Cellulose nanocrystals (CNCs) extracted from corn husks were used as additive to modify the hydrophilicity and anti-fouling properties of polysulfone (PSf) membrane. The PSf/CNCs blend membranes were prepared via an immersion phase inversion method. The influence of CNCs content on the morphology, structure, and performances of PSf membrane were carefully investigated by SEM, TG, DTG, DSC, break strength, elongation-at-break, Young modulus, contact angle and filtration experiment. The results showed that the isolated CNCs from corn husks were a promising additive for modifying the properties of PSf membrane. CNCs can improve mechanical property, thermal stability, hydrophilicity and anti-fouling performance of the pure PSf membrane. The PSf/CNCs blend membrane reached optimal properties at 2 wt% CNCs content, which was 2.76 and 1.57 times in pure water flux and FRR values respectively as compared to pure PSf membrane. Meanwhile, PSf-2 also can maintain a relatively high BSA rejection.
Junjie Yang,Wen Sun,Boyu Zhu,Hong Wang,Feng Yan,Jianxin Li,Zhenyu Cui
In this study, polyvinylidene fluoride (PVDF)/styryl maleic anhydride (SMA) hollow fiber membrane was fabricated using the Thermally Induced Phase Separation (TIPS) technique. Subsequently, zwitterion-sulfobetaine methacrylate (SBMA) was introduced to the membrane surface through a Michael addition reaction to create a nearly electrically neutral membrane surface. This modification effectively mitigated the high adsorption of differently charged protein pollutants on the membrane surface, thereby enhancing its anti-fouling performance. Simultaneously, the membrane surfaces with positive and negative charges were separately constructed, and the impact of membrane surface charge properties on the anti-fouling performance against positively and negatively charged foulants was investigated. Furthermore, detailed studies were conducted on the chemical structure, surface morphology, performance, and anti-fouling mechanism of the modified membranes. The results indicate that the electrically neutral membrane modified by zwitterionic SBMA exhibited excellent anti-fouling properties against both bovine serum albumin (BSA) and lysozyme (LYZ), with a flux recovery rate (FRR) reaching 96.5 % and 94.6 %, respectively. The static adsorption capacities of BSA and LYZ on the membrane surface decreased to 5.89 μg cm −2 and 9.53 μg cm −2 , respectively. Furthermore, the study investigated the structure of the hydration layer formed by zwitterionic SBMA on the membrane surface, as well as its hydration capacity and anti-fouling mechanism. Subsequently, through an assessment of the long-term stability of the modified membrane and its flux recovery rate (FRR), in conjunction with theories related to hydration layers and thermodynamics, it elucidated the anti-fouling mechanism involving “autonomy-response” synergistic enhancement of zwitterions. These findings will offer new strategies for researching hollow fiber membranes with superior anti-fouling properties and for applying zwitterions in membrane technology.
Herein, a new and facile approach by in situ cross-linking polymerizationcoupled with a post-functionalization procedure was developed to prepare functional PES composite membranes to improve its over-all performance as hemodialysis membrane. In our strategy, poly(acrylate acid-co-2-hydroxyethyl methacrylate) P(AA-co-HEMA) as a macromonomer, was firstly synthesized by free radical copolymerization , then blended in PES solution and in situ cross-linked polymerization via the reaction of the hydroxy group of HEMA and the isocyanate group of 4,4′-diphenylmethane diisocyanate (MDI) to prepare the carboxylic membranes. To further enhance the hemocompatibility , the carboxylic membranes were post-functionalized by grafting sulfonic acid groups onto the membrane surfaces via a “grafting from” method. The chemical compositions and surface morphologies of the prepared membranes were investigated by ATR-FTIR, XPS , SEM and AFM . After introducing the functional groups, the surface hydrophilicity of the membranes was significantly improved, demonstrated by the reduced water contact angles (WCAs) and enhanced permeability. The decreased protein adsorptions and higher flux recovery ratios (F RR s) revealed that the modified membranes showed improved protein antifouling property. The improvement of hemocompatibility was confirmed by the inhibited platelet adhesion, prolonged clotting times , and suppressed blood-related complement activation. Moreover, the post-functionalized membranes also showed good cytocompatibility. In general, the in situ cross-linking technique is a suitable route in the field of membrane modification for its facile and easy operation; and the post-functionalization operation could endow the membranes with efficiently improved properties.
危险品化学品经营许可证（带存储）