Preparation of Hemicellulose-based Hydrogel and its Application as an Adsorbent Towards Heavy Metal Ions

Water contamination by heavy metal ions is a worldwide problem. In this work, a type of hydrogel, based on hemicellulose, was prepared via graft copolymerization. The reaction time and cost were reduced by modifying the traditional preparation process. The hemicellulose-based hydrogel was an opaque, smooth, well-distributed, and high resilience hydrogel. To better understand the application of hemicellulose-based hydrogel as an absorbent for the removal of Pb(II) (lead nitrate) from heavy metal contaminated water, the hydrogel was used to adsorb Pb(II) from aqueous solution. The various factors that influenced the Pb(II) removal efficiency were studied, including concentration and temperature. The results showed that the hemicellulose-based hydrogel was assessed as an ideal absorbent towards Pb(II), showing maximum monolayer adsorption capacity of 5.88 mg/g. The Pb(II) adsorption isotherm was determined to further understand the adsorption mechanism. The results demonstrated that the adsorption of the hemicellulose-based hydrogel on Pb(II) belongs to the monolayer adsorption and that adsorption conforms to the Langmuir model better than the other model. It revealed that the adsorption process of Pb(II) on hemicellulose-based hydrogel was spontaneous and endothermic in nature. The hemicellulose-based hydrogel was proven as a good material for potential application.