Papers by Patrick Rodgers
Corrosion Control of Rod Pumped Wells in Varied Carbon Dioxide Environments using Batch Treatment
Corrosion, 2017
Corrosion Control of Rod Pumped Wells in Varied Carbon Dioxide Environments using Batch Treatment
Corrosion, 2017
A New Top-of-the-Line Corrosion Inhibitor to Mitigate Carbon Dioxide Corrosion in Wet Gas Systems
Corrosion, 2013
Broad Shear-Range Corrosion Inhibitor Development for Oil and Gas Facilities at Cold Temperatures

Multifunctional Chemical for Simultaneous Dissolution of Iron Sulfide, Corrosion Inhibition, and Scale Inhibition
SPE International Conference on Oilfield Chemistry, 2019
Operators producing hydrocarbons from conventional and unconventional wells often encounter inter... more Operators producing hydrocarbons from conventional and unconventional wells often encounter interconnected production-related challenges that exacerbate one another. Challenges during production include the corrosion of steel caused by acid gases, as well as the precipitation and accumulation of iron sulfide, calcium carbonate scale, and barium sulfate scale. The accumulation of solids on pipe walls can facilitate under-deposit corrosion and plugging. Each of these issues can lead to failures and costly workovers. To address these issues, current treatment approaches require multiple chemical applications, frequent batch treatments, mechanical intervention, or a combination of approaches. In certain scenarios, these approaches can be impractical, ineffective, and/or uneconomical. The objective of this study was to develop a solution to overcome the aforementioned production challenges simultaneously and continuously with a single chemical application. The design strategy was to form...

Recognition and transport of important species at the membrane of a biological cell are critical ... more Recognition and transport of important species at the membrane of a biological cell are critical for regulation of intracellular communication, metabolic pathways, vital internal conditions, and pharmaceutical drug uptake. Both processes are mediated by membrane-bound proteins functioning as pores, channels, and transporters that recognize and facilitate the transport of ions, nucleic acids and sugars. This whole process can be driven actively by membrane potential against the concentration gradient of transported species. In my PhD work, I fundamentally characterized dynamics of active ion transport, both in the presence and absence of recognition events, at liquid/liquid interfaces to understand electrochemically-controlled interfacial ion recognition and transfer. A deeper understanding of the kinetic and thermodynamic properties is achieved to realize applications in biomedical and environmental science, sensor technology and nanotechnology. The interface between two immiscible solutions served as an artificial model of a cell membrane. By manipulation of the interfacial potential, the active transport of ionic species was mimicked, which was monitored by an ionic current. Micrometer and nanometer sized interfaces were formed experimentally at the orifice of micropipets and nanopipets to probe ion-transfer reactions. Micropipet/nanopipet voltammetry was advanced to accurately obtain quantitative kinetic and thermodynamic parameters through numerical simulations of ion transfer and diffusion. Ion transfer rates for reversible and

Recognition and transport of important species at the membrane of a biological cell are critical ... more Recognition and transport of important species at the membrane of a biological cell are critical for regulation of intracellular communication, metabolic pathways, vital internal conditions, and pharmaceutical drug uptake. Both processes are mediated by membrane-bound proteins functioning as pores, channels, and transporters that recognize and facilitate the transport of ions, nucleic acids and sugars. This whole process can be driven actively by membrane potential against the concentration gradient of transported species. In my PhD work, I fundamentally characterized dynamics of active ion transport, both in the presence and absence of recognition events, at liquid/liquid interfaces to understand electrochemically-controlled interfacial ion recognition and transfer. A deeper understanding of the kinetic and thermodynamic properties is achieved to realize applications in biomedical and environmental science, sensor technology and nanotechnology. The interface between two immiscible solutions served as an artificial model of a cell membrane. By manipulation of the interfacial potential, the active transport of ionic species was mimicked, which was monitored by an ionic current. Micrometer and nanometer sized interfaces were formed experimentally at the orifice of micropipets and nanopipets to probe ion-transfer reactions. Micropipet/nanopipet voltammetry was advanced to accurately obtain quantitative kinetic and thermodynamic parameters through numerical simulations of ion transfer and diffusion. Ion transfer rates for reversible and

Journal of the American Chemical Society, 2008
Electrochemically controlled molecular recognition of a synthetic heparin mimetic, Arixtra, at ni... more Electrochemically controlled molecular recognition of a synthetic heparin mimetic, Arixtra, at nitrobenzene/water microinterfaces was investigated to obtain a greater understanding of interfacial recognition and sensing of heparin and its analogues with biomedical importance. In contrast to unfractionated heparin, this synthetic pentasaccharide that mimics the unique Antithrombin III binding domain of heparin possesses well-defined structure and ionic charge to enable quantitative interpretation of cyclic voltammetric/chronoamperometric responses based on the interfacial recognition at micropipet electrodes. Arixtra is electrochemically extracted from the water phase into the bulk nitrobenzene phase containing highly lipophilic ionophores, methyltridodecylammonium or dimethyldioctadecylammonium. Numerical analysis of the kinetically controlled cyclic voltammograms demonstrates for the first time that formal potentials and standard rate constants of polyion transfer at liquid/liquid interfaces are ionophore dependent. Moreover, octadecylammonium and octadecylguanidinium are introduced as new, simple ionophores to model recognition sites of heparin-binding proteins at liquid/liquid interfaces. In comparison to octadecyltrimethylammonium, the best ionophore for heparin recognition at liquid/liquid interfaces reported so far, these new ionophores dramatically facilitate Arixtra adsorption at the interfaces. With a saline solution at physiological pH, an Arixtra molecule is selectively and cooperatively bound to 5 molecules of the guanidinium ionophore, suggesting hydrogen-bond-directed interactions of each guanidinium with a few of 10 negatively charged sulfo or carboxyl groups of Arixtra at the interfaces.

Journal of the American Chemical Society, 2009
Here we report on remarkably high lipophilicity of perfluoroalkyl carboxylate and sulfonate. A li... more Here we report on remarkably high lipophilicity of perfluoroalkyl carboxylate and sulfonate. A lipophilic nature of this emerging class of organic pollutants has been hypothesized as an origin of their bioaccumulation and toxicity. Both carboxylate and sulfonate, however, are considered hydrophilic while perfluroalkyl groups are not only hydrophobic but also oleophobic. Partition coefficients of homologous series of perfluoroalkyl and alkyl carboxylates between water and noctanol were determined as a measure of their lipophilicity by ion-transfer cyclic voltammetry. Very similar lipophilicity of perfluoroalkyl and alkyl chains with the same length is demonstrated experimentally for the first time by fragment analysis of the partition coefficients. This finding is important for pharmaceutical and biomedical applications of perfluoroalkyl compounds. Interestingly, ∼2 orders of magnitude higher lipophilicity of a perfluoroalkyl carboxylate or sulfonate in comparison to its alkyl counterpart is ascribed nearly exclusively to their oxoanion groups. The higher lipophilicity originates from a strong electron-withdrawing effect of the perfluoroalkyl group on the adjacent oxoanion group, which is weakly hydrated to decrease its hydrophilicity. In fact, the inductive effect is dramatically reduced for a fluorotelomer with an ethylene spacer between perfluorohexyl and carboxylate groups, which is only as lipophilic as its alkyl counterpart, nonanoate, and is 400 times less lipophilic than perfluorononanoate. The high lipophilicity of perfluoroalkyl carboxylate and sulfonate implies that their permeation across such a thin lipophilic membrane as a bilayer lipid membrane is limited by their transfer at a membrane/water interface. The limiting permeability is lower and less dependent on their lipophilicity than the permeability controlled by their diffusion in the membrane interior as assumed in the classical solubility-diffusion model.
Analytical Chemistry, 2007
Model. The geometry of a micropipet electrode is defined in cylindrical coordinates, where r and ... more Model. The geometry of a micropipet electrode is defined in cylindrical coordinates, where r and z are the coordinates in directions parallel and normal to the interface, respectively (Figure 1). The inner and outer solutions (phases 1 and 2, respectively) are denoted as phase 1 and 2. The pipet size is defined by the inner and outer tip radii, a and r g. The inner and outer tip angles are given by θ 1 and θ 2. The pipet shaft is long enough for semi-infinite diffusion in the inner solution on a simulation time scale. The space behind the tip in the outer solution is large enough to accurately simulate back diffusion from behind the tip. An ion with the charge z i , i i z , is initially present only in the outer solution so that simple transfer of the ion is defined by

Analytical Chemistry, 2009
Subnanomolar limits of detection (LODs) are obtained for stripping voltammetry based on ion trans... more Subnanomolar limits of detection (LODs) are obtained for stripping voltammetry based on ion transfer at the interface between the aqueous sample and the thin polymeric membrane supported with a solid electrode. It has been predicted theoretically that a lower LOD can be obtained for a more lipophilic analyte ion, which can be preconcentrated at a higher equilibrium concentration in the solid-supported thin polymeric membrane to enhance a stripping current response. This study is the first to experimentally confirm the general theoretical prediction for both cationic and anionic analytes. Proof-of-concept experiments demonstrate that a subnanomolar LOD of (8 (4) × 10-11 M tetrapropylammonium is significantly lower than a LOD of less lipophilic tetraethylammonium. Importantly, stripping voltammetry of the cationic analytes is enabled by newly introducing an oxidatively doped poly(3,4-ethylenedioxythiophene) film as the intermediate layer between a plasticized poly(vinyl chloride) membrane and a Au electrode. On the other hand, an undoped poly(3-octylthiophene) film is used as an intermediate layer for voltammetric detection of a lipophilic inorganic anion, hexafluoroarsenate, an arsenical biocide found recently in wastewater. A LOD of (9 (2) × 10-11 M hexafluoroarsenate thus obtained by ion-transfer stripping voltammetry is comparable to a LOD of 80 pM by inductively coupled plasma mass spectrometry with anion-exchange chromatography. Great sensitivity for a lipophilic ion is potentially useful for environmental analysis because high lipophilicity of an ion is relevant to its bioaccumulation and toxicity.

Kinetic Study of Rapid Transfer of Tetraethylammonium at the 1,2-Dichloroethane/Water Interface by Nanopipet Voltammetry of Common Ions
Analytical Chemistry, 2010
Steady-state voltammetry at the pipet-supported liquid/liquid interface has previously been used ... more Steady-state voltammetry at the pipet-supported liquid/liquid interface has previously been used to measure kinetics of simple and facilitated ion transfer (IT) processes. Recently, we showed that the conventional experimental protocol and data analysis produce large uncertainties in kinetic parameters of rapid IT processes extracted from pipet voltammograms. Here, we used a new mode of nanopipet voltammetry, in which a transferable ion is initially present as a common ion in both liquid phases, and improved methodology for silanization of the outer pipet wall to investigate the kinetics of the rapid transfer of tetraethylammonium (TEA(+)) at the 1,2-dichloroethane/water interface. This reaction was often employed as a model system to check the IT theory. The determined standard rate constant and transfer coefficient of the TEA(+) transfer are compared with previously reported values to demonstrate limitations of conventional nanopipet voltammetry with a transferrable ion present only in one liquid phase.
Analytical Chemistry, 2010
Finite Element Simulation. CVs at nanopipet electrodes were simulated by the finite element metho... more Finite Element Simulation. CVs at nanopipet electrodes were simulated by the finite element method using the COMSOL Multiphysics software package as reported elsewhere. S1 A simulation report is attached. See ref S1 for definition of normalized parameters.
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Papers by Patrick Rodgers