Adsorption Of Phenol Onto Activated Carbon Prepared From ‎coffee Extract Residue Chemically Activated Using Zncl2‎

Résumé: In this work, coffee residue, a natural precursor of vegetal origin ‎was used as a source material to prepare activated carbons by ‎chemical activation with zinc chloride. The effects of differences ‎found in the surface functional groups and textural ‎characteristics of five activated carbons prepared with different ‎impregnation ratios (activating agent/precursor) on their ‎capacity to retain phenol from aqueous solutions are reported. ‎Batch experiments were conducted to study the main parameters ‎such as initial adsorbate concentration, contact time, pH ‎solution, temperature and adsorbent concentration. ‎ It was found that retention of phenol is less in acidic carbons ‎than in basic nature carbons. Activated carbon prepared with ‎‎25 % impregnation ratio showed best adsorption capacity and ‎waschosen for further studies. Optimum conditions for phenol ‎removal were found to be pH = 3, adsorbent concentration = 2 ‎g/L and equilibrium time = 20 min. Under optimised conditions, ‎the prepared activated carbon showed 85 % removal efficiency ‎for a solution concentration of 30 mg/L. The experimental data ‎were analysed by the Langmuir and Freundlich isotherm models. ‎The results clearly showed that the adsorption data of phenol ‎onto activated carbon fit perfectly to the Langmuir model with ‎correlation coefficient higher than 0.99 at all temperatures. The ‎surface chemistry of activated carbon affects the adsorption ‎capacity significantly while the texture characteristics of surface ‎area and pore volume play a minor role in phenol adsorption. ‎Therefore, the surface chemistry must be taken into account in ‎the decision-making process of choosing an adsorbent for phenol ‎removal.‎

Publié dans la revue: algerian journal of environmental science and technology