Date of Graduation

12-2023

Document Type

Thesis

Degree Name

Master of Science in Chemistry (MS)

Degree Level

Graduate

Department

Chemistry & Biochemistry

Advisor/Mentor

Chen, Jingyi

Committee Member

Heyes, Colin D.

Second Committee Member

Wang, Feng

Third Committee Member

Tian, Z. Ryan

Keywords

photocatalyst; methylene blue; wastewater pollution; purification; pollution reduction

Abstract

The purpose of this study was to examine the dye degradation on the titanium dioxide (TiO2)-based membranes. While many studies have shown photocatalytic degradation of dye on TiO2 in solution, few studies have been reported on the solid TiO2 substrate. In this work, a new method is developed to quantify the dye degradation on TiO2-based membranes. A hydrothermal method is used to synthesize the photocatalytic TiO2 nanofibers; vacuum filtration is applied to fabricate a self-assembled membrane. Silver is incorporated into the nanofibers through in situ reduction before vacuum filtration to fabricate Ag/TiO2 membrane in an attempt to red shift the material’s photoactive range; however, oxidized Ag species, such as Ag2O and AgOH, are likely incorporated due to the nanofibers’ basic environment. The catalytic properties of TiO2 and Ag/TiO2 membranes are then evaluated by the dye – methylene blue degradation under different conditions. A digital method by coupling the image-capturing method using a Gel Imaging System and the analysis using ImageJ has been standardized to monitor the dye degradation over time on the membranes. This study successfully calibrates the linear region (0 – 72.3 ng) of methylene blue drop cast on the membranes. The color intensity of two methylene blue droplets’ mass (36.3 ng and 49.6 ng) is traced under dark and light conditions. The dye degradation on the membranes follows 1st order reaction kinetics while dye degrades faster on the Ag/TiO2 membrane than the TiO2 membrane. This method may potentially be used to quantify other dye degradation on the semiconductor membranes in an effort to develop (photo)catalysts for applications such as water treatment.

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