Cu(II) ion-imprinted polymer (IIP) was prepared by a surface molecular imprinting technique using Cu(II) as the template ion, aniline as the functional monomer, attapulgite (ATP) as the support and epichlorohydrin (ECH) as the cross-linking agent. In this study, the IIP was characterized using scanning electron microscope and Fourier transmission infrared spectrometry, and then the factors affecting adsorption were discussed. The selectivity and adsorption capacity for the Cu(II) ions on Cu(II) IIP were systematically studied. Under optimal conditions, the results of this study revealed that the IIP possesses a very strong adsorption and recognizing ability for the Cu(II) ions. The maximum adsorption capacity of IIP for Cu(II) was about 32.0 mg/g and its selectivity is twice that of a non-imprinted polymer. When the Cu(II)-polyaniline/ATP IIP was used repeatedly, its adsorption capacity remained constant.
Steam electrolyzers, utilizing molten hydroxide electrolyte, offer potential for improvement in electrochemical efficiency, cost reduction, use of conventional materials of construction and process scale up for large scale hydrogen production. Stainless steels, used for the fabrication of cell components (current collector, gas separator, wet seals, and manifolds) experience accelerated corrosion in the presence of molten hydroxide electrolyte in both oxidizing (anodic) and reducing (cathodic) atmospheres. In this study, the corrosion behavior of AISI 310 and 316 has been studied at 600 °C using melt immersion and cyclic voltammetry tests. Melt immersion test revealed formation of the porous lithium iron oxide at the melt-oxide interface for both AISI 310 and 316. Oxide scale cross-sectional study conducted by FIB/TEM showed multi-layer oxide scale formation. Inductively Coupled Plasma (ICP) Spectroscopy analysis showed the presence of Cr in the electrolyte melt obtained from samples exposed to oxidizing atmosphere. Cyclic voltammetry tests showed the breakdown of passive metal-oxide under anodic overpotential in molten hydroxide. Mechanisms for hydroxide-induced corrosion is proposed and discussed.
In this study polypyrrole (PPy) was synthesised chemically on the surface of attapulgite (ATP) to form nanocomposites using ATP as nucleus and PPy as shell. Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) showed that ATP was coated with a PPy layer. PPy/ATP nanocomposites as adsorbents were used to remove Cr(VI) from aqueous solutions. External factors were investigated, including contact time, adsorbent dose, initial concentration of adsorbate and pH. The experimental data are well fitted with the Langmuir isotherm model. The thermodynamic parameters were evaluated and the results revealed that the adsorption process was exothermic and spontaneous. The kinetic data indicated that the adsorption process followed a pseudo-second-order equation, implying that the adsorption process was predominantly controlled by chemical processes. The associated adsorption mechanism for Cr(VI) removal by the PPy/ATP nanocomposites was investigated using X-ray photoelectron spectroscopy (XPS), which suggests that ion change and reduction processes on the surface of the nanocomposites may be the possible mechanism.
Hydrogen production from water electrolysis is attractive due to its high efficiency, fast ramp rates, and high-pressure capability. However, current hydrogen production from electrolysis comprises only a small fraction of the global hydrogen market due to the high cost associated with expensive stack materials and electricity consumption. Currently commercial alkaline electrolyzers or proton exchange membrane electrolyzers operate at low temperatures. Intermediate or high temperature can effectively boost electrode kinetics and lower cell over-potential, thus improving the efficiency of water electrolysis. In this regards, Giner has developed a high-temperature alkaline water electrolysis (HTAWE), which employs lithium, sodium, or potassium hydroxides impregnated into a porous alumina or zirconia matrix [1]. The operating temperature can vary from 350 to 550 °C, depending on the category and ratio of binary or ternary electrolytes. In this work, both aluminate and zirconia-based matrix metal oxides were used as the matrix support materials. Thin aluminate and zirconia based matrices were fabricated using the tape casting method. Precious or non-precious electrodes (e.g. Ir, Ni, Co-based) were optimized using a solvent-based slurry formulation process. Green sheet electrodes with a variety of thicknesses were developed using a doctor blade approach. Design of experimental techniques were applied to optimize the ceramic membrane properties and to select hydrogen evolution reaction (HER)/oxygen evolution reaction (OER) catalysts. The impact of various catalyst and electrode designs on the HTAWE will be evaluated. Polarization curves and long-term durability will be demonstrated at variety of temperatures. Hot-corrosion mitigation strategies will also be discussed to extend the lifetime of HTAWE cells in this work. References Hui Xu and Kailash Patil, “High Temperature Alkaline Water Electrolysis,” presented at the 2018 DOE Annual Merit Review and Peer Evaluation Meeting, Washington, DC, June 2018. Acknowledgement: The project is financially supported by the Department of Energy’s Fuel Cell Technology Office under the Grant DE-EE0007644
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