The preparation and application of a low-cost multi-channel tubular inorganic–organic composite microfiltration membrane

• Composite membranes were prepared conveniently by compression coating approach.
• Composite membranes exhibit higher retention rate than ceramic membrane (50 nm).
• A high turbidity removal rate was achieved for fermentation broth treatment.
• A high flux recovery rate was obtained after simple physical cleaning.
• Composite membranes are of low cost compared to ceramic membrane (50 nm).

Low-cost multi-channel tubular inorganic–organic composite microfiltration membranes were prepared by a convenient compression coating approach employing 19-channel ceramic support (pore sizes ranging from 5 to 20 μm) as substrate, and PVDF/CA blend as separation layer. The membranes were characterized in terms of water permeability, selectivity, as well as the performance of purifying rice bran fermentation. Obtained results show that the pure water flux of composite membranes with PVDF/CA skin layer increases from 200 to 2000 L/m2 h as the PVDF/CA concentration in coating solution decreases from 18 to 8 wt%, and the retention rate to polyethylene oxide (Mw = 1,000,000) is much higher than that of ceramic membrane with an average pore diameter of 50 nm, and the ratio of turbidity removal is up to 99% when the composite membranes were applied to treat rice bran fermentation broth. More significantly, the composite membranes showed a high recovery rate of pure water flux after a simple physical cleaning process. It is found that the concentration of PVDF/CA coating solution appeared to be the key factor on the separation performance of composite membrane, and higher concentration would result in a higher rejection rate. To understand the relationship between the preparation condition and membrane performance, the viscosity of coating solution and morphology of composite membranes were characterized by arotational viscometer and scanning electron microscope (SEM), respectively. Finally, the result of cost analysis shows that the composite membranes have an advantage over the commercial ceramic membranes and could be recognized as a promising a candidate for industrial applications.

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