Effective parameters of adsorption of asphaltenes from toluene on mineral surface LECA, Perlite and Bentonite

This paper presents the feasibility 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, size of adsorbent particles 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 h, temperature of 50°C 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, and the results indicated a good fitting by Langmuir isotherm. Thermodynamic parameters such as ΔH, ΔS and ΔG were calculated. It was revealed that the adsorption was spontaneous and of exothermic nature, which was evident by decreasing the randomness of the dye at the solid and liquid interfaces. The characteristic results and dimensionless separation factor (RL) showed that perlite and bentonite can be employed as an alternative to commercial adsorbents in the removal of asphaltenes from aqueous solution and oil.

Keywords:

Asphaltenes , Adsorption , Leca , Perlite , Bentonit