(206d) Particle Image Velocimetry (PIV): An Important Tool for Understanding the Fluid Dynamics of Magnetically Responsive Membranes

Particle image velocimetry (PIV) is an approach for measuring two dimensional fluid velocity field in the region of interest at a very high spatial resolution. Visualizing the flow field at the surface of the membrane can help in designing magnetically responsive membranes that actively break up the concentration polarization boundary layer at the surface of the membrane. The present investigation deals with understanding the effect of the movement of magnetically responsive polymer brushes on the concentration polarization boundary layer. The interaction of external magnetic field with the superparamagnetic nano particle attached via thermos-responsive Poly(N-isopropylacrylamide), PNIPAM polymer on regenerated cellulose ultra-filtration (RC-UF) membrane leads to local perturbation and is proposed break up concentration polarization. Laser illuminated fluorescent particles were used as probes to get two consecutive images at a definite time interval. The small displacement of these particles was used to define the velocity vectors. The influence of the experimental conditions on the velocity vectors of the fluid at the surface of the membranes was investigated. The results revealed that the nanoparticle attachment was more homogeneous for 100 kDa membrane surface compared to 300 kDa. The PIV images of the modified membrane by longer atom transfer radical polymerization (ATRP) time, were found to show more perturbation in the fluid field and can be attributed to the longer polymer chains. The outcome of the PIV image analysis was found to be in good agreement with the data obtained Bovine serum albumin (BSA) rejection studies.