Physical Chemistry Commons^™

Neutron Study Of Structured Polymers At Interfaces, Thusitha Etampawala

All Dissertations

This work focuses on interfacial structure and dynamics of structured polymers in thin films and in solutions using neutron techniques accompanied by atomic force microscopy. We probed polymers with a common theme that were highly segregated either because of presence of ionic groups or topological constraints. In these polymers the interfacial regions often define their function in different applications such as clean energy, printing adhesions and drug delivery systems. Thin film studies include systems of polystyrene/sulfonated polystyrene, a rigid sulfonated polyphenylene and polystyrene three-arm stars/linear polystyrene. The first two systems include ionic components and the last exhibits topological constraints. Polystyrene …

Synthesis Of Pani/Nihcf Nanocomposite Particles And Eqcm Measurement Of Ion Exchange Properties In Solutions Containing Cd2+, Yu-Jiao Yang, Xiao-Gang Hao, Xu-Li Ma, Zhong-De Wang, Zhong-Lin Zhang, Nian-Chen Han

Journal of Electrochemistry

The PANI/NiHCF nanocomposite particles were synthesized on the CNTs-modified Pt substrate by one-step co-polymerization using cyclic voltammetry. Electrochemical quartz crystal microbalance (EQCM) technique was adopted to investigate the polymerization process of the nanocomposite particles and the mechanism of ion exchange in aqueous solution containing Cd²⁺． The morphology and structure of the as-prepared composite particles were characterized by scanning electron microscope (SEM), transmission electron microscope (TEM), and Fourier transform infrared spectroscopy (FT-IR). Combined with cyclic voltammetry (CV) and energy dispersive spectroscopy (EDS), the electrochemical behavior and the mechanism of ion exchange were also investigated in electrolytes of Cd^{2+ …}

Anaerobic Biotransformation Of Environmental Pollutants Stimulated By Electric Field: Electron-Transfer Mechanisms And Application Examples, Chun-Hua Feng, Dao-Hai Xie, Yun-Meng Pang, Tao Han, Chao-Hai Wei

Journal of Electrochemistry

The ability of some microorganisms to accept electrons from an electrode for the reduction of terminal electron acceptors in anaerobic environments has attracted growing interest on the electric field-stimulated biological reduction technology, which may open new possibility for the sustainable wastewater treatment and bioremediation in the field of environmental engineering. Here, we reviewed the extracellular electron transfer mechanism which is thought to play a key role in determining the feasibility and efficiency for the anaerobic biotransformation of environmental pollutants. Possible mechanisms that may be involved in bioelectrochemical reactors (BERs) with biocathodes include indirect electron transfer via hydrogen generated from water …

Electrochemically Switched Separation Of Yttrium Ion Using Electroactive Nickel Hexacyanoferrate Thin Films In Rare Earth Metal Solution, Hao Zhang, Xiao-Gang Hao, Zhong-De Wang, Zhong-Lin Zhang, Xu-Li Ma, Yi-Bing Li, Shi-Bin Liu

Journal of Electrochemistry

Electroactive nickel hexacyanoferrate (NiHCF) thin films were synthesized by cathodic deposition and investigated as electrochemically switched ion exchange (ESIX) materials for the separation of Y³⁺ from aqueous solutions. In 0.1 mol·L^-1 Y(NO₃)₃ solution, cyclic voltammetry (CV) combined with electrochemical quartz crystal microbalance (EQCM) technique was used to investigate the electroactivity, reversibility of the film electrodes and the mechanism of ion exchange. The electrochemical behavior of NiHCF film electrodes was also compared with that in Sr(NO₃)₂ solutions. The ion selectivity of the film was investigated in 0.1 mol·L^-1 solutions containing [Y(NO_{3 …}

A Comparative Study In Pretreatments Of Acid Chemical Wastewater By Electrochemical Oxidation And Ozonation, Han-Shui Liu, Su Yu, Shao-Ping Tong, Chun-An Ma

Journal of Electrochemistry

Under the condition of keeping certain acidity, the pretreatment efficiency of an acid chemical wastewater (pH 0.85) by electrochemical oxidation was compared with that by ozonation. The results showed that the electrochemical oxidation pretreatment could obtain a better result than the ozonation at pH 0.85. After the addition of 2 g·L^-1 NaCl and with the electrochemical oxidation pretreatment at 30 mA·cm^-2, the removal rate of chemical oxygen demand (CODCr) reached 43.4%, and the value of biochemical oxygen demand/chemical oxygen demand (BOD₅/COD_Cr) also increased from 0.034 to 0.14 in 20 minutes, indicating significantly improvement …

Electrocatalytic Properties Of The Keggin-Type Co(Ii)-Substituted Heteropolyanion Pw11O39Co(Ii)(H2O)5-, Bin Wang, Chong-Tai Wang, Ying-Jie Hua, Jin-Yuan Liu, Liang-Fei Zheng

Journal of Electrochemistry

The electrochemical properties of the Keggin-type Co(II)-substituted heteropolyanion PW₁₁O₃₉Co(II)(H₂O)^5- (PW₁₁Co), as well as the electrocatalytic properties of PW₁₁Co towards the anodic oxidations of H₂O₂ and CH₃OH were studied using the electrochemical methods such as cyclic voltammetry and AC impedance spectroscopy in this paper. An electrocatalytic mechanism of PW₁₁Co as an anodic medium was also proposed. It was found that PW₁₁Co showed a pair of pseudo-reversible redox peaks at the potentials of 1.367 V/1.266 V, corresponding to the redox responses of …

An Investigation Of Photocatalytic Degradation Reactions Of Pollutants By Combination Of (Photo)Electrochemical Measurements, Wen-Hua Leng, Hong-Qiao Zhu

Journal of Electrochemistry

Semiconductor photocatalysis plays a critical role in the environment protection and future energy development. (Photo)electrochemical measurements are powerful tools for studying the kinetics and mechanism of photocatalytic reactions, since photo-carriers, as reactants of photocatalytic reactions, are involved in the interfacial transfer and recombination of semiconductor/electrolyte interface. This review describes the part of our recent results regarding aqueous photocatalytic decontamination obtained by these methods, and the focus of future work in this field is suggested.

Preparation Of Benzoquinone From Phenol By Electrooxidation, Dong-Fang Niu, Cheng-Kai Yu, Xin-Sheng Zhang

Journal of Electrochemistry

The benzoquinone was prepared from phenol by electrooxidation in an H-type cell with cation exchange membrane, in which lead plates were used both as an anode and a cathode, while H₂SO₄ was used as a supporting electrolyte. The effects of current density, concentration of sulphuric acid, concentrations of benzoquinone in electrolyte and extractant on the yields and efficiencies of electrolysis were investigated. Under the optimized conditions of current density being 4 A·dm^-2, concentration of sulphuric acid 1 mol·L^-1, passed charge 3.2 A·h, the yield and current efficiency of benzoquinone could reach 68% and …

Continuous Electroextraction And Concentration Technology, Qiong Ren, Wen Liao, Zu-Cheng Wu

Journal of Electrochemistry

Electrodeionization process combined electrodialysis with ion exchange provides a method to produce pure water and ultrapure water due to the ions accumulated in the resin instantaneously to reduce the system resistance. Meanwhile, large numbers of hydrogen ions and hydroxyl ions are dissociated by water hydrolysis, thus, the ion exchange resins are in-situ regenerated electrochemically. This technology has been utilized to retrieve useful ions which are enriched in the concentrated compartment from a dilute solution. This hybrid process is consequently developed as a new type of extraction and concentration technology and has been gradually employed in the recoveries of heavy metals, …

Experimental Design Methodology Applied To The Oxidation Of Quinolines In Aqueous Medium By Electro-Fenton Process, Souhaila Trabelsi Souissi, Nihal Oturan, Nizar Bellakhal, Mehmet A. Oturan

Journal of Electrochemistry

The degradation behavior of 8-hydroxyquinoleine sulfate (8-HQS), a model molecule of quinolines, was studied in an aqueous medium by electro-Fenton process using a carbon felt cathode and a platinum anode. The great oxidation ability of this process is due to a large production of hydroxyl radical (OH) by electrochemically induced Fenton’s reagent (H₂O₂, Fe²⁺). Hydroxyl radicals are very powerful oxidizing agents which react on organics up to complete mineralization. A factorial experimental design was used for determining the operating parameters on the degradation of 8-HQS in an aqueous medium. The results showed that the …

Basic Principles And Applications Of Secm In Metal Corrosion, Fa-He Cao, Yan Xia, Wen-Juan Liu, Lin-Rong Chang, Jian-Qing Zhang

Journal of Electrochemistry

Scanning electrochemical microscopy (SECM) is chemical microscopy with higher spatial resolution. After 24 years of development, SECM has been widely applied in mapping and kinetics study of heterogeneous electron transfer in localized processes at solid-liquid or liquid-liquid interfaces. The fundamentals and recent advances of SECM in corrosion applications are described, including SECM mapping and kinetics on localized corrosion of metal or coating. Research work of SECM in corrosion by our group is also introduced. Future applications of SECM in corrosion are highlighted.

Applications Of Spectroscopic Ellipsometry In Corrosion Investigation, Ling-Jie Li, Yu-Ling He, Jing-Lei Lei, Sheng Tao Zhang

Journal of Electrochemistry

As a highly-sensitive and non-destructive in situ technique, spectroscopic ellipsometry has been widely applied in corrosion investigation to acquire the dynamic information of the “electrode-medium” interface during corrosion. This paper lays out some representative demonstrations in several established optical models used to interpret data obtained with spectroscopic ellipsometry in corrosion investigation. In addition, the latest trends in development of this technique are analyzed.

An Investigation Of Thin Films Formed On Zinc By Spectroscopic Ellipsometry, Juan Zuo, Ying Chen, Chang-Jian Lin, Andreas Erbe

Journal of Electrochemistry

The formation of natural oxide films on polycrystalline zinc surface, the growth of natural oxide films in different atmospheres, as well as the electrochemical process of metal zinc in alkaline carbonate solution, studied recently by using spectroscopic ellipsometry in our group, are introduced. The objective of this paper is to outline that the optical, electrical properties, the change and growth kinetics of zinc metal oxide film on the surface can be investigated by in-situ and ex-situ ellipsometry, which makes significant sense to evaluate the overall performance of zinc oxide layer.

Corrosion Behavior Of A High Strength Low Alloy Steel Under Hydrostatic Pressure In Deep Ocean, Hai-Jing Sun, Li Liu, Ying Li

Journal of Electrochemistry

The corrosion behavior of a high strength low alloy steel (HSLA steel) in 3.5% NaCl solution under hydrostatic pressure (HP) in deep ocean has been investigated by performing weight loss measurement, obtaining potentiodynamic polarization curve and emplying electrochemical impedance spectroscopy (EIS) using the set up for simulation of deep sea environment in laboratory. The results were compared with that at atmospheric pressure and the influence of HP was emphatically discussed. The results revealed identical corrosion mechanism for HSLA steel at 3.5 × 10⁶ Pa and 1 × 10⁵ Pa. Howevere, the development of such a corrosion process was …

Corrosion Resistance Of Low Pressure Cold Sprayed Al Coating On Q235 Steel In Seawater, Xiang-Bo Li, Li-Kun Xu, Shan-Guang Qiu, Jia Wang, Guo-Sheng Huang, Cai-Chang Dong

Journal of Electrochemistry

Taking aluminium (Al) powder mixed with 10% (by volume) of Al₂O₃ powder as raw materials, the Al coating was prepared on the Q235 carbon steel substrate using a portable low pressure cold spraying equipment. Through the measurements of the corrosion potential and potentiodynamic polarization, the electrochemical corrosion behavior of the low pressure cold sprayed Al coating in seawater was studied in comparison with those of the Al coatings deposited with high pressure cold spray and thermal spray processes. At the same time, the surface and cross-section morphologies of these coatings were observed with scanning electron microscope. The …

Corrosion Behavior Of Zinc Covered With Thin Electrolyte Layers Under External Electric Field, Xu-Jie Yuan, Jun-Xi Zhang, Shi-Ming Zhang, Tian Tan, Qi-Meng Chen

Journal of Electrochemistry

The corrosion behavior of zinc covered with thin electrolyte layers (TELs) under an application of external electric field was investigated by performing corrosion potential and cathodic polarization current measurements. The results showed that the Ecorr and ic values first increased and then decreased with the increase of electrolyte layer thickness. Pure zinc exhibited the maximum corrosion potential as the TELs increased to 400 μm under the controls of cathodic process and corrosion products. The application of external electric field resulted in either a negative shift in corrosion potential of zinc or an increase of cathodic current. The effect of external …

Investigating Intermolecular Interactions In Crystalline Aspirin Using Cdft, Nicholas Turner, Tonglei Li, Mingtao Zhang

The Summer Undergraduate Research Fellowship (SURF) Symposium

Drugs today are widely administered in their crystalline form, namely via tablets and capsules. The crystal structure of a drug molecule affects important drug qualities such as solubility, bioavailability, shelf life, and compaction properties. In order to form a basis for crystal structure prediction, it is necessary to first understand how intermolecular interactions cause molecules to pack in certain ways. Being able to predict and perhaps even control a drug molecule’s crystal structure will lead to the development of higher quality drugs that perform more consistently. Scientists and engineers do not fully understand the reasons for a molecule assuming a …

Investigation Of Major Intermolecular Interactions In 7,8-Dihydrobenzo(K)Phenanthridin-6(5h)-One Crystal Using Quantum Calculations And Crystallographic Visualization Programs, Zhiwei Liao, Tonglei Li, Mingtao Zhang

The Summer Undergraduate Research Fellowship (SURF) Symposium

Currently, tablets and capsules are the most common ways of delivering drugs. The active pharmaceutical ingredients and excipients used to make those tablets and capsules are in their crystalline form generally. However, a single molecule can form multiple different crystal structures because of different packing arrangements of the molecules. These different crystal structures have identical chemical composition but different properties such as solubility, density, stability, etc. This phenomenon is called polymorphism. Occurrence of polymorphism could be a disaster for both patients and pharmaceutical companies, as the drug could lose its efficacy due to changes in properties. Studying intermolecular interactions in …

Construction And Demonstration Of A Tandem Mass Spectrometer Based Instrument For Cold Ion Spectroscopy, James Gerhardt Redwine

Open Access Dissertations

A new instrument incorporating ion trap based tandem mass spectrometry and cold ion UV and UV-IR double resonance spectroscopy has been developed at Purdue University for the study of gas phase, biologically relevant ions. The instrument incorporates multiple quadrupole linear ion trap mass analyzers to prepare and isolate the precursor ions as well as to analyze the resultant photofragments. A 22-pole ion trap cooled to 5 K via a closed cycle helium cryostat is used to cool the ions for spectroscopic interrogation. Results show the vibrational and rotational temperature of a wide assortment of ions to be 12±2 K.

The …

Gas-Phase Covalent And Non-Covalent Ion/Ion Chemistry Of Biological Macromolecules, John Robert Stutzman

Open Access Dissertations

Gas-phase ion/ion chemistry involves the interaction of oppositely charged ions inside of the mass spectrometer. During this gas-phase chemistry, particle transfer (i.e., proton and electron) or synthesis can occur at rapid reaction rates. Particle transfer represents a mature area of ion/ion chemistry, while selective covalent modification represents a fairly new area of gas-phase chemistry. Gas-phase covalent chemistry is based on traditional solution phase organic chemistry.

The work demonstrated in this dissertation greatly involves gas-phase covalent and non-covalent Schiff base chemistry on peptide and protein ions. The reagent dianion, 4-formyl 1,3-benzene disulfonic acid, has been used to covalently modify unprotonated primary …

Spectroscopic Characterization Of The Water-Oxidation Intermediates In The Ru-Based Catalysts For Artificial Photosynthesis, Dooshaye Moonshiram

Open Access Dissertations

Utilization of sunlight requires solar capture, light-to-energy conversion and storage. One effective way to store energy is to convert it into chemical energy by fuel-forming reactions, such as water splitting into hydrogen and oxygen. Ruthenium complexes are among few molecular-defined catalysts capable of water splitting. Insight into the mechanism of their action will help to design future robust and economically feasible catalysts for light-to-energy conversion. Mechanistic insights about the design of such catalysts can be acquired through spectroscopic analysis of short-lived intermediates of catalytic water oxidation. Development of time-resolved approaches through stopped flow UV-Vis Spectroscopy to follow the catalysis of …

Conversion Of Iodide To Hypoiodous Acid And Iodine In Aqueous Microdroplets Exposed To Ozone, Elizabeth A. Pillar, Marcelo I. Guzman, Jose M. Rodriguez

Chemistry Faculty Publications

Halides are incorporated into aerosol sea spray, where they start the catalytic destruction of ozone (O₃) over the oceans and affect the global troposphere. Two intriguing environmental problems undergoing continuous research are (1) to understand how reactive gas phase molecular halogens are directly produced from inorganic halides exposed to O₃ and (2) to constrain the environmental factors that control this interfacial process. This paper presents a laboratory study of the reaction of O₃ at variable iodide (I^–) concentration (0.010–100 μM) for solutions aerosolized at 25 °C, which reveal remarkable differences in the reaction intermediates …

On The Origin Of Mode- And Bond-Selectivity In Vibrationally Mediated Reactions On Surfaces, Daniel Killelea, Arthur L. Utz

Chemistry: Faculty Publications and Other Works

The experimental observations of vibrational mode- and bond-selective chemistry at the gas–surface interface indicate that energy redistribution within the reaction complex is not statistical on the timescale of reaction. Such behavior is a key prerequisite for efforts to use selective vibrational excitation to control chemistry at the technologically important gas–surface interface. This paper outlines a framework for understanding the origin of non-statistical reactivity on surfaces. The model focuses on the kinetic competition between intramolecular vibrational energy redistribution (IVR) within the reaction complex, which in the long-time limit leads to statistical behavior, and quenching, scattering, or desorption processes that restrict the …

Development Of Novel Reaction-Based Fluorescent Probes, Weimin Xuan

Chemistry and Chemical Biology ETDs

Fluorescent probes have been proved to be very valuable tools in chemical and biological applications, and extensive exploration has been made. Recently, reaction-based fluorescent probes became a new design trend and displayed great potential with remarkable implementation to the conventional design method. However, this field is still underdeveloped, and a lot of problems remain to be solved. As part of our groups research interest, my Ph.D. study centered on the development of new reaction-based fluorescent probes. Firstly, our previous research on Hg²⁺ was continued. In this work, we developed a novel ratiometric fluorescent probe for Hg²⁺ with impressive …

Antimicrobial Activity And Mechanistic Study For The Poly(Phenylene Ethynylene) (Ppe)-Based Cationic Conjugated Polyelectrolytes And Oligo-Phenylene Ethynylenes, Ying Wang

Chemistry and Chemical Biology ETDs

My dissertation work focuses on recent progress made in elucidating the intermolecular interactions between a novel class of synthetic phenylene ethynylene (PPE)-based conjugated polyelectrolyte polymers (CPEs) and oligomers (OPEs) and multiscale cellular targets that give rise to their remarkable broad spectrum biocidal activity. We studied the interactions and self-assembly behaviors of the CPEs and OPEs with a set of vital biomolecules, including lipids, proteins and nucleic acids, that reveal the potential pathways by which the synthetic biocidal agents could exert toxicity. Then, we explored the antimicrobial effects and mechanisms of the CPEs and OPEs on multiple clinically relevant pathogens, with …

Structure, Theoretical Studies And Coupling Reactions Of Some New Cyclic Boronic Esters, Andrew Kuttler, Sravanthi Durganala, Albert Fratini, Alexander Morgan, Vladimir Benin

Chemistry Faculty Publications

The present report describes the X-ray structural and theoretical studies of some new pinacolboronate esters, and it also outlines the use of the target structures in Suzuki coupling reactions to produce new aromatic or heteroaromatic esters and amides. X-ray structural analysis of the studied compounds revealed that the pinacolborane ring's position with respect to the benzene ring varies, depending on the particular environment. An ortho-positioned carboxylic ester (methyl ester) causes a nearly perpendicular orientation of the pinacolborane unit with respect to the benzene ring, whereas an ortho-positioned amide (N,N-dimethylamide) causes the pinacolborane unit to orient itself nearly coplanar. A plausible …

Electrosynthesis Of Glycerol Carbonate From Co2 And Glycerol, Huan Wang, Mei-Xia Zhu, La-Xia Wu, Xiao-Ming Xu, Xue-Ru Zhao, Jia-Xing Lu

Journal of Electrochemistry

Glycerol carbonate was obtained from glycerol and carbon dioxide under room temperature and normal pressure by electrochemical method. The effects of synthesis conditions, such as cathode, charge, current density and temperature, on the reaction of glycerol and carbon dioxide have been investigated. The yields of 73% were produced by electrosynthesis of carbonate under the optimized condition, which is much higher than that by common catalysis method. The electrochemical behavior of the reaction system has been studied by cyclic voltammetry, through which the reaction process has been proposed.

Influence Of Pretreatment On Electrocatalytic Property For Methanol Oxidation Of Ptru/Wc, Xiao-Ling Lang, Mei-Qin Shi, Ye-Kun Jiang, Chun-An Ma

Journal of Electrochemistry

The surface of tungsten carbide (WC) was treated by potassium hydroxide (KOH) at different pH values for different time. The PtRu/WC composite was prepared by microwave-assisted polyol method. The phase structure of PtRu/WC composites were characterized by XRD. The electrocatalytic activity was tested by cyclic voltammetry and chronoamperometry. The results indicated that with different pH treatments WC became more readily supported on PtRu. When treating WC in KOH at pH = 14, PtRu exhibited the best degree of crystallinity on WC surface, leading to the highest electrocatalytic activity of PtRu/WC. Moreover, the optimized activity of PtRu/WC towards methanol oxidation was …

Synthesis And Electrochemical Properties Of Li(Ni0.5Co0.2Mn0.3)1-2xTiXNbXO2, Yong Tang, Qin-Lin Liao, Xiang-An Guo

Journal of Electrochemistry

The cathode-active materials of layered Li(Ni_0.5Co_0.2Mn_0.3)_1-2xTi_xNb_xO₂（x=0, 0.002, 0.005, 0.01, 0.02）composites were synthesized by the thermal treatment of the coprecipitated precursor at 900 ^oC in air. The effects of Ti-Nb co-dopants on the structural and electrochemical properties of Li(Ni_0.5Co_0.2Mn_0.3)O₂ were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and electrochemical experiments. The results show that the small amounts of Ti-Nb co-dopants in Li(Ni_0.5Co_0.2Mn_0.3)O₂significantly decreased the degree of cation mixing in …

Effects Of Fluoroethylene Carbonate Additive On Low Temperature Performance Of Li-Ion Batteries, Feng-Ju Bian, Zhong-Ru Zhang, Yong Yang

Journal of Electrochemistry

The effects of fluoroethylene carbonate (FEC) on the low temperature performance of lithium ion phosphate full battery are evaluated by different techniques. By addition of 5 wt% FEC into a commercial electrolyte, effective solid electrolyte interface (SEI) film can be formed on the graphite electrodes, the discharge capacity retention at -40 ^oC was increased from 31.7% to 43.7%, and the discharge voltage plateau of the cell is raised. This is attributed to a reduced charge transfer resistance and a lowered polarization on the graphite electrode by electrochemical impedance spectroscopy (EIS) and reference electrode test.