High crosslinked sodium carboxyl methylstarch-g-poly (acrylic acid-co-acrylamide) resin for heavy metal adsorption: its characteristics and mechanisms

A lower expansive heavy metal adsorbent, high crosslinked sodium carboxyl methylstarch-g-poly (acrylic acid-co-acrylamide)resin (HCAA), has been prepared by enhancing the crosslinking degree of the traditional water-absorbing polymer under the graftcopolymerization reaction. Further heavy metal adsorption experiments, morphology analysis, and structure characteristic ob-servations indicate that HCAA resin has an excellent heavy metal adsorption properties for Cr3+, Cu2+, Ni2+, and Zn2+of 80.08,158.07, 155.71, and 137.15 mg/g, respectively. The nanoholes in network structures of HCAA resin expanding in solutionprovide an effective diffusion and exchange channels for heavy metal ions and Na+. The adsorption process of HCAA containing –COONa is attributed to ion exchange process, and its essence is to form the coordination bond with heavy metals. Theadsorption capacity differences of –COO−have been explained by using the coordination chemistry theory. In addition, theadsorption selectivity of an expansive adsorbent containing–COONa are heavy metals > H2O >> Na+. Our research puts forwardan insight that increasing the crosslinker content on the basis of the traditional super absorbent resin can obtain a lower expansiveadsorbent to heavy metal pollutant