Enhanced removal of ammonia induced by the co-existing halogenated organics in wastewater via reutilization of spent lithium-ion batteries for peroxymonosulfate activation

Abstract

Halogenated phenol and ammonia nitrogen (NH4+-N) are typical composite pollutions in wastewater. It is still unclear how the transformation of halogenated phenol affects the fate of co-existing NH4+-N. In this study, the removal performance of the NH4+-N containing the co-existed halogenated organic, using 2, 4, 6-trichlorophenol (TCP) as the model pollutant was firstly investigated in the waste lithium-ion batteries (LIBs) material-derived catalysts activating peroxymonosulfate system (LIBs/PMS). The rapid degradation of TCP and the selective transformation of NH4+-N to N2 were simultaneously achieved. TCP could be degraded rapidly (within 2 min) whether with or without NH4+-N. Interestingly, the NH4+-N removal was initiated by the co-present TCP, strongly dependent on TCP dechlorination. And NH4+-N removal displayed a thermally accelerated process in the temperature range of 25 to 60 °C. With the co-present TCP (60 mg/L), 93.7% of NH4+-N could be removed at 50 °C. Based on the capture and the electron spin resonance (ESR) experiments, the generated reactive oxygen species (•OH, SO4•− and 1O2) participated in the TCP dechlorination, particularly 1O2 with dominant roles, whereas ClO• played an important role on NH4+-N removal. Theoretical calculations were used not only to predict the possible reactive site of TCP, but also evaluate the difficulty of reaction between NH4+-N and different active species. Moreover, NH4+-N could be removed 80% in outdoor simulated experiment (in Wuhan) and 100% for chlorobenzene and nitrogen-containing wastewater. This study unveiled the influence of the co-existed halogenated phenol toward the fate of NH4+-N in LIBs/PMS system and enriched the treatment of NH4+-N wastewater strategies.