Ultrafiltration Membranes Based on Various Acrylonitrile Copolymers

Abstract

The structure and properties of ultrafiltration membranes synthesized from bicomponent solutions in N,N-dimethylformamide using five commercial acrylonitrile copolymers of various compositions and molecular masses have been studied. The molecular mass characteristics of the copolymers (M w , M w /M n) have been determined; the viscosity properties of dilute and concentrated solutions have been studied. It has been shown that depending on the chemical composition and molecular mass of the copolymer, the concentration dependence of the water flux is different: for copolymers with a molecular mass of M w of 76000-81000 g/mol, with an increase in the copolymer concentration in solution from 12 to 16%, the water flux of the membranes decreases from 300-500 to 40-150 L/(m 2 h) depending on the copolymer composition. For samples with a higher molecular mass (M w = 99 000 and 107000 g/mol), the water flux of the membranes hardly depends on the copolymer concentration in the casting solution; it is 150 and 75 L/(m 2 h), respectively. The rejection factor of the membranes with a molecular mass of 40000 g/mol for polyvinylpyrrolidone increases with increasing copolymer concentration in the casting solution regardless of the chemical composition and molecular mass of the copolymer. Scanning electron microscopy studies of the membrane structure have shown that membranes synthesized from copolymers with a higher molecular mass have a denser structure and a thicker selective layer than the respective parameters of membranes synthesized from acrylonitrile copolymers with a lower molecular mass, which are characterized by the presence of large macrovoids in the membrane matrix. These differences in the membrane structure are attributed to different viscosities of the casting solutions at identical copolymer concentrations.

Effect of the Formation of Ultrathin Selective Layers on the Structure and Performance of Thin-Film Composite Chitosan/PAN Membranes for Pervaporation Dehydration

“…Four porous membranes from PAN were prepared marked as PAN-2, PAN-3, PAN-4, PAN-5 which feature different structure, pore size, porosity of the selective layer and performance. The compositions of the casting solution were selected according to [ 34 ]. PAN-2 membrane was prepared from 16 wt.% PAN casting solution in DMF, PAN-3—from 15 wt.% PAN solution in DMF.…”

A Comprehensive Review of Performance of Polyacrylonitrile-Based Membranes for Forward Osmosis Water Separation and Purification Process

“…This is mainly due to the PAN polymer having superior characteristics, which make it desirable for FO operation. Recent researchers in 2020, have realized the capability of PAN membranes to elevate FO performance, as PAN has several benefits, including hydrophilicity [53], comparatively good chemical and thermal stability, particularly resistance to active chlorine, stability in a medium of nonpolar and low-polar organic solvents, such as hydrocarbons, alcohols, and esters, and is considerably cheap [56]. Moreover, PAN is also attractive as the support layer in the membranes due to its superior chemical and solvent stability, and high hydrophilicity; hence, it is possible to use TFC membranes in a wider range of advanced membrane processes, including forward osmosis and organic solvent nanofiltration.…”

Acrylonitrile–Acrylic Acid Copolymer Ultrafiltration Membranes for Selective Asphaltene Removal from Crude Oil

“…Copolymerization of the basic polymer with hydrophilic monomers modifies the surface properties while retaining the advantages of the basic polymer. Commercial PANs are often copolymers with methyl acrylate or itaconic acid [ 45 ], which improves their mechanical properties. Copolymerization with methacrylic acid was also used for modification of an acrylonitrile-based polymer [ 46 ].…”