Removal of phosphate and nitrate ions from aqueous solution using La3+ incorporated chitosan biopolymeric matrix membrane.

The present investigation was carried out for the removal of phosphate and nitrate ions from aqueous solution using lanthanum incorporated chitosan membrane (La@CS) prepared by casting method. Systematic adsorption studies were performed by varying the influencing parameters like contact time, dosage, pH, interfering anions and temperature were optimized for the maximum phosphate and nitrate adsorption capacities. The adsorption equilibrium process was examined by Freundlich, Langmuir and Dubinin-Radushkevich isotherm models. The La@CS membrane showed an adsorption capacity of 76.6 and 62.6 mg/g for phosphate and nitrate ions respectively. Thermodynamic parameters such as ∆G°, ∆H° and ∆S° were calculated to understand the nature of adsorption. The synthesized La@CS membrane was characterized by FTIR, SEM, EDAX with mapping analysis, XRD, AFM, TGA-DSC and zero point charge analysis. The possible adsorption mechanism was found to be electrostatic attraction as well as by ion exchange between La@CS membrane and both anions like phosphate and nitrate. The experimental results clearly indicated that the prepared La@CS membrane could be utilized for the removal of phosphate and nitrate ions from aqueous solution.