Ethylenediamine Plasma Deposited Membranes for Gas Separation

• Main Author: 吳東興
• Other Authors: 賴君義
• Format: Others
• Language: zh-TW
• Published: 1997
• Online Access: http://ndltd.ncl.edu.tw/handle/90541098166998328542

碩士 === 中原大學 === 化學工程學系 === 85 === In order to improve the membrane's oxygen selectivity, ethylenediamine was deposited on a polybutadiene/porous polycarbonate (PB/PC) composite membrane and a polyurethane (PU) membrane. The latter was further immered in a Cobalt salt solution to form a cobalt complex. Plasma treatment result in physical and chemical change on the surface of PB/PC composite membrane. To study the chemical effect, a PB/PC composite membrane was modified chemically by ethylenediamine, compared with the composite membrane treated with nonreactive plasma, at the same N2 flux, the former owned a higher oxygen selectivity(α=5.7). It was obvious that the grafted ethylenediamine enhance the oxygen selectivity. Then, the PB/PC composite membrane was modified by ethylenediamine plasma treatment, as the plasma power increased, the selectivity increased by a sacrifice of permeability. We also found that the 70w plasma treated membrane(α=10.5, P/l=0.07GPU) owned both higher selectivity and permeability than the 50w one(a=8.9, P/l=0.04GPU). We recognized that it was the competition of etching and grafting effect on the surface of PB/PC membrane. From the SEM analysis, the top layer thickness of 70w plasma treated membrane was half of the 50w one. From the ESCA analysis, N/C ratio of 70w plasma treated membrane was higher than the 50w one. It was indicated that a high nitrogen containing thin top layer of the 70w plasma treated membrane was responsible for the higher oxygen selectivity and permeability. The PU membrane was modified by ethylenediamine plasma treatment, the selectivity increased from 2.6 to 3.1 but the permeability decreased from 35 barrer to 15 barrer. The selectivity was further improved to 4.4 by immersing the plasma treated membrane in a solution of CoCl2.6H2O/Formamide for 1 hr, but the permeability decreased to 9 barrer. We also found that as the immersing time increased the permeability could be greatly increased by slightly sacrificing the selectivity. This is the result of swelling effect of the PU membrane caused by Formamide solution.