چكيده به لاتين
This project has been carried out with the approach to investigate the effect of X additives on the preparation of polyvinylidine fluoride membranes for water purification. For this purpose, a variety of flat sheet membranes were prepared in two bench and pilot scales by phase inversion process, in four different sections, with various combinations of mixed materials. Solvent and non-solvent are N-N-dimethyl acetamide and water, respectively. Also, X, Y and Z additives have also been used. Structural and functional characteristics of the membranes were evaluated using SEM images, viscosity, porosity, water content, membrane thickness, pure water flux, BSA and dextran rejection tests. In the first section of the project, the effect of primary factors affecting the structure and performance of the membrane, including polymer concentration, molecular weight of the X additive (200, 400, 2000, and 6000 daltons), X200 concenrtation, film thickness and casting speed were investigated and X200 was selected as a more effective molecular weight. In order to increase both pure water flux and membrane retention, a combination of additives has been used in the following three sections. In this way, in the second section, the combination of X200 with different molecular weights of X (600, 1500, 3000, 6000 and 10,000 Daltons) as the first and second additives in the 5: 5 and 7: 2.5 ratio, was used. In this section, the membranes containing X1500 and X200 additives in both mass ratio, have a lower pure water flux and a higher rejection rate, than others. In the third section, the effect of X200 and Y additives on the performance of ultrafiltration membranes was investigated. The presence of Y in the polymer solutions increased the viscosity, balk and surface porosity, pure water flux, both BSA and Dextran rejection, and decreased pore size. In the fourth section, the combination of X200 (5%) and Z (1-5 wt%) was used. The membrane obtained from 3% of Z had the highest BSA rejection. Considering the remarkable membrane performance results of the third section, this composition can be proposed to make commercial membranes for water treatment industry.
