High Performance Ultrafiltration Membranes Prepared by the Application of Modified Microwave Irradiation Technique

Aminolysis-Based Zwitterionic Immobilization on Polyethersulfone Membranes for Enhanced Hemocompatibility: Experimental, Computational, and Ex Vivo Investigations

Dialysis membranes are not hemocompatible with human blood, as the patients are suffering from the blood-membrane interactions' side effects. Zwitterionic structures have shown improved hemocompatibility; however, their complicated synthesis hinders their commercialization. The goal of the study is to achieve fast functionalization for carboxybetaine and sulfobetaine zwitterionic immobilization on PES membranes while comparing the stability and the targeted hemocompatibility. The chemical modification approach is based on an aminolysis reaction. Characterization, computational simulations, and clinical analysis were conducted to study the modified membranes. Atomic force microscopy (AFM) patterns showed a lower mean roughness for carboxybetaine-modified (6.3 nm) and sulfobetaine-modified (7.7 nm) membranes compared to the neat membrane (52.61 nm). The pore size of the membranes was reduced from values above 50 nm for the neat PES to values between 2 and 50 nm for zwitterionized membranes, using Brunauer-Emmett-Teller (BET) analysis. More hydrophilic surfaces led to a growth equilibrium water content (EWC) of nearly 6% for carboxybetaine and 10% for sulfobetaine-modified membranes. Differential scanning calorimetry (DSC) measurements were 12% and 16% stable water for carboxybetaine- and sulfobetaine-modified membranes, respectively. Sulfobetaine membranes showed better compatibility with blood with respect to C5a, IL-1a, and IL-6 biomarkers. Aminolysis-based zwitterionization was found to be suitable for the improvement of hemodialysis membranes. The approach introduced in this paper could be used to modify the current dialysis membranes with minimal change in the production facilities.

Effect of Dope Flow Rate and Post-Treatment on the Morphology, Permeation and Metal Ion Rejection from PES/LiBr-Based UF Hollow Fiber Membranes

This study investigated the influence of dope extrusion rate (DER) and post-treatment effect on the morphology, permeation, and metal ion rejection by polyethersulfone/lithium bromide (PES/LiBr)-based hollow fiber (HF) membranes. HF fibers were spun with 2.25, 2.5, and 3.1 ratios of DER to bore fluid rate (BFR), wherein DER varied from 11.35, 12.5, to 15.6 mL/min with a fixed BFR (5 mL/min). Molecular weight cutoff (MWCO), pore size, water flux, and flux recovery ratio were determined, whereas lake water was used to observe the rejection rate of dissolved metallic ions. Results showed that with the increase of the DER wall thickness (WT), HFs increased from 401.5 to 419.5 um, and furthermore by the post-treatments up to 548.2 um, as confirmed by field emission scanning electron microscope (FESEM) analysis. Moreover, MWCO, pore size, and the pure water permeation (PWP) of the HF membranes decreased, while the separation performance for polyethylene glycol (PEG) solute increased with increasing DER. Post-treated HFs from 11.35 mL/min of DER showed 93.8% of MWCO value with up to 90% and 70% rejection of the arsenic and chromium metallic ions, respectively, in comparison with all other formulated HFs.

Fabrication of mixed nanoceramic waste with polymeric matrix membranes for water desalting

Mixed matrix membranes were prepared by blending technique between nanoceramic powder and polyethersulfone. Nanoceramic powder (NC) as a fine powder was produced from ceramic industries. The effect of NC as an additive on the membrane matrix was studied. Increasing in NC% on polymeric blend enhances the membrane mechanical properties, where the tensile strength was 13.92 MPa with elongation of 23.67 mm for prepared blend membrane with NC 1 wt%. The highest salt rejection was about 89.3% with permeate flux of 34.6 L/m2 h for R1 membrane using NS of percentage 4 wt% and nonwoven polyester support. The increase in NS% to 6 wt % leads to an increase in the salt rejection to 94.2% after 1 h operating time. The coating was achieved using the layer by layer technique which was carried out on the membrane surface to improve the salt rejection percentage. The salt rejection was found to reach about 99.8% after such coating process; but for permeate flux, it shows a certain decrease. The flux of membrane before the coating was 23.4 L/m2 h for R2 membrane (1 wt% NC & 6 wt% NS), while after coating the flux was reduced to reach 21.6 L/m2 h.

Amino-functionalized mesoporous silica based polyethersulfone–polyvinylpyrrolidone composite membranes for elevated temperature proton exchange membrane fuel cells

It is important to find alternative membranes to the state-of-the-art polybenzimidazole based high temperature proton exchange membranes with high proton conductivity at elevated temperature but with simple synthesis procedures.

Preparation and Characterization of Newly Developed Polysulfone/Polyethersulfone Blend Membrane for CO2 Separation

Polymeric membranes suffer from so called upper bound tradeoff between permeability and selectivity as described by Robeson. Polymer blending is a valuable technique to tune the properties of polymeric membranes by physical mixing of different polymers in a single mixture. In this study, preparation and characterization of newly developed polysulfone/polyethersulfone (PSF/PES) blend flat sheet dense membranes is described for CO2/CH4 separation. Blend membranes with different blending ratios were prepared and the developed membranes were characterized by FESEM, FTIR and TGA to see the effect of blend ratio on morphology, bonding and thermal stability respectively. Permeability of CO2 and CH4 gases in pressure range of 2-10 bar is recorded to find out the ideal selectivity of prepared membranes. The results are discussed and compared with individual polymer membranes.