Thermogravimetric Analysis of Huadian Oil Shale Combustion at Different Oxygen Concentrations

As the simplest conversion route, combustion is extensively applied to oil shale utilization. To improve oil shale conversion techniques, we used non-isothermal thermogravimetric analysis to explore the combustion reactivity and kinetics of Huadian oil shale at various oxygen concentrations (10, 20, 30, 50, 65, and 80 vol %) and heating rates (5, 10, and 20 °C min^–1). With an increase in oxygen concentration, the combustion performances of oil shale could be significantly improved; the volatile-releasing temperature, ignition temperature, and burnout temperature decreased; the mass loss rate increased; and the integrated combustion characteristics of oil shale were enhanced. These improvements were attenuated when the oxygen concentration exceeded 50 vol %. When the oxygen concentration increased from 10 to 80 vol %, the average activation energy in the second combustion stage increased from 46.85 to 117.98 kJ mol^–1 by the Kissinger–Akahira–Sunose method, from 46.85 to 117.98 kJ mol^–1 by the Starink method, from 59.08 to 129.17 kJ mol^–1 by the Friedman method, and from 36.34 to 57.58 kJ mol^–1 by the Coats–Redfern method at a heating rate of 20 °C min^–1. Results indicated oxygen enrichments beyond which additional enrichment yields significantly less enhancement to the combustion process

Amine functionalized mesocellular silica foam as highly efficient sorbents for CO2 capture

 A series of amine-functionalized CO2 sorbents were synthesized by grafting mono- and tri-amine substituted trialkoxysilanes on mesocellular siliceous foam (MCF) via a facile wet grafting method. The effect of amine type, amine loading level, and porous structure of silica on the CO2 adsorption performance was investigated. MCF silica with a three-dimensional (3D) interconnected porous structure was found to be suitable for preparing amine-grafted sorbents. Tested at 25 °C and 0.15 bar of CO2, the mono- and tri-amine grafted MCFs exhibited a fast adsorption rate and excellent CO2 adsorption capacity of 1.71 mmol/g for mono-amine and 2.07 mmol/g for tri-amine, which was much higher than amine grafted PQ and SBA-15 with a 2D porous structure, and the amine grafted silica sorbents prepared in previous studies. The large pore volume and pore size coupled with superior interconnectivity of MCF enable more surface silanol groups available and accessible for amino silanes, leading to a high amine loading level and excellent amine dispersion on the silica surface, which enhances both the CO2 adsorption capacity and adsorption rate of the developed sorbents. Cyclic adsorption–desorption tests confirmed the excellent stability of the amine grafted MCF. </p

Polymorph Control by Investigating the Effects of Solvent and Supersaturation on Clopidogrel Hydrogen Sulfate in Reactive Crystallization

Reactive crystallization and polymorphic transformation of clopidogrel hydrogen sulfate (CHS) in nine pure solvents were studied at 313.15 K. It is found that thermodynamically stable polymorphic form tends to be obtained in solvents with higher solubility of CHS and the conversion rates from form I to form II are also mainly increased with increasing solubility. The solvent hydrogen bond donor ability is essential for determining the solvent effects on solubility and polymorphic formation of CHS. Besides, the reactive crystallization of CHS at different supersaturations in 2-propanol and 2-butanol was monitored online by using ATR-FTIR and FBRM with a calibration-based approach. The results indicate the nucleation induction period is the kinetic-determining stage and supersaturation is a direct factor to determine the polymorphic formation of CHS: form II was obtained with <i>s</i> under 18 while form I was produced when <i>s</i> increases above 21

Determination and Correlation of Solubility of Quetiapine Fumarate in Nine Pure Solvents and Two Aqueous Binary Solvents

A gravimetric method was used to determine the solubility of quetiapine fumarate (QF) in nine pure solvents and two aqueous binary solvents (water + methanol/ethanol) at different temperatures from 283.15 to 323.15 K. The solubility of QF increases with the increase of temperature in nine pure solvents, and it is in the order DMF > methanol > ethanol >1-butanol > isopropyl alcohol > (acetone > ethyl acetate > isobutyl alcohol) > water at low temperature, and in the order DMF > methanol > ethanol >1-butanol > isopropyl alcohol > (acetone > isobutyl alcohol > ethyl acetate) > water at relatively high temperature at a given temperature. The solubility of QF in the binary solvents also shows temperature dependence, while at a given temperature the solubility is mainly influenced by the solvent composition with the presence of maximum, reflecting cosolvency. Also the solubility of QF increases with the increase of temperature in binary solvents in a given composition. The Hansen solubility parameters were used to explain the cosolvency and maxima shift, confirming that for large values (>25 MPa^1/2) of solute, the solubility shows a peak in the range of 35 to 31 MPa^1/2 of solubility parameters of alcohol mixtures. The experimental solubility of QF in pure and binary solvents is well correlated by modified Apelblat equation, the nonrandom two-liquid model, and the CNIBS/R-K equation, respectively

Solubility of Benzoin in Six Monosolvents and in Some Binary Solvent Mixtures at Various Temperatures

The solubility of benzoin in monosolvents (acetone, ethyl acetate, methanol, ethanol, 1-propanol, and 1-butanol) and binary solvent mixtures (ethyl acetate + methanol, ethyl acetate + ethanol) was measured using UV–vis spectroscopy at temperatures ranging from 283.15 K to 323.15 K. It can be seen from the data that the solubility of benzoin increases expectedly as temperature increases in a given solvent or solvent mixture, the solubility in acetone is maximum among six monosolvents which could be well explained by the existence of strong H-bonds, rather than the “like dissolves like” rule. In binary solvent mixtures, the solubility reaches maximum when the mole fraction of methanol is 0.1 in ethyl acetate + methanol mixed solvents, while the maximum exhibits at 0.2 of mole fraction of ethanol in ethyl acetate + ethanol. The solubility parameter was interpreted as the cosolvency of benzoin solubility in binary solvent mixtures. The solubility data were correlated by modified Apelbalt equation, CNIBS/R-K equation, λ<i>h</i> equation, Jouyban–Acree model, and Van’t–JA equation. Mixing thermodynamic properties were further calculated and discussed regarding their roles in dissolution and solubility

Highly Conductive and Robust Three-Dimensional Host with Excellent Alkali Metal Infiltration Boosts Ultrastable Lithium and Sodium Metal Anodes

The direct utilization of metallic lithium and sodium as the anodes for rechargeable batteries would be highly advantageous, which has been considered as one of the most promising choices for next-generation high-energy-density storage devices. Although the induced safety concerns, inferior rate, and cycling performance severely hinder the commercialization of lithium metal batteries (LMBs) and sodium metal batteries (SMBs), the recent development of nanotechnology-based solutions really revives the lithium/sodium metal anodes for high-energy batteries. In this work, an ultrastable carbon textile (CT)-based host with excellent infiltration for both metallic Li and Na has been designed and exhibits more flat voltage profiles, lower stripping/plating overpotential, and better cycling stability both in symmetric cell and full cell configurations, even in additive-free carbonate-based electrolyte compared with pure Li/Na electrodes. The highly conductive and mechanically robust three-dimensional CTs not only offer a stable scaffold against hyperactive lithium and sodium but also enable uniform nucleation and growth during stripping/plating process, which effectively suppress the dendrite growth and stabilize the electrode dimension. This facile strategy provides new insights into the design of stable hosts with prestored alkali metal to address the multifaceted issues in LMBs and SMBs simultaneously

Metabonomics Approach to Assessing the Metabolism Variation and Endoexogenous Metabolic Interaction of Ginsenosides in Cold Stress Rats

Metabolic profiling technology, a massive information provider, has promoted the understanding of the metabolism of multicomponent medicines and its interactions with endogenous metabolites, which was previously a challenge in clarification. In this study, an untargeted GC/MS-based approach was employed to investigate the urinary metabolite profile in rats with oral administration of ginsenosides and the control group. Significant changes of urinary metabolites contents were observed in the total ginsenosides group, revealing the impact of ginsenosides as indicated by the up- or down-regulation of several pathways involving neurotransmitter-related metabolites, tricarboxylic acid (TCA) cycle, fatty acids β-oxidation, and intestinal microflora metabolites. Meanwhile, a targeted UPLC-QQQ/MS-based metabonomic approach was developed to investigate the changes of urinary ginsenoside metabolites during the process of acute cold stress. Metabolic analysis indicated that upstream ginsenosides (rg1, re, and rf) increased significantly, whereas downstream ginsenosides (ck, ppd, and ppt) decreased correspondingly after cold exposure. Finally, the relationships between ginsenosides and significantly changed metabolites were investigated by correlation analysis

Toward a Mechanistic Understanding of Vertical Growth of van der Waals Stacked 2D Materials: A Multiscale Model and Experiments

Vertical stacking of monolayers <i>via</i> van der Waals (vdW) interaction opens promising routes toward engineering physical properties of two-dimensional (2D) materials and designing atomically thin devices. However, due to the lack of mechanistic understanding, challenges remain in the controlled fabrication of these structures <i>via</i> scalable methods such as chemical vapor deposition (CVD) onto substrates. In this paper, we develop a general multiscale model to describe the size evolution of 2D layers and predict the necessary growth conditions for vertical (initial + subsequent layers) <i>versus</i> in-plane lateral (monolayer) growth. An analytic thermodynamic criterion is established for subsequent layer growth that depends on the sizes of both layers, the vdW interaction energies, and the edge energy of 2D layers. Considering the time-dependent growth process, we find that temperature and adatom flux from vapor are the primary criteria affecting the self-assembled growth. The proposed model clearly demonstrates the distinct roles of thermodynamic and kinetic mechanisms governing the final structure. Our model agrees with experimental observations of various monolayer and bilayer transition metal dichalcogenides grown by CVD and provides a predictive framework to guide the fabrication of vertically stacked 2D materials

Measurement of Solubility of Thiamine Hydrochloride Hemihydrate in Three Binary Solvents and Mixing Properties of Solutions

Data on (solid + liquid) equilibrium of thiamine hydrochloride hemihydrate (HH) in {water + (ethanol, acetone, or 2-propanol)} solvents will provide essential support for industrial design and further theoretical studies. In this study the solid–liquid equilibrium (SLE) was experimentally measured over temperatures ranging from 278.15 to 313.15 K under atmospheric pressure by a dynamic method. For the temperature range investigated, the equilibrium solubility of thiamine hydrochloride hemihydrate (HH) varies with temperature and the composition of the solvents. The experimental solubility was regressed with different models including the modified Apelblat equation, λ<i>h</i> equation, as well as NRTL equation. All the models gave good agreements with the experimental results. On the basis of the solubility data of HH, the thermodynamic properties of mixing process of HH with mixed solvents were also discussed. The results indicate that the mixing process of HH is exothermic. Besides, the model outwardly like the Arrhenius equation was employed to quantitatively exhibit the relationship between solubility and solvents mixtures polarity of solvents mixtures

Seed-Assisted Effects on Solution-Mediated Phase Transformation: A Case Study of l‑Histidine in Antisolvent Crystallization

In this study, the effects of crystal nucleation–growth on subsequent solvent-mediated phase transformation experiments of l-histidine (l-his) in antisolvent crystallization were performed at 298.15 K. The unexpected acceleration of the overall transformation rate in antisolvent crystallization with solution-mediated phase transformation was found for a methanol volume fraction of 0.35 < <i>x</i>₂ < 0.60. Interestingly, concomitant polymorphs were obtained for a methanol volume fraction of 0.30 ⩽ <i>x</i>₂ ⩽ 0.65 in antisolvent crystallization, whereas only form B was observed for other volume fractions of methanol, which indicated that the concomitant polymorphic phenomenon was the main reason for the accelerated transformation rate in antisolvent crystallization. Furthermore, seed-assisted experiments and suspended solution-mediated phase transformation experiments were designed to uncover the role of the nucleation of form A accompanying with form B in the subsequent transformation process