Chemical Engineering Commons^™

Investigation Of Pulsed Electrolysis For Hypochlorous Acid Production, Khoa V. Kieu

Electronic Theses and Dissertations

Because of the Covid-19 pandemic along with the delay in the worldwide supply chain, there were disinfectant shortages that lasted for weeks around the world. Therefore, on-site production is a promising solution to satisfy the increasing demand. As more and more people are shifting toward safer and more environmentally friendly products, we are interested in investigating the electrolysis of sodium chloride (NaCl) solution to produce hypochlorous acid (HOCl). Electrolysis is inexpensive as it requires only sodium chloride and electricity, and it does not have any negative impact on the environment. Moreover, electrolysis can be coupled with renewable energy to utilize …

Disinfection Applications Of On-Site Hypochlorous Acid Production, Deborah Ngabanyi Sebagisha

Electronic Theses and Dissertations

Hypochlorous acid (HOCl) is a weak acid, but strong oxidizing agent produced naturally in the human body to fight viruses and bacteria. Hypochlorous acid can be produced by electrolysis of sodium chloride and water enabling local production of disinfectant, where it is needed. Hypochlorous acid has many applications including in wound care, skin care, and disinfection of health and dental clinics. In this work, two hypochlorous acid applications were explored that could utilize local production by electrolysis. These applications were wastewater treatment and sanitization of dental operating rooms.

An electrochemical reactor and process were designed, constructed, and tested for hypochlorous …

Evaluation Of Aluminum Dissolution, Current Density, And Pitting Patterns During Electrocoagulation, Monica Castro Carias

USF Tampa Graduate Theses and Dissertations

Electrocoagulation (EC) is a sustainable water treatment process involving the generation of coagulants on-site through the application of a voltage on metal (usually aluminum or iron alloys). The factors that impact EC system performance have been well researched, however further research is needed on the factors that impact anodic dissolution of aluminum electrodes, especially when the technology is transferred to full-scale applications. Electrode fouling is one of the factors that can impact dissolution of the anode during EC due to the formation of a protective oxide/hydroxide layer on the electrode surface. Previous studies have addressed electrode fouling by reversing polarity, …

Observing And Modeling Water Electrolysis Performance Limitations Attributed To Gas Generation And Porous Media Properties, Joseph S. Lopata

Theses and Dissertations

Water electrolysis has been a simple method of hydrogen production for over two centuries, but the exploration of its nuances is still accelerating. This work compiles numerous mechanisms via which electrolysis efficiency is influenced by phenomena that occur within, adjacent to, and nearby functional porous media. Computational and experimental methods are applied to electrolysis systems to quantify the impact of twophase flow patterns and porous media properties on energy losses, primarily those linked directly to the presence of the gas phase.

First, an introduction to the chemistry and operating principle of water electrolysis is presented and relevant works from the …

Oxidative Efficiency Of Ozonation Coupled With Electrolysis For Treatment Of Acid Wastewater, Ze-You Hu, Feng-Yun Xiang, Ji-Qiang Mao, Ya-Lei Ding, Shao-Ping Tong

Journal of Electrochemistry

Establishment of an ozone-based advanced oxidation process (AOPs-O₃) for effective treatment of acid wastewater is an important and difficult task. The process of ozonation coupled with electrolysis (electrolysis-ozonation, E-O₃) has been reported to effectively degrade pollutants in neutral solution. We studied the efficiency of E-O₃ for degradation of acetic acid (HAc, an ozone inert chemical) in acid solution and found that E-O₃ had high oxidative efficiency at pH less than 3. For example, 52.2% of 100 mg·L-1 HAc could be removed by E-O₃ in 120 min at pH 1.0, but only 2.2% and …

Polymeric Nanofibers Supported Metal Oxides For Electrochemical Energy Storage Devices, Rutul Patel

Electronic Theses & Dissertations

With increasing demand for energy, there is an increased need to find effective ways to store the available energy to sustain current and future generations. Thus, the research investigates whether polymetric nanofibers support metal oxide are a good solution to store energy. The materials used for synthesis includes N-dimethylformamide, nickel nitrate, cobalt nitrate and polyacrylonitrile.

These fibers are developed three phases. First, a homogenous mixture is prepared, followed by electrospinning of the mixture. Next, calcination of the prepared nanofibers was done to generate the 1D nanofibers embedded with metal oxides. The samples are primarily tested for supercapacitor applications, hydrogen evolution …

Improving The Electrochemical Method Of Wastewater Treatment, Dilrabo Akramovna Muhammadieva, Diyor Asadullaevich Hadjibaev, Furkat Ilyasovich Erkabaev

Chemical Technology, Control and Management

With an electrochemical method of wastewater treatment, the preliminary isolation of iron, calcium and magnesium compounds from them contributes to a more intensive recovery process. The purpose of this work is to improve the efficiency of electrochemical treatment of industrial wastewater contaminated with chromium(III) and chromium(VI) ions. The research has determined the optimal conditions for increasing the yield of chromium in the Park during electrochemical treatment of chromate-containing wastewater by using modified bentonite for pre - treatment of wastewater. Pre-softening of wastewater with modified bentonite before electrochemical treatment made it possible to increase the current yield of chromium from 17% …

Engineering Of Earth-Abundant Electrochemical Catalysts, Dylan D. Rodene

Theses and Dissertations

Alternative energy research into hydrogen production via water electrolysis addresses environmental and sustainability concerns associated with fossil fuel use. Renewable-powered electrolyzers are foreseen to produce hydrogen if energy and cost requirements are achieved. Electrocatalysts reduce the energy requirements of operating electrolyzers by lowering the reaction kinetics at the electrodes. Platinum group metals (PGMs) tend to be utilized as electrocatalysts but are not readily available and are expensive. Ni_1-xMo_x alloys, as low-cost and earth-abundant transition metal nanoparticles (NPs), are emerging as promising electrocatalyst candidates to replace expensive PGM catalysts in alkaline media. Pure-phase cubic and hexagonal Ni_{1-x …}

Reaction Mechanism For Oxygen Evolution On Ruo2, Iro2, And Ruo2@Iro2 Core-Shell Nanocatalysts, Julie N. Renner

Faculty Scholarship

Iridium dioxide, IrO2, is second to the most active RuO2 catalyst for the oxygen evolution reaction (OER) in acid, and is used in proton exchange membrane water electrolyzers due to its high durability. To improve the activity of IrO2-based catalysts, we prepared RuO2@IrO2 core-shell nanocatalysts using carbon-supported Ru as the template. At 1.48 V, the OER specific activity of RuO2@IrO2 is threefold that of IrO2. While the activity volcano plots over wide range of materials have been reported, zooming into the top region to clarify the rate limiting steps of most active catalysts is important for further activity enhancement. Here, …

Pathways To Ultra-Low Platinum Group Metal Catalyst Loading In Proton Exchange Membrane Electrolyzers, Julie N. Renner

Faculty Scholarship

Hydrogen is one of the world's most important chemicals, with global production of about 50 billion kg/year. Currently, hydrogen is mainly produced from fossil fuels such as natural gas and coal, producing CO2. Water electrolysis is a promising technology for fossil-free, CO2-free hydrogen production. Proton exchange membrane (PEM)-based water electrolysis also eliminates the need for caustic electrolyte, and has been proven at megawatt scale. However, a major cost driver is the electrode, specifically the cost of electrocatalysts used to improve the reaction efficiency, which are applied at high loadings (>3 mg/cm2 total platinum group metal (PGM) content). Core-shell catalysts …

Parallel Plate Electrochemical Reactor Model, Ralph E. White, Mike Bain, Mike Raible

Ralph E. White

No abstract provided.

Predicting Shunt Currents In Stacks Of Bipolar Plate Cells With Conducting Manifolds, H. S. Burney, Ralph E. White

Ralph E. White

A method is presented for predicting shunt currents in stacks of bipolar plate cells with conducting manifolds. The method is based on the requirement that the potential drop through the solution in a manifold be large enough to force current to leave the solution and to enter the conducting manifold. The current that leaves the solution in the manifold enters the conducting manifold at the anode end of the stack and returns to the solution at the cathode end. This could cause catastrophic failure of a manifold.

Using Parameter Estimation Techniques With A Simple Model Of A Diaphragm-Type Electrolyzer To Predict The Electrical Energy Cost For Naoh Production, John Van Zee, Ralph E. White

Ralph E. White

Predictions of the electrical energy cost for NaOH production are determined as a function of the independent operating variables and diaphragm characterizing properties. The predictions are based on data from a statistically designed experiment, a simple model of a diaphragm-type electrolyzer, a simple model of the cell voltage losses, and parameter estimation techniques. The data were obtained over a sufficiently large range of operating conditions so that the resulting design equation may be industrially useful. The simple model of the diaphragm is based on the mass transport of the hydroxyl ion, a linear potential gradient, and is presented in terms …

Preparation And Characterization Of Carbon Black Diamond Composite Electrodes For Anodic Degradation Of Phenol

Faculty of Engineering University of Malaya

Carbon black diamond (CBD) composite electrodes have been prepared with different percentages of carbon black (5% (5CBD), 20% (20CBD) and 40% (40CBD) as the conductive agent. This article reports for the first time the electrochemical behavior of CBD electrodes. The electrochemical properties of these three electrodes were characterized by cyclic voltammetry in 0.5 M H2SO4 and at 100 mV/s scanning rate. The working potential windows of 5CBD, 20CBD and 40CBD electrodes were 3.35, 2.4 and 1.75V vs. Ag/AgCl respectively. Anodic oxidation behavior of phenol was studied by cyclic voltammetry on CBD electrodes in aqueous solution of 0.5 M H2SO4, 0.5 …

Quantifying Individual Potential Contributions Of The Hybrid Sulfur Electrolyzer, John A. Staser, Maximilian B. Gorensek, John W. Weidner

Faculty Publications

The hybrid sulfur cycle has been investigated as a means to produce clean hydrogen efficiently on a large scale by first decomposing H₂SO₄ to SO₂, O₂, and H₂O and then electrochemically oxidizing SO₂ back to H₂SO₄ with the cogeneration of H₂. Thus far, it has been determined that the total cell potential for the hybrid sulfur electrolyzer is controlled mainly by water transport in the cell. Water is required at the anode to participate in the oxidation of SO₂ to H₂SO_{4 …}

Effect Of Water Transport On The Production Of Hydrogen And Sulfuric Acid In A Pem Electrolyzer, John A. Staser, John W. Weidner

Faculty Publications

The thermochemical cycle involving the interconversion between sulfur dioxide and sulfuric acid is a promising method for efficient, large-scale production of hydrogen. A key step in the process is the oxidation of sulfur dioxide to sulfuric acid in an electrolyzer. Gaseous SO₂ fed to a proton exchange membrane (PEM) electrolyzer was previously investigated and was shown to be a promising system for the electrolysis step. A critical factor in the performance of this gas-fed electrolyzer is the management of water since it: (i) is needed as a reactant, (ii) determines the product sulfuric acid concentration, …

Sulfur Dioxide Crossover During The Production Of Hydrogen And Sulfuric Acid In A Pem Electrolyzer, John A. Staser, John W. Weidner

Faculty Publications

A proton exchange membrane (PEM) electrolyzer has been investigated as a viable system for the electrolysis step in the thermochemical conversion of sulfur dioxide to sulfuric acid for the large-scale production of hydrogen. Unfortunately, during operation, sulfur dioxide can diffuse from the anode to the cathode. This has several negative effects, including reduction to sulfur that could potentially damage the electrode, consumption of current that would otherwise be used for the production of hydrogen, introduction of oxygen and SO₂ to the hydrogen stream, and loss of sulfur to the cycle. However, proper water management can reduce or eliminate the …

Selection Of Additions In The Process Of Electrochemical Synthesizing Of K_2feo_4, Wei-Hua Yang, Dong-Qin Bi, Yan Zhou, Hong-Hui Wang, Xin-Ren Lan

Journal of Electrochemistry

Some of different additions including KIO4 was added to the anodic electrolyte for electrochemical synthesizing of K2FeO4,the effects of these additions on current yield were investigated.XRD and SEM were used to characterize the structure and image of K2FeO4.The results show that KIO4 is a preferable addition.When the mass dosage of KIO4 is 0.02%,electrolysis time is 1 h,the current yield is enhanced by 31.6% and the corresponding purity of the product is improved by 3.85 %.

The Influence Of Electrolytic Conditions On Synthesis Of Feo_4~(2-), Yan Zhou, Wei-Hua Yang, Dong-Qin Bi, Ting-Ting Huang, Zhen Sun, Quan-Feng Guo

Journal of Electrochemistry

The FeO42-was synthesized using iron lattice as anode and the solid K2FeO4 was also prepared.Influence of electrolytic conditions,such as stir,ultrasonic,temperature and current density on the current efficiency were studied.The results showed that preferable ferrate(VI) current yield was obtained in a current density of 10 mA·cm-2,temperature 30℃ and 14 mol/L NaOH as electrolyte under at stirring effect.

Water Transport In Polymer Electrolyte Membrane Electrolyzers Used To Recycle Anhydrous Hcl: I. Characterization Of Diffusion And Electro-Osmotic Drag, Sathya Motupally, Aaron J. Becker, John W. Weidner

Faculty Publications

In this paper, diffusion and electro-osmotic drag of water across Nafion® membranes in the presence of HCl are characterized. For all the measurements, one side of the Nafion membrane was in contact with liquid water and the other side with gaseous anhydrous HCl. To characterize diffusion of water, the open-circuit flux of water across a catalyst-coated Nafion 115 membrane was measured as a function of HCl flow rate and temperature at a constant cell pressure of 1 atm. Due to the nature of varying driving force for diffusion as a function of HCl flow rate, the experimental data was analyzed …

Fuel Cells, Frederick J. Munster Jr.

Maine Collection

Fuel Cells

by Frederick J. Munster Jr.

Edited by: Mr. Christopher Carroll

Maine Department of Economic Development, Augusta, Maine, 1998.

Contents: Hydrogen / Hydrogen Safety / Electrolysis / Electrolyzers / History of Fuel Cells / How Fuel Cells Operate / Fuel Cell Types / Fuel Cell Electrochemistry / Power Systems / Fuel Cells in Transportation / Hydrogen Powered Internal Combustion Engines / Home, Garden, Education and Industry / For More Information / Glossary / References

Anodic Oxidation Of Ethylenediaminetetraacetic Acid On Platinum Electrode In Alkaline Medium, S. N. R. Pakalapati, Branko N. Popov, Ralph E. White

Faculty Publications

The anodic oxidation of ethylenediaminetetraacetic acid (EDTA) was studied in alkaline medium on a smooth platinum electrode. Bulk electrolysis indicated that stable organic intermediates (formaldehyde and glyoxal) are formed during the oxidation of EDTA and that complete oxidation to CO₂ can be achieved. The proposed pathway suggests that the acetate groups in EDTA are initially oxidized, generating formaldehyde and ethylenediamine. The rest potential of EDTA (0.066 to 0.164 V vs. Hg/HgO) was observed to be higher than for other organic species. In alkaline medium, very little EDTA oxidation was found to occur on bare platinum. Limiting-current behavior due to …

Mathematical Modeling Of An H2s Removal Electrolyzer, Z. Mao, P. Adanuvor, Ralph E. White

Faculty Publications

A mathematical model is presented for a high temperature H₂S electrolyzer. It is shown that the maximum current in this type of a cell is determined entirely by the transport rate of sulfide ions through the separator. It is suggested that this model could be used to determine the feasibility of various designs for this electrolyzer.

Electrochemical Production Of Hydrogen And Sulfur By Low-Temperature Decomposition Of Hydrogen Sulfide In An Aqueous Alkaline Solution, A. A. Anani, Z. Mao, Ralph E. White, S. Srinivasan, A. J. Appleby

Faculty Publications

Electrolysis of hydrogen sulfide to its constituents in a solution containing equimolar concentrations of NaOH and NaHS has been carried out at 80°C. In a double-compartment cell employing Nafion membrane as a separator, both crystalline elemental sulfur and high-purity hydrogen have been produced at high current efficiencies. Only minimal, if any, passivation of the anode by sulfur product was observed. According to solution composition, electrolysis could result in gas evolution at the anode, passivation of the anode by sulfur deposition, or oxidation of sulfide (S^2–) or polysulfide (S) to sulfur oxyanions. However, in an optimized solution, electrolysis gave …

Predicting Shunt Currents In Stacks Of Bipolar Plate Cells With Conducting Manifolds, H. S. Burney, Ralph E. White

Faculty Publications

A method is presented for predicting shunt currents in stacks of bipolar plate cells with conducting manifolds. The method is based on the requirement that the potential drop through the solution in a manifold be large enough to force current to leave the solution and to enter the conducting manifold. The current that leaves the solution in the manifold enters the conducting manifold at the anode end of the stack and returns to the solution at the cathode end. This could cause catastrophic failure of a manifold.

A Mathematical Model For A Parallel Plate Electrochemical Reactor, Cstr, And Associated Recirculation System, T V. Nguyen, C W. Walton, Ralph E. White

Faculty Publications

A mathematical model is presented for a system comprised of a parallel plate electrochemical reactor (PPER) and a continuous, stirred-tank reactor (CSTR) under both total and partial recycle. The model is used to predict the time dependent behavior of the electrowinning of copper from an aqueous, hydrochloric acid solution. The model includes many important aspects of a PPER/CSTR system which have been neglected previously. These aspects are the kinetics of electrode reactions, the electroneutrality condition, three mass transfer processes for ionic species in the electrolyte (diffusion, ionic migration, and convection) and the electrode gap in the PPER, and the inclusion …

Using Parameter Estimation Techniques With A Simple Model Of A Diaphragm-Type Electrolyzer To Predict The Electrical Energy Cost For Naoh Production, John Van Zee, Ralph E. White

Faculty Publications

Predictions of the electrical energy cost for NaOH production are determined as a function of the independent operating variables and diaphragm characterizing properties. The predictions are based on data from a statistically designed experiment, a simple model of a diaphragm-type electrolyzer, a simple model of the cell voltage losses, and parameter estimation techniques. The data were obtained over a sufficiently large range of operating conditions so that the resulting design equation may be industrially useful. The simple model of the diaphragm is based on the mass transport of the hydroxyl ion, a linear potential gradient, and is presented in terms …

Parallel Plate Electrochemical Reactor Model, Ralph E. White, Mike Bain, Mike Raible

Faculty Publications

No abstract provided.