Obtaining and properties of a composite membrane with a surface layer of cellulose acetate

Abstract

AnnotationTo reduce the concentration of dissolved salts in water treatment processes, a composite nanofiltration membrane with a surface layer of cellulose acetate on a polytetrafluoroethylene substrate was obtained. The cellulose acetate content was 17.6% by weight, upon receipt from a 10% solution of cellulose acetate in acetone. An increase in the membrane moisture capacity after modification from 0.6% to 68.5% was established, which is associated with an increase in the hydrophilicity of the membrane. The contact angle of the membrane with a drop of distilled water as a result of the deposition of cellulose acetate particles on the surface of the original membrane decreased from 130º to 53.8º. According to the results of scanning electron microscopy, it was found that the cellulose acetate particles are not located on the surface of the polytetrafluoroethylene substrate, but in the depth of its structure — in the pores, between the fibers, as a result, open pores overlap. After applying a layer of cellulose acetate to the surface of the membrane, the specific productivity of the membrane decreases by 10 times due to the accumulation of particles of cellulose acetate in the pores of the membrane. The maximum specific productivity of the modified membrane 412 dm3/m2 h, is observed when passing distilled water. The retention capacity of the membrane in terms of total salinity in the separation of tap water with an initial salinity of 323 mg/dm3 was 75%.