Experimental and theoretical study on BTEX removal from aqueous solution of diethanolamine using activated carbon adsorption

• Removal of BTEX from DEA solution by commercial activated carbon was performed.
• The Freundlich and Sips isotherms have best agreement with the experimental.
• A mathematical model was proposed for continuous adsorption of BTEX by carbons.
• Predicted breakthrough curves have good agreement with experimental results.

Activated carbon beds are extensively used in sweetening units of natural gas refineries for the purification of contaminated amine solutions. Correlation of experimental adsorption data using an analytical isotherm equation is need to design an accurate activated carbon bed. In the present study, the adsorption of BTEX from Diethanolamine (DEA) solution by commercial and granular activated carbon (AC) were performed. The Langmuir, Freundlich and Sips isotherm models were used to describe the equilibrium data. The accuracy of the results obtained from the adsorption isotherm models was compared and the values for the regressed parameters were reported. The results show that the Freundlich and Sips isotherms have better agreement with the experimental data than Langmuir isotherm for all AC samples. According to the adsorption isotherm curves obtained from experiments, the amount of adsorption of metaxylene, ethylbenzene, toluene, benzene increases respectively. In addition, a mathematical model was proposed for describing the BTEX transfer between the amine solution and solid particles. The breakthrough predicted by the proposed model was compared with the experimental results and a satisfactory agreement was observed between them.