Abstract
This paper deals with the transport properties of inorganic solutes through cellulose acetate membranes. The main purpose of the study is to clarify the effect of both pH and other solutes on the rejection of a particular solute, such as alkali and heavy metal ions. Reverse osmosis experiments were carried out with a batchwise apparatus for several kinds of solution systems in which the concentration of each solution was relatively low. It was found that the rejection of a metal ion is strongly influenced by the pH value of a feed solution. It was also found that the rejection of a particular solute in a mixed-salt solution system is different from that in a single-salt solution system. The degree of the change in rejection depends on the species, concentration and permeation of solutes present in aqueous solutions. In particular, it may be affected strongly by exceedingly permeable or impermeable ions. It is recognized that pH dependence of rejection is attributable to the problem of coexisting solute in mixed-salt solution systems.
