Facile fabrication of S-scheme Bi2MoO6/g-C3N4/sepiolite ternary photocatalyst for efficient tetracycline degradation under visible light

In this study, S-scheme Bi2MoO6/g-C3N4/sepiolite ternary photocatalyst with improved visible-light-driven photodegradation activity for tetracycline (TC) was obtained via the calcination process followed by solvothermal method. Bi2MoO6/g-C3N4/sepiolite ternary composite exhibited significantly enhanced photocatalytic degradation performance for TC (92.70% within 180 min), and its reaction rate constant was almost 2.66, 20.06, 2.37, 2.04 and 2.43 times higher than those of Bi2MoO6, g-C3N4, Bi2MoO6/g-C3N4, Bi2MoO6/sepiolite and g-C3N4/sepiolite, respectively. The improvement of photocatalytic activity for Bi2MoO6/g-C3N4/sepiolite was mainly attributed to the construction of synergistic system between S-scheme Bi2MoO6/g-C3N4 heterojunction and sepiolite, leading to the enhancement of the adsorption capacity and the visible light response ability as well as the enhancement of photoinduced carriers’ separation efficiency. The quenching experiment and EPR test results indicated the h+ and O2•- radicals played major roles in TC degradation process. Furthermore, the effects of different factors on the TC degradation performance were investigated such as solution pH, catalyst dosage and initial concentration of TC. The photocatalytic degradation mechanism and TC degradation pathway were also proposed. Overall, this study is expected to provide a new insight for the rational design of ternary natural mineral-based visible-light-driven photocatalyst to effectively remove the organic pollutants from wastewater. [Display omitted] •A novel S-scheme Bi2MoO6/g-C3N4/sepiolite composite was successfully synthesized.•The ternary photocatalyst showed excellent TC photodegradation activity.•The enhanced TC degradation mechanism of Bi2MoO6/g-C3N4/sepiolite was proposed.