Nafion-117 Behavior during Cation Separation from Spent Chromium Plating Solutions

作者：Ahmed M Elmuntasir I; Huang Kuo Lin^*; Holsen Thomas M

来源：Industrial & Engineering Chemistry Research, 2009, 48(14): 6805-6810.

DOI：10.1021/ie900149a

This study investigated the behavior of Nafion-117 ion-exchange membranes that are commonly used as the separator in electrolytic re-generation of spent chromium plating Solutions. fit the co-presence of Cu(2+), Ni(2+), and Fe(3+) impurities (similar to 0.01-0.1 M) in similar to 0.5-2.0 M H(2)CrO(4), the exchange equivalents of Ni(2+) by Nafion-117 was double that Of Cu(2+) (0.02 mmol of H(+)/(g of Nation)) but smaller than that (similar to 0.03-0.15 mmol of H(+)/(g of Nafion)) of Fe(3+), exhibiting the order Fe(3+) >= Ni(2+) >= Cu(2+) in Nafion affinity. The water content (similar to 41%) of a Nafion-117 membrane soaked in 2 M H(2)CrO(4) was greater than those (similar to 35-38%) in the contaminated 2 M chromic acid solutions, whereas the porosity (0.24) of the former was smaller than those (0.29-0.37) of the latter. For the Nafion-117 in 2 M chromic acid solutions with/without cation impurities, (1) the tortuosity coefficient of Fe(3+) was about 1.8 times that Of Cu(2+) or Ni(2+), (2) the calculated pore radius was 3.2 nm for a multiimpurity case (0.1 M Cu(II), Fe(III), Ni(II), and Cr(III) each) based on the Gierke's model, and (3) the cation impurities did not significantly influence the numbers of water molecules in Nation clusters. The Nafion-117 withstood the pH < 0 environment with only minor rotation in the fluorocarbon backbone clue to accommodation of anionic Cr(VI) within clusters.

• 出版日期2009-7-15