Influence of acidic and basic treatments of activated carbon derived from waste rubber tires on adsorptive desulfurization of thiophenes

This work reports on the influence of treatment conditions on the waste tire-derived activated carbon for adsorptive desulfurization. The rubber tires were carbonized and activated. The obtained activated carbon (AC) was treated with HNO₃ or NaOH at a temperature range of 30-90 °C. The morphology and surface properties of AC were characterized by surface pH, Boehm's titration, N₂ adsorption-desorption isotherms, Fourier-transform infrared spectroscopy, X-ray diffraction, and scanning electron microscope. The AC sample, treated with HNO₃ at 90 °C, possess the highest surface oxygen containing functional groups (2.39 mmol/g), surface area (473.35 m²/g) and pore volume (0.70 cm³/g) and the more adsorption capacity to the refractory sulfur compounds. The Boehm's titration experiments indicated that the amount of surface oxygen containing functional groups on the surface of the acid-treated AC increases with treatment temperatures. Acid-treated AC at 90 °C proves to be optimum for adsorptive desulfurization with the order of dibenzothiophene > benzothiophene > thiophene.