulfate degradation is observed when elevated AC dosage is used. Higher initial persulfate concentration results in a decrease of the persulfate degradation rate. Upon persulfate oxidation, the AC surface properties are altered including: all increase in acidity of surface concentration, a decrease in pH(zpc), and a slight decrease in the surface area. The results Of a Study of adsorption kinetics and isotherms suggest that the adsorption behavior for the original AC fits the pseudo-second-order kinetic model while the pseudo-first-order kinetic model is suitable for predicting oxidized AC performance. During the persulfate oxidation of TCE with AC as an activator, studies show that TCE removal call be a net result of adsorption and oxidation, in which a partial mineralization of TCE to release chloride occurs.