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Rational Design and Characterization of Adsorbents for Environmental Remediation of FGD Wastewater

Malibekova, Alma
http://orcid.org/0000-0003-1320-0346
http://rave.ohiolink.edu/etdc/view?acc_num=ucin1668617308225204

Abstract Details

2022, PhD, University of Cincinnati, Engineering and Applied Science: Chemical Engineering.
The surface structure–binding property relationships in the selective removal of regulated ions in complex wastewaters were investigated in order to aid in the surface design strategies that can be applied to tackle a wide range of environmental challenges presented by regulated cations and anions. Functionalized silica adsorbents and zero-valent iron (ZVI) materials were studied in order to meet the new US EPA effluent limitation guidelines. The binding of Hg2+ by mercaptan-functionalized silica possessing different physical characteristics was explored through experimental investigations and theoretical calculations. The DFT calculations suggested a simultaneous monodentate and bidentate Hg2+ complex formation on sulfur-containing surface functional groups that strongly depends on the Hg2+ concentration. Theoretical Hg2+ adsorption isotherms predicted by DFT calculations have shown that even when the adsorbent surface had heterogeneous adsorption sites capable of a simultaneous monodentate and bidentate complexation, the adsorption still followed the Langmuir model. Five sulfur-containing functional groups were studied for the adsorption of Hg2+ from simulated wastewater with toxic and nontoxic compositions reported in flue gas desulfurization (FGD) wastewater. It was found that the molecular structure of a functional group greatly influences its activity toward cation binding.The affinity of Hg2+ towards the functional groups of this research as measured by the experimental Henry’s Law constants suggested a correlation with corresponding theoretical HOMO energies and interaction energies. A systematic study of the application of ZVI materials for FGD wastewater remediation has established optimal process conditions, and nanoparticle structure-property relationships for the reduction and removal of Se6+, a key regulated species, using pure ZVI and several bimetallic ZVI compositions, as well as an improved mechanistic understanding of Se sequestration. The improved Se sequestration occurs through the corrosion of nanosized ZVI (nano ZVI), which facilitates direct Se6+ reduction to elemental Se0 and Se2- at the ZVI surface. Finally, the mechanism involved in the reaction of regulated ions with nano ZVI in the presence of an applied weak magnetic field (WMF) was also investigated. The magnetic gradient force produced by ferromagnetic ZVI particles had a greater influence on the rate of selenite diffusion in solution than the Lorentz force due to the externally applied weak magnetic field. Moreover, the magnetic gradient force was suggested to suppress ZVI corrosion reactions. Despite changes in the iron oxide layer under the WMF influence, the rate of selenate reduction has not been significantly affected in the short-term reactions of a few hours. Most crucially, WMF had a negligible effect on the rate of mass transport of selenate anions, as compared to the dominant effect of forced convection. On the other hand, magnetic field gradient force suppressing corrosion of ZVI may be beneficial for longer-term stability of ZVI in aqueous environmental conditions, where longer reaction times are necessary. The suppression of ZVI corrosion can prevent the depletion of electrons in the ZVI particle, extending the effectiveness of ZVI for the target reactions.
Vadim Guliants, Ph.D. (Committee Member)
Stephen Thiel, Ph.D. (Committee Member)
Julio Landero Figueroa, Ph.D. (Committee Member)
Junhang Dong, Ph.D. (Committee Member)
292 p.
Chemical Engineering
FGD wastewater; adsorbent; functional groups; zero valent iron; bimetallic nanoparticles

Recommended Citations

Citations

  • Malibekova, A. (2022). Rational Design and Characterization of Adsorbents for Environmental Remediation of FGD Wastewater [Doctoral dissertation, University of Cincinnati]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1668617308225204

    APA Style (7th edition)

  • Malibekova, Alma. Rational Design and Characterization of Adsorbents for Environmental Remediation of FGD Wastewater. 2022. University of Cincinnati, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=ucin1668617308225204.

    MLA Style (8th edition)

  • Malibekova, Alma. "Rational Design and Characterization of Adsorbents for Environmental Remediation of FGD Wastewater." Doctoral dissertation, University of Cincinnati, 2022. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1668617308225204

    Chicago Manual of Style (17th edition)

ucin1668617308225204
26
© 2022, some rights reserved.Creative Commons License Rational Design and Characterization of Adsorbents for Environmental Remediation of FGD Wastewater by Alma Malibekova is licensed under a Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported License. Based on a work at etd.ohiolink.edu.
This open access ETD is published by University of Cincinnati and OhioLINK.
Release 3.2.12