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Membrane Water Treatment
  Volume 5, Number 2, April 2014 , pages 109-122
DOI: https://doi.org/10.12989/mwt.2014.5.2.109
 


Preparation of PVDF/PEI double-layer composite hollow fiber membranes for enhancing tensile strength of PVDF membranes
Jun-Gui Yuan, Bao-Li Shi and Ling-Yun Ji

 
Abstract
    Polyvinylidene fluoride (PVDF) hollow fiber membrane is widely used for water treatment. However, the weak mechanical strength of PVDF limits its application. To enhance its tensile strength, a double-layer composite hollow fiber membrane, with PVDF and polyetherimide as the external and inner layers, respectively, was successfully prepared through phase inversion technique. The effects of additive content, air gap distance, N,N-dimethyl-acetamide content in the inner core liquid, and the temperature of external coagulation bath on the membrane structure, permeation flux, rejection, tensile strength, and porosity were determined. Experimental results showed that the optimum preparation conditions for the double-layer composite hollow fiber membrane were as follows: PEG-400 and PEG-600, 5 wt%; air gap distance, 10 cm; inner core liquid and the external coagulation bath should be water; and temperature of the external coagulation bath, 40 C. A single layer PVDF hollow fiber membrane (without PEI layer) was also prepared under optimum conditions. The double-layer composite membrane remarkably improved the tensile strength compared with the single-layer PVDF hollow fiber membrane. The permeation flux, rejection, and porosity were also slightly enhanced. High-tensile strength hollow fiber PVDF ultrafiltration membrane can be fabricated using the proposed technique.
 
Key Words
    PVDF; PEI; ultrafiltration; tensile strength
 
Address
Department of Chemistry, College of Science, Northeast Forestry University, Harbin 150040, PR China.
 

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