Microstructured hollow fibers and microsieves: fabrication, characterization and filtration applications

This thesis describes the preparation, characterization and applications of microstructured membranes. Phase Separation MicroFabrication (PSµF) is used to prepare the membranes. This technique relies on using microstructured silicon or metal templates during the preparation of the membranes and transferring the microstructure of these templates to the membranes during the phase inversion process which forms the membranes. The main focus of the work is on hollow fiber membranes with microstructured outer or inner surfaces. The fabrication of these membranes and the effect of various parameters on the microstructure, the permeability and separation properties of the membranes are described. The fouling behavior of these membranes is explored in dead-end, cross-flow and submerged and aerated filtration operations. The Permeate Flux-Transmembrane Pressure relationship and real-time observation methods such as NMR imaging and Direct Visual Observation are used to study the fouling on the membranes. Apart from microstructured hollow fibers, in one chapter, the fabrication of polymeric microsieves by PsµF is described. This chapter focuses on a solvent-based method to downscale microsieve perforation size and the effect of mold design on the release of the microsieves from the molds. The results presented in the thesis shed insight on the processes which occur during the formation of the microstructured membranes and the filtrations carried out with these membranes.