Development of Nanomaterials and Technologies for Environmental Applications

• Main Author: Genuino, Homer
• Format: Text
• Language: unknown
• Published: OpenCommons@UConn 2013
• Subjects: nanomaterials; nanotechnology; manganese oxides; titanium dioxide; photocatalysis; Prudhoe Bay
• Online Access: https://opencommons.uconn.edu/dissertations/233; https://opencommons.uconn.edu/cgi/viewcontent.cgi?article=6441&context=dissertations

This research work focused on the preparation of manganese oxide-based nanomaterials using a simple reflux method, characterization, and various applications including laboratory-scale development of emulsion and microwave (MW) photocatalysis technologies. This dissertation consists of five major sections. Chapter 2 describes the enhancement of the photodegradation of toxic N-Nitrosodimethylamine (NDMA) in water using amorphous manganese oxide (AMO) and crystalline platinum manganese oxide catalysts. Results from spectroscopic, chromatographic, and voltammetric studies were interpreted to study the role of the catalysts and the reactive oxygen species that form, and the kinetics and mechanism of catalyzed NDMA photodegradation. Mixed valencies of Mn and the presence of physisorbed oxygen, which reacts with photogenerated electrons to form reactive oxygen species, played significant roles in the enhancement of the photodegradation of NDMA. Chapter 3 presents the investigation of the effects of visible and UV light on the characteristics and properties of Prudhoe Bay and South Louisiana emulsions to better understand the role of sunlight on the fate of spilled crude oils that form emulsions with a dispersant in the aquatic environment. The unique changes in emulsion properties were attributed to direct photodegradation and photooxidation of crude oil components. Chapter 4 describes the development of a novel continuous-flow reactor to investigate the synergetic effects of UV and MW radiation on TiO2 nanoparticles for the enhancement of photodegradation of Direct Red-81 and Bromothymol Blue dyes. The efficiency of the combined UV and MW radiation was higher than the sum of the isolated and corresponding thermal effects and directly proportional to the MW power and dissolved oxygen concentration. Accelerated rates of dye degradation on incorporation of MW were attributed to the generation of more hydroxyl and superoxide anion radicals and an increase in hydrophobicity of TiO2. Chapter 5 describes the synthesis of ...