The immobilization of photocatalysts is considered an effective approach to solve the problem of the difficult recycling of powdered nanocatalysts after photocatalytic degradation. In this paper, tin dioxide/titanium dioxide (SnO2/TiO2) composite nanoparticles with excellent photodegradation performance and poly(vinylidene fluoride) (PVDF) resin were used as raw materials to prepare composite membranes for the catalytic degradation of rhodamine B (RhB) dye via a non-solvent-induced phase separation method. Specifically, the basic properties of SnO2/TiO2 composite nanoparticles were systematically analyzed, the photocatalytic performance of SnO2/TiO2/PVDF composite membranes was thoroughly investigated, and the photocatalytic mechanism has been revealed. Experimental results showed that the SnO2/TiO2 composite photocatalyst demonstrates a higher photocatalytic activity than the single photocatalyst with the SnO2/TiO2 composite comprising Sn/Ti in a molar ratio of 1 : 6, showing the highest photocatalytic performance. After SnO2/TiO2 composite particles were used as a kind of raw material for the production of PVDF membrane, the photocatalytic degradation rate of RhB by the SnO2/TiO2/PVDF composite membrane was as high as 91.84%. Moreover, ˙OH and h+ play a very important role in the whole photocatalytic degradation process. In summary, this paper will provide an effective guidance to improve the photocatalytic degradation of SnO2/TiO2/PVDF composite membranes, which will ultimately provide a broad potential application of photocatalysis in the field of water treatment.
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.
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