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Microwave-hydrothermal (M − H) synthesis of α-Sn(HPO4)2·H2O (α-SnP) was achieved here in as low as 5 min at 194 °C compared to several days by others previously. The use of microwaves in conjunction with the hydrothermal process enhanced the α-SnP synthesis reaction at least by two orders of magnitude. The super fast synthesis was apparently due to localized superheating where nucleation started and the reactions occurred very quickly in the localized superheated spots. The synthesized α-SnP was characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). TEM revealed worm-like morphology at both low temperature and short duration of M − H treatment but at higher temperature platy morphology typical of layered phases resulted. The synthetic tin phosphate (α-SnP) phase is potentially useful as a cation exchanger, proton conductor and electrode material.

Here, we coined the term "clayene" for a single layer of clay and "few-layer clayene" for clays with 2-10 layers. Few-layer clayenes, which are Fe2+-rich and mica-type, were prepared hydrothermally at 200 °C and characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM)/high-resolution transmission electron microscopy (HRTEM) to determine the crystalline phases and morphology, respectively. Chemical composition by energy-dispersive spectroscopy (EDS) and X-ray photoelectron spectroscopy confirmed the iron-rich mica composition, and the latter also revealed the presence of both Fe2+ and Fe3+. Mossbauer spectroscopy further confirmed the presence of Fe2+ and Fe3+ and their proportions in the mica-type few-layer clayenes. All of the synthesized mica-type few-layer clayenes except one exhibited high specific surface areas (SSAs) ranging from 94 to 149 m2/g as determined by N2 adsorption-desorption isotherms and the Brunauer-Emmett-Teller (BET) equation. The high surface areas are in conformity with the crystal sizes calculated from XRD peaks and also as revealed by HRTEM. Taking advantage of the interfacial reactions of the high surface area of few-layer clayenes, two potential applications of clayenes were demonstrated in materials and environmental fields.

Anthracite briquettes were developed using mainly waste anthracite fines, plant byproducts of rice hulls and rice hull ash and silicon metal powder as an ecofriendly fuel and as an alternative to conventional coke used in a cupola furnace. Si metal powder reacts with anthracite to form SiC, which provides high mechanical strength to an anthracite briquette when it is exposed to a high temperature in the cupola furnace. Rice hull and rice hull ash, which are agricultural byproducts with high SiO2 content were investigated as partial substitutes for silicon as the former are inexpensive relative to silicon metal. The formation of SiC was investigated under different conditions using X-ray diffraction and transmission electron microscopy. In addition, unconfined compressive strength of the briquettes was measured when the rice hull or ash substituted Si powder partially or completely. When anthracite briquettes prepared with elemental Si powder and either rice hull ash or rice hull powder were pyrolyzed at 1400 °C for 2 h, SiC formed and the briquettes showed high mechanical strength in the range of 2000–4000 kPa, which is enough to keep their structural integrity in a cupola furnace.

Here, we report a remarkable 15 A nanolayered tin phosphate, Sn(HPO4)2·3H2O (SnP–H+ or SnP), and its clay-like gel, which are multifunctional and are prepared using earth-abundant Sn and P chemicals by a facile, environmentally benign and potentially cost-effective process. This new energy material is discovered here as the best proton conductor among all the known layered phosphates with a very high proton conductivity of over 1 × 10−2 S cm−1 at 100 °C for potential use in PEM fuel cells. But it is also a very good capacitor material with fast Li-storage kinetics (charging time of 13 s).

Herein, we report a unique tin phosphate that is remarkably selective to (137)Cs(+) from extremly acidic solutions because of its special layered structure with an unusually large interlayer space. This acidic exchanger is superior to other existing materials in terms of its selectivity and capacity for (137)Cs(+) from acidic solutions.

Crystalline Co3O4 and Co(OH)(2) were synthesized using Co(NO3)(2) as a precursor by conventional-hydrothermal and microwave-hydrothermal routes, respectively. The Co3O4 phase showed cubic morphologies while the beta-Co(OH)(2) phase exhibited plate-like shapes. The electrochemical performances of Co3O4 and Co(OH)(2) phases were evaluated as electrode materials for lithium-ion battery anodes, cathodes and supercapacitors. Both Co3O4 and Co(OH)(2) phases showed pseudocapacitive performances in Li2SO4 and KOH electrolytes. The Co3O4 and Co(OH)(2) phases were found to be more promising as anodes than as cathodes in lithium-ion batteries. The Co(OH)(2) electrodes showed higher specific capacitances than those of Co3O4 materials. (C) 2014 Elsevier Ltd and Techna Group S.r.l. All rights reserved.

The LiMn2O4 electrode materials were synthesized by the conventional-hydrothermal and microwave-hydrothermal methods. The electrochemical performances of LiMn2O4 were studied as supercapacitors in LiNO3 electrolyte and lithium-ion battery cathodes. The microwave-hydrothermal method can synthesize LiMn2O4 electrode materials with reversible electrochemical reaction in a short reaction time and low reaction temperature than conventional-hydrothermal route. The capacitance of LiMn2O4 electrode increased with increasing crystallization time in conventional-hydrothermal route. The results showed that LiMn2O4 supercapacitors had similar discharge capacity and potential window (1.2 V) as that of ordinary lithium-ion battery cathodes. In LiNO3 aqueous electrolyte, the reaction kinetics of LiMn2O4 supercapacitors was very fast. Even, at current densities of 1 A/g and 5 A/g, aqueous electrolyte gave good capacity compared with that in organic electrolyte at a current density of 0.05 A/g.

Fe-based materials, fe2o3, fe3o4, and feooh, were synthesized by the microwave-hydrothermal process in the temperature range of 100-200 degrees c and under very short reaction times of 15 min to 2 h. under microwave-controlled hydrolysis and redox reactions, cube-like fe2o3 was crystallized using fecl3, fe3o4 particles were crystallized from fecl2 and feooh nanorods were crystallized using fecl3. the fe-based materials were fabricated to make anodes and cathodes of lithium-ion battery and supercapacitor electrode materials to study their potential electrochemical applications. the electrochemical results showed that feooh had better anode capacity as lithium-ion batteries than those of fe2o3 and fe3o4. the present results suggest that the microwave-hydrothermally synthesized fe-based materials are promising lithium-ion battery anode materials. (c) 2013 elsevier ltd and techna group s.r.l. all rights reserved.

Nanophase anatase was synthesized by a novel simplified one-pot method using Ti alkoxides and hydrogen peroxide under conventional- and microwave-hydrothermal conditions. The specific surface areas (SSAs) of anatase ranged from 147 to 298 m2/g under different hydrothermal conditions but higher SSAs were obtained under microwave-hydrothermal conditions. The novel method developed here results in nanophase anatase with superior DeNOx properties.

Several organoclays were synthesized from different types of high charge synthetic clays using octadecyltrimethylammonium (ODTMA) chloride or polyethylenimine (PEI). Two alumina pillared clays were also prepared using two naturally occurring montmorillonites. These organic–clay and inorganic–clay nanocomposites were characterized by powder X-ray diffraction (XRD) and tested for perchlorate uptake. The results showed that the highest perchlorate uptake capacity of 0.436 ± 0.001 was achieved with ODTMA Na-3-mica followed by 0.269 ± 0.016 meq/g with ODTMA Na-2-mica. The uptake of perchlorate by synthetic Na-n-micas is as follows: ODTMA Na-3-mica > ODTMA Na-2-mica > ODTMA Na-1-mica > ODTMA Na-4-mica. Perchlorate uptake isotherms were determined for both ODTMA Na-3-mica and ODTMA Na-2-mica as a function of perchlorate concentration but apparently equilibrium was not achieved in both cases. The uptake of perchlorate by the ODTMA Na-n-micas could be attributed to exchange with chloride ions of the neutral surfactant occluded in between cationic chains during the cation exchange process. Organoclays prepared with PEI and hydroxy Al polymer pillared clays and their calcined counterparts showed little or no uptake because excess positive charge was not created in the interlayers in these nanocomposites unlike in the organoclays with Na-n-micas.

We report a coupled microwave–hydrothermal process to crystallize polymorphs of MnO2 such as α-, β-, and γ-phase samples with plate-, rod-, and wirelike shapes, by a controllable redox reaction in MnCl2–KMnO4 aqueous solution system. MnCl2–KMnO4 redox reaction system was for the first time applied to MnO2 samples under the coupled microwave–hydrothermal conditions, which shows clear advantages such as shorter reaction time, well-crystallized polymorphic MnO2, and good electrochemical performances as electrode materials for lithium ion batteries. For comparison, we also did separate reactions with hydrothermal only and microwave only in our designed MnCl2–KMnO4 aqueous system. The present results indicate that MnCl2–KMnO4 reaction system can selectively lead to α-, β-, and γ-phase MnO2, and the as-crystallized MnO2 samples can show interesting electrochemical performances for both lithium-ion batteries and supercapacitors. Electrochemical measurements show that the as-crystallized MnO2 supercapacitors have...

Highly charged swelling sodium micas (Na-2-, Na-3-, and Na-4-micas) with different layer charge densities were synthesized and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and solid-state 29Si and 27Al magic-angle spinning nuclear magnetic resonance (MASNMR) spectroscopy. Their ion exchange properties were examined for Sr2+ and Ba2+ ions using isotherms and Kielland plots. XRD patterns after 2Na+ → Sr2+ or Ba2+ exchange were investigated to check for change in ‘d’ values of 0 0 1 reflections of Na-micas. The ‘d’ values of 0 0 1 reflections were shifted from two-layer hydrate to one-layer hydrate depending on layer charge density and the extent of ion exchange by divalent cations. A comparison of shifting in ‘d’ values of 0 0 1 reflections indicates that there are two different hydration states of Sr2+ and Ba2+ in the interlayer space of Na-micas. Na-2-mica showed the highest selectivity for Sr2+ and Ba2+ among Na-micas because of easier expansibility of its interlayers and thus accessibility to exchanging sites. Therefore, Na-2-mica is a good candidate for decontamination of Sr2+ and Ba2+ from drinking water and contaminated soils or nuclear waste solutions.

Apparently C-doped and undoped or pure nanoparticles of anatase were synthesized using a microwave hydrothermal process in the temperature range of 140–180 °C for 1 h from several Ti precursors, such as Ti ethoxide, Ti isopropoxide and Ti oxysulfate. Nanoparticles of anatase samples were characterized by powder X-ray diffraction, transmission electron microscopy (TEM) and photocatalytic activity measurements. Results showed that nanoparticles in the size range of 4–17 nm of anatase were obtained in all cases with surface areas in the range of 151–267 m 2 /g. The photocatalytic activity of the prepared titanias was measured using methylene blue (MB) and NO x molecules. Because MB has very strong adsorption on the samples, photocatalytic degradation under either solar light or black light irradiation was found to be very limited. However, the DeNO x abilities of carbon-doped titanias were higher than those of Degussa P25 commercial titania sample and undoped or pure titanias especially under irradiation by long wavelength or visible light (>500 nm).

Co2+ exchange isotherms and Kielland plots were determined for highly-charged sodium swelling mica (Na-2-mica) and sodium Engelhard Titano-Silicate-4 (Na-ETS-4). The results showed that both Na-2-mica and Na-ETS-4 were highly selective for Co2+ at (equivalent fraction) of < 0.3. X-ray diffraction (XRD) patterns after 2Na+ → Co2+ exchange process were examined to check for change in d001-spacing of Na-2-mica. As the uptake of Co ions increased, strong ∼14 A phase (two-layer hydrate) of Na-2-mica increased, while the ∼12 A phase (one-layer hydrate) decreased. These synthetic ion exchangers have a great potential for decontamination of radioactive or stable cobalt from waste water and soils.

Two different microporous Na-titanosilicates with high cation exchange capacities were synthesized and characterized by X-ray diffraction, scanning electron microscopy (SEM) and solid-state 29 Si and 27 Al magic-angle spinning nuclear magnetic resonance (MASNMR) spectroscopy. The ion exchange properties of Na-ETS-4 (ETS = Engelhard TitanoSilicate) and Na-titanosilicate were investigated for Sr 2+ and Ba 2+ using isotherms and Kielland plots in order to check the potential for the decontamination of 90 Sr and 133 Ba from nuclear waste solutions. Na-ETS-4 and Na-titanosilicate show high affinity for Sr 2+ to high equivalent fraction of Sr 2+ on solid phase. In case of Ba 2+ the selectivity coefficient of both titanosilicate exchangers rapidly decreased due to the steric hindrance at exchange sites at X ¯ Ba > ∼0.5. However, Na-ETS-4 was still selective for Ba 2+ even after the above rapid decrease in selectivity, unlike Na-titanosilicate. Therefore, Na-ETS-4 is one of the best candidates for the removal of both Sr 2+ and Ba 2+ from nuclear waste solutions.

Parameters such as temperature, time and presence or absence of microwaves affected the particle size and magnetic properties of synthetic magnetite. The presence of microwaves during crystallization significantly increased the particle size of magnetite in a short time with improved magnetic properties. Magnetite samples were characterized by X-ray diffraction, transmission electron microscopy (TEM) and saturation magnetization measurements. The TEM crystal sizes varied from about 40 to 50 nm at room temperature to greater than 50 nm with wider crystal size distribution at higher temperatures. The saturation magnetization values of synthetic magnetites ranged from 57.4 to 89.0 emu/g.

Selective Hg(2+)-exchange properties of highly charged sodium swelling micas (Na-2-, Na-3-, and Na-4-micas), sodium Engelhard titanosilicate-4 (Na-ETS-4), and sodium titanosilicate were determined by use of distribution coefficients (K(d)), ion-exchange isotherms, and Kielland plots for their potential use of Hg decontamination from groundwater and soils. X-ray diffraction (XRD) patterns after 2Na(+) → Hg(2+) exchange were collected to check for change in (001) spacings of differently charged sodium micas. The isotherms and Kielland plots suggested that Na-ETS-4 was highly selective for Hg(2+). Also, the K(d) value of Na-ETS-4 was the highest among the tested exchangers, supporting its high selectivity. Hg releases from Hg-exchanged Na-4-mica and Na-ETS-4 were found to be lower compared to other samples tested with simulated groundwater. The (001) spacings of sodium micas after Hg(2+) exchange changed from ∼ 12 to ∼ 14 Å or/and 12 Å depending on their layer charge density and the uptake amount of Hg. Our results suggest that Na-ETS-4 is a good candidate for mercury(II) decontamination from groundwater and soils.

Anatase and Ca, Sr and Ca0.5Sr0.5 hydroxyapatites were synthesized by conventional-hydrothermal (C-H) as well asmicrowave-hydrothermal (M-H)methods.Microwave-assisted reactions led to accelerated syntheses of anatase but no such acceleration of reactions could be detected with the syntheses of hydroxyapatites because the crystallization of the latter materials occurred at very low temperature. Cu and Au metal powders were produced by using glucose, fructose or sucrose as reducing agents under C-H conditions at 160 ℃, where fructose and sucrose were found to be stronger reducing agents than glucose. The crystallinity of all the powders was characterized by powder X-ray diffraction, and morphology and particle sizes were determined by scanning or transmission electron microscopy

This work reports a solid-state synthesis of low-charge mica-type clay minerals using a fluoride flux method. Synthesized mica-type clay samples yielded hydrated phases with d -spacings in the range of 12.1–12.5 A as revealed by powder X-ray diffraction (XRD). 29 Si and 27 Al magic angle spinning nuclear magnetic resonance (MASNMR) spectroscopy revealed the Si and Al nearest neighbor environments as well as the presence of impurities such as amorphous silica and forsterite in these samples.

TiO2 and Ca, Sr, and Ca0.5Sr0.5 hydroxyapatites are synthesized by conventional hydrothermal as well as microwave hydrothermal methods.

LiMn 2 O 4-based materials such as LiMn 2 O 4 and LiMn 1.53 Ni 0.47 O 3.67 were synthesized by both conventional-hydrothermal (CH), microwave-hydrothermal (MH) methods and calcination route. Both reaction temperature and reaction time during MH routes were lower than those of CH routes. LiMn 2 O 4 electrode materials were assembled into lithium-ion battery anodes and their electrochemical performances were studied. The results proved that these LiMn 2 O 4 electrodes can be served as conversion anode materials, and show electrochemical activity during the potential range of 0.01–3.0 V versus Li +/ Li . For LiMn 1.53 Ni 0.47 O 3.67 materials when used as lithium-ion battery anodes, we found that the introduction of Ni can change their electrochemical reaction and thus improve their electrochemical performances.