Chem. J. Chinese Universities ›› 2023, Vol. 44 ›› Issue (6): 20230085.doi: 10.7503/cjcu20230085

• Physical Chemistry • Previous Articles     Next Articles

Efficient Oil-water Separation at the g-C3N4/TiO2-PVDF Photoresponsive Membrane Interface: Permeability and Selectivity Differences Induced by Different Exposed Crystal Planes and Performance

ZU Peng1, YUAN Pengcheng2, WANG Shuguang2, SUN Xuefei1()   

  1. 1.School of Resources and Environmental Engineering,Hefei University of Technology,Hefei 230009,China
    2.School of Environmental Science and Engineering,Shandong University,Qingdao 266237,China
  • Received:2023-02-28 Online:2023-06-10 Published:2023-03-29
  • Contact: SUN Xuefei
  • Supported by:
    the National Natural Science Foundation of China(51978227)


Membrane technology is constrained by membrane fouling of oil droplet obstruction in oil-water separation. A crucial step toward effective oil-water separation is the construction of a functional interface for selective separation of the oil-water mixture. In this paper, g-C3N4/TiO2-PVDF(polyvinglidene fluoride) photocatalytic membranes with different exposed crystal planes of TiO2 were prepared, and the effects of different exposed crystal planes on oil-water separation were studied. The experimental results show that the TiO2(001) surface endows the g-C3N4/ TiO2(001)-PVDF membrane with excellent superhydrophilicity and underwater superoleophobicsuperoil transport properties under sunlight irradiation, and compared with the TiO2(101) surface exposed membrane, g-C3N4/ TiO2(001)-PVDF membrane has better oil-water separation performance. Under visible light, the pure water flux of g-C3N4/TiO2(001)-PVDF membrane reaches 2002.9 L·m‒2·h‒1, which is 60.8% higher than that of g-C3N4/TiO2(101)- PVDF membrane, and 47.1% higher than that under dark conditions. Simultaneously, the rejection efficiency of the five kinds of oil substances is more than 99%, and the high permeation flux of 420.4—665.2 L·m‒2·h‒1 is maintained. The highest rejection efficiency of g-C3N4/TiO2(101)-PVDF membrane is only 61.8%, and the permeation flux is less than 200 L·m‒2·h‒1. The mechanism of different crystal planes was explored by transient photocurrent response and electron paramagnetic resonance technology. The results showed that the g-C3N4/TiO2(001)-PVDF membrane had a stronger light response current and more hydroxyl radical production. The permeation flux of g-C3N4/TiO2(001)-PVDF membrane was still 264 L·m‒2·h‒1 after a 360 min continuous experiment. High rejection efficiency and permeation flux were always maintained in the 8 cycles of regeneration experiments. Obviously, the photocatalytic membrane with exposed TiO2(001) has a greater permeability, selectivity, and stability, which is more appropriate for the effective separation of oil-water wastewater.

Key words: Oil-water separation, Light induced conversion, g-C3N4/TiO2, Crystal face exposure

CLC Number: