A water-soluble polycarbobetaine for sustainable copper recovery

Abstract

This study targets betaine-type polymers (polycarbobetaines -PCBets) as complexing agent of metal ions. As PCBets are pH-sensitive, the adsorption isotherms of copper onto PCBet were monitored at various pH (from 3 to 6) by electrochemical measurements. The best fit to the Langmuir model translates the predominantly homogeneous distribution of the chelating groups on the polymer chains because the Langmuir equation assumes that the adsorbent surface is energetically homogeneous. The results obtained for the complexation of copper were greatly enhanced as the pH increase and reached 250 ± 10 mg g −1 at pH = 6. Such maximal adsorption capacities compete with recent results obtained for molecules of environmental interest such as chitosan, for example. The copper adsorption efficiency was shown stable for soft to hard water. The selectivity of the target PCBets for copper was indicated in the presence of nickel, cobalt, manganese, zinc, calcium or magnesium and partially accounts for the interest in this material and demonstrated the relevance of using PCBet in environmental applications such as copper recovery. The reusability of PCBet was explored by pH adjustment. The results confirm that the efficiency of copper adsorption was maintained over five cycles of PCBet reuse (99 ± 3%). A full process for copper recovery was then designed at laboratory scale for copper recovery from synthetic wastewaters.

Using Polycarbobetaines for Cu Recovery From Catholytes Generated by Electrodialytic Treatment of Sewage Sludge Ash

“…7 for both PCBets which differs from previous results obtained for PCEAC [5]. The methodology used in this previous article [5] was considering other metal ion adsorption favouring copper desorption. Here as exposed in Fig.…”

“…In the case of PCEAC, some copper desorption occurs (-25%) with the increase of spiking copper concentration from 77-319 mg/L. Considering our previous results [5] showing that no copper desorption takes place in the presence of Ca or Zn (whatever is the ratio between 0.5-10), it is suggested that some copper is desorbed in favour of Al adsorption. No such desorption was observed in the case of PCEAMC suggesting that the chemical structure of PCBets can lead to different properties.…”

“…Two PCBets were used for the Cu removal from the catholytes: polycarboxyethyl-3aminocrotonate (PCEAC) and polycarboxyethyl-3-aminomethylcrotonate (PCEAMC). The PCBets were synthesised and characterized (results not shown) according to the procedure described by Mouton et al [5]. Methacrylic acid was used in the synthesis of PCEAMC instead of acrylic acid as in the synthesis of PCEAC.…”

“…3 and was operated in triplicate. The pH of catholytes was first adjusted from pH 2 to pH 5 with NaOH, due to the pH sensitivity of PBCets [5]. Some elements were visibly precipitated and the solution was then filtered at 0.45 µm and the pH adjusted catholyte sample was named C-L/S XpH5.…”

“…One group of adsorbents are synthetic polybetains, where novel water-soluble polycarbobetaines (PCBets) have shown potential for selective removal of metal ions from solutions. The PCBets have especially shown good results of up to 100% removal of Cu in synthetic solutions, however PCBets have still not been tested with real contaminated samples [5], [6].…”