A MORPHOLOGICAL STUDY OF NICKEL OXIDE HOLLOW FIBER MEMBRANES: EFFECT OF AIR GAP & SINTERING TEMPERATURE

A systematic study of the air gap effects on morphology and mechanical strength of Nickel Oxide (NiO) hollow fiber membranes has been carried out. The hollow fibers were prepared using the dry-jet wet spinning process using a dope solution containing NiO/N-methyl-2-pyrrolidone (NMP)/Arlacel/Poly(ethylene sulphide) with a weight ratio of 70/22.9/0.1/7. Tap water was used as internal and external coagulants. The cross-sectional structure of precursors hollow fiber membrane was studied by scanning electron microscopy (SEM). The results showed that both inner and outer finger-like voids of the hollow membrane were determined by the air gap distance. Experimental results indicated that an increase in air gap distance, from 100 mm to 200 mm, gave a hollow fiber with a lower mechanical strength and higher percentages of cross section surface area covered by finger-like voids structures. This study also revealed that the air gap introduced an elongation stress because of gravity on the internal or external surfaces of the NiO hollow fibers. A more effective hollow fiber membrane which is in asymmetric structure instead of symmetric structure can be produced by using air gap higher than 200 mm.