Physical Sciences and Mathematics Commons^™

Effects Of So2 In Air On Performance Of Direct Methanol Fuel Cell, Bin Qin, Fen-Ning Jing, Xue-Jing Sun, Gong-Quan Sun, Hai Sun

Journal of Electrochemistry

Direct methanol fuel cells (DMFC) generally use oxygen as an oxidant. Contaminants such as sulfides and nitrides in the air can affect the performance of the DMFC. In this work, the effects of SO₂ on the performance of DMFC were investigated and the mechanism of poisoning was analyzed, by means of constant current discharge curve, polarization performance curve, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). In the CV scan, the permeated methanol was oxidized at a low potential to eliminate its effect on the SO₂ poisoning behavior test. The results showed that the SO₂ poisoning resulted …

Atom-Specific Activation In Co Oxidation, Simon Schreck, Elias Diesen, Jerry Larue, Hirohito Ogasawara, Kess Marks, Dennis Nordlund, Matthew Weston, Martin Beye, Filippo Cavalca, Fivos Perakis, Jonas Sellberg, André Eilert, Kyung Hwan Kim, Giacomo Coslovich, Ryan Coffee, Jacek Krzywinski, Alex Reid, Stefan Moeller, Alberto Lutman, Henrik Öström, Lars G. M. Pettersson, Anders Nilsson

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

We report on atom-specific activation of CO oxidation on Ru(0001) via resonant X-ray excitation. We show that resonant 1s core-level excitation of atomically adsorbed oxygen in the co-adsorbed phase of CO and oxygen directly drives CO oxidation. We separate this direct resonant channel from indirectly driven oxidation via X-ray induced substrate heating. Based on density functional theory calculations, we identify the valence-excited state created by the Auger decay as the driving electronic state for direct CO oxidation. We utilized the fresh-slice multi-pulse mode at the Linac Coherent Light Source that provided time-overlapped and 30 fs delayed pairs of soft …

Graphene-Based Materials Coated On Zeolite For The Removal Of Persistent Organic Pollutants From Water, Yan Zhang

Theses and Dissertations

Adsorption is a fast, low-cost and the most commonly implemented water treatment technology for the removal of multiple contaminations from ground water, drinking water or wastewater. Difficulties in removing persistent organic pollutants (POPs) to improve quality and safety of treated water sources require the exploration of novel and multifunctional materials. Graphene-based materials having unique structures, high specific surface areas and tailorable functional groups are promising candidates as adsorbents.

The main goal of this work is to fabricate a novel adsorbent made of GO/rGO attached on natural zeolite substrates for the removal of variably charged organic model compounds and POPs in …

The Effect Of Ionic Liquid Adsorption On The Electronic And Optical Properties Of Fluorographene Nanosheets, Mehdi Shakourian-Fard, S. Maryamdokht Taimoory, Volodymyr Semeniuchenko, Ganesh Kamath, John F. Trant

Chemistry and Biochemistry Publications

In the present study, we investigate the adsorption characteristics of six different ionic liquids (ILs) on a fully-fluorinated graphene (fluorographene, FG) surface using electronic structure studies and associated analysis methods. A systematic comparison of differences in IL binding energies (ΔEb) with fluorographene, graphene and hexagonal boron nitride surfaces indicates that fluorination strongly decreases the binding energy compared to the other two surfaces, hence resulting in the binding energetics: ΔEb (Graphene…IL) > ΔEb (Hexagonal boron-nitride…IL) > ΔEb (Fluorographene…IL). To probe the reasons for this difference, quantum theory of atoms in molecules (QTAIM) analysis and non-covalent interactions (NCI) analyses were carried out. Results indicate …

Adsorption Of Uv-Quenching Substances (Uvqs) From Landfill Leachate With Activated Carbon, Yang Deng, Chanil Jung, Renzun Zhao, Kevin Torrens, Laying Wu

Department of Earth and Environmental Studies Faculty Scholarship and Creative Works

Co-treatment of landfill leachate with sewage at publicly owned treatment works (POTWs) is a common leachate management practice. However, the UV absorbing property of UV-quenching substances (UVQS) present in municipal landfill leachate may significantly reduce the efficiency of disinfection at POTWs that adopt ultraviolet irradiation for disinfection. The UVQS represents an emerging concern in the solid waste and wastewater treatment industries. This study aimed to evaluate the performance of activated carbon (AC) for removal of UVQS from landfill leachate in order to address the leachate UV-quenching issue. Results showed that the abatement of leachate UV254 absorbance with AC followed a …

An Experimental And Modelling Study On The Adsorption Characteristics Of Activated Carbon Under Different Challenge Concentration Levels, Chuan He, Jingjing Pei, Jensen Zhang

International Building Physics Conference 2018

Applying air cleaning devices is an effective approach to control targeted indoor gaseous pollutants. It is important to understand the adsorption characteristics of filter media (e.g, activated carbon) at typical indoor application conditions as well as standard test conditions. Tests per ASHRAE Standard 145.1 for filter media performance evaluation can provide a relative comparison among different media. However, as the tests are conducted at elevated gas concentrations (1~100 ppm), they do not represent the media performance under lower concentrations typical of indoor applications (

Preparation And Characterization Of Chemically-Modified Biomaterials And Their Application As Adsorbents Of Penicillin G, Jesie Silva, Lizebel Morante, Tesfamichael Demeke, Jacqueline Baah-Twum, Abel E. Navarro

Publications and Research

The prevalence of antibiotics in water creates microbial resistance and has a negative impact on the ecosystem. Biomaterials such as spent tea leaves are rich in functional groups and are suitable for chemical modification for diverse applications. This research proposes the use of spent tea leaves of chamomile (CM), green tea (GT), and peppermint (PM) as structural scaffolds for the incorporation of carboxyl, sulfonyl, and thiol groups to improve the adsorption of Penicillin G (Pe). Adsorbents characterization reported a higher number of acidic functional groups, mainly in thiolated products. Scanning electron microscopy (SEM) analysis showed changes on the surfaces of …

Removal Of Cu2+ And Ni2+ From Aqueous Solution Using Sno2 Nanomaterial Effect Of: Ph, Time, Temperature, Interfering Cations, Abigail M. Zepeda, Daisy Gonzalez, Luis Gonzalez Heredia, Karina Marquez, Cesar Perez, Erika Pena, K. Flores, Carolina Valdes, Thomas Eubanks, Jason Parsons, J. Cantu

Chemistry Faculty Publications and Presentations

Tin oxide, SnO2, nanomaterial was synthesized and tested for the removal of Cu2+ and Ni2+ ions from aqueous solutions. Various parameters for the binding were investigated in batch studied, which included pH, time, temperature, and interferences. In addition, isotherm studied were performed to determine the maximum binding capacity for both Cu2+ and Ni2+ ions. The optimal binding pH determined from the effects of pH were to be at pH 5 for both the Cu2+ and Ni2+ ions. The isotherm studies were performed at temperatures of 4°C, 25 °C, and 45 °C for both the Cu2+ and Ni2+ ions and were …

The Investigation Of Photocatalytic And Adsorptive Properties Of Humic Acid Grafted Magnetite Nanoparticles For The Remediation Of Arsenic, Selenium And Phosphorous From Water, Mohammad Mamunur Rashid

FIU Electronic Theses and Dissertations

The crisis of freshwater has been a big concern worldwide. Water contamination that occurs through the discharge of toxic pollutants from different natural and anthropogenic sources have worsened the situation. Adsorption has emerged as a simple and economical water treatment procedure although the challenge is to find the right adsorbent that can efficiently remove the target contaminant followed by their easy recovery from the reaction vessel. In this dissertation, I have focused on the synthesis, characterizations and applications of environmentally compatible and magnetic humic acid coated magnetite nanoparticles (HA-MNP) as a potential adsorbent for water purification.

Phosphate is an essential …

The Impact Of Small Organic Acids On Iron And Manganese Mineral Transformations And The Fate Of Trace Metals, Elaine Denise Flynn

Arts & Sciences Electronic Theses and Dissertations

Iron and manganese oxides are ubiquitous in soils and sediments and play a critical role in the geochemical distribution of trace elements and heavy metals through adsorption and coprecipitation. At redox interfaces, biogeochemical processes generate conditions with coexisting dissolved Fe(II) and solid-phase Fe(III). In such systems, Fe(II) induces the recrystallization of iron oxides through coupled mineral growth and dissolution due to electron transfer as oxidative adsorption of Fe(II) and reductive dissolution of Fe(III) occur. Aqueous Mn(II) adsorption onto Mn(III/IV) oxides also likely involves oxidation although likely through different mechanisms than that of the Fe system because of the potential for …

Removal Of Chromium(Vi) And Chromium(Iii) Ions From Aqueous Solution Using Bio-Char Generated From Agricultural Waste Products, Diego Fernando Gonzalez

Theses and Dissertations

Heavy metals are one of the most persistent and prevalent contaminants in the aquatic environment. The removal of chromium from aqueous solution, especially in the hexavalent form is difficult. New technologies, techniques and/or new materials have been designed in order to effectively and efficiently remove chromium from the aqueous environment. The project focuses on the comparison of the effects of pH, time, temperature, binding capacity on bio-char’ generated from agricultural waste produces vs an amino modified derivative of the bio-char. Pineapple skins were dried, ground, sieved, and pyrolyzed to produce a bio-char material. The bio-char was analyzed using FTIR to …

Design Improvements To Sulfate-Reducing Bioreactors For Mine-Influenced Stream Remediation In Cold Climates, Katrina Moreira

Graduate Theses & Non-Theses

Mine-influenced water (MIW), a waste water product containing heavy metals and sulfates, is a significant pollution source to waters in Montana. Implementing a low cost, passive treatment system, such as a sulfate-reducing bioreactor (SRBR), is desired for remediation of streams influenced by heavy metals in remote locations. SRBR systems operate by using organic matter and sulfate-rich water to precipitate and immobilize dissolved heavy metals. Sulfate-reducing bacteria utilize the organic matter as an electron donor to convert sulfate to sulfide, and then sulfide in the bioreactor is utilized to precipitate heavy metals. Under ideal operating conditions, SRBR systems can remove >98% …

Adsorption Of Tnt, Dnan, Nto, Fox7, And Nq Onto Cellulose, Chitin, And Cellulose Triacetate. Insights From Density Functional Theory Calculations, Guido Todde, Sanjiv K. Jha, Gopinath Subramanian, Manoj K. Shula

Faculty Publications

Insensitive munitions (IM) compounds such as DNAN (2,4-dinitroanisole), NTO (3-nitro-1,2,4-triazol-5-one), NQ (nitroguanidine), and FOX7 (1,1-diamino-2,2-dinitroethene) reduce the risk of accidental explosions due to shock and high temperature exposure. These compounds are being used as replacements for sensitive munition compounds such as TNT (2,4,6-trinitromethylbenzene) and RDX (1,3,5-hexahydro-1,3,5-trinitro-1,3,5-triazine). NTO and NQ in IM compounds are more soluble than TNT or RDX, hence they can easily spread in the environment and get dissolved if exposed to precipitation. DNAN solubility is comparable to TNT solubility. Cellulosic biomass, due to its abundance in the environment and its chemical structure, has a high probability of adsorbing …

Use Of Calcined Layered Double Hydroxide [Zn$_{2}$-Al-Co$_{3}$] For Removal Of Textile Dye Acid Green 1 From Wastewater: Kinetic, Equilibrium, Comparative, And Recycling Studies, El Hassane Mourid, Mohamed Lakraimi, Souad El Abridi, Lhaj Benaziz, El Hassan Elkhattabi, Moha Berraho

Turkish Journal of Chemistry

In the present study, calcined layered double hydroxides (CLDHs) were obtained by heating [Zn$_{2}$-Al-CO$_{3}$] at 500 $^{\circ}$C. The adsorption of the textile dye acid green 1 (AG1) by CLDH was carried out at different pH levels, adsorbent--adsorbate contact times, and AG1/CLDH mass ratios. Equilibrium at room temperature was reached after 24 h, which was confirmed by the kinetic modeling of the experimental data by the pseudo-second-order model. The adsorption is described by a Langmuir-type isotherm. The comparative study of adsorption isotherms in calcined and uncalcined phases reveals that the former could be a good candidate for trapping such pollutants. After …

Optimization Of Sugarcane Bagasse Activation To Achieve Adsorbent With High Affinity Towards Phenol, Seyed-Abolfazl Mohtashami, Neda Asasian Kolur, Tahereh Kaghazchi, Reza Asadi-Kesheh, Mansooreh Soleimani

Turkish Journal of Chemistry

Sugarcane bagasse as an agricultural/industrial biomass was converted into a low-cost activated carbon via an acid activation procedure under optimized conditions. Phosphoric acid was applied as a cost-effective and environmentally friendly chemical activator. The optimized activated carbon produced under temperature of 550 \textdegree C and impregnation ratio of 1.5 showed a micromesoporous structure with specific surface area and pore volume of 972.5 m$^{2}$/g and 0.43 cm$^{3}$/g, respectively. The adsorption capacity of the produced AC towards phenol was measured and, after only 30 min, the removal percentage reached over 95%. The greatest affinity towards phenol was obtained at pH of 4 …

Experimental And Theoretical Study Of Nh$_{3}$ Adsorption And Desorption Over A Cu-Chabazite Nh$_{3}$-Scr Catalyst, Selmi̇ Eri̇m Bozbağ, Mutlu Şi̇mşek, Onur Demi̇r, Deni̇z Şanli Yildiz, Hüseyi̇n Barkin Özener, Gökhan Hi̇sar, Can Erkey

Turkish Journal of Chemistry

NH$_{3}$ adsorption and desorption behavior of a commercial Cu-chabazite (CHA) NH$_{3}$ selective catalytic reduction (NH$_{3}$-SCR) catalyst was studied in the presence and absence of H$_{2}$O. NH$_{3}$ uptake values at various adsorption temperatures were obtained during various steps of the adsorption and temperature-programmed desorption (TPD) experiments. Total NH$_{3}$ uptake decreased from 4.6 to 1.6 g NH$_{3}$/L catalyst when the adsorption temperature was increased from 50 to 300 $^{\circ}$C. Three major adsorption sites for NH$_{3}$ adsorption could be identified and quantified using TPD experiments, namely loosely, moderately, and strongly bound NH$_{3}$ with peak centers at around 147, 266, and 447 $^{\circ}$C. The …

Transfer Of The Protonable Surfactant Dipalmitoyl-Phosphatidylcholine Across A Large Liquid/Liquid Interface: A Voltammetric Study, İbrahi̇m Uyanik

Turkish Journal of Chemistry

Adsorption behavior of the zwitterionic phospholipid dipalmitoyl-phosphatidylcholine (DPPC) at the polarizable liquid/liquid interface formed between water and 1,2-dichloroethane electrolyte solutions is studied taking into account both the pH of the aqueous phase and the concentration of the phospholipid in the organic phase by cyclic voltammetry. Experimental results showed that the adsorption of the phospholipid strongly depends on the pH of the aqueous phase, which determines the surface ionization of the polar head of the phospholipid molecule and hence the stability of the adsorbed layer of phospholipids.

Experimental Evaluation Of Uranyl Transport Into Mesoporous Silica Gel Using Fluorescence, Brandon M. Dodd

Theses and Dissertations

This research investigated parameters that can affect the use of nanoporous silica gel as a media for accumulating a detectable amount of uranium. The unique fluorescence of the Uranyl (UO₂²⁺) ion was used to evaluate the transport kinetics and accumulation within silica gel in a static fluid and under pressure driven flow. The addition of fluid flow decreased the time constant from on the order of an hour to approximately 2s with a very low fluid velocity of 0.36cm/s. The 0.36cm/s fluid velocity was found to be the critical velocity above which there was no gain in …

Understanding The Adsorption And Nucleation Of Transition Metals On A Model Carbon Support, Grant S. Seuser

Theses and Dissertations

Heterogeneous catalysis plays a vital role in the commercial production of chemicals. However, much is still unknown about the fundamental surface chemistry involved in catalyst preparation and the surface chemistry of the catalysts themselves. In the first part of this work, a surface science approach was employed to develop a fundamental understanding of the surface chemistry of strong electrostatic adsorption (SEA) of metal precursors on a model carbon support, highly oriented pyrolytic graphite (HOPG). SEA is a wet impregnation method in which anionic/cationic metal precursors are adsorbed onto positively/negatively charged functional groups by adjusting the pH of the solution above …

Quantum Many - Body Interaction Effects In Two - Dimensional Materials, Sanghita Sengupta

Graduate College Dissertations and Theses

In this talk, I will discuss three problems related to the novel physics of two-dimensional quantum materials such as graphene, group-VI dichalcogenides family (TMDCs viz. MoS2 , WS2, MoSe2 , etc) and Silicene-Germanene class of materials.

The first problem poses a simple question - how do the quantum excitations in a graphene membrane affect adsorption? Using the tools of diagrammatic perturbation theory, I will derive the scattering rates of a neutral atom on a graphene membrane. I will show how this seemingly naive model can serve as a non-relativistic condensed matter analogue of the infamous infrared problem in Quantum Electrodynamics. …

Surface Oxygenation Of Biochar Through Ozonization For Dramatically Enhancing Cation Exchange Capacity, Matthew D. Huff, Sarah Marshall, Haitham A. Saeed, James Weifu Lee

Chemistry & Biochemistry Faculty Publications

Background

Biochar cation exchange capacity (CEC) is a key property that is central to biochar environmental applications including the retention of soil nutrients in soil amendment and removal of certain pollutants in water-filtration applications.

Results

This study reports an innovative biochar-ozonization process that dramatically increases the CEC value of biochars by a factor of 2. The ozonized biochars also show great improvement on adsorption of methylene blue by as much as a factor of about 5. In this study, biochar samples treated with and without ozone were analyzed by means of pH and CEC assays, water field capacity measurement, elemental …