Synthesis and characterization of CuO, ZnO and CeO2 adsorbents based on silica derived from Rice husk ash and evaluation of its performance in the desulfurization process of model fuel

In this study, the aim is to extract pure amorphous silica from rice husk ash by acid leaching, then calcination and base leaching, and finally titration by acid. Then, the synthesis of adsorbents was performed through loading of copper, zinc and cerium at the rate of 13% by weight of metal by impregnation method on silica support. Finally, the performance of the synthesized adsorbents in the adsorptive desulfurization process was investigated to remove 4, 6-dimethyldibenzothiophene from the model fuel. Nitrogen adsorption - desorption isotherms for the samples showed that the pores are in the mesopore range. The highest adsorption capacity was obtained at a concentration of 500 ppm for CuO/SiO2 adsorbent equal to 23.7 mg/g. Also, by examining the Langmuir, Freundlich and Dubinin-Radushkevich equilibrium isotherms, the Langmuir isotherm was most consistent with the experimental data. Also, according to Dubinin-Radushkevich isotherm it was proved that the dominant mechanism in adsorption is chemical. In order to investigate the adsorption kinetics in this study, pseudo-first order and pseudo-second order equations were also examined. The pseudo-second order kinetic was fitted with experimental data with R-squared of 0.99 were fitted to the experimental data. BET and FESEM equipped with EDX analyzes have been used to investigate the physicochemical properties of the synthesized adsorbents. Also, the concentration of fuel solution was determined by UV-VIS.