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

• Magnetic CoFe 2 O 4 /AC was synthesized as the catalysts for PMS with AOPs. • CoFe 2 O 4 /AC could absorb MB in high concentration near catalysts. • CoFe 2 O 4 /AC adsorption and degradation with PMS both contributed to MB removal. • The synergistic effect of CoFe 2 O 4 /AC and PMS increased the MB removal to 100%. • CoFe 2 O 4 /AC separated easily by magnetic separation from solution. • CoFe 2 O 4 /AC presented the good repeatability and could be recycled and reused. Magnetic cobalt ferrites (CoFe 2 O 4)/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% CoFe 2 O 4 nanoparticles supplied the sufficient magnetic response for magnetic separation and activated PMS to generate SO 4 − radicals. The pore-structures of AC could adsorb the residual MB in high concentration near CoFe 2 O 4 catalysts, and promoted MB degradation with SO 4 − radicals. CoFe 2 O 4 /AC nanocomposites presented the good stability and reusability. It was proved that the synergistic effect of PMS and CoFe 2 O 4 /AC nanocomposites could greatly improve the MB removal to 100% at the optimized conditions for 60 min. [ABSTRACT FROM AUTHOR]