الفهرس 
CHAPTER ONE INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
The main objective of this research work is to fabricate a novel, efficient, and cheap membrane suitable for membrane distillation (MD) process. Performance and economic aspects of MD unit were studied to achieve the optimum thermal and flow conditions. In addition, as a pretreatment process, a new method was developed to prepare a low-pressure nano-filtration membrane based on the membrane surface reaction (functionalized ultrafiltration (UF) blend membrane) with polyethyleneimine (PEI) to fabricate thin film composite (TFC) membranes for water softening applications. For distillation process, a novel triple-layer nanocomposite membrane based on the cheap and commonly used polyethersulfone (PES) in composite with carbon nanotubes (CNTs) as the primary bulk material sandwiched in poly (vinylidene fluoride-co-hexafluoro propylene) (PcH) /CNTs as the outer surface layers of the membrane by using electrospinning technique was fabricated. Modified PES with CNTs was also chosen as the bulk material of the triple-layer membrane to obtain a high porosity membrane. Both the upper and lower surfaces of the triple-layer membrane were coated with PcH/CNTs using electrospinning to get a triple-layer membrane with high total porosity and noticeable surface hydrophobicity. Combining both characteristics, next to an acceptable bulk hydrophobicity, resulted in a compelling membrane for MD applications. The prepared membrane was utilized in a direct contact MD (DCMD) system, and its performance was evaluated in different salt solution concentrations, feed velocities and feed solution temperatures. The results of the prepared membrane in this study were compared to those reported in previously published papers. Based on the evaluated membrane performance, the triple-layer nanocomposite membrane can be considered as a potential alternative with reasonable cost relative to other commercial MD membranes. Both pure PcH and its composite membrane with the two fillers together carbon nanotubes and titanioum dioxide, PcH/TiO2-CNTs were fabricated using electrospining technique to overcome scaling problems. This novel PcH/TiO2-CNTs composite membrane is good candidate for further investigation. To study the effect of fluid flow on the heat and mass transfer in MD system, two different cell designs were fabricated and compared. It was obvious that the cell material and flow pattern have significant effect on the MD permeability for same membrane.