Adsorption/desorption of BTEX on activated carbon prepared from rice husk

Abstract

The differences in the adsorption/desorption behavior of benzene, toluene, ethyl-benzene, and p-xylene (BTEX) using rice husk activated carbon (RHAC) were studied. It was proved that RHAC were quite effective in removing BTEX compounds from aqueous solutions. About 48 h was sufficient to attain maximum BTEX adsorption and desorption. Adsorption kinetics data proved a closer fit to the Weber–Morris model, while the isotherm experimental data were better fit to the Freundlich model, producing values of 1/n less than one, indicating favorable adsorption. Adsorption isotherms were determined in polluted surface water and it was found that the removal efficiency depends on the initial concentration of BTEX pollutants. Desorption equilibrium is less rapid than the adsorption equilibrium. BTEX adsorption/desorption was affected by chemical structure, solubility, and molecular weight. About 22% benzene, 33% toluene, 58% ethylbenzene, and 18.8% of p-xylene were released from RHAC after contact between the loaded matrix and reagent water. Sorption/desorption of p-xylene in RHAC was found to yield co-incident equilibrium isotherms and no significant hysteresis was observed.

Keywords:

• Adsorption
• BTEX
• Activated carbon
• Rice husk
• Desorption
• Reversibility

Acknowledgments

The authors extend their appreciation to the Deanship of Scientific Research at the King Saud University for funding the work through the research group project (Project No. RGP-VPP-184).