A new water-soluble polycarbobetaine showing high selectivity toward copper

ABSTRACT

In this study, betaine-type polyampholytes (polycarbobetaines, PCBets) are investigated as complexing agents of metal ions. Because PCBets are pH-sensitive due to the presence of amine and carboxylic acid groups, the complexation of copper was monitored at various pH values (from 3 to 6) by UV–vis spectroscopy and/or electrochemical measurements. The results obtained for the complexation of copper were greatly enhanced as the pH increased and reached 264 ± 11 mg g1 at pH = 6. This maximum adsorption capacity rivals the recent results obtained for molecules of environmental interest, such as chitosan. The selectivity of the target PCBets for copper was indicated in the presence of nickel and/or cobalt and partially accounts for the interest in this material and demonstrated the relevance of using
PCBet in environmental applications (such as metal recovery from wastes/wastewaters or environmental sensors). The efficiency of copper adsorption was maintained over 5 cycles of PCBet reuse (91 ± 4%).