Cobalt ferrites/activated carbon: Synthesis, magnetic separation and catalysis for potassium hydrogen persulfate

[Display omitted] •Magnetic CoFe2O4/AC was synthesized as the catalysts for PMS with AOPs.•CoFe2O4/AC could absorb MB in high concentration near catalysts.•CoFe2O4/AC adsorption and degradation with PMS both contributed to MB removal.•The synergistic effect of CoFe2O4/AC and PMS increased the MB removal to 100%.•CoFe2O4/AC separated easily by magnetic separation from solution.•CoFe2O4/AC presented the good repeatability and could be recycled and reused. Magnetic cobalt ferrites (CoFe2O4)/activated carbon (AC) nanocomposites were prepared by the hydrothermal method, and then the catalysis for potassium hydrogen persulfate (PMS) to degrade methylene blue (MB) was investigated. The results indicated that 9 wt% CoFe2O4 nanoparticles supplied the sufficient magnetic response for magnetic separation and activated PMS to generate SO4− radicals. The pore-structures of AC could adsorb the residual MB in high concentration near CoFe2O4 catalysts, and promoted MB degradation with SO4− radicals. CoFe2O4/AC nanocomposites presented the good stability and reusability. It was proved that the synergistic effect of PMS and CoFe2O4/AC nanocomposites could greatly improve the MB removal to 100% at the optimized conditions for 60 min.