Evaluation of the Zn2+ transport properties through a cation-exchange membrane by chronopotentiometry.
In this work the effect of zinc concentration, pH, and boric acid concentration on the zinc transport properties through an IONICS 67-HMR-412 cation-exchange membrane was evaluated. The limiting current density and the transport numbers were determined by means of chronopotentiometry. A model between the limiting current density and the bulk zinc concentration was established, assuming a potential relationship between the zinc transport number through the membrane and the bulk zinc concentration together with the Levich equation for the DBL thickness. A decrease in the initial pH value of the solutions causes considerable modifications both in the plateau region and in the overlimiting current density region of the current-membrane potential curves. The results show that the presence of boric acid produces the precipitation of zinc metaborate on the anodic layer of the cation-exchange membrane.
Herraiz-Cardona
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I
Departamento de Ingeniería Química y Nuclear, Universidad Politécnica de Valencia, Camino de Vera s/n, 46022 Valencia, Spain.
Ortega
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E
Pérez-Herranz
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V