A novel quaternized chitosan–melamine–glutaraldehyde resin for the removal of nitrate and phosphate anions

A terpolymer of chitosan–melamine–glutaraldehyde was prepared for the first time and it was quaternized with glycidyl trimethyl ammonium chloride (GTMAC). The quaternized chitosan–melamine–glutaraldehyde resin (QCMGR) was found to be effective for the removal of nitrate and phosphate oxyanions. The resin was characterised with FTIR, SEM, EDAX, TGA, DTA, XRD and water regain property. Batch method was followed to optimise the conditions for the removal of nitrate and phosphate. Chemical kinetics of the adsorption was well fitted by pseudo-second order and particle diffusion models and the adsorption process followed the Freundlich isotherm model well. The nitrate and phosphate adsorption capacity of QCMGR from 1000 mg/L respective solutions were 97.5 and 112.5 mg/g, respectively. Nitrate and phosphate anions adsorbed effectively on QCMGR by replacing Cl− ions at the quaternary ammonium group by exchange mechanism. Even after 10th regeneration cycle the adsorbent fully retained its adsorption efficiency. Nitrate and phosphate removal efficiency of QCMGR was also tested by column method.

Graphical abstractQuaternary ammonium chloride introduced chitosan–melamine–glutaraldehyde resin showed high adsorption capacity from aqueous nitrate and phosphate solutions in addition to tremendous regenerability and high stability.Figure optionsDownload full-size imageDownload as PowerPoint slide