Quantitative analysis of internal flow distribution and pore interconnectivity within asymmetric virus filtration membranes

Several studies have demonstrated that the filtration performance and fouling characteristics of porous membranes can be significantly influenced by the pore interconnectivity. However, there are no available techniques that can quantify the pore connectivity of highly asymmetric membranes with small pore size used in ultrafiltration and virus removal filtration. In this study, a novel approach was developed to measure the pore interconnectivity from SEM images of gold nanoparticles captured within a membrane in which flow through the exit (skin side) was partially blocked by a stainless steel support. The pore interconnectivity parameter was then evaluated by comparison of the observed capture profile with numerical simulations of the flow and particle capture. Results for the Viresolve (R) Pro membranes showed much greater pore interconnectivity than for the Viresolve (R) NFP membranes. SEM images of the Ultipor (R) DV20 membrane showed nanoparticle capture only at regions of the inlet located directly over the open portions of the membrane exit, indicating that there is minimal lateral flow in this membrane. These results provide the first quantitative measurements of the extent of pore interconnectivity within virus filtration membranes having highly asymmetric pore structures.