טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
M.Sc Thesis
M.Sc StudentMoldavsky Alexander
SubjectProduction of Hollow Fibers Membranes Using the
Electrospining Process
DepartmentDepartment of Chemical Engineering
Supervisors Professor Emeritus Raphael Semiat
Professor Eyal Zussman
Full Thesis textFull thesis text - English Version


Abstract

This work describes a unique way to produce hollow fiber membranes using the electrospinning process. Today the smallest diameters of the hollow fiber membranes are around 80-100 μm. In our work we focused on producing hollow fibers membranes with diameter less than 15 μm. This may increase the pressure drop due to flow but presents high surface area. Smaller fibers mean more fiber surface area per unit volume of equipment, thus increasing the total surface area, which will likely cause an improvement in separation.

Membrane preparation process includes the polymer solution preparations, the electrospinning process, cutting the membranes produced with liquid nitrogen, gluing the membranes to bundles and module preparation. Membranes performance was checked for recovery, flux and rejection of solutes. The polymer drop exiting the tip of the pipette is drawn into a fiber due to the applied high voltage. The exiting jet looped due to charged field, and the fibers are collected as a web of fibers on the rotating grounded wheel. Two solutions are needed in co-electrospinning process, one for the shell and one for the core. Different polymers were used in order to produce UF\MF membranes, while the most successful combinations were PCL/PEO and PVDF-HFP/PVP. Membranes performances were checked by examination of the recovery, permeate flux and rejection of the solute by the membranes. PVDF-HFP/PVP gave the highest membrane performance. The recovery was around 30%, flux 30-60 L/m2 hr, and rejection up to 40% of the Poly acrylic acid with MW of 50000 g/mol.