Modification of cellulose acetate membrane via low-pressure plasma polymerization for sugar separation applications: Part I. Membrane development and characterization

The aim of this study is to illustrate the low-pressure plasma modified cellulose acetate (CA) membranes can display a fractionation capability that can be of major importance for the operation of continuous enzymatic membrane reactors. For this purpose, low-frequency (LF) and/or radio-frequency (RF) excitations were applied to coat ethylenediamine (EDA) monomer to alter physico-chemical characteristics of surface as well as narrowing pore size of CA type common ultrafiltration membrane. Membrane characteristics were evaluated using various physical and chemical techniques including contact angle, Fourier Transform Infrared Spectroscopy with Horizontal Attenuated Total Reflection attachment and scanning electron microscopy. Membrane performance based on efficient monosaccharide removal was tested by using a diffusion cell. The contact angle results showed that the grafted amino groups caused great increase on the polar nature of the CA membranes studied. A complete and permanent hydrophilic modification of a CA was achieved by LF plasma treatment. From the fractionation point of view, 120 W and 10 min seemed to be a better plasma condition for membrane modification using LF plasma system. Very high retention (>94%) was obtained with the LF/PlzP-modified CA membrane for disaccharides, while the retention for monosaccharides was rather low (<73%) at the same reaction time.