Poly(ethylene‐alt‐maleic acid) as complexing reagent to separate metal ions using membrane filtration

Commercial, water‐soluble poly(ethylene‐ alt ‐maleic anhydride), P(E‐ alt ‐MAn), was quantitatively hydrolyzed by 0.2 M NaOH to yield poly(ethylene‐ alt ‐maleic acid), P(E‐ alt ‐MAc). The polymer structure is confirmed by FT‐IR spectroscopy. As the pH increases, metal ion affinity increases because the majority of the functional groups are present as carboxylate anions, which can form more stable complexes at a higher pH. By increasing the filtration factor, Z , metal ion affinity does not significantly decrease, which means that the ligand–metal interaction is strong and cannot be destroyed by washing with water at the filtration cell's pH.