Degradation of Toluene by a Selective Ferrous Ion Activated Persulfate Oxidation Process

The Fe2+-activated persulfate (PS) oxidation of toluene was evaluated using single-factor tests and response surface methodology (RSM). The results indicated the degradation efficiency increased as the PS and Fe2+ concentrations increased, while excessive dosages inhibited the degradation efficiency. The pH had an insignificant effect on the degradation of toluene. Based on the RSM optimization approach, the degradation efficiency reached a maximum of 84.4%. The main intermediates were also separated and identified by GC MS, and a plausible degradation pathway of toluene was proposed. Further studies of surfactant recovery from flushing effluents mixed with toluene and surfactant were explored. Compared with the Fe2+/H2O2 process, a great enhancement of the toluene degradation efficiency and lower sodium dodecyl sulfate (SDS) degradation efficiency were obtained by the Fe2+/PS process. The results demonstrated that the Fe2+/PS selective oxidation process could be used for SDS recovery and for the degradation of contaminants present in soil flushing effluents.