Degradation of trichloroethylene in aqueous solution by nanoscale calcium peroxide in the Fe(II)-based catalytic environments

Abstract

In this study, nCaO2 was synthesized successfully and applied in the Fe(II)-based catalytic environments in investigating trichloroethylene (TCE) removal performance. nCaO2 with the particle sizes in the range of 50–200 nm was prepared, and it performed better for TCE removal when compared to the conventional CaO2. Further experimental results showed that 70.4% of TCE could be removed in 180 min at the nCaO2/Fe(II)/TCE molar ratio of 1/2/1, while this data was elevated to 86.1% in the presence of citric acid (CA) at the nCaO2/Fe(II)/CA/TCE molar ratio of 1/2/2/1 in the same test period. Probe compound tests, specifically designed for free radicals confirmation, demonstrated the presence of HO and O2−. Moreover, scavenging tests indicated that HO was the major radical responsible for TCE degradation but O2− promoted the removal of TCE in both nCaO2/Fe(II) and nCaO2/Fe(II)-CA system. In addition, the effects of initial solution pH and anions (Cl−, HCO3−) were also evaluated. The performance of TCE degradation in actual groundwater demonstrated that both nCaO2/Fe(II) and nCaO2/Fe(II)-CA systems can be applicable for TCE removal in ISCO practice and the nCaO2/Fe(II)-CA system is much promising technique. These fundamental data strongly confirmed the feasibility and potential of nCaO2 based technique in the remediation of TCE contaminated groundwater.