Surface modification of polyacrylonitrile based ultrafiltration membrane

Abstract

Ultrafiltration membrane based on polyacrylonitrile prepared by phase inversion method using zinc chloride as an additive showed more than 90% rejection for BSA and 90 -110 lm Ϫ2 h Ϫ1 water flux. The surface modification of this membrane was studied using ethanolamine, triethylamine, sodium hydroxide, and potassium hydroxide solutions. The effect of base treatment time and temperature on water flux and rejection was investigated. The membranes exhibited swelling by NaOH treatment followed by deswelling by HCl post-treatment, similar to pH responsive membranes. The treatment by organic as well as inorganic bases improved water flux with a slight lowering in BSA rejection by dead-end mode type treatment. A 230% increase in water flux was achieved by sodium hydroxide treatment in crossflow mode without a noticeable pore swelling by SEM. The contact angle of the modified membranes was decreased as compared to the unmodified one indicating appreciable surface modification. As the treatment time or temperature increased, the ESCA analysis showed increased population of Na-carboxylate groups.

Surface modification of PAN hollow fiber membrane by chemical reaction

“…In the diagram related to PAN sample, regardless to previous investigations [2,15,26], the peak observed at 2937 cm -1 can be attributed to C-H bond, or so-called CH stretching. The peak at 2243 cm -1 is related to the nitrile group (-CN).…”

“…Reduction in water permeation, whereas it seems by the rise of -OH and -NH 2 groups on the membrane surface, membrane becomes more active according to the hydrophilicity, maybe occurred as a process like steric hindrance (or swelling the unstable chains of the polymer), because this phenomenon has been confirmed by many studies on polyacrylonitrile with bases such as NaOH and KOH [15,25].…”

“…Also, the reaction of polyacrylonitrile with phenylhydrazine and paratoluenesulfamide was used for chelating ion exchange fiber synthesis [14]. Chemical modification with alkaline solutions is one of the easiest and the most well-known methods used for PAN membrane modification [15]. Several studies showed that PAN nitrile groups can be to an extent converted to carboxyl groups by an alkaline solution such as NaOH.…”

Protection of polymeric membranes with antifouling surfacing via surface modifications

“…Pulp and paper effluent filtration [106] Organics and bacteria filtration, modification leads to the reduction of membrane charge [107] MBR, wastewater treatment [108] Modified membranes have great potential on reduction of protein fouling [109] Low flux decline in NOM solution of NF [110] UF, reduction of deposited BSA on modified membrane [111] NOM filtration; surfactant significantly reduced the foulants adsorption [112] BSA filtration [113] Aq. gelatin filtration; increased the flow rates of pure water and gelatin solution increases at all pH [114] [115] MBR, HF and flat sheet membranes, synthetic waste water; it exhibited better flux recovery ratio [116] UF-HF, flux reduction in NOM solution [117] MF, BSA solution; resulted high flux and fouling resistance against BSA [118] Modified surface reduced the BSA rejection and increased water [119] UF, Salvia Miltiorrhiza decoction filtration, the antifouling property increased with increase of hydrophilicity [120] Protein filtration; exhibited excellent fouling resistance properties [121] Protein treatment by UF, fouling less than negatively or positively charged membrane, and adsorption of BSA; protein-polymer surface interactions were diminished [122] UF, BSA filtration; the fouling reistance property enhanced by hydrolysis of butyral and acetate group [123] BSA, dextran and triton X-100 filtration; higher flux values are observed [124] MBR, synthetic waste water treatment, and exhibited higher flux [125] Seawater/surface water filtration; modified membranes adsorbed low organic material [126] UF, treatment of textile auxiliaries; the modified surface decreased the fouling tendency and acts as antiwrinkle agent [127] Polyvinylamine grafting and PVA coating UF, BSA filtration; the antifouling property was enhanced due to the presence of brushes of comb-like polymers [128] Adhesion, it exhibited good antibacterial activity against Methicilin -resisitant Staphylococus aureus [129] Decreases flux decline of BSA & SA solution during membrane separation process. Fouling release membrane surface was developed [130] Superior antifouling properties of PES membranes were obtained by successful modification us...…”

Preparation and Characterization of Homopolymer Polyacrylonitrile-Based Fibrous Sorbents for Arsenic Removal

“…The weight loss shown in the absence of cross-linking contrasts with the weight gain found in the fibers first treated with HH. The slow dissolution of unmodified fabric during alkali treatment can be attributed to transition of nitrile into hydrophilic carboxamide and carboxylate groups, which then promote dissolution of the fiber (Lohokare et al, 2006;Yan et al, 2012). Although similar dissolution behavior was found in 10% and 20% NaOH solutions over the first 2 h elapsed, the destruction and complete dissolution of the fabric in 20% NaOH was obtained after *2.5 h. In addition, without prior cross-linking, the color of the fiber treated with 10% NaOH gradually changed from light orange to light pink after 2.5 h.…”