Date of Award

Spring 1-1-2012

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Mechanical Engineering

First Advisor

John Pellegrino

Second Advisor

Alan R. Greenberg

Third Advisor

Virginia Ferguson

Abstract

Gas-liquid porometry is the most common method for characterizing microfiltration membranes. This thesis provides a new approach to analyze data from gas-liquid porometry. Here, we combine porometry results with porosity measurement to determine the transport through the membranes. The pore size distribution and porosity measurements were performed for a range of membranes from straight through to asymmetric membranes. There was high discrepancy between the measured pore size and manufacturer data. Our study also examined the effect of asymmetry in pore size distribution of the membranes as compared to symmetric membranes. The asymmetric membranes were found to give smaller pore size compared to symmetric membranes. The orientation of asymmetric membranes provided different results for the mean pore size. A comparison between the classical approach and modified approach to analyze the data and thus in the estimation of transport parameter was made. Better correlation of measured and estimated transport parameter was found for modified approach as compared to classical approach. In addition modified approach determines the tortuosity for each pore size range during the estimation of transport parameters. The average tortuosity of the membranes under study varied from 0.707 to 6.48 with larger nominal pore membranes having higher values compared to smaller ones. This research also studied the transport of particles through the symmetric membranes. Theoretical model based on sieving was examined. The actual rejection increased for more tortuous membranes in comparison to theoretical rejection prediction with the difference being greater for the highest tortuosity. With this study, we hope to further elucidate the characterization of membranes via porometry and hope to provide useful information regarding the development and end use of these membranes.

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