Cellulose-Based Composite Gas Separation Membranes

A "green" method to synthesize new composite membranes from a cellulose solution in phosphoric acid on various ultrafiltration substrates is proposed. The method can be used in industry; it differs from the conventional viscose method for producing cellophane and other known methods for synthesizing cellulose-based gas separation membranes by the absence of gaseous emissions and wastewater. The structure of the synthesized samples is studied by electron microscopy, X-ray diffraction, and thermal analysis (DSC). Analysis of the mechanical properties of the samples shows that the new membranes have better mechanical characteristics than those of homogeneous pure cellulose films synthesized in this study and commercial cellophane films. The gas transport properties of new membranes with respect to O-2, N-2, CO2, CH4, and He are studied. It is found that the proposed membrane synthesis method provides the formation of uniform dense gas separation layers of cellulose; the membranes show a three orders of magnitude higher gas permeability than that of cellophane films. It is shown that the highest ideal selectivity is exhibited by membranes with a gas separation layer of cellulose on viscose fabric substrates.