USE OF NEGATIVELY-CHARGED ULTRAFILTRATION MEMBRANES.

This paper is concerned with the ultrafiltration with negatively-charged, noncellulosic membranes which is a promising technique for the separation and concentration of inorganic salts present in aqueous solution, particularly for industrial waste treatment and in systems designed for water reuse. Because charged membranes reject ionic solutes via repulsion of coions by the fixed charged groups on the membrane skin, the membrane rejection is expected to depend on solute type and coion charge. Results of an experimental study are presented which was conducted with a continuous-flow ultrafiltration unit to determine the relative rejection behavior of several metal salts as a function of metal ion (present as chloride or sulfate salts or as complexed ion) characteristics. The application of the process is also experimentally evaluated with acid mine water (at greater than 95% water recovery) to establish ultrafiltrate reuse. Experimental data are tabulated and evaluated.