• Login
    View Item 
    •   Home
    • UA Graduate and Undergraduate Research
    • UA Theses and Dissertations
    • Dissertations
    • View Item
    •   Home
    • UA Graduate and Undergraduate Research
    • UA Theses and Dissertations
    • Dissertations
    • View Item
    JavaScript is disabled for your browser. Some features of this site may not work without it.

    Browse

    All of UA Campus RepositoryCommunitiesTitleAuthorsIssue DateSubmit DateSubjectsPublisherJournalThis CollectionTitleAuthorsIssue DateSubmit DateSubjectsPublisherJournal

    My Account

    LoginRegister

    About

    AboutUA Faculty PublicationsUA DissertationsUA Master's ThesesUA Honors ThesesUA PressUA YearbooksUA CatalogsUA Libraries

    Statistics

    Most Popular ItemsStatistics by CountryMost Popular Authors

    Experimental and Theoretical Investigation of Electrochemical Water Treatment Processes

    • CSV
    • RefMan
    • EndNote
    • BibTex
    • RefWorks
    Thumbnail
    Name:
    azu_etd_16611_sip1_m.pdf
    Size:
    34.52Mb
    Format:
    PDF
    Download
    Author
    Chen, Yingying
    Issue Date
    2018
    Keywords
    bipolar membrane
    bipolar membrane electrodialysis
    brine treatment
    electrocoagulation
    water softening
    Advisor
    Farrell, James
    
    Metadata
    Show full item record
    Publisher
    The University of Arizona.
    Rights
    Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction, presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
    Abstract
    Two kinds of electrochemical methods for water treatment were investigated, namely electrocoagulation and bipolar membrane electrodialysis (BMED). Electrocoagulation with mild steel anode was investigated to remove dissolved silica from simulated high efficiency reverse osmosis (HERO) concentrate solutions, and was compared with traditional chemical coagulation with FeCl3. The recommended optimal initial pH value for electrocoagulation is 8. 76-89% silica removal was achieved with 4.0 mM iron dose in electrocoagulation, while a maximum of 64% removal was achieved by chemical coagulation with a dose of 4.0 mM FeCl3. BMED was used to produce acid and base from dilute sodium sulfate or sodium chloride salt solutions. Using single pass BMED, >75% current utilization was achieved producing acids and bases with concentrations of ~75% of the feed salt concentration. Factors affecting current utilization and limiting current density were investigated. The energy required to produce a mole of acid or based increased linearly with increasing current density. The energy costs for producing acids and bases were ~10 times lower than costs for purchasing bulk HCl and NaOH from local suppliers. A BMED stack was used in a zero-liquid-discharge (ZLD) system of water softening for regenerating ion exchange media and for promoting crystallization of hardness minerals in a fluidized bed crystallization reactor (FBCR). The overall closed-loop process eliminates the addition of extra chemicals and the creation of waste brine solutions. However, the key component in BMED – bipolar membranes (BPMs) are ill suited for water/wastewater treatments, due to low stability in alkaline solutions and high voltage drop at low current densities. The alkaline stability of the BPMs was improved by replacing the anion exchange layer with base-stable anion exchange membranes designed for alkaline fuel cells. In order to decrease the water splitting voltage, different electronically conductive materials and graphene oxide were tested as the interlayer catalyst of BPMs. Two methods of modeling were applied to study the structure of BPM and the mechanisms of water splitting in BPM. A 3-D point-charge method was used to model the 3-D interlayer of the BPM, where each functional group in both ion exchange layer (IEL) was treated as a point charge and different charge screening was applied. A one-dimensional continuum model of BPM was also applied to investigate ion concentration gradients in BPMs under reverse bias conditions.
    Type
    text
    Electronic Dissertation
    Degree Name
    Ph.D.
    Degree Level
    doctoral
    Degree Program
    Graduate College
    Chemical Engineering
    Degree Grantor
    University of Arizona
    Collections
    Dissertations

    entitlement

     
    The University of Arizona Libraries | 1510 E. University Blvd. | Tucson, AZ 85721-0055
    Tel 520-621-6442 | repository@u.library.arizona.edu
    DSpace software copyright © 2002-2017  DuraSpace
    Quick Guide | Contact Us | Send Feedback
    Open Repository is a service operated by 
    Atmire NV
     

    Export search results

    The export option will allow you to export the current search results of the entered query to a file. Different formats are available for download. To export the items, click on the button corresponding with the preferred download format.

    By default, clicking on the export buttons will result in a download of the allowed maximum amount of items.

    To select a subset of the search results, click "Selective Export" button and make a selection of the items you want to export. The amount of items that can be exported at once is similarly restricted as the full export.

    After making a selection, click one of the export format buttons. The amount of items that will be exported is indicated in the bubble next to export format.