キトサン限外ろ過膜 ＩＩ． タンパク質排除に与える膜電荷効果

Abstract

Chitosan membranes for ultrafiltration were prepared by casting acetic acid solutions of chitosan including polyethylene glycol (PEG) as an additive. The additive was eliminated by elution in hot water after the neutralization of membrane. The ultrafiltration through the chitosan membrane was carried out using the solutions of proteins such as bovine serum albumin and γ-globulin. It was found that the rejection of proteins depended on the pH of the solution and it changed drastically in the vicinity of the pH of the isoelectric point of the protein (pHI ). The high rejection was observed at the pH lower than the pH, and the rejection was no longer observed beyond the pHI. These facts mean the interaction between the membrane charge and the protein.The permeation rate of the solution was kept constant in the pH region more than pH 6 but it largely decreased in the lower pH region. It was considered from the SEM observations that the chitosan membrane was partially desolved in the low pH buffer solution and at the same time some micropores which had existed on the air-side surface disappeared and became the dense layer.In addition, it was recognized that an appropriate membrane structure was required for the charged ultrafiltration membrane.