Chelating–Ultrafiltration Treatment of Some Heavy Metal Ions in Aqueous Solutions by Crosslinking Carboxymethyl Modified Cornstarch

Crosslinking carboxymethyl starch (CCMS) powder of degree of substitution (DS) 0.43–0.59 was prepared by the process of two steps of alkali addition synthesis. The technique of powder coupling with ultrafiltration was used to absorb Cu 2+ , Zn 2+ , Ni 2+ , Pb 2+ , and Cd 2+ from aqueous solutions. FTIR was used to demonstrate the successfully grafting of carboxymethyl groups, and the technique of microwave plasma torch atomic emission spectrometer was applied in rapid determination of the aforementioned heavy metals ions. The results revealed that the removal sequence of heavy metal ions followed the order of Pb 2+ >Cu 2+ >Cd 2+ >Zn 2+ >Ni 2+ . By assistant of diethylene triamine penlaacetic acid, the quaternary system of Pb 2+ /Ni 2+ /Cd 2+ /Cu 2+ mixture solution could have the ideal separation. Besides, the influence of pH, ζ potential, DS value, and membranes molecular weight cut-off on removal of 20 mg L −1 Pb 2+ or Ni 2+ was also investigated.