Co-catalytic of aluminosilicate stabilized cobalt for peroxymonosulfate activation to degrade levofloxacin

Abstract

Stabilization of Co was essential to address its pollution. In this work, geopolymerization was used to stabilize the Co2+ in the presence of alumina-silicate under hydrothermal process, in which the Co2+ is hypothesized to be a substitute of cation to balance the charge. Then the Co2+ could be incorporated into the geopolymer stably being named as AlxSiyCoz-T. Interestingly, the Co2+ stabilized AlxSiyCoz-T was recycled and reused for peroxymonosulfate (PMS) activation. The stability and catalytic activity of the AlxSiyCoz-T in PMS activation was evaluated. Results showed that the alumina and silicate geopolymerization played positive role in Co2+ stabilization, what were determined by the molar ratio of alumina to silicate, hydrothermal process. Besides, the AlxSiyCoz-T performed favorable activity in PMS activation for LEV degradation with an efficiency of 98.84 % and rate constant of 0.1154 min−1. In this case, the Co2+ was the main catalyst in PMS activation, while the alumina-silicate geopolymerization not only contributed to Co2+ stabilization, but also resulted in the formation of oxygen vacancy. Then the co-catalytic of alumina-silicate in PMS activation was understood by the synergy factor. The Co2+ leaching efficiency of AlSi2Co4-200 is only 0.011 %, confirming the heterogeneous catalytic in PMS activation. The AlxSiyCoz-200 performed favorable stability that could be used for five cycles at least. 1O2, SO4−• and •OH contributed to LEV degradation. Thus, the alumina and silicate geopolymerization could play important role in stabilization and co-catalytic for activating PMS, performing the dual effect on waste treatment and resource recycle.