Preparation of heterogeneous TiO2/g-C3N4 with a layered mosaic stack structure by use of montmorillonite as a hard template approach: TC degradation, kinetic, mechanism, pathway and DFT investigation

Abstract

Photocatalysis is considered one of the most promising methods for removing antibiotics from wastewater. In this work, natural mineral montmorillonite was used as a hard template to prepare g-C3N4 and TiO2 composite photocatalysts with a layered mosaic stack structure through a double intercalation process for the first time. Benefiting from the layered mosaic stack structure, enhanced visible-light response, and effective charge transfer induced by uniform and compact heterojunctions, the prepared photocatalyst showed excellent photodegradation efficiency to remove tetracycline (TC) pollutants. The degradation rate of TC was 97.0% within 60 min. The photocatalytic degradation rate constant of the optimized composite was 0.058 min−1, which was approximately 6.21 higher than that of g-C3N4 (0.009 min−1). Density functional theory (DFT) calculations predicted that the degradation of TC mainly occurred at the boundaries rather than in the interlayer spaces. The layered mosaic stack structure of g-C3N4 and TiO2 prepared with montmorillonite suggests its potential to serve as an efficient photocatalyst for TC in wastewater treatment, and the method could provide some inspiration for the design and construction of efficient photocatalysts.