Facile introduction of Cu⁺ on activated carbon at ambient conditions and adsorption of benzothiophene over Cu⁺/activated carbon

CuCl-supported carbon based adsorbents were prepared, for the first time, through a facile and mild reduction of CuCl₂ to improve the desulfurization capability of the porous activated carbon (AC). Reduction of CuCl₂ was carried out at room temperature and atmospheric pressure with sodium sulfite as a mild reducing agent. Liquid-phase adsorption of benzothiophene (BT) over CuCl/ACs was studied to understand the effect of Cu⁺ on adsorption/removal. The CuCl-supported AC adsorbed around 30% more BT with faster adsorption kinetics compared with the virgin AC. Since the surface area and pore volume of the AC decreased with the loading of the copper species, the increased adsorption capacity over the Cu⁺-supported AC adsorbents suggests the formation of a π-complex between Cu⁺ and BT. Additionally, in the presence of air/moisture, the obtained Cu⁺ species oxidized readily to a Cu^{2 +} state and showed a negligible increment in adsorptive desulfurization compared with the virgin AC; therefore, the adsorbent should be stored/applied under an inert atmosphere.