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

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