Effect of Preparation Variables On Morphology and Water Flux of PVDF Hollow Fiber for Membrane Distillation

In this study, porous poly (vinylidenefluoride) (PVDF) hollow fiber membranes for (DCMD) were fabricated by the phase inversion technology. Effects of spinning conditions on membrane morphology and performance were investigated. Taguchi experimental design was used in this study to identify the optimal conditions with the highest flux in a set of the nine experiments and to predict the performance of membranes prepared using other conditions. Analysis of variance (ANOVA) showed that among the factors selected, non-solvent additive glycerol had the most significant effects on the response. Pore size test by gas permeation revealed that surface pore size correlates positively with both DCMD and gas flux, but influenced more obviously on the latter. The highest water flux achieved in desalinating 3wt.% NaCl aqueous solution was more than 20kg/m²-hr at average feed temperature of 62.5^oC with 99.9% rejection. It was also found that the surface morphology influenced membrane long-term performance in desalination of waste acid discharged from metallurgical process. Membrane morphologies and microstructures were examined with FESEM; mechanisms for the membrane morphologies evolved were discussed based on XRD characterization along with phase inversion process in the membrane formation.