Adsorptive desulfurization of thiophene, benzothiophene and dibenzothiophene over activated carbon manganese oxide nanocomposite: with column system evaluation

Activated carbon was successfully treated with manganese oxide to further improve its surface properties for adsorptive desulfurization. The activated carbon-manganese oxide nanocomposite consisting 10% optimum metal loading showed significant adsorptive desulfurization efficiency. The textural properties (surface area 160.98 m²g⁻¹, total pore volume 0.141 cm³g⁻¹, and average pore diameter 9.27 nm) and surface chemistry of the as-synthesized activated carbon-manganese oxide adsorbent were crucial to the efficient desulfurization. The as-synthesized adsorbent displayed oxygen-containing functional groups and distinct pore structures that enabled rapid uptake of the refractory sulfur compounds within the initial 5 min of the adsorption process. The adsorption experimental data were best fitted to pseudo-second order kinetic and Temkin isotherm models. Adsorption capacities of 4.5 mg g⁻¹, 5.7 mg g⁻¹, and 11.4 mg g⁻¹ were obtained for simultaneous adsorption of thiophene, benzothiophene, and dibenzothiophene on the as-synthesized adsorbent in a batch process, and the same trend was retained in the fixed bed model. The π-complexation and the direct sulfur-metal interaction could justify the greatest adsorption capacity for dibenzothiophene.