Preparation and antifouling performance of PVDF-DCOIT composite hollow fiber membranes

Membrane fouling is the main bottleneck that hinders the applications of membrane bioreactors (MBRs). 4,5-Dichloro-2-n-octyl-4-isothiazolin-3-one (DCOIT), as an environmentally-acceptable antifouling biocide, was mixed with Polyvinylidene fluoride (PVDF) to fabricate hollow fiber membrane via non-solvent induced phase separation (NIPS), which was able to effectively improve the antifouling performance of the membranes in this work. Overall research of the prepared membrane revealed that membranes with 3 wt% DCOIT exhibited the optimum antifouling performance. With the addition of DCOIT, hydrophilicity and pure water flux of 3 wt% DCOIT membranes maintained remarkable improvement by 22.9% and 64.6% than that of membranes without DCOIT. Meanwhile, the surface morphologies of 3 wt% DCOIT membranes were smoother than the control group in terms of SEM and AFM images, which was beneficial to alleviate membrane fouling. In antifouling experiments, the flux variation rate of membranes with 3wt% DCOIT filtrated in bull serum albumin, sodium alginate and humic acid solution were 81.42%, 54.25%, 50.5%, while membrane without DCOIT were 64.6%, 24.72% and 29%, respectively. Similar results were obtained by filtrating anaerobic sludge for 24 h. The flux variations of 3 wt% DCOIT membranes were 59.4%, 47.8% and 46.0%, respectively in three stages. However, the flux variations of membranes without DCOIT were 44.8%, 36.7% and 19.8%, respectively, which showed better antifouling ability and higher flux recovery efficiency The novel membranes would provide some theoretical basis and technical support for the rational combinations in elevating the overall antifouling properties of membranes.