Fabrication and characterization of chitosan-crosslinked-poly(alginic acid) nanohydrogel for adsorptive removal of Cr(VI) metal ion from aqueous medium

•Chitosan based nanohydrogel (Chitosan-crosslinked-poly (aliginic acid)) have been prepared by co- polymerization method.•Chitosan-crosslinked-poly (aliginic acid) based nanohydrogel have been used for the removal of chromium from the aqueous solution.•Increasing the temperature increases the adsorption ability of the prepared nanohydrogel.

In this study, chitosan-crosslinked-poly (alginic acid) nanohydrogel (CN-cl-PL(AA)NHG) was synthesized by co-polymerization method. It was used an effective adsorbent for the exclusion of Cr(VI) metal ion from aqueous medium. The synthesized nanohydrogel was characterized by FTIR, SEM and TEM. The TEM images clearly indicated the appearance of smooth surface with average size of particles ranging from 30 to 80 nm. The effect of different adsorption parameters like agitation time, temperature, initial metal ion concentration and adsorbent dosage was studied and optimized. The results demonstrated that the prepared chitosan-crosslinked-poly (alginic acid) nanohydrogel had high adsorption tendency for the removal of Cr(VI) from the aqueous solution. The pseudo-second-order equation represented the better adsorption kinetics for the adsorption process. The thermodynamic studies showed the adsorption of Cr(VI) onto CN-cl-PL(AA)NHG was spontaneous and chemical in nature.

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