Application of soils for removal of methyl tertiary butyl ether (MTBE) from aqueous solution: adsorption kinetics and equilibrium study

Methyl tertiary butyl ether (MTBE) is widely used as a gasoline additive. The contamination of surface water and groundwater with MTBE has attracted further attention due to the relatively high potential MTBE related health risks. In the current research, the adsorption capability of MTBE by kaolinite, bentonite, sandy loam and clay loam was studied through series of batch sorption procedures. The results were investigated with respect to the linear, Freundlich, Langmuir, Toth and Langmuir-Freundlich sorption isotherms. In the equilibrium condition, the MTBE concentration (Ceq) was 0.68–6.88 mg/L for clay loam, 0.89–8.94 mg/L for sandy loam, 1.3–11.26 mg/L for bentonite and 1.56–13.5 mg/L for kaolinite. The obtained modeling results revealed that the sorption affinity of the studied soils for MTBE increases in the order of kaolinite < bentonite < sandy loam clay loam. Moreover, the effects of contact time, pH, and temperature on the sorption affinity of MTBE into the soil samples were investigated and the thermodynamic parameters (ΔG, ΔH and ΔS) were calculated. Approximately 80% of the total MTBE removal was occurred within the first 80 min of experiments. Moreover, the maximum MTBE removal (57.4%) was obtained at pH of 3 while the least efficiency (23.1%) at pH of 11. A decrease in sorption distribution coefficient (Kd) was observed with increasing the temperature and its maximum value was found at 298.15°K. According to our findings, different types of soils due to their acceptable efficiency and low cost could be applicable for the MTBE removal from the aqueous solutions.