Selective transformation and removal of As(III) by constructed Fe−N bonds: The generation of singlet oxygen from the photoexcitation of MnPc leads to abundant ZnFe−LDH interface OH radical

In this study, MnPc intercalated Zn/Fe layered double hydroxides (MnPc/ZF−LDH) were synthesized by pillared intercalation modification with different MnPc intercalation amounts and used for the selective transformation and removal of As(III) from the arsenate-phosphate mixed solution. Fe−N bonds were constructed by the complexation of MnPc and iron ions on the Zn/Fe layered double hydroxides (ZF−LDH) interface. The DFT calculation results show that the binding energy of Fe−N bonded to arsenite (−3.75 eV) was higher than that of phosphate (−3.16 eV), resulting in MnPc/ZnFe−LDH exhibiting high As(III) selective adsorption performance and anchoring it rapidly in the arsenite -phosphate mixed solution. The maximum adsorption capacity of 1MnPc/ZF−LDH for As(III) could reach 180.7 mg·g−1 under dark conditions. MnPc also acts as a photosensitizer to provide more active species for the photocatalytic reaction. A series of experiments demonstrated that MnPc/ZF−LDH exhibits high As(III) selective photocatalytic performance. A total of 10 mg·L−1 of As(III) was completely removed in the reaction system within 50 min in a single As(III) environment. In an environment with As(III) and PO43−, it achieved 80.0 % removal efficiency of As(III) and showed a good reuse effect. The introduction of MnPc could improve the utilization of visible light by the MnPc/ZnFe−LDH. The singlet oxygen generated from photoexciting MnPc leads to abundant ZnFe−LDH interface OH. In addition, MnPc/ZnFe−LDH shows good recyclability, making it a promising multifunctional material for the purification of arsenic-polluted sewage.