Effective Parameters of Adsorption of Asphaltenes from Toluene on Mineral Surface LECA, Perlite and Bentonite

This paper presents the feasibility (or possibility) of removal of asphaltenes from aqueous solutions by using low-cost natural adsorbents; such as, light expanded clay aggregate (LECA), perlite and bentonite. The effect of adsorbent type, initial asphaltene concentration, particle size of adsorbent and temperature on the adsorption capacity was investigated. The results showed that at the initial asphaltene concentration of 125 mg L 1-, contact time of 24 hrs, temperature of °50C and adsorbent dosage of 1 g, removal of asphaltenes onto LECA, perlite and bentonite was 53.59, 93.01 and %99.77, respectively. Also, Langmuir and Freundlich models were applied to describe the experimental data; moreover, the results indicated a good fitting by Langmuir isotherm. Thermodynamic parameters; such as, ∆H, ∆S and ∆G were calculated. It was revealed that the adsorption was spontaneous and exothermic nature, which was evident by decreasing the randomness of the dye at the solid and liquid interfaces. The characteristic results and the dimensionless separation factor (RL) showed that perlite and bentonite could be employed as an alternative to commercial adsorbents in the removal of asphaltenes from aqueous solution and oil.