Silver Nanoparticle-Assisted Adsorptive Desulfurization by Composted Agro-Waste Activated Carbons

This study reports the use of composted agro-waste activated carbons assisted by silver nanoparticles as adsorbents for removal of dibenzothiophene (DBT) from model oil. The adsorbents were characterized using Fourier transform infrared spectroscopy (FTIR), N-2 adsorption-desorption surface area analyzer, energy-dispersive X-ray diffractogram (EDX) and high-resolution transmission electron microscope (HRTEM). Freundlich adsorption isotherm best represented the adsorption data, and removal of DBT from model oil is best described by pseudo-second-order (PSO) kinetic model. Freundlich isotherm model fits equilibrium data very well for the adsorption of DBT from model oil onto the adsorbents, while removal of DBT from model oil is best described by pseudo-second-order (PSO) kinetic equation. The highest adsorption capacity at equilibrium (q(e)) was achieved by silver nanoparticles-modified RBPAC with a q(e) of 26.9 mg DBT/g of adsorbent at 298 K. A significant decrease from 416.3 to 215.7 and 417.1 to 223.5 m(2)/g in the Brunauer-Emmett-Teller surface areas of RPAC and RBPAC, respectively, is observed following impregnation with AgNPs. The heats of adsorption and change in entropy for DBT adsorption onto these adsorbents are in the range of 24.7-39.6 kJ/mol and 0.19-0.25 kJ/mol K, respectively.