Efficient Adsorption of Hydrogen Sulfide at Room Temperature Using Fumed Silica-supported Deep Eutectic Solvents

Supported deep eutectic solvents (SDESs) using fumed silica as the supporting material and TAECuCl_3 as the loading substance, were developed for H_2S removal. The highest breakthrough sulfur capacity, 9.97 mg g^(-1), was achieved when the molar ratio of the TEACl to the CuCl_2 was 1:1, the loading rate of the DES was 10%, and the temperature was 30°C. TAECuCl_3 proved to be a more effective loading substance than pure TEACl, pure CuCl_2, or blends of these substances at other ratios. Due to the high utilization rates of the metal-activated sites, the SDESs were more economical. The excellent capacity for H_2S removal was attributable to the formation of a thin layer of DES, nano-sized in thickness, on the fumed silica. The XRD and XPS analysis showed that the products of desulfurization were S and Cu_2S, the latter of which was then oxidized to S and SO_4^(2-) by air at room temperature. After regenerating 4 times, the breakthrough sulfur capacity of the SDESs was still as high as 7.39 mg g^(-1). The nonlinear curve fitting demonstrated that the adsorption kinetics followed those of the Bangham kinetic model.