Pb(ΙΙ) removal from water using porous hydrogel of chitosan-2D montmorillonite.

An eco-friendly chitosan-2D montmorillonite (CTS/2DMMT) hydrogel with the characteristics of high surface area, porous structure and easy separation as a new type of adsorbent was investigated. Hydrogel was prepared via self-assembling 2DMMT and CTS. 2DMMT and hydrogel were characterized by particle size analysis, SEM and AFM, respectively. The results showed the 2DMMT was well exfoliated and the porosity of hydrogel's structure could be adjusted by the CTS/2DMMT ratio. The effect of pH, adsorption kinetics and adsorption isotherm of Pb(ΙΙ) from aqueous solution onto hydrogels were investigated. Adsorption could proceed without the pH adjustment and hydrogel with a looser structure has better adsorption effectiveness. The Pseudo-first-order kinetics model and Freundlich isotherm model could fit well with the Pb(ΙΙ) adsorption process onto hydrogel. The adsorption mechanism was the ion-exchange according to the analysis of XPS and EDS.