Efficient removal of Hg2+, Cu2+and Cd2+from aqueous solutions with polyaspartic acid: Influencing factors and mechanism analysis

The removal rates of polyaspartic acid (PASP) for Hg2+, Cu2+ and Cd2+ were evaluated, and the complexes formed after the reaction were characterised. With increasing PASP dosage, the removal rate increased. At pH 5.0-9.0, the removal rates increased as the pH increased. The removal rates of three heavy metal ions from Clions were higher than those from NO3- ions. The removal amounts of Hg2+, Cu2+ and Cd2+ by PASP were 1058.46, 203.07 and 459.20 mg center dot g- 1, respectively. The SEM images reflected the significant interactions between the heavy metal ions and PASP. The FTIR spectra revealed that carboxylate and nitrogen were the significant groups in the reactions of PASP with Hg2+ and Cu2+, and carboxylate was the significant group in the reaction of PASP with Cd2+. Overall, the results demonstrate that PASP is a promising candidate for removing Hg2+, Cu2+ and Cd2+ from aqueous solutions.