Seven-bore hollow fiber membrane (HFM) for ultrafiltration (UF)

Abstract

Membrane technology has been widely applied for wastewater reclamation and desalination due to the water shortage in various regions resulted from an ever growing demand of fresh water. Between hollow fiber membrane (HFM) and flat sheet membrane, HFM has advantages sometime to address the water shortage and quality issue because of its high water productivity per unit volume and its self-supporting structure. Traditional HFMs, however, have only one single bore and may suffer from a decreased stability and potting durability with time. This study explored the development of a seven-bore polyvinylidene difluoride (PVDF) HFM for ultrafiltration (UF) with a goal to manipulate water flux and membrane durability and antifouling property. This new type of HFM with seven-bores was spun on a custom-made spinning system, using polyethylene glycol (PEG) as the pore forming agent with different weight ratios: 0%, 1%, 2%, 3%. The membranes were characterized by the contact angle measurement, scanning electron microscopy (SEM), and mechanical strength test. Results showed the membrane hydrophilicity and water flux were enhanced with the addition of PEG. Compared to a single-bore HFM, the tensile strength of the seven-bore HFM was improved. The pure water flux of membrane prepared at 16wt% PVDF and 3wt% PEG (16_3_81) was around 12.5L/m2h under 6psi transmembrane pressure, as measured on a cross-flow testing system. When a humic acid (HA) solution was used as feed, the membrane rejected approximately 98% of the HA. This study demonstrated the novel seven-bore HFMs had an improved durability and life time when used for water ultrafiltration.