Optimization of sugarcane bagasse activation to achieve adsorbent with high affinity towards phenol

Sugarcane bagasse as an agricultural/industrial biomass was converted into a low-cost activated carbon via an acid activation procedure under optimized conditions. Phosphoric acid was applied as a cost-effective and environmentally friendly chemical activator. The optimized activated carbon produced under temperature of 550 C and impregnation ratio of 1.5 showed a micromesoporous structure with specific surface area and pore volume of 972.5 m²/g and 0.43 cm³/g, respectively. The adsorption capacity of the produced AC towards phenol was measured and, after only 30 min, the removal percentage reached over 95%. The greatest affinity towards phenol was obtained at pH of 4 justified by the pHpzc of the sorbent and speciation of phenol in solution. Under the intermediate concentration range, the Dubinin--Radushkevich isotherm was the best-fit model for describing the equilibrium data. The apparent adsorption energy was equal to 10.94 kJ/mol. All the evidence showed that the mechanisms involved in phenol adsorption were ion-exchange, electrostatic, and physical adsorption.