Cellulose acetate and sulfonated polysulfone blend ultrafiltration membranes. I. Preparation and characterization

Modification of polymeric membrane materials by incorporation of hydrophilicity results in membranes with low fouling behavior and high flux. Hence, Polysulfone was functionalized by sulfonation and ultrafiltration membranes were prepared based on sulfonated polysulfone and cellulose acetate in various blend compositions. Polyethyleneglycol 600 was employed as a nonsolvent additive in various concentrations to the casting solution to improve the ultrafiltration performance of the resulting membranes. The total polymer concentration, cellulose acetate, and sulfonated polysulfone polymer blend composition, additive concentration, and its compatibility with polymer blends were optimized. The membranes prepared were characterized in terms of compaction, pure water flux, membrane resistance, and water content. The compaction takes place within 3–4 h for all the membranes. The pure water flux is determined largely by the composition of sulfonated polysulfone and concentration of additive. Membrane resistance is inversely proportional to pure water flux, and water content is proportional to pure water flux for all the membranes. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 1749–1761, 2002     

Polyurethane and sulfonated polysulfone blend ultrafiltration membranes: II. Application studies

Ultrafiltration membranes are largely being applied for macromolecular and heavy metal ion separations from aqueous streams. Polyurethane‐ and sulfonated‐ polysulfone‐based membranes prepared in the absence and presence of the polymeric additive, poly(ethylene glycol) 600, in various compositions, were subjected to the rejection of macromolecular proteins, such as bovine serum albumin, egg albumin, pepsin and trypsin. Toxic heavy metal ions such as Cu²⁺, Ni²⁺, Cd²⁺ and Zn²⁺ were subjected to rejection by the blend membranes by complexing them with a polymeric ligand, polyethyleneimine. The effects of polymer blend compositions and additive concentrations on the rejection and permeate flux of both proteins and metal ions are discussed. The rejection and permeate flux efficiencies of the blend membranes are compared with pure sulfonated polysulfone membranes. © 2003 Society of Chemical Industry     

Pore morphology control and hydrophilicity of polyacrylonitrile ultrafiltration membranes

The effects of different solvents (dimethyl formamide: DMF and dimethylsulfoxide: DMSO) on the solubility of polyacrylonitrile (PAN) were investigated by the phase diagrams of H₂O/DMF/PAN and H₂O/DMSO/PAN ternary systems through cloud‐point titration method at low polymer concentration. The influences of polymer concentrations and temperatures on the morphologies of PAN ultrafiltration membranes were elucidated. The morphologies of fabricated UF membranes were characterized by scanning electron microscopy (SEM) and atomic force microscope (AFM), and the basic performance of ultrafiltration including pure water flux and rejection of BSA were explored. At 25°C, the pure water flux of ultrafiltration membranes at the lower PAN content (16 wt % PAN in 84 wt % DMSO) reached 213.8 L/m/bar and the rejection of BSA was 100%. Interestingly, the water flux of UF membranes dramatically decreased to 20.6 L/m/bar (20 wt %) and 2.9 L/m/bar (24 wt %) when increasing PAN concentrations in DMSO. On the other hand, the hydrophilicity of membranes can be enhanced by increasing coagulation temperatures and polymer concentrations which were characterized by static contact angle, fitting well with the variation tendency of roughness. Although there are many works concerning on the effects of phase inversion conditions on the performance of PAN UF membranes, to our best knowledge, there is seldom works focusing on investigating the membrane hydrophilicity trend by adjusting phase inversion conditions. To disclose the reason of the enhanced hydrophilicity, the water and glycol contact angles of various membranes were measured and the surface tensions were presented. The results illustrated that the enhanced hydrophilicity of PAN UF membranes fabricated at higher temperatures or higher polymer concentrations was due to the higher polarity on membrane surface. Since the vast majority of ultrafiltration membranes in labs and in industrial scale have been fabricated by immersion phase inversion method, this work can provide a guidance to obtain hydrophilic PAN UF membranes by adjusting the process of phase inversion. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41991.     

Polyurethane and carboxylated polysulfone blend ultrafiltration membranes. I. Preparation and characterization

Polysulfone was functionalized by carboxylation and blended with polyurethane (ether type). Blend membranes were prepared in the presence and absence of the additive poly(ethylene glycol) 600 and subjected to ultrafiltration characterizations such as compaction, pure water flux, water content, and hydraulic resistance. Morphological studies of the membranes were performed with scanning electron microscopy. The effects of the polymer composition and additive concentrations on the above parameters were analyzed and the results compared. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 1307–1315, 2005     

Protein separation by cellulose acetate/sulfonated poly(ether imide) blend ultrafiltration membranes

A process for purifying aqueous solutions containing macromolecular proteins such as bovine serum albumin (BSA), egg albumin (EA), pepsin, and trypsin has been investigated. Protein removal from food and biorelated industrial waste streams are gaining increased visibility due to environmental concern and saving precious materials. Ultrafiltration (UF) processes are largely being applied for protein separation from aqueous streams. In this work, an attempt has been made to separate the valuable proteins using cellulose acetate (CA)/sulfonated poly(ether imide) (SPEI) blend UF membranes prepared in the absence and presence of the additive, polyethyleneglycol (PEG600) in various compositions. The blend membranes were subjected to the determination of pore statistics and molecular weight cut‐off (MWCO). Porosity and pore size of the membranes increased with increasing concentrations of SPEI and PEG600 in the casting solution. Similarly, the MWCOs of the blend membranes ranged from 20 to greater than 69 kDa, depending on the various polymer blend compositions. Surface morphology of the blend membranes were analyzed using scanning electron microscopy. Studies were carried out to find the rejection and permeate flux of proteins. On increasing the concentration of SPEI and PEG600, the rejection of proteins is decreasing, whereas the permeate flux has an increasing trend. The effect of hydrophilicity of SPEI on fouling of protein for CA/SPEI blend membranes was also discussed. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Cellulose acetate–poly(ether sulfone) blend ultrafiltration membranes. II. Application studies

Ultrafiltration membranes are largely applied as macromolecular solutes and heavy‐metal‐ion separation from aqueous streams. Cellulose acetate and poly(ether sulfone) blend ultrafiltration membranes were prepared by the precipitation phase‐inversion technique in 100/0, 95/5, 85/15, and 75/25% polymer blend compositions in the absence and presence of a polymeric additive, poly(ethylene glycol) 600, at different additive concentrations and were used for the rejection of proteins trypsin, pepsin, egg albumin, and bovine serum albumin; a maximum of 94% rejection was achieved. The toxic heavy metal ions copper, nickel, and cadmium from dilute aqueous solutions were subjected to rejection by the blend membranes by complexation of the ions with the water‐soluble polymeric ligand, polyethyleneimine (PEI). Permeate flux studies of proteins and metal ions were performed simultaneously with the rejection experiments. The atomic absorption spectra results reveal maximum rejection for copper complex and a minimum rejection of about 60% for the cadmium complex. The rejection and permeate flux of the blend membranes were compared with those of pure cellulose acetate membranes. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 3659–3665, 2004     

Studies on cellulose acetate–polysulfone ultrafiltration membranes: I. Effect of polymer composition

Ultrafiltration techniques have particular advantages for simultaneous purification, concentration and fractionation of macromolecules. Studies are presented on novel ultrafiltration membranes, based on cellulose acetate and polysulfone blends, for the separation of proteins and heavy metal ions. The effects of polymer composition on pure water flux, water content, molecular weight cut‐off and hydraulic resistance are discussed. Scanning electron microscopy images of the membranes show the presence of segregated individual domains of cellulose acetate and polysulfone. The molecular weight cut‐off obtained from the protein separation studies is also presented. Applications of these membranes for separating metal ions from aqueous streams are discussed. Copyright © 2005 Society of Chemical Industry     

Separation of CO2 from CH4 by pure PSF and PSF/PVP blend membranes: Effects of type of nonsolvent,solvent, and PVP concentration

Complete CO₂/CH₄ gas separation was aimed in this study. Accordingly, asymmetric neat polysulfone (PSF) and PSF/polyvinylpyrrolidone (PVP) blend membranes were prepared by wet/wet phase inversion technique. The effects of two different variables such as type of external nonsolvent and type of solvent on morphology and gas separation ability of neat PSF membranes were examined. Moreover, the influence of PVP concentration on structure, thermal properties, and gas separation properties of PSF/PVP blend membrane were tested. The SEM results presented the variation in membrane morphology in different membrane preparation conditions. Atomic forced microscopic images displayed that surface roughness parameters increased significantly in higher PVP loading and then gas separation properties of membrane improved. Thermal gravimetric analysis confirms higher thermal stability of membrane in higher PVP loading. Differential scanning calorimetric results prove miscibility and compatibility of PSF and PVP in the blend membrane. The permeation results indicate that, the CO₂ permeance through prepared PSF membrane reached the maximum (275 ± 1 GPU) using 1‐methyl‐2‐pyrrolidone as a solvent and butanol (BuOH) as an external nonsolvent. While, a higher CO₂/CH₄ selectivity (5.75 ± 0.1) was obtained using N‐N‐dimethyl‐acetamide (DMAc) as a solvent and propanol (PrOH) as an external nonsolvent. The obtained results show that PSF/PVP blend membrane containing 10 wt % of PVP was able to separate CO₂ from CH₄ completely up to three bar as feed pressure. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 1139‐1147, 2013     

High density polyethylene/ultra high molecular weight polyethylene blend. II. Effect of hydroxyapatite on processing,thermal, and mechanical properties

Hydroxyapatite (HA) is part of bone mineral composition. Several attempts have been made to incorporate HA into high density polyethylene (HDPE) to produce bone replacement biomaterials since neat HDPE is not suitable as bone replacement. The blending of HDPE with ultra high molecular weight polyethylene (UHMWPE) up to 50% by weight was performed with the aim of improving the toughness of composites. Reinforcement of blend with HA of up to 50% by weight was carried out. Methods of characterizing the composites included density, differential scanning calorimetry, thermal gravimetric analysis, ash content, and morphological examination using scanning electron microscope. For the mechanical properties of the composites, tensile, flexural, and impact tests were carried out. Incorporation of HA into HDPE has resulted in the brittleness of the composites. Blending of HDPE with UHMWPE in the presence of HA was found to improve the mechanical properties and promote a ductile failure of the resulting composites. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 3931–3942, 2006