Lin Wang,Qiya Sun,Yicheng Dou,Zhipeng Zhang,Tingting Yan,Yongmei Li
A novel ternary recyclable Fe 3 O 4 /graphene/sulfur-doped g-C 3 N 4 (Fe 3 O 4 /GE/SCN) composite catalyst was synthesized and adopted in a visible-light driven catalytic system for the degradation of ranitidine, which is an important precursor of the emerging disinfection by-product of N-nitrosodimethylamine (NDMA). The addition of GE and Fe 3 O 4 significantly improved the interface charge transfer of SCN, increased the light collection efficiency and decreased the photogenerated charge recombination efficiency. Considering both the ranitidine removal efficiency and catalyst recovery, the Fe 3 O 4 mass fraction of 20% (20%-Fe 3 O 4 /GE/SCN) was recommended. Ranitidine (≤ 2 mg/L) was completely removed in 60 min under the conditions of an initial pH of 7.0 and a 20%-Fe 3 O 4 /GE/SCN dose of 1.0 g/L, and its degradation fitted well with the pseudo first-order kinetics model. Electron paramagnetic resonance analysis and trapping experiments confirmed that ·O 2 − , ·OH and h + participated in the degradation of ranitidine. Ranitidine was removed through the pathways of demethylation and hydroxylation based on the analysis of the detected degradation intermediates, and 57.3% of the NDMA formation potential (FP) was reduced after the reaction. The visible-light driven 20%-Fe 3 O 4 /GE/SCN catalytic technology is a promising method not only for the control of NDMA FP but also the catalyst could be recovered and reused.
Zehao Li,Haibo Li,Xianglong Zeng,Shuming Liu,Yongsheng Yang
The world faces increase in water scarcity and water pollution. A combined effect of adsorption and photodegradation is potential way to remove pollutants from water. In this work, mannose grafted chitosan (CSMan) films were synthesized due to Schiff base. To improve the adsorption and photodegradation capacity of films, graphite carbon nitride-zinc oxide (gCNMZnO0.3) was introduced into a system through solvent volatilization to remove tetracycline (TC). Comfortingly, the composite films of CSMan-gCNMZnO0.3-1 displayed outstanding adsorption capacity and excellent activity of degrading organic pollutant by visible light in water. The maximum adsorption capacity of CSMan-gCNMZnO0.3-1 was 164.627 mg g −1 through surface complexation, cation exchange, electrostatic attraction, hydrogen bonding, π–π interaction and plane strengthening effect. The analysis revealed that OH and h + were the crucial radicals in photodegradation process. Meanwhile, CSMan-gCNMZnO0.3-1 possessed superior reusability and broad applicability in five distinct types of water. The simulation experiment of silicone tube showed the combined effect had a removal ratio of 84.3 % in 120 min, and the adsorption-photodegradation efficiency was constant in operating after five continuance usages.
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