Oxidation absorption of gaseous H2S using UV/S2O82- advanced oxidation process: performance and mechanism

H2S existed in many industrial processes and needed to be removed for safety and environmental concerns. Herein, an excellent H2S removal performance could be achieved by wet scrubbing persulfate (S2O82-) solution combined with UV irradiation. The effects of some key operating parameters, including initial solution pH, initial (NH4)(2)S2O8 concentration, initial H2S concentration, gas flow, reaction temperature on H2S removal performance were investigated based on a bubble column reactor under different UV powers. The results indicated that H2S removal performance could be enhanced with the increase of UV power and initial (NH4)(2)S2O8 concentration, but would be restrained with the increase of initial H2S concentration and gas flow. As reaction temperature increased from 288 to 328 K, it imposed a double impact on H2S removal efficiency. H2S removal efficiency changed little in the initial pH range of 3-7 under the same UV power. The reaction products in scrubbed solution were characterized by ion chromatography (ICs) and high-performance liquid chromatography (HPLC), while free radicals generated in the reaction process was analyzed by electron spin resonance (ESR) spectroscopy. The results showed that the reaction products in scrubbed solution were SO42- and elemental S. There were mainly three pathways for H2S removal in the advanced oxidation process (AOP) of UV/S2O82- : free radical oxidation, S(2)O(8)(2-)oxidation and H2S ionization. Among them, the free radicals of sulfate radicals (SO4-center dot) and hydroxyl radicals (center dot OH) played a leading role in H2S oxidation. (C) 2021 Published by Elsevier B.V.

Automated summary

In this study, excellent H2S removal performance was achieved by wet scrubbing persulfate solution combined with UV irradiation. The H2S removal efficiency was enhanced with the increase of UV power and initial (NH4)2S2O8 concentration, but restrained with the increase of initial H2S concentration and gas flow. Free radicals of sulfate radicals and hydroxyl radicals played a leading role in H2S oxidation in the advanced oxidation process.