Protein Retention Analysis in 316L Stainless Steel Open-Cell Metal Foams for Biofiltration

Open-cell metal foams are emerging as reliable materials for liquid filtration systems owing to their high permeability, chemical stability, and mechanical durability. Despite these promising properties, their thorough characterization for filtration efficiency and protein retention remains limitedly developed. This work studies 316L stainless steel (SS) open-cell metal foam by integrating computed tomography with experimental-numerical framework to study pressure-flow behavior along with dynamic protein retention analysis. Using X-ray computed tomography, the intricate three-dimensional pore-scale structure of a 316L SS foam sample, which has a porosity of 46.29%, was reconstructed into a comprehensive, watertight CAD model. This digital reconstruction formed basis for computational fluid dynamics (CFD) simulations, which were thoroughly validated with experimental pressure drop measurements over flow rates ranging from 1 to 10 mL/min. The CFD model exhibited an average prediction error of ~6.2%, confirming the dependability of the CT-to-CFD process and determining a foam permeability of 1 × 10⁻⁸ cm². Based on this established framework, dynamic flow experiments with bovine serum albumin (BSA) protein were conducted over three consecutive trials producing an areal retention ranging between 5.32 and 5.77 mg/m². These values reached a saturation point of ~5.8 mg/m², representing 31.66% of the total protein mass introduced. This saturation pattern highlights the surface area as a key factor in adsorption, an observation further corroborated by Discrete Phase Model (DPM) simulations that accurately forecast particle-surface interaction of 35.7%. To further achieve a retention rate as high as 95%, analytical prediction models were formulated based on the experimental protein retention data to determine the ideal combinations of pore size and foam thickness as the primary design factors.