Phenol removal from aqueous solution by carbon xerogel

Carbon xerogel (CX) was used for phenol adsorption from aqueous solution. CX was synthesized by sol–gel polycondensation of resorcinol with formaldehyde using sodium carbonate (Na₂CO₃) as catalyst. Then, it was dried by convective drying technique and pyrolyzed under inert atmosphere. Phenol adsorption kinetics was very fast, what was attributed to the presence of open pore structure. The kinetic studies showed that the adsorption process could be fitted to a pseudo-second-order model and the particle diffusion process is the rate-limiting step of the adsorption. The phenol removal was maximum and unaffected by pH changes when the initial pH of the phenol solution was in the range of 3–8. The optimum adsorbent dose obtained for phenol adsorption onto CX was 0.075 g/50 cm³ solution. The Langmuir model described the adsorption process better than the Freundlich isotherm model and the monolayer adsorption capacity is 32 mg g⁻¹. Among the desorbing solutions used in this study, the most efficient desorbent was EtOH (100 %) which released about 87 % of phenol bound with the CX.