Strontium oxide modified mesoporous graphitic carbon nitride/titanium dioxide nanocomposites (SrO-mpg-CN/TiO2) as efficient heterojunction photocatalysts for the degradation of tetracycline in water

Abstract We report herein a facile synthesis of a ternary nanocomposite of strontium oxide modified mesoporous graphitic carbon nitride supported titanium dioxide (SrO-mpg-CN/TiO2) as an efficient heterojunction photocatalyst for the degradation of tetracycline (TC) in water. The morphology, optical and textural properties of as-prepared nanocomposites are systematically investigated by various advanced analytical techniques, and the structure-photocatalytic efficiency was related by proposing a plausible mechanism. The photocatalytic performance of SrO-mpg-CN/TiO2 nanocomposites was evaluated in the TC degradation in water by studying several reaction parameters including the catalyst dosage, initial TC concentration, pH and irradiation time. The photocatalytic experiments exhibited that the activity of SrO-mpg-CN/TiO2 nanocomposites for TC degradation was higher than binary SrO-mpg-CN nanocomposites and pristine TiO2. The enhanced photocatalytic activity of SrO-mpg-CN/TiO2 nanocomposites is attributed to the moderator role of SrO for electron transportation in the photocatalysis mechanism, which ensures a high charge mobility, suppresses electron/hole recombination, and improves the redox capacity under UVA irradiation. The detailed optimization studies revealed that the highest TC degradation efficiency of 91.73% was obtained by using 0.1 g/L catalyst dosage and 10 mg/L TC concentration at natural pH of 5.06 for 180 min reaction time under UVA irradiation. Moreover, the scavenging experiments showed that O H ads · and  O 2 · - radicals are the dominant species for the TC degradation in water. Moreover, SrO-mpg-CN/TiO2 nanocomposites were reusable up to the five successive runs without a significant drop in their initial activity.