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 Co₃O₃ nanocrystals for the degradation of IOH were 98.7%, 15.8% and 79.8% at 15 min, and their corresponding reaction rate constants (k_app) were 0.21 min^-1, 0.0077 min^-1 and 0.080 min-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. [ABSTRACT FROM AUTHOR]