Distinctive binary g-C3N4/MoS2 heterojunctions with highly efficient ultrasonic catalytic degradation for levofloxacin and methylene blue

Sonocatalytic degradation was considered as a new and advanced strategy for the elimination of hazardous organic pollutants from wastewater. Until now, the synergy of employing ultrasonic irradiation with g-C3N4-based catalysts for the removal of antibiotic residues is rarely reported. In this paper, a binary g-C3N4/MoS2 heterojunctions was successfully fabricated by using a facile hydrothermal strategy and applied to investigate the degradation efficiency of levofloxacin and methylene blue (MB) under ultrasonic condition for the first time. Physicochemical characterizations indicated that MoS2 particles presented irregular shapes with 80 nm and adhered onto the surface of g-C(3)N(4 )micro-rods with different lengths ranging from 2 to 5 mu m. The ultrasonic degradation experiments indicated that g-C3N4/MoS2 could eliminate 75.81% of levofloxacin within 140 min and 98.43% of MB in 14 min with excellent recyclability. The excellent activity and stability could mainly be attributed to synergetic effects including (1) highly efficient separation and transfer system of sonogenerated charge from g-C3N4 to MoS2; (2) typical sonoluminescence and transient cavitation effects in ultrasonic system are apt to increase the radical generation and (3) keeping the interspaces and reactive sites clean by continuous strong surface cleaning. The reactive species detecting experiments revealed that the center dot OH and center dot O-2(-) played key roles in MB degradation. Furthermore, a possible mechanism for ultrasonic catalytic performance of g-C3N4 enhanced by MoS2 was proposed based on the detail analysis of the band gaps of g-C3N4 and MoS2, together with the "hot spot" theory of ultrasonication. This work gives an effective and alternative approach for the removal of antibiotic residues and organic dyes in wastewater.