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

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%. Confining cobalt oxides in porous material is an effective way to enhance their catalytic performance.