Date of Graduation

8-2017

Document Type

Dissertation

Degree Name

Doctor of Philosophy in Engineering (PhD)

Degree Level

Graduate

Department

Chemical Engineering

Advisor/Mentor

Wickramasinghe, S. Ranil

Committee Member

Ulbricht, Mathias

Second Committee Member

Barabote, Ravi D.

Third Committee Member

Qian, Xianghong

Keywords

ATRP; Beverage industry; Biochemical; Membrane; Surface modification

Abstract

Synthetic membranes have been frequently used for many fields, such as, the food and beverage, biopharmaceutical, and biofuel industries. In the beer industry, microfiltration frequently suffers from fouling due to the interaction between different species. It is shown that polyphenols can form cross-links with protein molecules, forming insoluble aggregates. However, by adding an optimal amount of polysaccharides these aggregates can be disrupted thus reducing fouling by the aggregates. Confocal laser scanning microscopy (CLSM) is a powerful technique to locate the foulants inside the wet membrane in order to understand more about the behavior of fouling in microfiltration.

Membrane surface modification is used to impart desirable membrane surface properties. Here membrane surface modification is used to develop membrane adsorbers for protein purification. Hydrophobic interaction membrane chromatography (HIMC) has gained interest due to its excellent performance in purification humanized monoclonal antibodies. HIMC affords all the advantages of membrane adsorbers, which is dynamic capacities that are independent of flow rate, higher throughput and easy to scale up. Unique inverse colloidal crystal (ICC) membranes were developed with highly periodic structures, high porosity, and fully interconnected pores. ICC membranes offer a very high binding capacity for IgG4. On the other hand, salt responsive membranes were developed by grafting responsive ligand, poly vinylcaprolactam (PVCL), from the surface of the membrane by atom transfer radical polymerization (ATRP). The nanostructure can vary its conformation and hydrophobicity when the temperature changes. After modification, membrane is able to provide a very high recovery and yield.

Membrane modification is also well applied for biofuel industry. Duel nanostructures, poly styrene sulfonic acid (PSSA) and poly ionic liquid (PIL) were grafted separately and neighborly from the surface of ceramic membrane substrate by control ATRP and UV initiated radical polymerization. Modified membrane substrates were challenged with cellulose and corn-stovers biomass hydrolysis in pure ionic liquid (IL) and mixture of IL and co-solvent. High yield in total reducing sugar (TRS), 95% and 60% for cellulose and corn-stovers biomass respectively, indicates strong activity of polymeric solid acid catalysts.

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