Microstructure evolution and properties of YSZ hollow fiber microfiltration membranes prepared at different suspension solid content for water treatment

Yttria-stabilized zirconia (YSZ) hollow fiber ceramic membranes for microfiltration applications were prepared by the phase inversion and sintering technique. The influence of suspension solid content on the rheological behavior of suspension, and the microstructure and properties of the hollow fiber membranes were investigated. With the addition of YSZ powder, the viscosity of the spinning suspension increased obviously, and the rheological behavior of the suspension changed from Newtonian fluid into thinning behavior fluid. The increment of suspension viscosity upon the YSZ content led to a more porous inner surface, larger inner finger-like pores extending outward, and reduced outer finger-like layer for the prepared hollow fiber membrane. When the YSZ content was increased to 65%, a double-layer structure mostly consisting of outer sponge-like layer and inner finger-like structure layer was formed. The pure water flux of the hollow fiber membrane decreased with the increment of YSZ content, while the bending strength showed obvious enhancement. The prepared membranes showed good oil/water separation performance, and steady permeate flux of more than 0.85m(3)/(m(2)hbar) and high oil rejection rate of 99.2-99.7% were attained. Transmembrane resistance analysis indicated that the membranes prepared at 50 and 65% YSZ content had different dominant fouling mechanism in oil/water separation process.