Synergistic and efficient degradation of acid red 73 by UV/O3/PDS: Kinetic studies, free radical contributions and degradation pathways

Acid red 73 (AR73) is a representative dye pollutant that poses a threat to the environment and human health. Effectively removing this type of pollutant by conventional processes is difficult. However, this study found that compared with UV/PDS, UV/O 3 , and PDS/O 3 , UV/O 3 /PDS composite system had the highest degradation effect on AR73. The degradation efficiency in the composite system reached 97.61% within 30 min, and the synergistic coefficients in the composite system were all greater than 1. In the UV/O 3 /PDS system, ·OH was the main free radical that mainly degrades AR73. The increase of PDS dosage promoted the degradation of AR73, but the increase of O 3 dosage was difficult to greatly improve the degradation of AR73 effect. The kinetic model of the apparent reaction rate was determined. The UV/O 3 /PDS system can efficiently degrade AR73 in a wide range of substrate concentrations and pH levels, and at the same time showed good adaptability to various concentrations of anions (Cl − , CO 3 2− , SO 3 2− , and C 2 O 4 2− ). Under raw water quality, the degradation effect of AR73 was still as high as approximately 90%. The theoretical attack site was obtained by DFT calculation , and the possible degradation pathway of AR73 was proposed based on the GC-MS spectrum and UV–Vis absorption spectrum . The attack of –N N- by ·OH, SO 4 − , and O 3 was proposed to be the main possible degradation pathway for AR73. Therefore, this study further improves the understanding of the UV/O 3 /PDS system and shows the potential applicability of this system in the treatment of dye wastewater.