Removal of Cu2+ ions by cellulose nanofibers-assisted starch-g-poly(acrylic acid) superadsorbent hydrogels

Removal of pollutants by bio-superadsorbent is currently in the limelight due to their low cost and biocompatibility with the environment. This research, we investigated the potential of cellulose nanofibers (CNFs) treated starch-g-poly(acrylic acid) (St-g-PAA) superadsorbent hydrogels in removing Cult ions from water. It was found that CNFs-incorporated starch-g-poly(acrylic acid) hydrogel exhibit the highest amount of Cu2+ uptake in a solution containing 0.1 g/L Cu2+ ions, and that adsorption capacity rises significantly with the increase in Cu2+ concentration from 0.1 to 0.6 g/L. The influence of CNFs on the adsorption of Cu2+ ions was studied by Langmuir and Freundlich adsorption isotherm models, the graphs verged on linearity in Langmuir model while the maximum monolayer adsorption capacity was found to be 0.736 g/g for the untreated St-g-PAA hydrogels and 0.957 g/g for the CNFs-treated hydrogels in 0.6 g/L Cu2+ solution at pH 5. In this study, the adsorption capacity was enhanced by increasing the contact time between the bio-adsorbent and solution up to 5 h while longer contact time resulted in reduced adsorption and desorption phenomenon. In addition, desorption results showed that maximum adsorbent recovery for pH near to 1-2. This study confirms that the starch-based hydrogel is promising to be used for removal of pollutants from water efficiently.