Date of Award

Fall 2002

Document Type

Dissertation

Degree Name

Doctor of Philosophy in Chemical Engineering - (Ph.D.)

Department

Chemical Engineering

First Advisor

Kamalesh K. Sirkar

Second Advisor

Piero M. Armenante

Third Advisor

Dana E. Knox

Fourth Advisor

Gordon Lewandowski

Fifth Advisor

Chao Zhu

Abstract

To improve liquid membrane selectivity and stability for removal of vapor and gases from a gas stream, a thin immobilized liquid membrane (ILM) has been studied. Low vapor pressure liquid solvent/solutions were immobilized in part of the micropores of a hydrophilic, hydrophobic or ceramic hollow fiber substrate. To prepare such thin ILMs, three approaches were used: evaporation of the a volatile solvent; acrylic acid-grafted hollow fibers providing a thin hydrophilic layer; pressurization technique.

For removal of volatile organic compound (VOC), a thin ILM of silicone oil incorporated in the micropores of a hydrophobic hollow fiber with a silicone rubber coating yielded a highly VOC-enriched permeate and increased separation factor. The same ILM was stable over an extended period (6 months - 2 years) demonstrating the potential utility of such an ILM-based hollow fiber device for VOC-N2/air separation. A mathematical model was successfully developed to describe the VOC-N2 permeation-separation in a hollow fiber permeator having this special type of membrane containing a thin ILM.

Grafting method used for the preparation of a thinner ILM resulted in various hollow fibers having different hydrophilic layer thickness. These fibers were used to study the effect of various glycerol-based and aqueous liquid membranes immobilized in the thin hydrophilized part of the fiber. Glycerol-based ILMs resulted in low CO2 permeances in the range of 1*10-6 cm3/cm2*s*cmHg for enclosed atmosphere application; aqueous based ILMs has much better performance.

A pressurization technique was used to prepare a thin ILM in porous hydrophilic and ceramic substrates. It was shown that when appropriate asymmetric hollow fibers substrates were used, increase in CO2 permeance was achieved.

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