Highly efficient degradation of sulfamethoxazole (SMX) by activating peroxymonosulfate (PMS) with CoFe2O4 in a wide pH range

The cobalt ferrite materials (CoxFe3−xO4) with different molar ratios of Co:Fe (1:16, 1:8, 1:4, 1:2, and 3:4) were synthesized by simple co-precipitation method, and used for catalyzing activation of peroxymonosulfate (PMS) to degrade sulfamethoxazole (SMX). The effects of catalyst dose, PMS dose, pH value, and inorganic ions on the degradation of SMX were investigated. Particularly, the degradation efficiency of SMX reached 91% within 10 min in CoFe2O4/PMS, and the removal rate of SMX achieved 81% at first 1 min. Meanwhile, the CoFe2O4/PMS reaction system exhibited excellent catalytic performance at a wide pH range from 3.00 to 11.00. The CoFe2O4 catalyst could be easily magnetically separated and exhibited high stability in cycle experiments. EPR and quenching experiments showed that 1O2, SO4−, and OH species were produced in the CoFe2O4/PMS system, especially OH and 1O2 played dominant roles during the degradation of SMX. The catalytic degradation mechanism of SMX in the CoFe2O4/SMX system was proposed, involving radical process and non-radical process. This work will provide a new way for the efficient treatment of wastewater especially those containing SMX compounds.