Biosorption of direct azo dye from aqueous phase onto Spirogyra sp. I02: Evaluation of kinetics and mechanistic aspects

Sorption of azo dye from aqueous phase was evaluated using non-viable algal Spirogyra I02 as biosorbent. Agitated non-flow batch sorption studies revealed the capacity of algal biosorbent to adsorb the azo dye. Influence of dye concentration, effect of pH, biosorbent dosage, temperature effect and sorption–desorption were studied to evaluate the algal-dye sorption mechanism. Sorption interaction of dye on to algal species obeyed the pseudo second-order rate equation. Experimental data showed good fit with the Langmuir's adsorption isotherm model. Dye sorption was found to be dependent on the aqueous phase pH and the uptake was observed to be higher at lower pH. Maximum dye sorption was observed at 30 °C temperature. Sorption–desorption of dye into organic and/or inorganic solutions were observed and this indicated the combined effect of chemical and ion-exchange sorption phenomena.