Preparation of deep eutectic solvent/graphene composite materials and their removal from fuel organic sulfide performance research

Abstract

Although desulfurization of deep eutectic solvents (DESs) can achieve high desulfurization efficiency, as liquids, there are many unnecessary troubles in their industrial application, so the immobilization of deep eutectic solvents is very important. In order to develop a more convenient, effective, and green solid extraction desulfurization technology to remove sulfides in fuel, we solidified deep eutectic solvents onto reduced graphene oxide (rGO) with good chemical stability, large specific surface area, and strong adsorption capacity to prepare deep eutectic solvent/rGO composite materials. The deep eutectic solvent/rGO composite materials were characterized by thermogravimetric analysis (TGA), scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). Through a large number of comparative experiments, the effect of various factors on the removal rate of sulfides in simulated oil was explored. The desulfurization results show that the prepared (TBAC/2p-TsOH)/rGO composite has the best desulfurization effect. With the initial concentration of 1600 ppm dibenzothiophene deep eutectic solvent simulated oil as the substrate and H₂O₂ as the oxidant, m((TBAC/2p-TsOH)/rGO) : m(simulated oil) : m(H₂O₂) = 3 : 10 : 1, after reacting for 40 minutes at 25 °C and 800 rpm, the single desulfurization rate of the composite material can reach 99.19%, achieving the deep desulfurization of fuel oil. Besides, the composite material can be separated and recovered by centrifugation or filtration to be reused, and the desulfurization efficiency is hardly reduced. The high desulfurization rate of DES/rGO is mainly due to the following two reasons. The hydrogen bond between the S atom in the sulfide and the active H in the deep eutectic solvents promotes the removal of the sulfide. The advantages of graphene such as ultra-high specific surface area, better adsorption capacity, and amphiphilic properties enhance the affinity of the simulated oil and the composite material so that the sulfur compounds in the simulated oil are in full contact with the deep eutectic solvents on the composite material, and then the sulfur compounds can be efficient removal.