Cobalt oxide confined in mesoporous SBA-15 as a highly efficient catalyst for enhanced degradation of sulfamethoxazole

Abstract

Pure Co₃O₄ samples with different Co precursors were prepared and their catalytic activities were closely related to the morphology. Furthermore, a series of confined catalysts (Co₃O₄@SBA-15) were prepared to confine Co₃O₄ particles in a mesoporous material with different Co precursors by incipient wetness impregnation method. Two supported catalysts (Co₃O₄/SBA-15 and Co₃O₄/SiO₂) were prepared for comparison. The prepared catalysts were well characterized and their catalytic performance was further investigated. Results showed that the confinement effect effectively inhibited Co₃O₄ particle aggregation and enhanced the Co²⁺/Co³⁺ ratio. As a consequence, Co₃O₄@SBA-15 catalysts showed better activities for sulfamethoxazole (SMX) degradation compared with pure Co₃O₄, Co₃O₄/SBA-15 and Co₃O₄/SiO₂. The SMX degradation by Co₃O₄@SBA-15 was dominated by the non-free radical pathway with mediated electron transfer. In addition, the confinement effect inhibited Co leaching during the reaction. The leached Co amount from Co₃O₄@SBA-15 during the reaction was lower than those from Co₃O₄/SBA-15 and Co₃O₄/SiO₂. After three reaction cycles, the catalytic activity of Co₃O₄@SBA-15 remained over 97%.