低圧逆浸透膜の溶質分離に及ぼす膜のζ-電位の影響

抄録

Previous works on Low Pressure Reverse Osmosis (LPRO) have shown that the rejection of organic compounds is mainly controlled by molecular weight and dissociation constant. This study demonstrates that the membrane ζ-potential also can be considered as a key factor for rejections of ionic salts and dissociated organic compounds. We measured the membrane ζ-potential by using a streaming potential method. In addition, effects of the ζ-potential on rejection properties of some dissociated organic compounds and an ionic salt were investigated. The results of experiments are as follows.(1) The low pressure reverse osmosis membrane was positively charged under the strong acidic condition, and negatively charged under the weak acidic and alkaline condition.(2) The zero-point of charge (zpc) values of LPRO membranes were found to be between pH 2.66 and 3.74 by the ζ-potential measurement.(3) The rejections of an ionic inorganic salt and dissociated organic compounds with low molecular weight changed with pH, depending not only on the plus or minus sign of membrane ζ-potential but also on the absolute ζ-potential value.(4) Organic compounds with high molecular weight such as Pentachlorophenol showed high rejection without depending on the membrane ζ-potential.