The effect of ZnFe2O4/activated carbon adsorbent photocatalytic activity on gas-phase desulfurization

The effects of light exposure on the gas phase desulfurization of a reactive adsorbent consisting of ZnFe2O4 dispersed onto activated carbon (ZnFe2O4/AC) were investigated in both moist and dry conditions. The porosity and surface chemistry of the materials before and after the exposure to H2S were evaluated in details. The experimental results demonstrated that visible light irradiation has a negative effect on the H2S removal capacity. In moist conditions and under light, the photogenerated electron-hole pairs of ZnFe2O4 resulted in the formation of center dot OH, a strong oxidizer that directly oxidized H2S into H2SO3/H2SO4, which resulted in the deactivation of the adsorbent. In dry conditions, the photogenerated holes led to the oxidation of H2S to SO2, with the help of O-2, and SO2 was released in the outlet. These findings provide an insight on the rational designing and practical applications of efficient H2S removal adsorbents, which might differ in the performance depending on the conditions of their usage.