Preparation of a Hydrogel-Based Adsorbent for Metal Ions through High Internal Phase Emulsion Polymerization

In this work, a porous hydrogel-based adsorbent for metal ions was prepared through the copolymerization of acrylic acid and 2-hydroxyethyl methacrylate using a high internal phase emulsion (HIPE) method. Stretched molecular chains in the hydrogel ensure the excellent accessibility of functional sites by the metal ions. A highly open cellular structure endows the P(AANa- co -HEMA) gel with high transport rates as a promising adsorbent. Adsorption properties were investigated by three isotherm models and two kinetic models. X-ray photoelectron spectroscopy analysis proved a chelating interaction between -COO - and metal ions. The adsorption capacity reached 630 mg·g -1 for Pb 2+ under 303 K and a 400 μg·mL -1 initial concentration. The results show that the as-prepared PolyHIPE-based P(AANa- co -HEMA) gel possesses an open cellular structure, high adsorption capacity, and high selectivity for Pb 2+ .