Fig. 3: Characterizing flux through various types of membranes and air filter material.

a Water and b dry-air (0% RH) flux results for PVDF400-MF (orange circle and dashed line for normal orientation, purple cross mark and dashed line for reverse), PS35-UF (blue square and dashed line), and NF270-NF (green triangle and dashed line) membranes as a function of pressure drop (ΔP) (LMH or liters per m² per hour for volumetric, kg per m² per hour for mass). c Relationship between water permeability and air permeability for specific single sample MF membranes (orange circle for PVDF400, gray square for isopore-200 nm, dark blue invert pyramid for Durapore-220 nm, purple diamond for PVDF400-Double Layer, red triangle for Durapore-100 nm, and black dashed line for linear trendline). Note Durapore (100 nm) is hydrophilic. d Comparison of mask material (all layers) with PVDF400 polyester backing material (yellow diamond for polyester backing, green square for surgical mask-all layers, and gray circle for N95-all layers). No filter flow is airflow through the filtration cell with no filter/mask/membrane insert (light blue triangle and dashed line), indicating maximum flow through the cell at that applied pressure. Water flux results were obtained using a dead-end cell with a membrane are of 13.2 cm². Air flux data were collected using in-line flow cell with an area of 9.23 cm². Error bars represent standard deviations of triplicate data. Both horizontal axis (left and right) apply for all data displayed. Flow rate measurements normalized at STP. The PVDF400 membrane was tested in two orientations for air-filtration: with the surface facing the feed side (Normal) and the surface facing the permeate side (Reverse). Error bars represent the standard deviation of 3 different measurements taken on the samples.