Defect-rich heterojunction photocatalyst originated from the removal of chloride ions and its degradation mechanism of norfloxacin

Concentrated leachate (CL) contains typical high concentration of Cl-, and it is necessary to remove Cl- efficiently and even to achieve a high value-added product from the Cl- removal process. In this study, a Bicontained upconversion glass-ceramic (GC) is firstly explored for ultra-efficient removal and utilization of Cl-, wherein the abundant porous structure is continuously formed in the Cl- removal process to further provide channels for the deep migration of Cl- and H+ to its inner Bi source. The high Cl- removal rates above 96% were all achieved over the best GC sample at the Cl- concentrations of 1300-13,000 mg/L, then the terminal BiOClbased precipitates were directly collected as the near-infrared (NIR) GC photocatalysts, which possessed defectrich heterostructure with excellent upconversion luminescence and electronic energy transmission properties. In the degradation of norfloxacin (NOR), high removal rates of 98%, 73%, and 36% were achieved under UV-VisNIR, Vis-NIR, and NIR irradiations. On a basis of the four possible NOR degradation pathways discussed, we found that the primary active species were attributed to O2.- and .OH radicals under NIR and UV-Vis-NIR irradiations, respectively. Therefore, the Bi-contained GC will supply a new strategy for high-efficiency Cl- removal and value-added resource utilization.

Automated summary

In this study, a Bicontained upconversion glass-ceramic was explored for ultra-efficient removal and utilization of Cl-, achieving high Cl- removal rates and converting the BiOCl-based precipitates into NIR GC photocatalysts with excellent performance. The Bi-contained GC offers a new strategy for high-efficiency Cl- removal and value-added resource utilization.