Charged membrane ultrafiltration of heavy metal salts: Application to metal recovery and water reuse

An experimental investigation is presented of the thin‐channel ultrafiltration of 0.6 × 10 −3 M to 15.0 × 10 −3 M aqueous solutions of Cu 2+ , Ni 2+ , or Zn 2+ sulfate or chloride salts through a negatively‐charged, non‐cellulosic membrane. Multi‐salt solutions and the actual rinse water from a Watts‐type‐nickel‐plating process are also ultrafiltered. The membrane provides a Ni 2+ rejection of 0.83 and water flux of 1.0 × 10 3 cm/sec (23 gal/ft 2 day) at a transmembrane pressure difference of 4.0 × 10 5 N/m 2 (3.9 atm). The membrane rejection and water flux data are utilized in a computer simulation procedure for scale‐up to a multi‐module, two‐staged process for the closed‐loop operation of a plating plant.