Document Type

Dissertation

Date of Award

5-31-2017

Degree Name

Doctor of Philosophy in Environmental Science - (Ph.D.)

Department

Chemistry and Environmental Science

First Advisor

S. Mitra

Second Advisor

Edgardo Tabion Farinas

Third Advisor

Tamara M. Gund

Fourth Advisor

Yong Ick Kim

Fifth Advisor

Robert Benedict Barat

Abstract

Membrane separations have undergone rapid developments in recent years. The key component in the process is the membrane itself which acts as a selective barrier regulating transport of components between the two sections. The main advantage of membrane separation process in comparison to other unit operations is its unique separation principle, ease of operation, lower energy requirement, and can be easily coupled with other downstream processes. Different membrane based applications include filtration, osmosis, dialysis, gas separation, pervaporation, membrane extraction and membrane distillation (MD). The membranes can be fabricated by a variety of processes such as phase inversion, sol-gel, track etching, stretching, interfacial polymerization, etc. Much effort has gone into developing methods for enhancing the performance of the membranes by modifying membrane surface including immobilization of nanoparticles and nano carbons.

This research work demonstrates different surface modifying techniques to enhance the membrane performance for different applications such as extraction of volatile organics (VOCs) from air, generation of pure water from sea water via membrane distillation, removal of bacterial debris and endotoxin from water via membrane distillation. The techniques adapted in this research include immobilization of carbon nanotubes (CNTs) on membrane surface to alter the solute membrane interactions; hydrophilization of membrane surface to allow partial wetting of the membrane surface, thus enhancing the MD flux for desalination; incorporation of CNTs via phase inversion technique to form a composite CNIM layer on top of a porous support layer to enhance the membrane in MD application. For bacterial disinfection application, presence of CNTs provide anti-bacterial properties that result in effective rejection and removal of bacterial contaminants from water.

Overall the various membrane modification and membrane based separation approach results in enhanced removal of VOCs from air, higher salt rejection; better permeate flux and also as potential disinfectant for water treatment process.

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