High-temperature Dehydration Research Articles

Competitive oxidation mechanism endows MXene-based supercapacitors with high-temperature tolerance and self-healing capability

MXenes emerge as promising candidates for supercapacitors due to their tunable surface chemistry and high conductivity. However, high temperatures can accelerate MXenes oxidation when exposed to air, limiting their application in supercapacitors for extreme environment operations that require high-temperature tolerance. In this work, we propose introducing bentonite nanosheets between Ti3CNTx MXene layers to suppress the high-temperature oxidation of Ti3CNTx films via a competitive oxidation mechanism, and develope a matched self-healing solid-state bentonite-based electrolyte capable of spontaneously restoring its ionic conductivity after high-temperature dehydration. The Ti3CNTx/bentonite films demonstrate exceptionally high thermal stability at temperatures of up to 600 °C when exposed to air. The solid-state supercapacitors assembled using Ti3CNTx/bentonite films and the bentonite-based electrolyte achieve a high areal capacitance of 22.8 mF cm-2 and demonstrate high-temperature tolerance, exhibiting the ability to self-heal and recover the charge storage performance even after multiple cycles of heating to 300 °C and air cooling. This work could pave the way for the application of MXenes in high-temperature tolerant and self-healing supercapacitors with enhanced longevity.

Geochemical Evidence of Water-Fluxed Crustal Melting in the Northern Colombian Andes

Abstract The compositions of crustal magmas are powerful tools for understanding the formation and differentiation of continents. However, the geochemical fingerprints that distinguish the two dominant mechanisms of crustal melting, namely dehydration and water-fluxed melting, are still controversial. To provide new insights into this problem, we discuss the petrogenesis of the Paipa Volcanic Complex (PVC), an isolated Quaternary volcanic field in the Colombian Eastern Cordillera. The PVC is characterized by peraluminous trondhjemite-like rhyolites with exceptionally high Na2O contents (~6 wt %), super-chondritic Nb/Ta (~27), elevated Sr/Y ratios (~120), spoon-shaped REE patterns, and enriched isotopic compositions that overlap with those of the local basement. They also exhibit high pre-eruptive H2O contents (~up to 9.5 wt %) and abundant Paleozoic zircon inheritances. We demonstrate that these characteristics are inconsistent with a process of intra-crustal differentiation from a mafic or intermediate mantle-derived precursor. Instead, we propose that the origin of the PVC is best explained by melting the local (meta)sedimentary basement under H2O-saturated conditions, at middle-crustal pressures (~1.3 GPa) and relatively low temperatures (~690–740°C), following the complete breakdown of plagioclase and biotite, and the formation of reactive peritectic amphibole. This scenario differs from the high-temperature dehydration melting conditions that have been widely proposed for the Andes and globally, which result in the production of water undersaturated magmas in equilibrium with anhydrous lithologies rich in plagioclase and/or garnet. Accordingly, we speculate that an external H2O flux was ultimately sourced from a buoyant, cold, and hydrated mantle wedge that was extensively metasomatized by fluids derived from the Nazca and Caribbean flat-slab fronts. These conditions depressed the asthenospheric mantle potential temperature, likely inhibiting mantle melting. In turn, they facilitated the infiltration and ascent of mantle-derived H2O through pre-existing crustal faults and shear zones. Our results indicate that water-fluxed melting could be a plausible mechanism for generating crustal magmas in orogenic regions where the availability of free H2O has been difficult to confirm.

Directed preparation of N-(1-deoxy-d-ribulos-1-yl)-glutathione during short-term high temperature dehydration: Suppressing the side reactions of glutathione

The Amadori rearrangement product (GR-ARP) derived from glutathione/ribose mixture (GSH/Rib) was prepared through spray drying characterized by short-term high temperature dehydration. The water activity of spray-dried samples containing GR-ARP decreased continuously with an intensified degree of dehydration. Lower water activity (from 0.23 to 0.13) and higher GR-ARP yield (from 46.56% to 64.02%) in the spray-dried products were found with the increase of inlet temperature, the slowdown of feed speed, and the alkalization of stock solution. Moreover, during the spray drying and formation of powders, the intensified dissipation of bound water to free water promoted intermolecular condensation that compensated bound water, favoring the directed conversion of GSH/Rib into GR-ARP. Compared to rotary evaporation at 80 °C, spray drying enabled a stronger restraint of amide cleavage and sulfhydryl oxidation in GSH, which reduced the yield of GSH-derived byproducts by 16.39%. Thus, GR-ARP was achieved a peak yield of 64.02% at an initial pH of 7.00 based on more efficient intermolecular condensation and controlled side reactions of GSH when the inlet temperature was set at 170 °C. The spray-dried sample containing richer GR-ARP and other flavor precursors showed a more similar flavor profile to the heated GSH/Rib mixture (complete Maillard reaction products) than other GR-ARP-related thermal processing samples, such as vacuum-dehydrated, GR-ARP, GR-ARP + GSH, and GR-ARP + Rib samples, revealing a great potential of the ARP mixture prepared by spray drying for flavor enhancement.

Mechanochemical formation of highly stable amorphous calcium carbonate in calcium silicates: Potential long-term storage of CO2 in cement

We have investigated mechanochemical reactions with the calcium silicate wollastonite to probe potential mechanisms of sequestration and long-term storage of CO2 as mineral carbonates in cement pastes. Wollastonite, CaSiO3, was milled under ambient and 13C enriched CO2 atmospheres. Milling induced a structure change from monoclinic wollastonite−2M to triclinic−1T, consistent with high pressure treatment. The results from solid-state 13C nuclear magnetic resonance (NMR) spectroscopy shows this process forms an extraordinarily stable amorphous calcium carbonate (ACC) phase that remains despite a high temperature dehydration treatment (130 °C) and persists in the same form after 3 yrs. of storage at ambient conditions. Thermogravimetric analysis (TGA) of these samples indicates that ACC is produced at the similar solid concentrations in both CO2-enriched and ambient atmospheres. The observation of meta-stable ACC due to wollastonite carbonation may play an important role in further exploration and optimization of mineral carbonation reactions for CO2 capturing cement formulations.

Intrinsic Molecular Mechanisms of Transformation between Isomeric Intermediates Formed at Different Stages of Cysteine-Xylose Maillard Reaction Model through Dehydration.

2-Threityl-thiazolidine-4-carboxylic acid (TTCA) and Amadori rearrangement product (ARP), the isomeric intermediates derived from the cysteine-xylose (Cys-Xyl) Maillard reaction model, possessed the ability to produce similar flavor profile during the thermal process, but the flavor formation or browning rate of heated TTCA was significantly lower than that of ARP. Macroscopically, the yield of TTCA reached the maximum when the moisture content of the reaction system just dropped to nearly 0% during the thermal reaction-vacuum dehydration process. During the subsequent dynamic intramolecular dehydration process, the reaction remained at an early stage of the Maillard reaction, and TTCA was the main intermediate. Thereinto, the water activity of the samples decreased with the increased dehydration time. From a molecular perspective, the dissipation of free water promoted the conversion of combined water to immobilized water and free water, increasing the intramolecular dehydration. Instantaneous high-temperature dehydration during the spray drying process revealed a higher efficiency than the thermal reaction-vacuum dehydration process, which facilitated the specific conversion of substrates to intermediates (TTCA, ARP). The loss of free water and immobilized water was a key driving force for the direct formation of TTCA/ARP, regulating the formation stages of MRIs. The increase of the inlet air temperature could alter the ratio of TTCA and ARP at the equilibrium state.

Hierarchically nanostructured carbon nanotube/polyimide/mesoporous Fe2O3 nanocomposite for organic-inorganic lithium-ion battery anode

Integrating organic multiple-carbonyl polymers and inorganic mesoporous metal oxides on highly conductive carbon nanotubes is a promising strategy to manufacture high-performance lithium-ion battery anodes; however, developing multicomponent nanocomposites with a hierarchical architecture still remain challenging. Herein, we design and produce hierarchically nanostructured carbon nanotube (CNT)/polyimide (PI)/mesoporous Fe 2 O 3 (meso-Fe 2 O 3 /PI/CNT) ternary nanocomposite materials via a sequential assembly and high-temperature dehydration strategy, aiming to fabricate flexible PI-supported meso-Fe 2 O 3 stacked on a conductive CNT supporting skeleton. By controlling the linear PI mainchain through the comonomer composition, different PI assemblies can grow on the surface of CNT to anchor meso-Fe 2 O 3 nanoparticles as well as alleviate the structural strain resulting from the volume expansion of meso-Fe 2 O 3 in its phase conversion reaction. Considering the porosity and cavity, the mesoporous Fe 2 O 3 architecture can not only buffer its volume expansion but also accommodate a large number of electrolytes to promote Li + transport. In addition, the hierarchical architecture endows the meso-Fe 2 O 3 /PI/CNT nanocomposite materials with a high structural stability during the electrochemical process. Benefiting from these structural advantages, Li-ion batteries assembled with meso-Fe 2 O 3 /PI-EDA/CNT electrodes deliver high capacities of 708.9, 608.2, and 454.5 mAh g −1 at 0.1, 0.3, and 0.5 A g −1 , respectively. Even at a high current density of 1 A g −1 , a discharge capacity of 95.6 mAh g −1 is still obtained after 3000 cycles. This work provides a promising route to integrate multiple-carbonyl polymers and mesoporous metal oxides with the aim of developing multicomponent organic-inorganic composite anode for Li-ion battery. • Hierarchically tubular organic-inorganic nanocomposite anode from self-assembly-assisted fabrication technique is reported. • Polyimide assemblies with controllable architecture for organic anode material and strain buffer interlayer. • Fe 2 O 3 nanoparticle with mesoporous structures for inorganic anode material. • The organic-inorganic nanocomposite anode shows desirable lithium-ion battery performance.

Postharvest Dehydration Temperature Modulates the Transcriptomic Programme and Flavonoid Profile of Grape Berries.

Raisins are a popular and nutritious snack that is produced through the dehydration of postharvest grape berries under high temperature (HT). However, the response of the endogenous metabolism of white grape varieties to postharvest dehydration under different temperature have not been fully elucidated to date. In this study, the white grape cultivar ‘Xiangfei’ was chosen to investigate the effect of dehydration at 50 °C, 40 °C, and 30 °C on the transcriptomic programme and metabolite profiles of grape berries. Postharvest dehydration promoted the accumulation of soluble sugar components and organic acids in berries. The content of gallic acid and its derivatives increased during the dehydration process and the temperature of 40 °C was the optimal for flavonoids and proanthocyanidins accumulation. High-temperature dehydration stress might promote the accumulation of gallic acid by increasing the expression levels of their biosynthesis related genes and regulating the production of NADP+ and NADPH. Compared with that at 30 °C, dehydration at 40 °C accelerated the transcription programme of 7654 genes and induced the continuous upregulation of genes related to the heat stress response and redox homeostasis in each stage. The results of this study indicate that an appropriate dehydration temperature should be selected and applied when producing polyphenols-rich raisins.

Experimental Study on Physical and Mechanical Properties of Gypsum Rock During High-Temperature Dehydration–Hydration Expansion

In order to study the physical and mechanical properties of gypsum rock samples in three states (natural, high-temperature dehydration and hydration time), natural gypsum rock was put into high-temperature condition of 220°C for dehydration treatment, and then the high-temperature dehydrated gypsum rock was treated with different hydration time, and the gypsum rock samples in three states were subjected to ultrasonic test, density test and uniaxial compression test. The results show that the main components of natural gypsum minerals were gypsum dihydrate (71%), dolomite (27%) and potassium chloride (2%). The hydration of high-temperature dehydration samples was an extremely complex physical and chemical process. Hydration had a significant strengthening effect on gypsum rock, and the weak surface of the structure had a significant weakening effect on it during the hydration process. As hydration time increased, the apparent density increased gradually and the longitudinal wave velocity increased. The peak strength of the sample decreased first and then increased, and it generally had a logarithmic relationship with hydration time. The peak strain decreased first and then increased, then decreased and fluctuated, and the elastic modulus first increased and then decreased and then increased again. The expansion rate and limited expansion force of the sample increased with increase in hydration time. After a certain hydration time, the expansion rate of the sample tended to be stable, while the limited expansion force began to decrease slowly after reaching the maximum value.

Experimental study on static and dynamic mechanical properties of phosphogypsum.

Phosphogypsum (PG) is a solid waste product of the wet-process phosphoric acid industry that accumulates in large amounts on the ground, forming PG ponds. In recent years, the amount of PG produced and discharged into ponds has increased significantly with the increase in the market demand for phosphate fertilizers. To enrich the basic knowledge of PG properties and provide basic data for the stability analysis of PG dams, a series of laboratory geotechnical tests, including permeability tests, compressibility tests, triaxial shear tests, and dynamic triaxial tests, were conducted in this study. During the preparation of the test samples, solubility and high-temperature dehydration of PG were considered. The results indicated that PG exhibits medium compressibility and medium to weak permeability characteristics. The stress-strain curves of the triaxial shear tests were divided into three typical stages: initial deformation stage, strain hardening stage, and destruction stage. With increasing dry density and consolidation confining pressure, both the shear strength and deformation modulus significantly increased. The relationship between the deformation modulus and confining pressure gradually changed from linear to logarithmic with increasing density. The liquefaction resistance curves (CSR-NL curves) of PG were expressed by power functions. With increasing dry density, the curves shifted higher and became steeper. Compared with the Hardin-Drnevich model, the Davidenkov model was found to be more suitable for describing the relationship between the dynamic shear modulus ratio and damping ratio of PG and the dynamic shear strain. Furthermore, compared with those of tailings and natural soils, the engineering mechanical properties of PG were relatively poor, which may be related to its uniform particle distribution and neat particle stacking structure.

Preparation and Anti-frost Performance of PDMS-SiO2/SS Superhydrophobic Coating

Polydimethylsiloxane modified SiO2/organic silicon sol (PDMS-SiO2/SS) hybrid coating was synthesized via a simple two-step modification route. The nanoparticles (NPs) of PDMS-SiO2 were synthesized through a high temperature dehydration reaction by using silica and excessive PDMS. The NPs lapped with each other and formed a branch and tendril structure. Organic silicon sol (SS) added as basement introduced a hydrophobic group and protected the structure of the NPs. The PDMS-SiO2/SS hybrid coating exhibits a superhydrophobic performance with a maximum water contact angle of 152.82°. The frost test was carried out on a refrigerator evaporator, and the results showed that the coating did not merely delay the frost crystal time about 113 min but also increased the frost layer process time. Meanwhile, the defrosted water droplets rolled off from the coated surface easily which is a benefit for frost suppression performance of the next refrigeration cycle.

Nanoscale magnetite: New synthesis approach, structure and properties

Nanoscale magnetite (Fe3O4) (NM) is widely used for various industrial and biomedical applications. Nevertheless, the preparation of NM with desirable structure and properties by means of simple, rapid, and environmentally friendly synthesis remains a major challenge.In this study, NM was synthesized for the first time from a waste material, namely, water deironing sludge, using a novel “sharp high-temperature dehydration” (SHTDH) approach. The magnetite obtained was verified via Fourier-transform infrared (FTIR) spectroscopy, Raman spectroscopy, transmission electron microscopy (TEM), and X-ray diffraction (XRD). XRD results revealed that the as-synthesized NM crystallites were 7 nm in size. The TEM images showed a hierarchical nanostructure characterized by primary nanoparticles (with an average size of 4.5 nm) and their secondary arrays (mean size 57 nm). The N2 adsorption–desorption measurements have enabled classify the NM material as nanoporous. According to the magnetic measurements, the synthesized NM exhibited superparamagnetic behavior.The findings suggest that the SHTDH is a facile, time-effective, and environmentally friendly approach for the synthesis of nanoparticles with ultrasmall sizes. Furthermore, it can provide a new pathway for the preparation of novel materials for various industrial and biomedical applications.

Water-Flux Melting of Amphibolite in Paleozoic Leucogranite from the North Qinling, Central China: Implication for Post Collisional Setting

Paleozoic granites can provide important insights of crustal differentiation and collision process of the North Qinling terrane. The Dafanggou leucogranites that intruded in the Qinling Complex is a Paleozoic granite with zircon U-Pb age of 404±6.4 Ma (MSWD=0.13,n=9). The leucogranites display moderate SiO2 (68.4 wt.% to 71.7 wt.%) content and high Na2O/K2O (1.07 to 2.74) and Sr/Y (42 to 65) ratios,and low A/CNK (1.04 to 1.08) and Rb/Sr (0.09 to 0.16) ratios. Combined with negative eNd(t) (-10.4) and eHf(t) (-9.35 to -0.25) values and ancient TDM2 ages (1.2 to 1.7 Ga),suggesting the leucogranite are derived from ancient amphibolitic crust in the Qinling Group. In addition,the absence of coeval mafic igneous rocks or mafic enclaves occurred in the Dafanggou pluton and the low TZrn (~700℃) of leucogranites preclude that the leucogranites derived from high temperature dehydration melting of amphibolite. Thus,we propose that the occurrence of the Dafanggou leucogranite indicates that water-flux melting of middle-lower crust in post-collision setting may be a potential model for the genesis of granites in collisional orogenic belt.

Process Designs for Converting Propylene Glycol to Acrylic Acid via Lactic Acid and Allyl Alcohol

The chemical industry is currently facing the challenge of developing biobased production processes suitable for a more sustainable chemical industry. Acrylic acid produced from monopropylene glycol is a good candidate to become a cost-competitive and sustainable platform chemical. The propylene glycol price is expected to drop due to the expected abundance of propylene glycol as a sugar hydrogenolysis byproduct, which is required to make the conversion to acrylic acid cost-competitive. Two different processes for the conversion of propylene glycol to acrylic acid are evaluated in this work, either by (1) low temperature oxidation of propylene glycol to lactic acid and high temperature dehydration to acrylic acid or by (2) high temperature dehydration of propylene glycol to allyl alcohol and further high temperature oxidation to acrylic acid. Liquid-liquid extraction was found to be a key operation in both production processes. At similar overall yields, the allyl alcohol route appears inherently favored, as a result of the opportunity to integrate the reaction heat available at high temperature. To conclude, the price of propylene glycol has to drop by 45-55% to make the biobased production of acrylic acid from propylene glycol economically feasible.

The effect of dehydration temperatures on the performance of the CaO/Ca(OH)2 thermochemical heat storage system

A more fundamental understanding of the dehydration and hydration processes of Ca(OH)2 materials is very important for the proper design and operation of thermochemical heat storage systems. There is no simple and effective method which can solve the issues of the rate of the heat storage process and the influence of CO2 on Ca(OH)2 materials. Kinetic studies have proven that a high temperature can increase the storage speed, but a high temperature will aggravate sintering of the material. The problem of carbonate formation due to contact with CO2 can also be solved by a high temperature. Therefore, how to solve the problem of the aggravation of sintering of the material after a single high temperature dehydration is important. In this study, it was found that the heat release ability can be recovered if the heat storage process of the material is applied at a lower temperature in the next cycle. Kinetic studies cannot explain the reasons of these processes. Therefore, the methods of N2 adsorption–desorption and SEM were used to reveal the effects of different dehydration temperatures on the microstructure of the materials. The results showed that the change of the micro-pore structure was the reason for the above processes.

Hydrogeological characteristics of the Lower Cretaceous terrigenous complex of the Karkinit-Northern Crimean deep in the aspect of its potential for oil and gas presence

Purpose. To substantiate the prospects for oil and gas presence in the Lower Cretaceous sediments of the Karkinit-Northern Crimean deep based on hydrogeological (hydrogeochemical, gas-hydrogeochemical and geobaric) features. Methodology. Investigations of formation waters and water-dissolved gases were based on the methods of chemical, elementary spectral and gas chromatographic analyses executed at the laboratories of subsidiary joint-stock company "Chornomornaftogaz", subsidiary "Crimean Geology" and the Institute of Geology and Geochemistry of Combustible Minerals of NASU. For the comparison of formation pressure we applied the hydrostatic coefficient (Ch). Ch is the ratio of measured formation pressure to conditionally hydrostatic at the depth of the measuring with γ=1.000 (Рf/Рch), which eliminates the influence of uneven depths of measurement and different water densities, that is, to get the reduced value. For processing materials Excell, Corell Draw and Surfer are used. Results. Regional features of formation waters in the Lower Cretaceous complex as well as their chemical composition formation conditions are established. According to retrospective data analysis on the Crimean Plains, using the information received on the Black Sea shelf, we come to a conclusion that formation waters of the Lower Cretaceous complex are mainly sedimentogenic. The sulfate-natrium (S.Na) waters of the basal horizon and the Lower Cretaceous aquiferous complex most likely are infiltrative. This is evidenced by the decrease in the indicators of metamorphism of rCa/rMg, r(Cl-Na)/rMg and the increase in Cl/Br to over 1000, the lowered content of iodine (J) and bromine (Br). Infiltrative (paleoinfiltrative) waters mixed with primary sedimentogenic waters. This was accompanied by the decrease in their mineralization and thalassogenic trace elements contents in them. Modern infiltration from the land of meteoric waters at depths of more than 2000–3000 meters through the hydrodynamic barriers of the elision water drive system is impossible, but it could be realized at the continental infiltration stages of the foreground development and before the late Cretaceous time. This is evidenced by the continuous continental conditions marked by denudation of rocks. The main processes in the chemical composition formation of formation waters of Cretaceous and Lower Cretaceous complexes could have been: leaching rocks, mixing of infiltrative fresh or saline waters with thalassogenic waters; mixing of these waters with waters of the high temperature (>2000C) dehydration of clay rocks with formation of non-infiltrative (S.Na) and (Hyd.Car.Na) waters. Based on the analysis of the hydrostatic coeficient distribution (Ch) in the basal and Lower Cretaceous aquiferous complexes the existence of the elision water pressure system within the Karkinit-Northern Crimean deep is confirmed. The cause of overhydrostatic pressures is most likely to be the dehydration of clay rocks and the intrusion of deep gases. Geobaric conditions and filtration parameters suggest that the water flows of the elision water pressure system can move from the deepest parts of the Karkinit-Northern Crimean deep towards its sides. Originality and practical significance. The nature and forming conditions of formation waters have been substantiated. According to gas-hydrogeochemical and geobaric features it was possible to distinguish localities promising for hydrocarbon prospecting in the Lower Cretaceous deposits.

Study of thermal dehydration of sodium orthophosphate monosubstituted

Depending on the conditions of conducting the synthesis, it is possible to obtain polymeric phosphates of different composition and structure. The mixtures of polyphosphates, employed in the production of technological lubricants, are expedient to synthesize by the high-temperature dehydration of sodium orthophosphate monosubstituted. The temperature ranges, over which the thermochemical transformations of sodium orthophosphate monosubstituted with the formation of polyphosphates proceed, are established by the thermogravimetric method. The composition of polyphosphates is determined using the X-ray phase analysis. Quantitative composition of the mixtures of polyphosphates is determined by applying the original method of eluent ion-exchange chromatography. It is established that the basic products of thermal dehydration of sodium orthophosphate monosubstituted in the range of temperatures 200–650 °C are Na 3 Р 3 О 9 , Na 2 H 2 P 2 O 7 and Na 6 P 6 O 18 . Thermochemical transformations of NaH 2 PO 4 into Na 6 P 6 O 18 at temperature 650 °C are accompanied by the side reactions of formation of Na 3 H 2 P 3 O 10 . We proposed the chemical scheme of the high-temperature dehydration of sodium orthophosphate monosubstituted. Kinetics of the isothermal process of obtaining the polymeric phosphates from sodium orthophosphate monosubstituted at different temperatures is examined. We established quantitative composition of the mixtures of inorganic polymeric phosphates depending on the duration of isothermal process of dehydration. The possibility of obtaining a salt mixture of polymeric phosphates of the assigned qualitative and quantitative composition is demonstrated. We proposed to use the mixture: 76 % Na 6 P 6 O 18 , 8 % Na 2 H 2 P 2 O 7 , 8 % Na 3 H 2 P 3 O 10, 8 % NaH 2 PO 4 , obtained at 650 °C, as the basic phosphate component of technological lubricants for the hot rolling of pipes.

High capacity and energy-efficient dehydration of liquid fuel 2-dimethyl amino ethyl azide (DMAZ) over chromium terephthalic (MIL-101) nanoadsorbent

Nanoadsorbents from MIL-101(Cr) metal-organic framework were prepared via hydrothermal method with different additives (hydrofluoric acid, sodium acetate, acetic acid, expanded graphite and without additive) under different synthesis conditions. The samples were characterized by XRD, SEM and nitrogen sorption at 77 K. The frameworks were used for dehydration of liquid fuel DMAZ containing 3 wt% water, for several consecutive cycles between adsorption (at ambient temperature and atmospheric pressure) and desorption at 343 K. Water stability and recyclability of the frameworks were almost similar but the MIL-101 using acetic acid attribute to the higher pore volume and surface area, with $${\text{1}}{\text{.3 g}}_{{{\text{H}}_{{\text{2}}} {\text{O}}}} /{\text{g}}_{{{\text{ads}}}}$$ had the most capacity for water capture. Also, adsorption capacity of MIL-101 was compared with commercial zeolite adsorbents (3A and 4A) for dehydration of aforementioned solution. The uptake capacity of MIL-101 with $${\text{1}}{\text{.3 g}}_{{{\text{H}}_{{\text{2}}} {\text{O}}}} /{\text{g}}_{{{\text{ads}}}}$$ was 7–8.5 times higher than commercial 3A and 4A zeolites with 0.18 and $${\text{0}}{\text{.15 g}}_{{{\text{H}}_{{\text{2}}} {\text{O}}}} /{\text{g}}_{{{\text{ads}}}}$$ respectively. MIL-101 was almost fully dehydrated at 343 K, in contrast to conventional porous zeolites requiring high temperature dehydration (573 K). MIL-101 was shaped and used in an adsorption column with $${\text{1}}{\text{.1 g}}_{{{\text{H}}_{{\text{2}}} {\text{O}}}} /{\text{g}}_{{{\text{ads}}}}$$ capacity. Shaped MIL-101 showed robust cyclic performance in the dehydration tests.

Hematite nanoparticle clusters with remarkably high magnetization synthesized from water-treatment waste by one-step “sharp high-temperature dehydration”

Hematite (α-Fe2O3) nanoparticle clusters with an exceptionally high magnetization of 51 emu g−1 were synthesized for the first time. This material was prepared from water-treatment waste by a new “sharp high-temperature dehydration” process.

High-temperature dehydration behavior and ionic conduction of 2,5-dimethylanilinium chloride monohydrate

The 2,5-dimethylanilinium chloride monohydrate compound is obtained by slow evaporation at room temperature. This material is characterized by DSC, X-Ray powder diffraction, Raman and impedance spectroscopy technique measured in the 2.102–5.106 Hz frequency and 292–422 K temperature ranges. The calorimetric study has revealed three endothermic peaks at 355 K, 392 K and 403 K which defines four successive phases denoted I, II, III and IV. The first peak corresponds to water escape from the crystal. After heating above 355 K, the compound dehydrates and the crystal space group changes from non-centrosymmetric to centrosymmetric symmetry. The activation energy responsible for dielectric relaxation extracted from the modulus spectra is found to be almost the same as the value obtained from temperature variation of dc conductivity for phases I and IV. These results indicate that the transport is through ion hopping mechanism. The influence of the dehydration process on the compound conductivity was also discussed.

Phase Transformation between Anhydrate and Monohydrate of Sodium Dehydroacetate

The crystal structures of monohydrate and anhydrous substance were determined from the single crystals for the first time. The phase transformation between anhydrate and monohydrate of sodium dehydroacetate was in situ investigated by using Raman spectroscopy. The mechanism of the phase transformation was proposed. The results showed that the monohydrate crystalline phase of sodium dehydroacetate can transform to anhydrous phase through solid–solid transformation upon heating or solution-mediated phase transformation. From powder X-ray diffraction (PXRD) patterns and thermal gravimetric analysis (TGA) data, it was found that the anhydrous crystals obtained by these two methods are the same in structure. However, the scanning electron microscopy (SEM) results revealed that the surface of the anhydrous sodium dehydroacetate crystals obtained by high-temperature dehydration was much rougher than that obtained by solution-mediated phase transformation. Furthermore, the dynamic vapor sorption (DVS) results sho...