Solution (Chemistry)

This thesis was about finding a recovery method for TiO2, using a TiO2 recovery technology, which was high enough to be economical ($10 - $15 per 1,000 gallons) to be adopted by wastewater treatment plants. When comparing recovery technologies, the top three which were investigated further through experimentation were a centrifuge, sedimentation tank, and microfilter membrane. Upon experimentation and research, the TiO2 recovery efficiencies of these technologies were 99.5%, 92.5%, and 96.3%, respectively. When doing economic analysis on these technologies comparing TiO2 efficiencies and capital and operational costs, the centrifuge was the most preferred economic option. Also, its cost did were in the economical range ($10 - $15/1,000 gallons) which makes even this technology economical. Besides that, important and valuable information about TiO2: settling behavior, particle size and zeta potential, interactions with COD, and filter operations (particle characterization) were discovered for future research and future testing on this issue.

Ultraviolet spectrophotometry was employed to investigate the adsorption of phenylphosphonic acid onto the surface of alumina from aqueous solution. It was found that an initial chemisorption occurred with monolayer coverage, reaching a maximum at a solution pH of 3.0. The results were interpreted as indicating that this and related adsorptions are controlled by ligand exchange processes involving electrostatic attraction between oppositely-charged species. In a separate project, high performance liquid chromatography was employed for the quantitative analysis of aminophylline in commercial thigh cream formulations. The analysis required derivatization of the compound by dansylation under carefully-controlled conditions. This enhanced its detection and separation from other cream components.

Most living organisms utilize electron transport chains in order to obtain energy. Riboflavin, commonly known as vitamin B2, is the central component of the redox coenzymes flavin adenine dinucleotide (FAD) and flavin mononucleotide (FMN). These cofactors serve as a prosthetic group to flavoproteins and function as the energy-carrying molecules in electron transfer reactions. In this study, the different ionization and oxidation states of riboflavin were identified and quantified as a function of solution potential and pH. To accomplish this task, spectroelectrochemical reductions of riboflavin at different pH were performed. Spectroscopic data offer clues concerning the identity of underlying species, such as oxidation/ionization states and the controlling equilibria. The large data sets obtained from these experiments were analyzed and the acid dissociation constant for reduced riboflavin was determined.