Activation of peroxymonosulfate (PMS) by rGO supported Co3O4 catalyst for iohexol degradation

Sulphate radical (SO4·-) -based advanced oxidation process (SR-AOP) is a promising sewage treatment technology. Reduced graphene oxide (rGO) supported Co3O4 composites were synthesized by a hydrothermal method for the degradation of iohexol (IOH) in the rGO/Co3O4/peroxymonosulfate (PMS) system. Experimental results show that rGO/Co3O4 possessed much better PMS activated ability than pure GO or Co3O4, which is ascribed to the summation of rGO and Co3O4. The efficiency of rGO/Co3O4 composite, single GO and Co3O4 nanocrystals for the degradation of IOH were 98.7%, 15.8% and 79.8% at 15min, and their corresponding reaction rate constants (kapp) were 0.21min-1, 0.0077min-1 and 0.080min-1, respectively. The results of active species capture experiment and electron paramagnetic resonance (EPR) experiment, showed that singlet oxygen is the main active species, which is non-radical degradation. rGO is conducive to the electron conduction of Co3O4, thus improving the efficiency of PMS activation. The system is simple and efficient, which is an effective technology to remove IOH.