A study on the preparation and properties of the heterogeneous cation-exchange membranes of sulfonated polystyrene/divinyl benzene on an acetal base

The heterogeneous acetal-based membranes containing 50, 60, 70, 80, and 90% (w/w) of the sulfonated polystyrene crosslinked with 7% divinyl benzene were fabricated and studied. In addition, the heterogeneous acetal-based membranes of 85% (w/w) sulfonated polystyrene crosslinked with 1, 4, and 7% divinyl benzene were also prepared and studied. The gel water content, dimensional stability, ion-exchange capacity, area and specific ohmic resistance, permselectivity, and rate of ion exchange of the acetal-based membranes were determined. The sulfonated polystyrene crosslinked with 7% divinyl benzene resin was found to be the better material for preparing the acetal-based membrane with comparable good characteristics. A commercially available heterogeneous membrane (Shanghai Chemicals, 3361) of dry-molding sulfonated polystyrene–divinyl benzene resin was used as the reference membrane for the present investigation. © 1995 John Wiley & Sons, Inc.     

Water–alcohol separation by pervaporation through poly(amide-sulfonamide)s (PASAs) membranes

Pervaporation membranes derived from seven homopolymers of poly(amide-sulfonamide)s (PASAs) were prepared by casting 10–17% polymer solutions of N,N-dimethylacetamide. The membranes were characterized by sorption experiments, scanning electron microscope, and wide-angle X-ray diffraction. During the pervaporation of 90 wt % aqueous solution of methanol, ethanol, 1-propanol, and 2-propanol, all membranes were preferentially permeable to water, and their separation factors were mainly dependent on the molecular weight of the solvent. The exact structure of the PASAs had a profound effect on their pervaporation characteristics. Polymeric membrane based on N,N′-bis(4-aminophenylsulfonyl)-1,3-diaminopropane and isophthaloyl chloride exhibited the best selectivity factor of 1984 for a 10 : 90 (by weight) mixture of water/ethanol at 20°C. However, the permeation rates of all materials for dehydration of 90 wt % ethanol were slow in a range of 6.6–34.4 g m⁻² h⁻¹. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 65:1113–1119, 1997     

Synthesis and characterization of iminodiacetate cellulosic sorbent and its application in metal ion extraction

Iminodiacetate cellulosic chelating sorbent, derived from cotton fabric, was synthesized in a two-step reaction sequence. The pH dependence of the metal ion extraction for Cd (II), Co(II), Cu(II), Pb(II), and Ni(II) was studied. Under optimum conditions, the average sorptive capacity of the sorbent was found to be 0.38 mmol metal ion/sorbent. The viability of using this sorbent for recycling, preconcentration of metal ion, and selective metal ion extraction was demonstrated.     

Screening the fabrication conditions of ultrafiltration membranes by using the uniform design and regression analysis methods

In this work, the concerned casting conditions for the fabrication of the ultrafiltration (UF) membrane from polysulfone were the gelation medium used, the temperature of the gelation bath, the gelation period, and the evaporation time of the cast sheet. The uniform design method was applied to substantially reduce the number of experiments for studying the influence of each of four casting conditions introduced in the preparation of UF-membranes. The pure water flux and the molecular weight cutoff (MWCO) of each of the four macromolecule-standards, namely egg white lysozyme, egg white albumin, bovine serum albumin and bovine γ-globulius, of each prepared UF-membrane were determined. These experimental responses were then analyzed by using a non-linear model with the backward regression method. The results of this work showed that the uniform design-non linear model (UD-NLM) method can substantially reduce the number of experimental runs for predicting the influences of the studied casting conditions on the ultrafiltration performance of the prepared asymmetric polysulfone membranes.     

Evaluation of the possibility of utilization of poly(amidesulfonamide)s (PASAs) in ultrafiltration technology

Ultrafiltration (UF) membranes of six selected poly(amidesulfonamide)s (PASAs) were prepared and studied. The pure water flux and the retention of albumin (bovine serum) were used to evaluate the quality of the UF performance of the fabricated membrane. Membranes with good mechanical strength were obtained by using the phase inversion method. A comparison of the UF performance of the PASA membranes fabricated from a casting solution containing 12% w/w PASAs and 4% w/w lithium bromide in dimethylacetamide was made. The best retention of albumin (bovine serum) by membranes prepared under the conditions studied from the selected homopolymers of PASAs, and their corresponding pure water flux at 0.207 MPa, ranged from 84.6 to 100% and 120 to 396 L m⁻² h⁻¹, respectively. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 68: 2087–2093, 1998