Equilibrium studies on the removal of ACID green 9 dye from aqueous solutions by chitosan adsorbent: Batch studies

Chitosan is a natural, renewable, nontoxic and biodegradable polymer. This unique natural cationic polymer has been evaluated as adsorbent for removing Acid Green 9 (AG9) dye from aqueous solutions. The experiments were performed in a batch system, at room temperature (20 ± 0.5 °C) and the effects of various experimental parameters (pH, contact time, initial dye concentration, adsorbent dosage, temperature, ionic strength) on adsorption capacity were investigated. The results have shown the effectiveness of dye removal is mainly dependent on the ratio between initial concentration of AG9 and chitosan dosage. At a given ratio of AG9: chitosan, an acid pH range of 4-6 was identified as optimal for dye removal. The temperature raising and presence of sodium sulphate (Na2SO4) resulted in a decrease of adsorption yield. The experimental data were analyzed for possible agreement with the Langmuir, Freundlich and Temkin isotherm equations. The Langmuir model was demonstrated to provide the best correlation with the experimental data.