Abstract
The use of membrane-separation processes to treat organically contaminated water is becoming increasingly popular. Rejection measurements were determined for 1-propanol, 1-butanol, 2-butanol, 2-methyl-1-propanol, and 2-methyl-2-propanol using reverse-osmosis membranes. The test system used for the experiments is described. All feed concentrations were 20 mg/l at 25 degree C. With the exception of 2-methyl-2-propanol, all the organics showed a constant trend with pressure, increasing to a maximum at 120 140 psi, and decreasing at 160 psi. A mathematical model for determining the concentration polarization is proposed, and the membrane-permeability coefficient and the film-diffusion coefficient are quantified for each solute. Modeling results indicate that membrane permeability is the primary factor that determines rejection, with film diffusion only a supplementary mechanism.