Simultaneous removal of several pharmaceuticals and arsenic on Zn-Fe mixed metal oxides: Combination of photocatalysis and adsorption

- Bifunctional Zn-Fe mixed metal oxides were synthesized from LDH precursors and optimized.
- Mutual effects of arsenic and ibuprofen on removal efficiency were investigated.
- Pharmaceuticals and arsenic in actual water were removed simultaneously and efficiently.
- Mechanisms involving photodegradation and oxidation/adsorption were fully elucidated.

A series of ZnFe-MMOs were synthesized by in situ topotactic transformation of ZnFe-LDH precursors, and screened for obtaining an efficient functional material used in the simultaneous removal of pharmaceuticals and arsenic. In a mono-component system, the photodegradation efficiency of ibuprofen with optimal ZnFe-MMOs can reach 95.7% under simulated solar irradiation and the maximum adsorption capacity of arsenic was up to 176.3 mg·g−1. In the binary system of ibuprofen and arsenic, the degrading activity of ibuprofen inordinately decreased depending on both the arsenic species and concentrations, while the presence of ibuprofen had no significant impact on arsenic removal. The potential application of ZnFe-MMOs for the simultaneous removal of several pharmaceuticals (ibuprofen, acetaminophen and diclofenac) and arsenic in actual water matrix was also investigated. After 12 h, arsenic concentration decreased from 1000 to 1.61 μg·L−1 and no pharmaceutical was detected. Possible mechanisms were revealed, indicating that photogenerated h+ was primary reactive species for the photodegradation of ibuprofen, and arsenic species including As(III) and As(V) were removed by the combination of photocatalytic oxidation and surface complexation adsorption. Furthermore, ZnFe-MMOs exhibited good reusability after regeneration, rendering it a promising multi-functional material for the decontamination of polluted water with the coexistent pharmaceuticals and arsenic pollutants.

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