Improving antifouling performance of PAN hollow fiber membrane using surface modification method

• PAN membrane surface modification was performed in two steps.
• Membrane hydrophilicity was significantly increased using surface modification.
• Antifouling property of modified PAN membranes was assessed by determining FRR and RFR parameters.
• The effect of hydrolysis reaction time and its concentration on the pure water flux was also investigated.

In this study, a new approach to improve antifouling performance of polyacrylonitrile (PAN) hollow fiber membrane has been explained. Firstly, chemical modification with sodium hydroxide (NaOH) solution was performed on PAN membranes in various conditions, so that, as a result of hydrolysis, carboxyl groups emerge on membrane surface. Then, in order to improve surface hydrophilicity, the hydrolyzed membrane underwent a polyethylene glycol (PEG) deposition through a chemical reaction. Chemical changes in membrane were characterized via Fourier transform infrared spectroscopy/attenuated total reflectance (FTIR/ATR). In addition, measurement of contact angle and fouling test were performed to analyze hydrophilicity degree and performance of modified membrane, respectively. Results of measuring contact angle signified improvement of hydrophilicity of membrane after modification. Modified membranes showed lower tendency to foul during ultrafiltration (UF) of milk solution, which is confirmed by increase in flux recovery ratio (FRR) level following membrane modification. Three hours after hydrolysis process, though pure water flux through membrane reduced by 28% comparing with intact membrane, the level of polyvinyl alcohol (PVA-30 kDa) rejection and FRR increased 13 and 14%, respectively. Upon attachment of PEG to the membrane surface, the contact angle reduced from 64° for non-modified membrane to 21°.

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