Highly efficient removal of copper ions from water by using a novel alginate-polyethyleneimine hybrid aerogel

In this study, a novel alginate-polyethyleneimine hybrid aerogel (Alg-PEI) that could remove Cu2+ from wastewater was prepared by using a simple one-step synthesis and vacuum freeze-drying technology. As-prepared Alg-PEI exhibited high affinity and selectivity toward Cu2+ and could take up 95.1% of the Cu2+ in a 0.1 mM Cu2+ solution. The selectivity coefficients of Alg-PEI for Cu2+ exceeded 10 even in the presence of Co2+, Fe2+, Cr3+, or Cd2+. The maximum adsorption capacity of the Alg-PEI for Cu2+ reached 214.4 mg/g, which is higher than that of most reported Cu2+-sorbents. Moreover, Alg-PEI could be regenerated by simple acid-washing and used repeatedly. Analysis of the adsorption mechanism of the aerogel revealed that Alg-PEI binds Cu2+ mainly through ion exchange and chemical coordination effects.