Removal Mechanisms of Toluene from Aqueous Solutions by Chitin and Chitosan

Low-cost materials of natural origin such as chitin and chitosan were found to effectively remove toluene from aqueous solutions. Batch adsorption experiments for the removal of toluene (5–200 mg/L) were conducted to obtain the isotherm profile. The effects of various parameters such as initial concentrations, adsorbent dose, and contact time on the removal performance of toluene were evaluated. Chitosan shows better removal efficiency, compared to chitin, both in terms of the level of toluene adsorbed per unit mass of adsorbent and in terms of the adsorption kinetics. Adsorption capacity in the range of 33%–58% efficiency was obtained when the chitosan materials were used. The adsorption data on toluene were found to best fit the Langmuir and Redlich–Peterson isotherm models. The kinetic studies revealed that the adsorption of toluene followed the pseudo-second-order rate model. Overall, the study demonstrated that chitosan is a potential adsorbent for the removal of toluene at concentrations as high as 200 mg/L.