Synergistic effect of Co(II) doping on FeS activating heterogeneous Fenton processes toward degradation of Rhodamine B
Cheng Wang, Chaoyun Ying, Yadong Tang, Yupeng Yan, Xionghan Feng
Abstract
Iron-based heterogeneous Fenton systems have been widely proposed for recalcitrant contaminants degradation. However, low efficiency of H2O2 decomposition and Fe(II)/Fe(III) recycling quite limited their applications. In this work, Co-doped iron sulfide (FeS) was successfully prepared through a modified hydrothermal method, and characterized by XRD, FESEM, HRTEM, XPS and BET. With Co(II) substitution, FeS structure transformed from pyrrhotite to mackinawite. The 10% Co-FeS was highly effective in H2O2 activation toward Rhodamine B (RhB) degradation. The pseudo first-order kinetic constant of 10% Co-FeS was 0.323 min−1, which was 31.4 and 85 times higher than that of CoS2 and FeS, respectively. Quenching experiments and EPR analysis illustrated that •OH was the dominant radicals for RhB degradation and the role of Co(II) in H2O2 direct decomposition was negligible. Batch experiment suggested that the excellent catalytic performance of 10% Co-FeS were ascribed to: (i) Co incorporation into FeS structure facilitated electron transfer between S species and Fe3+, thus accelerating Fe(II)/Fe(III) conversion on the surface, and (ii) more active sites were exposed. The Co-doped FeS exhibited high stability with low Fe/Co leaching and great recyclability. This novel strategy brought potential insights to develop highly efficient catalyst like metal sulfides for wastewater treatment.