A Study On The Optimization Of A Novel Hydrophilic And Oleophobic Membrane And Its Application

Nowadays, the severe situation of water shortage and water pollution have promoted more and wider applications of the membrane technology, which can be characterized by high separation efficiency, low energy consumption, wide applicability and easiness to scale up. However, membrane fouling and low water flux remain the bottleneck problem that limits the wide application of the membrane technology. Hence, to develop a anti-fouling membrane with a high flux has been one of the most important research areas in the membrane separation field.In the present study, in order to get a membrane with a high water flux, good anti-fouling and mechanical properties, PVDF(polyvinylidene fluoride) and an polymer additive AP were used as the membrane materials to prepare flat sheet membranes via the dry/wet phase inversion method. The focus is in, the effect of membrane fabrication factors on the surface properties, mechanical strength and water flux of the prepared membranes, including four areas:post-treatment condition, casting solution composition, additive system and the coagulation bath system. The mechanisms of the various factors affecting the membranes, structure and performance were explored.From the study, it is found that the various fabrication factors have significant and complex influence on the properties of the prepared membranes. By optimizing those fabrication factors, the prepared membranes showed greatly improved mechanical strength and water flux, as well as anti-fouling performance. Hollow fiber membrane was prepared under the optimized fabrication conditions and its performance applied to preparation of oily wastewater treatment was treated. Compared with the membranes showing the oleophobic property only from conventional research approach, the prepared membranes in this study, exhibits a better hydrophilic and oleophobic surface properties, the water flux is larger, and shows a good resistance to acid/alkaline. In the application of oily wastewater, the initial water flux of the prepared membranes was 3-fold of that of the conventional hydrophilic membranes, and it showed a slow flux decay(only about two-thirds of conventional hydrophilic membranes). In the continuous 90 min filtration experiments,followed by a simple cleaning with water, the flux decay incurred during the filtration can be fully recovered. The removed efficiency of oil content reached more than 98%. For feed water containing oil at 310-340 mg/L, oil content in the produced permeate water was less than 10 mg/L, which meet the oily wastewater treatment and discharge standard. The filtered water can be directly discharged or for use.