Electrospun mat swelling: An ally to improve membrane rejection ratio

NANCY LIS GARCIA; L. RIBBA ; J. D. CIMADORO; S. GOYANES

Berlin

Congreso; 8th World Congress in Biopolymers and Bioplastics; 2018

Electrospun polymer fbers have been widely applied as fltration media. Te meshes pore size, is usually estimated in literature from microscopy images. However, if the polymer undergoes a swelling process in the fltrated liquid this willchange, causing differences in both the particle size it is able to retain and the permeation rate. In this work the effect ofpolymer swelling on electrospun PVA mats morphology when used as water flters is studied. Electrospun mats were employedto flter pure water during different times (0, 5, 10, 30 and 60 minutes), and observed immediately afer that using an AFM. Teaverage diameter of PVA fbers notoriously increases (about a 68%) with fltering time afer a short transitory stage, evidencingthe swelling process. Tis effect causes a decrease in the effective spaces between fbers, through which water can permeate.On the other hand, the RMS roughness of the meshes was calculated by the program NanoSurf C3000 over an area of 10 x10 microns for each image taken. Again a strong change in this parameter is observed, showing a signifcant decrease in theroughness probably caused by the pressure produced by the water column and the swelling. It is interesting to study how thewater permeated volume changes as a function of time during the frst transitory stage. To evaluate this, the volume of waterpassing through the membrane was measured for 90 minutes. During a frst stage the system goes through a transitory stagein which the flow at which the water permeates is diminishing. Tis result is consistent with both the increase in diameter andthe change in mesh density.