Decolorization of dark brown colored coffee effluent using zinc oxide particles: The role of dissolved oxygen in degradation of colored compounds

Colored organic compounds (ROH) adsorbed on the surface of ZnO particles are oxidized by OH radicals (OH). The resulting intermediated radicals react with dissolved oxygen and generate oxygenated radical intermediates (ROO). The colored organic compounds and their intermediates are finally mineralized. Numbering corresponds to reactions in text.