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Elucidating nano and meso-structures of lignin carbon composites: A comprehensive study of feedstock and temperature dependence
Abstract not provided
Elucidation of reaction mechanism for m-cresol hydrodeoxygenation over Fe based catalysts: A kinetic study
Not Available
Reactions of SO2 on hydrated cement particle system for atmospheric pollution reduction: A DRIFTS and XANES study
Not Available
Combined Experimental and Modeling Study of Microwave-Assisted Methane Dehydroaromatization Process
ACS Fall Meeting 2022, Chicago, IL, August 21-25, 2022
Experimental and modeling study of calcium carbonate precipitation and its effects on the degradation of oil well cement during carbonated brine exposure
Decalcification of cement in solutions of carbonated brine is important to a host of engineering applications, especially in subsurface service environments where cementitious materials are frequently utilized as engineered barriers for wellbore seals, as well as shaft and drift seals and waste forms for nuclear waste disposal. Analysis of leaching simulations and experiments shows that, depending on solution compositions (dissolved CO{sub 2} concentration, pH, Ca ion concentration), calcite precipitation occurring during leaching of cement in contact with carbonated brine can have a significant impact on cement reactivity, in some instances leading to complete arrest of reactivity via calcium carbonate ''pore-clogging''. We present modeling and experimental results that examine the range of solution conditions that can lead to pore-clogging. Analysis of the results shows that distinct regimes of leaching behavior, based on pH and pCO2, can be used to form a framework to better understand the occurrence of pore-clogging.
New insights into the mechanism governing the elasticity of calcium silicate hydrate gels exposed to high temperature: A molecular dynamics study
When exposed to fire, the integrity of cement-based materials is governed by thermally-induced changes in the mechanical properties of their binding phase, i.e., the calcium–silicate–hydrate (C–S–H) gel. However, the effect of temperature on the structure, density, and mechanical properties of C–S–H remains only partially known. Here, based on reactive molecular dynamics simulations, we reveal the nature of thermally-induced damage in C–S–H gels. In general, we show that, at the atomic scale, exposure to high temperature results in partial dehydration, volumetric shrinkage, disordering, and stiffening in the C–S–H grains. However, we show that the thermal response of C–S–H strongly depends on its chemical composition, wherein C–S–H systems associated with lower Ca/Si molar ratios are able to undergo higher temperatures before amorphization. Based on these results, we demonstrate that the stiffness of C–S–H gels (i.e., including porosity—as probed by nanoindentation) is governed by a competition between the stiffening of the grains and the decrease in packing density—wherein the latter eventually become predominant.
Antimonate and arsenate speciation on reactive soil minerals studied by differential pair distribution function analysis
Not Available
A kinetic analysis of the transformation from akaganeite to hematite: An in situ time-resolved X-ray diffraction study
Not Available
Thermodynamic studies of zippeite, a uranyl sulfate common in mine wastes
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Lead and cadmium adsorption by electrospun PVA/PAA nanofibers: Batch, spectroscopic, and modeling study
Not Available