Simultaneous recovery and separation of Zn~(2+) and Cu~(2+) in hybrid membrane systems

摘要

Transport and separation properties of a double multimembrane hybrid system (d-MHS) composed of:stripping solution (1) | MHS( 1) | feed solution | MHS(2) | stripping solution (2) have been studied.In the system each MHS comprises an agitated bulk liquid membrane (BLM) placed between two cation-exchange polymer membranes (CEM).The simultaneous recovery and separation of Zn~(2+) and Cu~(2+) from a binary or multicomponent (Zn~(2+),Cu~(2+),Ca~(2+),Mg~(2+),K~+,Na~+) solution has been performed by using two parallel BLMs selectively transporting one of the two target cations.The d-MHS exploiting 5-nonylsalicyl-aldoxime (Acorga P-50,Cu~(2+) selective) and di-(2-ethylhexyl) phosphoric acid (D2EHPA,Zn~(2+) selective) in particular BLMs allows the simultaneous separation and up-hill transport of the two cations.A new d-MHS system integrated with the Donnan dialysis process (DD-d-MHS) has also been constructed in order to preconcentrate cations before their separation through the two MHS modules.The application of DD-d-MHS to remove Zn~(2+) and Cu~(2+) from contaminated (0.001 mol/dm~3 Zn(NO_3)_2 and Cu(NO_3)_2) tap water (model feed for electroplating rinse solution) results in approx 86-88% recovery of both cations from the feed and their active concentration with the following selectivity coefficients:beta_M~(Zn)=170 and beta_M~(Cu)=530.