Cooperation of multi-walled carbon nanotubes and cobalt doped TiO2 to activate peroxymonosulfate for antipyrine photocatalytic degradation

Abstract

• The photocatalyst was prepared through simple physical mixing of MWCNT and Co-TiO 2 . • The two catalyst have shown an obvious synergistic effect in the degradation process. • e − transferred between Co-TiO 2 and MWCNT clusters promoted the activation of PMS. • • O 2 − generated by MWCNT could accelerate the Co 3+ /Co 2+ redox cycles on Co-TiO 2 . • This study provided new ideas to use the catalyst more effectively. A hybrid catalyst system consisted of MWCNT and Co-TiO 2 through simple physical mixing was applied for peroxymonosulfate activation for antipyrine degradation. With 2 mM peroxymonosulfate, the removal rate of antipyrine is significantly increased from 53.24% and 86.23% to 100% in the presence of same weight of 0.2 g/L MWCNTs, Co-TiO 2 , and MWCNTs/Co-TiO 2 (half/half) mixture, respectively in 12 min. The influence of various parameters, including the ratio of Co-TiO 2 /MWCNT, catalyst dose, peroxymonosulfate dose, antipyrine concentration, and initial pH, were further investigated in detail. The underlying catalytic mechanism of the synergistic effect was unraveled by quenching tests and EPR analysis. It was attributed to the electrons tranferration between Co-TiO 2 and MWCNT, and the acceleration of Co 3+ /Co 2+ by generated superoxide. This work not only provides a novel and efficient method of pharmaceutical wastewater treatment, but also reveals a new perspective to use the catalyst more efficiently.