Ascorbic acid/Fe(0) composites as an effective persulfate activator for improving the degradation of rhodamine B

An ascorbic acid/Fe(0) composite (H(2)A/Fe(0))-activated persulfate (PS) process was provided for rhodamine B (RhB) removal. Experimental results demonstrated that the H(2)A/Fe(0)–PS system exhibits a rapid and continuous oxidation of organic contaminants, and shows great advantages over the conventional Fe(0)–PS system by significantly improving removal efficiency. This H(2)A induced dramatic enhancement for RhB degradation could be attributed to both the reduction and chelating ability of H(2)A. The H(2)A/Fe(0) composites were characterized using TEM, FE-SEM, FTIR and XPS, indicating that the obtained H(2)A/Fe(0) composites were prepared successfully. Key factors affecting the treatment were determined for the H(2)A/Fe(0)–PS system, including H(2)A/Fe(0) dosage, PS dosage, initial solution pH and temperature. Moreover, radical quenching tests revealed that sulfate radicals (SO(4)˙(−)), hydroxyl radicals (˙OH) and superoxide radicals (O(2)˙(−)) were generated in the H(2)A/Fe(0)–PS system, and SO(4)˙(−) was the main radical species responsible for RhB degradation. Finally, possible degradation pathways are proposed. These findings prove that the H(2)A/Fe(0)–PS system may provide a simple and effective technology for improving the degradation of refractory organic pollutants.