FeCl2, FeCl3, ethanol, K2SO4, K3PO4, K2CO3, Hg(NO3)2, AgNO3, ZnCl2, CuSO4, CdCl2, BaCl2, Pb(NO3)2, MnCl2, CaCl2, MgCl2, Cr2(SO4)3, and K2Cr2O7 were bought from Sinopharm Chemical Reagent Co. Ltd.
(Beijing, China).
Poly(ethylene oxide) (average Mw 900 kDa)
and Chitosan (average Mw 200 kDa) were
obtained from Sigma-Aldrich. Dialysis tubing with a flat diameter
of 28 mm and a molecular weight cutoff (MWCO) of 1 kDa were provided
by Biotopped (Viskase). Deionized water with a resistivity of 18.2
MΩ was provided by a GWA-UN water purification system. All materials
and chemicals were of analytical grade and used as received without
further purification.