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14-Thesis by Jianzhi Huang.pdf (4.99 MB)

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Removal of Organic Contaminants From Water By Redox Reactions Using Earth Abundant Metal Oxides

Huang, Jianzhi
http://rave.ohiolink.edu/etdc/view?acc_num=case1558358399401625

Abstract Details

2019, Doctor of Philosophy, Case Western Reserve University, Civil Engineering.
Redox reactions that include reduction and oxidation play an important role in biogeochemical processes and the removal of contaminants from the environment. For reduction, Fe(II) is a strong reductant in the presence of iron oxides, which plays an important role in controlling the fate and transport of numerous contaminants in the environment. However, most of the previous studies on the reductive reactivity of Fe(II) adsorbed onto iron oxides only investigated single well-defined iron oxides, without considering the effects of other metal oxides (e.g., SiO2 and TiO2) and ligands (e.g., carboxylic acid). The major goal of this research was to examine the effects of phthalic acid (PHA) and second metal oxides on the reductive reactivity of Fe(II)/goethite. PHA significantly inhibited the reductive reactivity of Fe(II)/goethite. The ATR-FTIR spectra and surface complexation modeling (SCM) results showed that the presence of PHA (L) led to the formation of a type A ternary species (≡FeOFe+)2…L2-) on the goethite surface, decreasing the abundance of the reactive species (≡FeOFeOH). Moreover, the adsorption of PHA on the surface of goethite blocked the reactive sites and inhibited the electron transfer between Fe(II) and goethite, thus decreasing the reactivity. SiO2 significantly inhibited the reductive reactivity due to its dissolution, while TiO2 greatly enhanced the reactivity, which can be ascribed to interparticle electron transfer. We believe that the conduction bands of goethite and TiO2 were used as conduits for electron transfer from Fe(II) through TiO2 to goethite and eventually to reduce pCNB. For oxidation, various manganese dioxides (MnO2) were synthesized and examined as either oxidants or catalysts for the activation of peroxymonosulfate (PMS). This is because they are one of the strongest natural oxidants and are among the most attractive oxide materials due to their high natural abundance, low cost, low toxicity, and environmental friendliness. The studies of the direct oxidative reactivity of MnO2 have evolved from investigating reductive dissolution of the oxides to quantifying contaminant transformation. However, most existing work only focused on naturally abundant MnO2. The goal of this part of the research was to understand the effects of various MnO2 phase structures on both the direct oxidative reactivity and their catalytic reactivity in PMS activation to degrade organic contaminants. For direct oxidation, eight MnO2 with five different phase structures, i.e., α-, β-, γ-, δ-, and λ-MnO2, were successfully synthesized with different methods. The results showed that the MnO2 oxidative reactivity correlated highly positively with surface Mn(III) content and negatively with surface Mn average oxidation state, indicating that surface Mn(III) played an important role in MnO2 oxidative reactivity. For catalytic reactivity in PMS activation, results showed that under acidic conditions, bisphenol A (BPA) was oxidized by both catalytic oxidation by PMS-MnO2 and direct oxidation by MnO2, and the relative importance of the two mechanisms differed for different MnO2. The crystallinity of MnO2 was the dominant factor in the catalytic reactivity. While for crystalline MnO2, the higher reactivity could be ascribed to lower Mn average oxidation state, higher Mn(III) content, and better conductivity.. These findings offer new insights into the contaminant degradation mechanisms in PMS-MnO2 systems and guidance to develop cost-effective catalysts for water/wastewater treatment.
Huichun Zhang (Advisor)
Environmental Engineering

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Citations

  • Huang, J. (2019). Removal of Organic Contaminants From Water By Redox Reactions Using Earth Abundant Metal Oxides [Doctoral dissertation, Case Western Reserve University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=case1558358399401625

    APA Style (7th edition)

  • Huang, Jianzhi. Removal of Organic Contaminants From Water By Redox Reactions Using Earth Abundant Metal Oxides. 2019. Case Western Reserve University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=case1558358399401625.

    MLA Style (8th edition)

  • Huang, Jianzhi. "Removal of Organic Contaminants From Water By Redox Reactions Using Earth Abundant Metal Oxides." Doctoral dissertation, Case Western Reserve University, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=case1558358399401625

    Chicago Manual of Style (17th edition)

case1558358399401625
168
© , some rights reserved.Creative Commons License Removal of Organic Contaminants From Water By Redox Reactions Using Earth Abundant Metal Oxides by Jianzhi Huang is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported License. Based on a work at etd.ohiolink.edu.
This open access ETD is published by Case Western Reserve University School of Graduate Studies and OhioLINK.