Study on Water State and Transport Coefficients of Pressurized CA-Membranes in RO

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  • 逆浸透酢酸セルロース膜の圧密化による膜含有水の性質および輸送係数の変化に関する研究
  • ギャクシントウ サクサン セルロース マク ノ アツミツカ ニ ヨル マク ガ

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Abstract

Two types of cellulose acetate membranes were prepared by Manjikian method; one was a F-30 membrane with high salt rejection and low flux, and the other one was a F-50 membrane with low salt rejection and high flux. For the two types of membranes, the changes of the total, free and bound water contents in the membranes compacted by the maximum operating pressure (Max-ΔP) from 20 to 100kg/cm: 2 were measured by using differential scanning calorimetry (DSC), and the pressure dependences of the transport coefficients (σ, P, Lp and Lpπ) in Spiegler-Kedem equations were studied by RO experiments.<BR>The free water contents in these F-30 and F-50 membranes rapidly decreased with an increase in the Max-ΔP. The bound water content gradually decreased above 60 kg/cm2. The melting point of free water in the pressurized membranes decreased with the deformation of the membrane matrix.<BR>The membrane selectivity was the best at the Max-ΔP 60 kg/cm2. Above 60 kg/cm2, these membranes were compacted, and the water flux in both the F-30 and F-50 membranes decreased. But solute permeability increased, and consequently the membrane selectivity was bad. An attempt was made to obtain the correlations between both free and bound water content and transport coefficients (Lp,pπ and σ). It was found that the σ-value for the F-50 membrane was proportional to the ratio of the bound water content to the total water content, and for the F-30 membrane it was concerned with the change of the nature in bound water.

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