Date of Award
2024
Document Type
Dissertation
Degree Name
Doctor of Philosophy (PhD)
Department
Civil Engineering
Committee Chair
Michael D. Anderson
Committee Member
Ashraf Z. Al-Hamdan
Committee Member
Abdullahi Salman
Committee Member
Yu Lei
Research Advisor
Jason Kirby
Subject(s)
Water--Purification, Water--Purification--Bromate removal, Ozonization, Plasmonics
Abstract
High energy consumption and the formation of harmful byproducts are significant challenges in advanced oxidation processes (AOPs). While much research has focused on improving treatment efficiency, controlling byproduct formation requires more attention. The focus of this dissertation is divided into three main focuses: Firstly, the underlying mechanism of bromate formation inhibition during a plasmon-enhanced catalytic ozonation (PE catalytic ozonation) process using silver-doped spinel ferrite (0.5wt%Ag/MnFe2O4) as the catalyst was investigated by scrutinizing the effects of each factors involved in PE catalytic ozonation including irradiation, catalyst, and ozone, both individually and in combination, on major bromine species involved in bromate formation. The study found that accelerated ozone decomposition inhibited two main bromate formation pathways. Additionally, surface reduction of bromine species (e.g., HOBr/OBr− and BrO3−) was enhanced by the plasmonic effects of Ag and the strong affinity between Ag and Br, contributing to the inhibition of bromate formation. Secondly, the efficacy of plasmon-enhanced catalytic ozonation in treating dissolved organic matter (DOM) fractions was assessed by utilizing the same catalyst in the first focus. This included evaluating alterations in mass distribution and total organic nitrogen quantity, investigating transformations of organic structures, and characterizing structural changes before and after each ozonation processes. Experiments were conducted at two different ratios of transferred ozone dose to initial total organic carbon (TOD/TOC=0.9, 1.5) to assess the impact of ozone concentration on DOM availability. DOM was fractionated based on chemical features, including hydrophobic and hydrophilic fractions with acidic, basic, and neutral characteristics, using raw water samples from Huntsville water utilities. The results indicated that fast decomposition of ozone molecules to hydroxyl radical and other reactive oxygen species resulted in a higher removal of DOM fractions in terms of TOC and COD. Thirdly, raw water samples underwent similar analyses to understand the combined role of these fractions in more realistic water treatment scenarios. High proportion of hydrophobic acid fraction played a role in controlling the behavior of raw water samples under the different ozonation processes.
Recommended Citation
Ahmadi Zahrani, Amir, "Unveiling the mechanisms of bromate formation and NOM treatment in drinking water via plasmon-enhanced catalytic ozonation" (2024). Dissertations. 434.
https://louis.uah.edu/uah-dissertations/434
Comments
Submitted in...the Joint Civil Engineering Program.