The removal of benzene toluene, ethyl benzene and p-Xylene (BTEX) from aqueous solution using granular activated carbon (GAC) was investigated in the study. To determine the efficiency of GAC, the removal of BTEX by GAC was carried out in relation to contact time, adsorption dosage and pH. Comparative studies of batch and column setup and adsorption/desorption were done to determine its efficiency in respect to its commercial application and mechanism of adsorption. The results from the overall study showed that BTEX removal by GAC increased with increase in contact time and adsorbent dosage, with optimum contact time and dosage determined as 30 min and 0.2 g, respectively. The pH was seen to have relatively little or no effect on BTEX removal, depicting a wide range of stability over pH. The Langmuir and Freundlich isotherms models were used to describe the adsorption equilibrium. The Freundlich plots showed higher R2 values, which suggests that adsorption into GAC allows more than one layer. The pseudo first and second order were used to understand the kinetics of GAC adsorption. The results showed that it fits the pseudo second order which indicates that the rate limiting step may be chemisorption. This was further confirmed in desorption study as low levels of BTEX (< 3%) were recovered. Finally, the comparison of batch and column set up showed that batch adsorption was more efficient than column setup. Generally, GAC showed excellent removal efficiency; and thus, should be used in large scale for removal of BTEX from water.
Keywords: Adsorption, benzene toluene, ethyl benzene and p-xylene (BTEX), granular activated carbon.