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Nitrate Reduction Over Red Mud Supported Iron Catalyst In and Lithium Recovery From Dilute Aqueous Solutions /

Record Type:	Electronic resources : Monograph/item
Title/Author:	Nitrate Reduction Over Red Mud Supported Iron Catalyst In and Lithium Recovery From Dilute Aqueous Solutions // Michael Huang.
Author:	Huang, Michael,
Description:	1 electronic resource (233 pages)
Notes:	Source: Dissertations Abstracts International, Volume: 86-03, Section: B.
Contained By:	Dissertations Abstracts International86-03B.
Subject:	Environmental engineering. -
Online resource:	https://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=30993192
ISBN:	9798384034094

Nitrate Reduction Over Red Mud Supported Iron Catalyst In and Lithium Recovery From Dilute Aqueous Solutions /
Huang, Michael,

Nitrate Reduction Over Red Mud Supported Iron Catalyst In and Lithium Recovery From Dilute Aqueous Solutions /Michael Huang. - 1 electronic resource (233 pages)

Source: Dissertations Abstracts International, Volume: 86-03, Section: B.

In an era where environmental degradation, wastewater management, and resource scarcity increasingly challenge our global communities, research that advances sustainable solutions is of crucial importance. This dissertation seeks to address two of these pressing issues: the contamination of drinking water by nitrates and the efficient recovery of lithium, a critical resource in modern technology.Initially, a synthesized red mud (RM) based catalyst combined with iron powder was developed to transform nitrate in drinking water to nitrogen gas. The overall goal was to reduce nitrate to gaseous nitrogen while minimizing ammonium production after the treatment. Several important factors, such as the iron to RM (Fe/RM) mass ratio, proton activity (i.e., pH), and current density (CD), were examined. The findings revealed rapid nitrate reduction under a CD of 7.5 mA/cm2 at pH 2 using the synthesized catalyst. As the Fe/RM mass ratio increased, the rate and extent of nitrate reduction also increased, but this enhancement plateaued and eventually decreased with further increase in the Fe/RM mass ratio. The results further indicated that maintaining an optimal pH was important for initiating the nitrate reduction process. Proton concentrations below 10-2 M notably diminished the reduction efficiency. Controlling the applied CD was essential for achieving high nitrogen selectivity. By experimenting with various CDs, the ideal experimental condition was identified. The interplay of the Fe/RM mass ratio, pH, and CD was found to be central to ensuring high nitrate removal and nitrogen selectivity.Subsequently, for the efficient recovery of lithium, capacitive deionization and precipitation for lithium recovery were investigated. For the capacitive deionization (CDI) technology section, this study examined the efficacy of loofah-derived activated carbon decorated with manganese dioxide graphite electrodes (denoted as MnO2/AC G). This research indicates that the adsorption density of lithium ions on MnO2/AC G electrodes was influenced by three master variables: lithium concentration, applied working potential, and the pH value of the solution. As the pH value of the solution rose, there is a corresponding increase in adsorption density across all types of MnO2/AC G electrodes. Moreover, more negative applied working potentials lead to enhanced adsorption densities. Notably, the -MnO2/AC G electrode achieved the highest adsorption density of 39.89% under conditions of a pH value of 5.5 and an applied working potential of -1.0 V. Another key insight from this research was the validation of performance predictions derived from zeta potential and cyclic voltammetry analyses. These analyses provide guidance in selecting the optimal electrode for varied conditions by evaluating both potential and pH effects. In conclusion, this study confirms the viability of CDI technology, using MnO2/AC G electrodes, for sustainable lithium recovery. It presents an environmentally friendly alternative to traditional methods and offers opportunities for further development.The final segment investigates the process of lithium recovery from spent lithium-ion batteries (LIBs) using sodium phosphate as a precipitating agent to yield Li3PO4. Both SEM and XRD analyses elucidated the significant role of temperature in influencing the crystallization and lattice structure of the Li3PO4 precipitates. Specifically, SEM findings showed that the Li3PO4 precipitates exhibited a columnar structure, and as the precipitation temperature decreased, the crystal size elongated notably. The XRD analysis affirmed the orthorhombic structure of these crystals. Additionally, the study further explored the solubility relationship between lithium and pH, identifying the optimal concentrations of lithium and phosphate for effective precipitation across various pH ranges. Major findings included the observation that a 60 ℃ temperature yielded the highest lithium recovery rate at 91.4%; a near ambient temperature of 30 ℃ also achieved a commendable 67.8% lithium recovery on average. Kinetic analyses revealed a first-order behavior, indicating a direct correlation between the reaction rate and lithium concentration, which offers guidance for future recovery optimizations. From an environmental perspective, this part of research aimed to reduce the reliance on primary lithium mining and decrease carbon emissions. In conclusion, this research provides a comprehensive understanding of lithium recovery through Li3PO4 precipitation, emphasizing the importance of optimizing conditions for practical applications.Throughout this dissertation, novel approaches to address critical environmental issues of nitrate contamination and lithium recovery were meticulously explored. The insights garnered highlight improvements in water purification and resource recovery, as well as emphasize sustainable solutions for pressing global challenges. Overall, this dissertation paves the way for further advancements in innovative environmental solutions.

English

ISBN: 9798384034094Subjects--Topical Terms:

548583
Environmental engineering.
Subjects--Index Terms:

Capacitive deionization

Nitrate Reduction Over Red Mud Supported Iron Catalyst In and Lithium Recovery From Dilute Aqueous Solutions /
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520 $a In an era where environmental degradation, wastewater management, and resource scarcity increasingly challenge our global communities, research that advances sustainable solutions is of crucial importance. This dissertation seeks to address two of these pressing issues: the contamination of drinking water by nitrates and the efficient recovery of lithium, a critical resource in modern technology.Initially, a synthesized red mud (RM) based catalyst combined with iron powder was developed to transform nitrate in drinking water to nitrogen gas. The overall goal was to reduce nitrate to gaseous nitrogen while minimizing ammonium production after the treatment. Several important factors, such as the iron to RM (Fe/RM) mass ratio, proton activity (i.e., pH), and current density (CD), were examined. The findings revealed rapid nitrate reduction under a CD of 7.5 mA/cm2 at pH 2 using the synthesized catalyst. As the Fe/RM mass ratio increased, the rate and extent of nitrate reduction also increased, but this enhancement plateaued and eventually decreased with further increase in the Fe/RM mass ratio. The results further indicated that maintaining an optimal pH was important for initiating the nitrate reduction process. Proton concentrations below 10-2 M notably diminished the reduction efficiency. Controlling the applied CD was essential for achieving high nitrogen selectivity. By experimenting with various CDs, the ideal experimental condition was identified. The interplay of the Fe/RM mass ratio, pH, and CD was found to be central to ensuring high nitrate removal and nitrogen selectivity.Subsequently, for the efficient recovery of lithium, capacitive deionization and precipitation for lithium recovery were investigated. For the capacitive deionization (CDI) technology section, this study examined the efficacy of loofah-derived activated carbon decorated with manganese dioxide graphite electrodes (denoted as MnO2/AC G). This research indicates that the adsorption density of lithium ions on MnO2/AC G electrodes was influenced by three master variables: lithium concentration, applied working potential, and the pH value of the solution. As the pH value of the solution rose, there is a corresponding increase in adsorption density across all types of MnO2/AC G electrodes. Moreover, more negative applied working potentials lead to enhanced adsorption densities. Notably, the -MnO2/AC G electrode achieved the highest adsorption density of 39.89% under conditions of a pH value of 5.5 and an applied working potential of -1.0 V. Another key insight from this research was the validation of performance predictions derived from zeta potential and cyclic voltammetry analyses. These analyses provide guidance in selecting the optimal electrode for varied conditions by evaluating both potential and pH effects. In conclusion, this study confirms the viability of CDI technology, using MnO2/AC G electrodes, for sustainable lithium recovery. It presents an environmentally friendly alternative to traditional methods and offers opportunities for further development.The final segment investigates the process of lithium recovery from spent lithium-ion batteries (LIBs) using sodium phosphate as a precipitating agent to yield Li3PO4. Both SEM and XRD analyses elucidated the significant role of temperature in influencing the crystallization and lattice structure of the Li3PO4 precipitates. Specifically, SEM findings showed that the Li3PO4 precipitates exhibited a columnar structure, and as the precipitation temperature decreased, the crystal size elongated notably. The XRD analysis affirmed the orthorhombic structure of these crystals. Additionally, the study further explored the solubility relationship between lithium and pH, identifying the optimal concentrations of lithium and phosphate for effective precipitation across various pH ranges. Major findings included the observation that a 60 ℃ temperature yielded the highest lithium recovery rate at 91.4%; a near ambient temperature of 30 ℃ also achieved a commendable 67.8% lithium recovery on average. Kinetic analyses revealed a first-order behavior, indicating a direct correlation between the reaction rate and lithium concentration, which offers guidance for future recovery optimizations. From an environmental perspective, this part of research aimed to reduce the reliance on primary lithium mining and decrease carbon emissions. In conclusion, this research provides a comprehensive understanding of lithium recovery through Li3PO4 precipitation, emphasizing the importance of optimizing conditions for practical applications.Throughout this dissertation, novel approaches to address critical environmental issues of nitrate contamination and lithium recovery were meticulously explored. The insights garnered highlight improvements in water purification and resource recovery, as well as emphasize sustainable solutions for pressing global challenges. Overall, this dissertation paves the way for further advancements in innovative environmental solutions.
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650 4 $a Environmental science. $3 677245
650 4 $a Chemical engineering. $3 560457
650 4 $a Water resources management. $3 794747
653 $a Capacitive deionization
653 $a Electrocatalytic nitrate reduction
653 $a Lithium phosphate
653 $a Lithium recovery
653 $a Red mud
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690 $a 0542
690 $a 0768
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710 2 $a University of Delaware. $b Civil and Environmental Engineering. $e degree granting institution. $3 3815315
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791 $a Ph.D.
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