Investigating the Impact of Dope Solution Composition on PVDF Membranes

This research aims to achieve the fabrication of a successful polyvinylidene fluoride (PVDF) membrane through the incorporation of an additive and support layer. The study involves comprehensive characteristic analysis of these membranes such as permeability, rejection and contact angle measurements. Due to the hydrophobicity of PVDF-based membranes, they are prone to fouling and inefficiently absorb organics [1]. The change in composition of the dope solution and addition of polyvinylpyrrolidone (PVP) will allow for surface modification of these membranes. To enhance the performance of the PVDF membrane this research explores the influence of different compositions of PVDF in the dope solution in addition to variations of PVP. 17% PVDF in the dope solution was found to be the most consistent when analyzing permeability and rejection data. To increase the permeability of the 17% PVDF membrane, 0.5% PVP was added to the dope solution. PVP functioned as a stabilizer and thickening agent due to its hydrophilic nature, therefore decreasing the contact angle of the 17% PVDF membrane. The evaporation time was explored and was found to have a small impact on the permeability of the membrane, decreasing it slightly and increasing the rejection. The successful development of a PVDF single layer membrane is paramount as it serves as a foundational milestone for initiating the fabrication of composite membranes with polysulfone (PSf). The inclusion of PVP in the dope solution may have played a role in the effective mixing of the two dope solutions when casting the composite. Due to the experimentation being done on a lab scale, collaboration with the Georgia Institute of Technology and their slot die coating machine will be helpful in creating large scale membranes for commercial water filtration.