MgFeTi-LDH/g-C3N4 composites promote sodium persulfate activation through Fe3+/Fe2+ cycles for efficient tetracycline degradation under visible light irradiation†

Abstract

In this study, various MgFeTi-LDH/g-C₃N₄ photocatalytic materials were successfully synthesized through self-assembly, and their physicochemical and photoelectric properties were thoroughly characterized. Optical performance characterization of band gaps and VB-XPS spectra revealed that the E_VB and E_CB alignments of MgFeTi(3 : 1)-LDH/g-C₃N₄ composites are consistent with the fundamental characteristics of S-type heterojunctions. MgFeTi(3 : 1)-LDH/g-C₃N₄ coupled with sodium persulfate activation for TCH degradation achieved nearly 100% removal efficiency under visible light, surpassing previously reported catalysts. Moreover, five repeated tests of MgFeTi(3 : 1)-LDH/g-C₃N₄ showed negligible change in the removal rate of TCH, indicating its potential value for industrial applications. Furthermore, the catalytic degradation pathway and mechanism for MgFeTi(3 : 1)-LDH/g-C₃N₄ have been elucidated through LC-MS analysis, radical capture, and characterization. In addition, the high efficiency of TCH degradation is attributed to the synergy of Fe³⁺, Fe²⁺, SPS, and active species such as ˙OH, SO₄˙⁻, and ˙O₂⁻. Finally, the QSAR analysis and OD₆₀₀ values suggest that the degradation pathway and time lead to a reduction in toxicity and the potential risk to the degradation liquid. This study offers a simple and economical approach to completely degrade TCH, also providing practical application prospects in wastewater treatment.