The Experts below are selected from a list of 87 Experts worldwide ranked by ideXlab platform
Stephen Maldonado - One of the best experts on this subject based on the ideXlab platform.
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electrochemically gated alloy formation of crystalline inas thin films at room temperature in aqueous electrolytes
Chemistry of Materials, 2014Co-Authors: Eli Fahrenkrug, Stephen MaldonadoAbstract:Crystalline InAs films have been prepared directly at room temperature through a new electrochemically induced alloying method by controllably reducing As2O3 dissolved in an alkaline aqueous solution at an indium (In) foil electrode. Steady-state Raman spectra, transmission electron microscopy, and selected area electron diffraction indicated that the as-prepared films crystallize in the zincblende phase with no further thermal treatments. Cyclic voltammetry measurements, optical images, and steady-state Raman spectra confirmed that a clean Oxide-free interface is critical for the successful formation of the binary InAs phase. The salient feature of this work is the use of simple aqueous electrochemistry to simultaneously remove passive metal Oxides from the In(s) metal surface while controllably reducing dissolved Arsenic Oxide at the interface to drive the In–As alloying reaction. Raman spectral mapping data illustrate that the resulting film coverage and homogeneity are a strong function of the formal ...
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Electrochemically Gated Alloy Formation of Crystalline InAs Thin Films at Room Temperature in Aqueous Electrolytes
2014Co-Authors: Eli Fahrenkrug, Stephen MaldonadoAbstract:Crystalline InAs films have been prepared directly at room temperature through a new electrochemically induced alloying method by controllably reducing As2O3 dissolved in an alkaline aqueous solution at an indium (In) foil electrode. Steady-state Raman spectra, transmission electron microscopy, and selected area electron diffraction indicated that the as-prepared films crystallize in the zincblende phase with no further thermal treatments. Cyclic voltammetry measurements, optical images, and steady-state Raman spectra confirmed that a clean Oxide-free interface is critical for the successful formation of the binary InAs phase. The salient feature of this work is the use of simple aqueous electrochemistry to simultaneously remove passive metal Oxides from the In(s) metal surface while controllably reducing dissolved Arsenic Oxide at the interface to drive the In–As alloying reaction. Raman spectral mapping data illustrate that the resulting film coverage and homogeneity are a strong function of the formal As2O3 concentration and the duration of the electrodeposition experiment. Potential-dependent in situ Raman spectroscopy was used to implicate the solid-state reaction as the rate-limiting step in InAs film formation over the first 160 min, after which solid-state diffusion dominated the kinetics. The collective results establish a precedent for an alternative synthetic strategy for crystalline InAs thin films that does not require vacuum or sophisticated furnaces, toxic gaseous precursors like arsine, or exotic solvents
Alla Marchuk - One of the best experts on this subject based on the ideXlab platform.
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inorganic Arsenic species removal from water using bone char a detailed study on adsorption kinetic and isotherm models using error functions analysis
Journal of Hazardous Materials, 2020Co-Authors: Susan S.a. Alkurdi, Jochen Bundschuh, Les Bowtell, Raed A Aljuboori, Alla MarchukAbstract:Abstract The removal of inorganic Arsenic (As) species from water using bone char pyrolyzed at 900 °C was investigated. Results revealed that the Sips model resulted in the best As(III) experimental data fit, while As(V) data was best represented by the Langmuir model. The adsorption rate and mechanisms of both As species were investigated using kinetic and diffusional models, respectively. At low As(III) and As(V) concentrations of 0.5 and 2.5 mg/L, the removal was due to intra-particle interactions and pore diffusion following Pseudo-first-order kinetics. However, at higher concentrations of 5 and 10 mg/L, the pore diffusion mechanism was ineffective, and the adsorption was best described by Pseudo-second-order and Elovich models. The goodness of the fit of linearized and nonlinear forms of all models against experimental data was tested using thorough error function analysis. Nonlinear regressions produced lower error values, so they were utilized to calculate the parameters of the models. The changes in bone char surface chemistry were examined using FTIR and Energy-dispersive X-ray spectroscopy (EDS). Arsenic Oxide and complexes with metals were the confirmed immobilized forms of As on the bone-char surface. To the authors’ knowledge, this study is the first attempt at As(III) adsorption analysis using bone char.
Eli Fahrenkrug - One of the best experts on this subject based on the ideXlab platform.
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electrochemically gated alloy formation of crystalline inas thin films at room temperature in aqueous electrolytes
Chemistry of Materials, 2014Co-Authors: Eli Fahrenkrug, Stephen MaldonadoAbstract:Crystalline InAs films have been prepared directly at room temperature through a new electrochemically induced alloying method by controllably reducing As2O3 dissolved in an alkaline aqueous solution at an indium (In) foil electrode. Steady-state Raman spectra, transmission electron microscopy, and selected area electron diffraction indicated that the as-prepared films crystallize in the zincblende phase with no further thermal treatments. Cyclic voltammetry measurements, optical images, and steady-state Raman spectra confirmed that a clean Oxide-free interface is critical for the successful formation of the binary InAs phase. The salient feature of this work is the use of simple aqueous electrochemistry to simultaneously remove passive metal Oxides from the In(s) metal surface while controllably reducing dissolved Arsenic Oxide at the interface to drive the In–As alloying reaction. Raman spectral mapping data illustrate that the resulting film coverage and homogeneity are a strong function of the formal ...
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Electrochemically Gated Alloy Formation of Crystalline InAs Thin Films at Room Temperature in Aqueous Electrolytes
2014Co-Authors: Eli Fahrenkrug, Stephen MaldonadoAbstract:Crystalline InAs films have been prepared directly at room temperature through a new electrochemically induced alloying method by controllably reducing As2O3 dissolved in an alkaline aqueous solution at an indium (In) foil electrode. Steady-state Raman spectra, transmission electron microscopy, and selected area electron diffraction indicated that the as-prepared films crystallize in the zincblende phase with no further thermal treatments. Cyclic voltammetry measurements, optical images, and steady-state Raman spectra confirmed that a clean Oxide-free interface is critical for the successful formation of the binary InAs phase. The salient feature of this work is the use of simple aqueous electrochemistry to simultaneously remove passive metal Oxides from the In(s) metal surface while controllably reducing dissolved Arsenic Oxide at the interface to drive the In–As alloying reaction. Raman spectral mapping data illustrate that the resulting film coverage and homogeneity are a strong function of the formal As2O3 concentration and the duration of the electrodeposition experiment. Potential-dependent in situ Raman spectroscopy was used to implicate the solid-state reaction as the rate-limiting step in InAs film formation over the first 160 min, after which solid-state diffusion dominated the kinetics. The collective results establish a precedent for an alternative synthetic strategy for crystalline InAs thin films that does not require vacuum or sophisticated furnaces, toxic gaseous precursors like arsine, or exotic solvents
Susan S.a. Alkurdi - One of the best experts on this subject based on the ideXlab platform.
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inorganic Arsenic species removal from water using bone char a detailed study on adsorption kinetic and isotherm models using error functions analysis
Journal of Hazardous Materials, 2020Co-Authors: Susan S.a. Alkurdi, Jochen Bundschuh, Les Bowtell, Raed A Aljuboori, Alla MarchukAbstract:Abstract The removal of inorganic Arsenic (As) species from water using bone char pyrolyzed at 900 °C was investigated. Results revealed that the Sips model resulted in the best As(III) experimental data fit, while As(V) data was best represented by the Langmuir model. The adsorption rate and mechanisms of both As species were investigated using kinetic and diffusional models, respectively. At low As(III) and As(V) concentrations of 0.5 and 2.5 mg/L, the removal was due to intra-particle interactions and pore diffusion following Pseudo-first-order kinetics. However, at higher concentrations of 5 and 10 mg/L, the pore diffusion mechanism was ineffective, and the adsorption was best described by Pseudo-second-order and Elovich models. The goodness of the fit of linearized and nonlinear forms of all models against experimental data was tested using thorough error function analysis. Nonlinear regressions produced lower error values, so they were utilized to calculate the parameters of the models. The changes in bone char surface chemistry were examined using FTIR and Energy-dispersive X-ray spectroscopy (EDS). Arsenic Oxide and complexes with metals were the confirmed immobilized forms of As on the bone-char surface. To the authors’ knowledge, this study is the first attempt at As(III) adsorption analysis using bone char.
Mohammad N M Ahmad - One of the best experts on this subject based on the ideXlab platform.
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Arsenic iii v adsorption onto charred dolomite charring optimization and batch studies
Chemical Engineering Journal, 2015Co-Authors: Yousef Salameh, Ahmad B Albadarin, S J Allen, Gavin Walker, Mohammad N M AhmadAbstract:Abstract In this work, the removal of Arsenic from aqueous solutions onto thermally processed dolomite is investigated. The dolomite was thermally processed (charred) at temperatures of 600, 700 and 800 °C for 1, 2, 4 and 8 h. Isotherm experiments were carried out on these samples over a wide pH range. A complete Arsenic removal was achieved over the pH range studied when using the 800 °C charred dolomite. However, at this temperature, thermal degradation of the dolomite weakens its structure due to the decomposition of the magnesium carbonate, leading to a partial dissolution. For this reason, the dolomitic sorbent chosen for further investigations was the 8 h at 700 °C material. Isotherm studies indicated that the Langmuir model was successful in describing the process to a better extent than the Freundlich model for the As(V) adsorption on the selected charred dolomite. However, for the As(III) adsorption, the Freundlich model was more successful in describing the process. The maximum adsorption capacities of charred dolomite for arsenite and arsenate ions are 1.846 and 2.157 mg/g, respectively. It was found that both the pseudo first- and second-order kinetic models are able to describe the experimental data (R2 > 0.980). The data suggest the charring process allows dissociation of the dolomite to calcium carbonate and magnesium Oxide, which accelerates the process of Arsenic Oxide and Arsenic carbonate precipitation.