A green, efficient and recyclable magnetic BiFeO3/Cl-g-C3N4 photocatalyst was prepared for the simultaneous removal of Cr(Ⅵ) and tetracycline (TC) from water by wet chemical and thermal synthesis methods. Experimental results revealed that BiFeO3/Cl-g-C3N4 achieved a removal efficiency of 96.1 % for Cr(Ⅵ) and 98.2 % for TC under visible light irradiation for 50 min at pH 6. The results of the work function, charge density difference, UV–vis DRS, PL, PC and EIS tests indicate the formation of S-scheme heterojunctions between BiFeO3 and Cl-g-C3N4, which exhibits superior carrier separation and migration efficiency. The evidence for interfacial charge transfer from BiFeO3 to Cl-g-C3N4 within BiFeO3/Cl-g-C3N4 was further corroborated by means of ISIXPS, EPR and KPFM. Moreover, calculations of the density of states demonstrate that the introduction of Cl enhances the reduction capability of BiFeO3/Cl-g-C3N4. Results from ESR tests and trapping experiments has demonstrated that the singlet oxygen (1O2) and electrons are the primary active species. Furthermore, the high removal rates of TC and Cr(VI) from industrial wastewater and groundwater, coupled with the lower ecotoxicity of TC degradation intermediates, indicate that BiFeO3/Cl-g-C3N4 has the potential for practical applications. After five cycles, the BiFeO3/Cl-g-C3N4 still removed 90.5 % of TC and 96 % of Cr(Ⅵ).

中文翻译：

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磁分离S型BiFeO3/Cl-g-C3N4异质结构光催化剂同时去除水溶液中Cr（VI.）和四环素的性能与机理见解


制备了一种绿色、高效、可回收的磁性 BiFeO3/Cl-g-C3N4 光催化剂，用于通过湿化学和热合成方法同时去除水中的 Cr（VI.） 和四环素 （TC）。实验结果表明，在 pH 6 的可见光照射 50 min 下，BiFeO3/Cl-g-C3N4 对 Cr（VI.） 的去除效率为 96.1%，对 TC 的去除效率为 98.2%。功函数、电荷密度差、紫外-可见光 DRS、PL、PC 和 EIS 测试结果表明，BiFeO3 和 Cl-g-C3N4 之间形成了 S 型异质结，表现出优异的载流子分离和迁移效率。BiFeO3/Cl-g-C3N4 中界面电荷从 BiFeO3 转移到 Cl-g-C3N4 的证据通过 ISIXPS、EPR 和 KPFM 进一步证实。此外，态密度的计算表明，Cl 的引入增强了 BiFeO3/Cl-g-C3N4 的还原能力。ESR 测试和俘获实验的结果表明，单线态氧 （1O2） 和电子是主要的活性物质。此外，工业废水和地下水中 TC 和 Cr（VI） 的高去除率，加上 TC 降解中间体的较低生态毒性，表明 BiFeO3/Cl-g-C3N4 具有实际应用的潜力。5 次循环后，BiFeO3/Cl-g-C3N4 仍去除了 90.5 % 的 TC 和 96 % 的 Cr（VI.）。