Document Type


Date of Award


Degree Name

Master of Science in Chemical Engineering - (M.S.)


Chemical Engineering

First Advisor

C. L. Mantell

Second Advisor

Joseph Joffe

Third Advisor

George C. Keeffe


The problem of the recovery of values from waste sulfate pickling solutions by electrolytic methods, using permselective anion exchange membranes, is here considered from both the viewpoint of technical and commercial feasibility.

Three different types of anion exchange membranes, i.e. NALFILM-1, PERMUTIT and AMBERPLEX A-1, were tested in a laboratory cell, using an acid ferrous sulfate solution having a composition as close as possible to that of the average waste pickle liquor from steel mills. Curves giving a relationship between both iron plated out and sulfate anions transported to the anolyte as a function of the amount of current passed through the cell and the variation in pH of the catholyte solution during electrolysis, are here presented for each type of membrane employed.

Curves relating total cell voltage to current density, temperature and bath composition are also given. The analysis of the general behavior of these membranes in the electrolysis of acid ferrous solutions showed that the controlling factors are: I. the hydrogen ion "leakage", or more exactly, the ratio of the hydrogen ions transported from anolyte to catholyte to the total current passed, II. the electrical resistivity of the membranes to the flow of current.

These fundamental properties of the membranes tested were found to vary over a wide range from one to the other, depending upon the chemical structure of the membrane itself.

On the basis of laboratory results for batch operation, a continuous process is visualized and costs calculated for a given daily iron output and for predetermined constant composition of cell feed, as well as operating temperature, current density and catholyte depletion. It is recognized that, although the process is technically sound, none of the membranes tested was found to have such a sufficiently high perms-electivity, together with low electrical resistivity, as to make the process economically practicable or at least to compete with the conventional methods of disposal of spent pickle liquors. It is pointed out, however, that a highly improved perm-selectivity of membranes at present available, would enable this process to become commercially attractive.



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