Enhanced removal of 1,2-dichloroethane by nanoscale calcium peroxide activation with Fe(III) coupled with different iron sulfides

Abstract

Fe(II) is of great importance in iron-based advanced oxidation processes. However, traditional methods to maintain Fe(II) concentration, such as the addition of chelating agents or reducing agents, may lead to an increase in chemical oxygen demand of secondary pollution. Therefore, in this study, iron sulfides, namely ferrous sulfide (FeS), pyrite (FeS2), and sulfidated nanoscale zero-valent iron (S-nZVI), were applied for not only the regeneration of Fe(II) but also the direct dissolution of Fe(II). Nanoscale calcium peroxide (nCaO2) was synthesized and used as the oxidant. The removal of 1,2-dichloroethane (1,2-DCA) were significantly promoted from 8.8 to 98.2, 79.2, and 80.8% with the aid of FeS, FeS2, and S-nZVI within 180 min, respectively. The dominant reactive oxygen species were demonstrated and their steady-state concentrations were quantified. Besides, the dechlorination of 1,2-DCA reached 90.4, 69.5, and 83.9% in nCaO2/Fe(III) systems coupled with FeS, FeS2, and S-nZVI, respectively. All three systems had high tolerance to the complex water conditions, of which FeS-enhanced nCaO2/Fe(III) system displayed the best performance, which could be recommended to put into practice for the remediation of 1,2-DCA contaminated groundwater. HIGHLIGHTS FeS, FeS2, and S-nZVI were applied for the enhancement of nCaO2/Fe(III) system.; The advantages of nCaO2 toward commercial CaO2 were elucidated.; The dominant ROS and their steady-state concentrations were determined.; The effect of complex solution matrixes on the performance of enhanced systems was investigated.; The universality on the removal of other typical contaminants was inspected.;

Keywords

• 1
• 2-dichloroethane
• groundwater remediation
• iron sulfides
• nanoscale calcium peroxide
• sulfur species