Effect of particle size of vermiculite on the microstructure and photocatalytic performance of g-C3N4/vermiculite composite

Abstract

g-C3N4/vermiculite composites were synthesized by calcining the wet-mixed mixture of melamine and pre-expanded vermiculite, which pre-heated from different particle size of vermiculite (30–60, 60–100, 100–200 and 200 mesh). Pre-heating destroyed the crystal structure of vermiculite and enlarged its interlayer space, which was beneficial to the synthesis of g-C3N4 nano-sheets or nano-particles. With the decrease of the particle size of vermiculite, the dispersity of vermiculite and g-C3N4 in g-C3N4/vermiculite composite improved and the specific surface area of the composites increased gradually, but the agglomeration of g-C3N4 enhanced a little due to the lowered expanding degree of vermiculite. The photocatalytic performance of the g-C3N4/vermiculite composite enhanced firstly, and then dropped down as vermiculite particles were smaller than 100 mesh. g-C3N4/vermiculite composite synthesized from vermiculite of 60–100 mesh exhibited the optimum photocatalytic activity. It degraded 95.68% of Rhodamine B molecules in aqueous solution (100 mL, 10 mg/L) after photocatalysis for 90 min, and its reaction rate constant was about 2.7 times as large as that of the pure g-C3N4. The weakened agglomeration, the closely contacted interface between g-C3N4 and vermiculite, the enhanced separation efficiency of photo-generated carriers and the narrowed the band gap were responsible for the excellent photocatalytic performance of this g-C3N4/vermiculite composite.