Adsorption of phenol from aqueous solutions onto natural and thermallymodified kaolinitic materials

Abstract

Phenol removal from aqueous solutions by kaolinite (KAO) and metakaolinite (MET) have been carried out at 25 °C in batch mode to evaluate the effects of parameters such as pH, initial phenol concentration and adsorbent mass on the extent of adsorption. It was observed that phenol uptake increased with increases in adsorbent concentration at maximum pH of 2 and equilibrium time of 40 minutes for both KAO and MET. Results showed that pseudo second-order kinetic model best describes the chemisorption of phenol from aqueous solutions onto the two clay samples. The low correlation coefficient of the intraparticle diffusion model proves that pore diffusion plays little or no significant role in the adsorption of phenol onto KAO and MET. Also, from adsorption isotherm analysis, only the Temkin equation modeled best the adsorption process of phenol from aqueous solutions onto MET while the Freundlich and Temkin models best described the adsorption of phenol onto KAO. Maximum adsorption capacity for KAO and MET were 1.71 and 5.82 mg/g respectively through Langmuir model equation. It can be inferred from experimental results and modeled parameters that clay samples are not very effective for the removal of phenol from aqueous solution.