Treatment of tetrachloroethylene-contaminated groundwater by surfactant-enhanced persulfate/BOF slag oxidation—A laboratory feasibility study

Abstract

The main objective of this study was to evaluate the feasibility of remediating tetrachloroethylene (PCE)-contaminated groundwater (with initial PCE concentration of approximately 20 mg L −1) via persulfate oxidation activated by basic oxygen furnace slag (S 2O 8 2−/BOF slag) with the addition of biodegradable surfactant (Tween 80). Results indicate that only 15% of PCE can be removed in experiment with the addition of S 2O 8 2− only (S 2O 8 2−/PCE = 30/1). PCE removal can be increased to 31% while both S 2O 8 2− and BOF slag (10 g L −1) were added. This indicates that BOF slag was able to activate the persulfate oxidation mechanism, and cause the decrease in PCE concentration via oxidation process. Results also reveal that PCE degradation rates increased to 92% with the presence of Tween 80 (S 2O 8 2−/Tween 80/PCE = 30/2/1). In the presence of 10 g L −1 BOF slag, the reaction rate constant ( k obs) values were found to be 3.1 × 10 −3, 8.7 × 10 −3, 1.6 × 10 −2, and 5.8 × 10 −2 h −1, as the S 2O 8 2−/Tween 80/PCE molar ratios were 30/0/1, 30/0.5/1, 30/1/1, and 30/2/1, respectively. The reaction rate constant increased as the Tween 80 concentration increased. The significantly increased k obs could be caused by the enhanced solubilization of PCE by Tween 80. The increase in initial surfactant concentration would cause the increase in the solubilization of PCE, and thus, enhance the oxidation rate. This was confirmed by the total amount of chloride ions produced after the reaction. Results from this study indicate that BOF slag-activated persulfate oxidation enhanced by surfactant addition is a potential method to efficiently and effectively remediate chlorinated solvents contaminated groundwater.