Fabrication of Composite Membranes Based on Polytetrafluoroethylene with a Cellulose Acetate Surface Layer for Water Deionization

Abstract

Composite PTFE–CA membranes have been prepared by spraying cellulose acetate (CA) aerosol in acetone onto the surface of a polytetrafluoroethylene (PTFE) substrate. The size and number of dispersed-phase particles of a 1% CA solution in acetone have been determined. It has been found that most of the particles are less than 0.225 μm in size. Changes in the surface properties of the obtained composite membranes, depending on the number of CA layers (from 1 to 3) deposited on PTFE, have been studied by scanning electron microscopy and the sessile drop method, and the internal structure has been investigated by FTIR spectroscopy. The resulting composite nanofiltration membranes have been used to explore the possibility of removing cations (K+, Na+, Ca2+, Mg2+) and anions (F−, Cl−, NO3–, \\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\\text{SO}}_{{\\text{4}}}^{{{\\text{2}} - }}$$\\end{document}) from tap water. The pure and raw water fluxes of the membranes have been determined depending on the number of CA layers deposited on PTFE. The selectivity of the composite membrane with respect to multivalent ions has been determined, and their rejection of 81% at a specific flux of 128 dm3/(m2 h) has appeared to be better than the performance of a commercial nanofiltration membrane.