Direct activation of petroleum pitch-based mesoporous carbon for phenol adsorption

Abstract

Phenol, a highly toxic substance that poses a serious threat to both environment and human, is difficult to degrade. Adsorption using porous adsorbents is an effective method for the removal of phenol from water. Herein, petroleum pitch-based mesoporous carbons (PPMCs) were prepared using magnesium citrate as a template and then PPMCs were used for the adsorption of phenol in water. By activating petroleum pitch at 900 ℃ with a mass ratio of MgO to petroleum pitch of 4:1, a mesoporous carbon (PPMC-4–900) with abundant mesopores (high specific area of 1627 m2·g−1 and pore volume of 1.81 cm3·g−1) was obtained. The phenol adsorption capacity of PPMC-4–900 reaches up to 189.96 mg·g−1. The adsorption behavior of phenol on PPMCs followed Freundlich model, indicating it is multilayer adsorption on PPMCs. The adsorption kinetics of phenol on PPMCs are consistent with pseudo-first-order adsorption and pseudo-second-order adsorption model, suggesting the adsorption process of phenol on PPMC-4–900 is not only influenced by physical adsorption but also controlled by chemical adsorption. And the thermodynamic parameters indicate that the adsorption process is spontaneous and exothermic. Furthermore, the PPMCs exhibited excellent recyclability (recovery rate of adsorption capacity over 91 %) after five adsorption/desorption cycles. These results reveal that PPMCs are a promising adsorbent for phenol removal from water.