The permeability coefficients of backing materials were measured and the effect of each material on the overall performance of the tublar type reverse osmosis module which was devised by Matsuda et al. was examined. The fundamental experiment with the cell shows that the mean volumetric permeability coefficient of a backing material,kb [cm3] strongly depends on the average effective pressure,ΔPavg[kg/cm2]. The relation is given by the following equation. kb=kb'ΔP-navg(1) where kb' and n are experimental constants. We, here, assumed the following equation by deducing from Eq.(1). kb=kb'Pa-nP-n(2) where kb[cm3] is the volumetric permeability coefficient of a backing material,kb' is a constant, pa [kg/cm2] is the applied pressure and P [-] is the dimensionless form of the effective pressure. The decrease of product water flux of the tublar module due to pressure loss in the backing material was calculated by Eq.(2). Among examined all materials, the most favorable one was 66 nylon #150. Other materials except a synthetic paper could be used for backing materials.
In the previous papers, the amount and the crystal-forms of impurities on and in crystals of Australian and Chinese solar salt were reported. In this paper, the author studied in the same way those of Mexican solar salt which was imported during 1969-1974. And the following results were obtained; 1. Mexican solar salt was composed of 96.8-98.0% sodium chloride. No remarkable change has observed on the qualities of Mexican solar salt for past seven years. 2. Mexican solar salt contained 0.12% water and 0.06% total impurities in crystals. 3. Strata of cavities and crystals of CaSO4·2H20 were observed in crystals of Mexican solar salts as other solar salts.