Композитные мембраны с поверхностным слоем из ацетата целлюлозы для водоочистки и водоподготовки

Abstract

Microporous composite membranes containing from one to three ultrathin layers were obtained by multistage immersion of a paper base in a solution of cellulose acetate in acetone. The physicochemical properties of membranes have been studied and the parameters of membrane separation of heavy metal ions from tap water have been determined. An increase in the particle size and a decrease in the absolute value of the ζ-potential with an increase in the concentration of cellulose acetate in acetone were revealed. It was found that the porosity of the membranes increased from 47 % to 51 % depending on the number of ultrathin cellulose acetate layers on the substrate surface. A decrease in the moisture absorption of composite membranes and an increase in the contact angle of wetting with distilled water from 30.0° to 68.8°, depending on the number of ultrathin layers, were noted. Microscopic examination of the membrane surface showed that the ultrathin layer consists of many pores with sizes less than 1 micron. The absorption bands in the IR spectra of cellulose acetate and the surface of the composite microporous cellulose acetate (MAC) membrane are identical. The retention capacity of MAC composite membranes, determined by iron ions from an iron (III) chloride solution, ranged from 47.5 to 97.4 % depending on the number of cellulose acetate layers on the substrate surface with a specific productivity of 27.9 to 7399 dm3/(m2·h) and a pressure of 0.35 MPa. A high selectivity of a microporous membrane of three layers of cellulose acetate (MAC3) with respect to heavy metal ions contained in tap water was established: Cr3+ (96 %) > Cu2+ (92 %) > Fe3+ (90 %) > Mn2+ (45 %).