Development of multivalent metal ions imprinted chitosan biocomposites for phosphate sorption

In this present work, to overcome the problem of eutrophication due to phosphate an attempt was made to develop eco-friendly composite materials using chitosan and bentonite. To improve the properties of bentonite (bent) and chitosan (CS), chitosan supported bentonite (CSBent) composites were prepared and utilized for phosphate removal. To enhance the uptake capacity of CSBent, various multivalent metal ions like Zr⁴⁺_, Fe³⁺ and Ca²⁺ were imprinted on CSBent composites namely Zr@CSBent, Fe@CSBent and Ca@CSBent biocomposites respectively. The synthesized Zr@CSBent, Fe@CSBent and Ca@CSBent biocomposites possess the efficient phosphate sorption capacities (SCs) of 40.86, 22.15 and 13.44mg/g than the individual CSBent composite. The systematic study for various adsorption influenced parameters such as agitation time, presence of co-existent anions, solution pH, temperature and initial phosphate concentration has been verified in batch mode. The prepared biocomposites was exemplified by FTIR, TEM, SEM and EDAX analysis. The experimental data was fitted to various isotherms and thermodynamic parameters. The mechanism of phosphate removal by M@CSBent composites was governed by ion-exchange, electrostatic attraction and inner sphere complexation. This study reveals a feasibility of biocomposites for phosphate uptake from polluted water sample at field situation.