Multidimensional response surfaces in the characterization, comparison and optimization of membranes

Mathematical functions relating salt rejection and flux rate to operating conditions were developed for two dynamic reverse osmosis membranes. Such a relation defines a response surface in multidimensional space, and can serve as a general expression of the character of a membrane. It is demonstrated that with the approriate experimental design, a large amount of information on the behaviour of membranes may be obtained from a moderately sized experiment. The information may be used in several ways: for design to predict the operation of a membrane under different sets of operating conditions; for optimization to find those operating conditions under which the membrane works best; and for fundamental research to gain a better understanding of and to compare the dynamics of different membranes.