Peroxymonosulfate activation with CuOX/MnFe2O4 for the regeneration of granular activated carbon after adsorption of organic pollutants

Abstract

Adsorption is a cost-effective technology for the removal of refractory organic pollutants, and the regeneration of the spent adsorbent is crucial in terms of environmental and economic aspects. Herein, CuOX/MnFe2O4 was synthesized by a two-step precipitation method and investigated as a peroxymonosulfate (PMS) catalyst for the regeneration of granular activated carbon (GAC) saturated with ofloxacin. The influences of reaction conditions on the regeneration of GAC with CuOX/MnFe2O4-PMS and the possible mechanism were explored. The results showed that CuOX/MnFe2O4 exhibited high catalytic activity for the regeneration of GAC via the high mineralization of the adsorbed ofloxacin. Singlet oxygen was the dominant reactive species for organics removal, while O2•− and SO4•− also made a contribution to the degradation of organic intermediates. Under the optimized conditions, the regeneration efficiency of the spent GAC reached 98%, 89%, 87% and 85% for ofloxacin, ciprofloxacin, Orange II and methylene blue, respectively. Moreover, CuOX/MnFe2O4 and GAC exhibited high stability and good reusability in this process, suggesting the potential application of this regeneration technology for removing refractory organic pollutants.