Alkaline Earth Compounds Research Articles

Recycling of flotation residual carbon from coal gasification fine slag through thermal combustion reaction: Insight into the spatial and temporal multi-scale evolution of typical heavy metals

The necessity for a fundamental comprehension of the migration and transformation patterns of heavy metals in the combustion reaction process is paramount to ensure the effective and targeted prevention and control of heavy metal pollution in the context of large-scale energy utilization of waste coal gasification fine slag. This study aims to reveal the fate of typical heavy metals during the combustion reaction of coal gasification fine slag to provide valuable insight for its clean secondary use. In this work, the thermal combustion reactivity of coal gasification fine slag was initially enhanced through froth flotation, and then the spatial and temporal multi-scale evolution of heavy metals in the flotation carbon-rich fraction was investigated by a series of analytical experiments. The results demonstrate a strong correlation between the volatility of typical heavy metals and the combustion reaction process of the flotation carbon-rich fraction. The volatility of V, Ni, Cu, Zn, and Pb is consistently high, of which the volatility of Zn and Pb is consistently above 50%, while the volatility of Cr, Mn, and Ba exhibits greater temperature sensitivity. As the reaction proceeds, the specific surface area of the solid residue expands, and then the smooth and dense mineral particles dissolve into each other to form a cluster structure simultaneously with the collapse of the pore structure, resulting in the volatility of the heavy metals firstly increasing and then decreasing. Furthermore, alkali metals and alkaline earth metal compounds are effective carriers of Cr, Mn, and Ba in the bottom residual. Additionally, the type and number of crystalline minerals in the bottom residual gradually increase as the reaction progresses. This results in the gradual conversion of the heavy metals bound to unstable carbonate minerals and sulphones into more stable chemical forms. The findings provide novel theoretical support and technical guidance for the environmentally sound and efficient utilization of residual carbon in the waste coal gasification fine slag.

Structural insight and in silico prediction of the pharmacokinetic parameters and toxicity of alkaline earth metal compounds strontium and barium with the non-steroidal anti-inflammatory drug nimesulide.

In the crystals of alkaline earth metal compounds strontium and barium with the non-steroidal anti-inflammatory drug nimesulide, the strontium cation is nine-coordinated with a distorted tricapped trigonal prismatic geometry TCTPR-9, whereas the ten-coordinated barium ion exhibits a distorted tetracapped trigonal prismatic geometry TCTPR-10.

From alkaline earth to coinage metal carboranyls.

The β-diketiminato calcium and magnesium complexes, [(BDI)MgnBu] and [(BDI)CaH]2 (BDI = HC{C(Me)NDipp}2; Dipp = 2,6-di-isopropylphenyl), react with ortho-carborane (o-C2B10H12) to provide the respective [(BDI)Ae(o-C2B10H11)] (Ae = Mg or Ca) complexes. While the lighter group 2 species is a monomer with magnesium in a distorted trigonal planar environment, the heavier analogue displays a puckered geometry at calcium in the solid state due to Ca⋯H-B intermolecular interactions. These secondary contacts are, however, readily disrupted upon addition of THF to provide the 4-coordinate monomer, [(BDI)Ca(THF)(o-C2B10H11)]. [(BDI)Mg(o-C2B10H11)] was reacted with [NHCIPrMCl] (NHCIPr = 1,3-bis(isopropyl)imidazol-2-ylidene; M = Cu, Ag, Au) to provide [NHCIPrM(o-C2B10H11)], rare C-bonded examples of coinage metal derivatives of unsubstituted (o-C2B10H11)- and confirming the alkaline earth compounds as viable reagents for the transmetalation of the carboranyl anion.

Unusual quadruple bonds featuring collective interaction-type σ bonds between first octal-row atoms in the alkaline-earth compounds AeOLi2 (Ae = Be-Ba).

Quantum chemical calculations are reported for the complexes of alkaline earth metals AeOLi2 (Ae = Be-Ba) at the BP86-D3(BJ)/def2-QZVPP and CCSD(T)/def2-QZVPPQZVPP levels. The nature of the Ae-OLi2 bond has been analyzed with a variety of methods. The AeOLi2 molecules exhibit an unprecedented σ donor bond Ae→OLi2 where the (n)s2 lone-pair electrons of the Ae atom are donated to vacant O-Li2 antibonding orbitals having the largest coefficient at lithium. This is a covalent bond where the accumulation of the associated electronic charge is located at two positions above and below the Ae-OLi2 axis. The bifurcated component of orbital interactions is structurally related to the recently proposed collective bonding model, but exhibits a completely different type of bonding. The most stable isomer of AeOLi2 has a C 2v geometry and a singlet (1A1) electronic ground state. The bond dissociation energy (BDE) of the Ae-OLi2 bonds exhibits a zig-zag trend from BeOLi2 to BaOLi2, with BeOLi2 having the largest BDE (D e = 73.0 kcal mol-1) and MgOLi2 possessing the lowest BDE (D e = 42.3 kcal mol-1) at the CCSD(T) level. The calculation of the atomic partial charges by the Hirshfeld and Voronoi methods suggests that Be and Mg carry small negative charges in the lighter molecules whereas the heavier atoms Ca-Ba have small positive charges. In contrast, the NBO and QTAIM methods give positive charges for all Ae atoms that are larger for Ca-Ba than that calculated by the Hirshfeld and Voronoi approaches. The molecules AeOLi2 have large dipole moments where the negative end is at the Ae atom with the polarity Ae→OLi2. The largest dipole moments are predicted for the lighter species BeOLi2 and MgOLi2 and the smallest value is calculated for BaOLi2. The calculation of the vibrational spectra shows a significant red-shift toward lower wave numbers for the Ae-OLi2 stretching mode in comparison to diatomic AeO. Besides the Ae→OLi2 σ-donor bonds there are also three dative bonds due to Ae←OLi2 backdonation which consist of one σ bond and two π bonds. The appearance of strong Ae→OLi2 σ donation leads to quadruple bonds AeOLi2 in all systems AeOLi2, even for the lightest species with Ae = Be, Mg. The valence orbitals of Ca, Sr, and Ba, which are involved in the dative interactions, are the (n)s and (n-1)d AOs whereas Be and Mg use their (n)s and (n)p AOs. The EDA-NOCV results are supported by the AdNDP calculations which give four 2c-2e bonding orbitals. Three bonding orbitals have occupation numbers ∼2. One σ orbital has smaller occupation numbers between 1.32 and 1.73 due to the delocalization to the lithium atoms. The analysis of the electronic structure with the ELF method suggests multicenter bonds with mainly trisynaptic and tetrasynaptic basins, which also support the results of the EDA-NOCV calculations.

Mineral, Chemical and Technical Characterization of Altered Pyroxenic Andesites from Southeastern Spain for Use as Eco-Efficient Natural Materials

Climate change is already an undeniable reality, and it is a direct consequence of our society’s lifestyle and the indiscriminate use of certain materials, such as Portland cement, which causes the emission of gases and waste that contributes to the greenhouse effect. The object of this work is to present the results obtained from research on pyroxenic andesites that have become altered to zeolite and their use as alternative, eco-efficient materials that improve the quality of cement through a standardized partial substitution. In this work, four samples of pyroxenic andesites altered to zeolites (PAAZ) and two samples of unaltered andesites (UPA) were analyzed. The methods used in this study are as follows: petrography of thin section (PTS), chemical analysis of X-ray fluorescence (XRF) and phase determination by X-ray diffraction (XRD). Other tests were carried out to determine the quality of the PAAZ from a technical and practical application point of view, such as chemical analysis of pozzolanicity (CPT) at 8 and 15 days, as well as mechanical compression tests at 2, 7, 28 and 90 days. Petrographic and phase analyses show that the original mineral components of the samples such as pyroxene, amphibole, plagioclase and mica were leached and replaced by more than 90% with mordenite and smectite. XRF analyses indicates an anomalous rise in SiO2, a drastic reduction in alumina Al2O3 and a significant increase in alkaline compounds over alkaline-earth compounds in samples of altered pyroxenic andesites (PAAZ) with respect to samples of unaltered andesites (UPA). The pozzolanicity test establishes that the samples of unaltered andesites do not behave like pozzolans at 8 or 15 days; however, altered andesites experienced remarkable pozzolanic reactivity in the same periods. The mechanical compression tests carried out on specimens made with PAAZ and Portland cement showed a growing increase in mechanical resistance from 2 days (15.2 MPa) to 90 days (72.1 MPa). These results suggest that pyroxenic andesites altered to zeolite can be an ideal alternative to partially replace Portland cement, which in turn could contribute to the preservation of the environment and a more rational use of traditional resources.

Crown Ether Complexes with Alkaline Earth Metal Chlorides ‒ Catalysts for the Decomposition of Isopropylbenzene Hydroperoxide

Kinetic and thermodynamic parameters of the decomposition of isopropylbenzene hydroperoxide in chlorobenzene in the presence of dibenzo-18-crown-6 ether (DBK) complexes with CaCl2, SrCl2, BaCl2 have been experimentally obtained. The catalytic activity of alkaline earth metal compounds decreases in the series SrCl2·DBK CaCl2·DBK BaCl2·DBK. The formation of intermediate intermediates in the metal‒complex-hydroperoxide system has been kinetically established. SrCl2·DBK forms the strongest and most ordered structures with isopropylbenzene hydroperoxide, which decay at the highest rates. The formation of intermediate intermediates has been confirmed using quantum chemical modeling.

Study of Factors Affecting the Copper Ore Leaching Process

This paper provides an overview of hydrometallurgical copper extraction studies in which liquid extraction technology has been used with four copper deposits of different compositions. The sulfuric acid consumption rate and copper extraction efficiency, which are dependent on the initial content and forms of calcium compounds and other impurities in ore samples, were calculated, and the results are presented herein. It was established that during the leaching process, silicate compounds of alkaline earth metals, in addition to calcium and magnesium carbonate compounds, would affect the levels of sulfuric acid consumption, thereby actively lowering the acidity of the environment. Moreover, these compounds could partially sorb copper ions from sulfuric acid leaching solutions. Thus, the analysis of waste ore samples showed that residual copper is mainly contained in the form of complex silicate complexes. The presence of divalent iron compounds in the composition from one of the deposits also allowed us to perform a biochemical leaching experiment with preliminary oxidation using an Acidithiobacillus ferrooxidans bacterial culture adapted to the ore composition. The use of this biochemical method in the copper leaching process resulted in a significant reduction in sulfuric acid consumption, by 40%, and a copper recovery rate of 87.2%.

The role of magnesium species in paper deacidification. A review

A major problem in the preservation of the cultural heritage of mankind is the degradation of acid paper, the essence of which is the decomposition of cellulose, as the main component of paper. To suppress this decomposition, deacidifying agents based on alkaline earth metal compounds are widely used. This work focuses on evaluating knowledge about the functioning of M2+ ions, solid and dissolved alkaline earth compounds used in paper conservation. The first part of this review is oriented toward studying the interaction of ions, oxides and hydroxides of metals in water. The second part focuses attention on the behavior of ions in the paper structure. Solid MO, M(OH)2, and hydrated M(OH)+ and OH− have a deacidifying effect. Their effect is conditioned by the presence of water in the cellulose/paper.

Influence of pressure and sunflower husks ash as catalyst on tire-char steam gasification

Catalytic gasification of low-reactive waste fuels, like tire-char, with the use of a different type of waste as a cheap and efficient catalyst seems to be an up-and-coming solution; however, requiring selecting appropriate process conditions. Therefore, this study aimed to assess the effect of various amounts (0, 5, 10, 15 wt%) of waste-based catalyst (sunflower husks ash, SHA) and pressure on tire-char gasification with steam. Feedstock and catalyst were characterised, then physically mixed, and the prepared samples were subjected to steam gasification. The gasification measurements were performed at 800, 850, 900 and 1000 °C and the pressures of 0.5 and 1 MPa, using the thermovolumetric method based on an analysis of the composition of the resulting gas (this research focused on the main gas components, i.e. CO and H2). The obtained results showed that the selected tire-char was characterised by a high calorific value; however, it contained a high content of carbon and catalytically inert ash, which may affect its reactivity. In turn, sunflower husk ash selected as catalyst consisted mainly of catalytically active compounds of alkali and alkaline earth metals (in particular K2O), while at the same time a low content of acid components that inhibit the process. The gasification measurements proved that the character of curves of formation rates of CO and H2 differed, indicating different formation mechanisms. Moreover, pressure and catalyst addition affected the gasification process, especially at low temperatures (∼800–850 °C). In this temperature range, an increase in pressure, catalyst addition, and increasing its loading improved the conversion reaction rate and maximum carbon conversion, as well as hydrogen yields. In turn, an increase in pressure and the addition of catalyst positively affected the yield of carbon monoxide in almost the entire range of analysed temperatures, whereas the effect of catalyst was not significant. Finally, the analysis of kinetic parameters of carbon conversion reaction during steam gasification showed that the addition of catalyst reduced both activation energy and pre-exponential factor (the most significant reduction was observed when using 5 wt% of SHA), while the increase in pressure had an inverse effect on these parameters. Nevertheless, the obtained results show that steam gasification of tire-char at low temperatures, the pressure of 1 MPa and in the presence of 15 wt% of SHA may be an attractive way to efficiently obtain gas rich in hydrogen — one of the most promising future fuels.

Conversion efficiency improvement of ELO GaAs solar cell, deposited on water soluble sacrificial buffer

We demonstrate the improvement of power conversion efficiency of an epitaxially-lifted-off single junction GaAs solar cell deposited on a water-soluble sacrificial buffer architecture by introducing an additional germanium (Ge) interlayer between GaAs and the fluoride buffer. The epitaxial lift-off (ELO) technique has been extensively used to separate III-V device layers from their single crystal GaAs substrates. However, conventional ELO requires the use of concentrated hydrofluoric acid (HF) for extended times to etch out the sacrificial layer, subsequently degrading the surface roughness of the parent wafer. As a result, the wafer has to undergo expensive and intensive chemical mechanical polishing (CMP) processes, costing about 25 % of a pristine 6-inch GaAs substrate. In our previous work, we demonstrated a method to eliminating the need for CMP post-processing by using water-assisted ELO (H2O-ELO). A water-soluble, 3-layer buffer architecture was developed using alkaline earth compounds. However, devices suffered low performance due to a high defect density in the GaAs active layers. A Ge interlayer was introduced to provide a more favorable surface energy for GaAs growth, which leads to an improvement of GaAs crystal quality. The Ge deposition conditions were optimized to achieve a high-quality Ge layer on triple-layer fluoride buffer. Single junction GaAs devices fabricated on Ge/(Ca,Sr)F2/BaF2/(Ca,Sr)F2 showed improvement of solar cell performance parameters featuring increases in Voc by 23.7 %, and fill factor (F.F.) by 4.9 %, which results in an overall improvement of power conversion efficiency from 10.3 % to 12.69 %.

Ionic conductivity and disorder in calcium and barium nitrogen hydrogen phases.

Nitrogen-hydrogen based alkali and alkaline earth metal compounds have recently received a substantial amount of attention as co-catalysts for heterogeneous mild condition ammonia synthesis (MCAS). The incorporation of these materials has been shown to result in positive reaction orders with respect to H2, solving the issue of hydrogen poisoning, e.g., the occupation of the majority of transition metal (TM) active sites by H-adatoms due to the significantly faster kinetics of H2 dissociation as compared to N2. The mechanism that underlies this is thought to be the incorporation (sinking) of H-adatoms from the surface of TMs to the bulk of the N-H phases. Thus, the slower kinetics of N2 dissociation no longer inhibit ammonia synthesis, and improvements in the kinetics dissociation for TM can be realised without consideration for which specific gases are affected (e.g., the circumventing of scaling relations). The ability to transport H-adatoms from the surface of TM is therefore of fundamental importance to the properties of the N-H co-catalyst implying that the conductivity of these species towards H and N ions, and NHx species, is of utmost importance. As such, we investigate two N-H systems that can be prepared by reacting the respective hydrides with nitrogen resulting in nitride-hydride and imide forms for Ca and Ba, respectively. These have both been previously shown to promote ammonia synthesis and here we investigate their conductive properties, and discuss these systems in the context of activity and stability of the total system with specific focus on the rise of secondary anion species, and the presence of barium in the system.

Constructing perovskite/alkaline-earth metal composite heterostructure by infiltration to revitalize CO2 electrolysis

Solid oxide electrolysis cell (SOEC) can efficiently convert CO2 to CO using renewable energy sources, which can alleviate the threatening impact of excessive CO2 emissions on the human life and environment. Moreover, it also realizes chemical storage of available electricity to ease the energy consumption crisis. Designing cathode materials with abundant active sites and high-efficiency electrochemical catalytic activity toward CO2 reduction is crucial for realizing practical applications of SOEC. Herein, construction of a composite heterostructure of alkaline-earth metal compounds and Sr2Fe1.5Mo0.5O6−δ (SFM) double perovskite oxides by alkaline-earth metal infiltration was proposed. This strategy enriched the reactive sites and led to the expansion of the triple-phase boundary, thereby effectively improving the electrochemical performance of SOEC. The experimental results show that the infiltration of alkaline-earth metal led to significant increase in the surface active sites, improvement in the adsorption and activation process of CO2, and promotion of the formation of activated carbonate intermediates. The current density on the CaCO3-infiltrated SFM cathode reached 1.723 A cm−2, while the current density on the SFM cathode could only reach 1.117 A cm−2 at 1.8 V and 800 °C. The alkaline-earth metal infiltration strategy not only improves the electrochemical performance, but also maintains excellent stability after 100 h of operation at high temperature and 12 redox cycles. All these results indicate that the construction of heterostructure through alkaline-earth metal infiltration provides an effectual strategy for improving the electrochemical performance of SOEC.

Study of alkali metals and alkaline earth metals in chlorobutyl rubber-based model truck inner tube compound

This paper describes the effects of various alkali metal and alkaline earth metal compounds, as well as walnut shell ash (WNS ash), on the cure characteristics (ts2, tc90) of a chlorobutyl rubber (CIIR)-based heat resistance truck inner tube compound. We observed that CIIR-F (KOH) has a very high scorch safety and a very slow cure. As it is a strong base with a high pH (13.84), it cures very slowly. Despite having a pH of 10.6, a ts2 of 6.36, and a tc90 of 18.84 min, CIIR-D (CaCO3) cures faster than CIIR-A (blank). The ts2 and tc90 values for CIIR-A (blank) were 6.55 and 18.88 min, respectively. Except for CIIR-D (CaCO3), all of the materials used to have higher scorch safety (ts2) and optimum cure time (tc90) in rheometer than CIIR-A (blank). CIIR-C (BaCO3) performed nearly as well as a blank. This study revealed that the trend of cure characteristics (ts2, tc90) in rheometer and Mooney scorch (t5) in Mooney viscometer not only depends on pH but also depends on ionic radius, ionization enthalpy and oxidation number of alkali metal and alkaline earth metal and the type of compound of alkali metal and alkaline earth metal.

Novel coordination compounds of alkaline earth metals with coumarilic acid. Synthesis and characterization

In this study, novel coordination compounds of coumarilic acid with 2A group alkaline earth metal cations [Mg2+ (1), Ca2+ (2), Sr2+ (3) and Ba2+(4)] were synthesized and structural characterized. The structural properties of the new molecules obtained were studied by melting point, elemental analysis, infrared spectroscopy, single crystal x-ray diffraction (SC-XRD), powder x-ray diffraction (P-XRD) spectroscopy. In addition, the thermal stability of the compounds were examined by thermal analysis (TGA/DTA) curves in an inert nitrogen atmosphere. When the structural properties of the molecules were examined, it was seen that the structure numbered 1 {[Mg(H2O)6].2(C9H5O3)} differed from the others and it was a kind of aqua complex. The coumarilate anions anionically located outside the coordination sphere serve as the counter-ion of the molecule. It has been determined that the other structures 2 {μ-(H2O)2[Ca(C9H5O3)(H2O)3]2.2(C9H5O3)}, 3 {μ-(H2O)3[Sr(C9H5O3)(H2O)2]2.2(C9H5O3)} and 4 {μ-(H2O)3[Ba(C9H5O3)(H2O)2]2.2(C9H5O3)} are in polymeric form and the coordination number of metals are eight. According to the spectroscopic analysis, these three structures are thought to be in isostructure form. It has been determined that in the unit cell in the structure 3 whose single crystal structure has been resolved, aqua and coumarilate ligands of two metal cations are connected to each other in the bridge position and coordination is ensured with aqua and bidentate anionic coumarilate ligands located in the terminal position. At the end of thermal decomposition, it was determined that relevant metal oxide residues remained in all structures and this situation was defined by powder XRD.

Zirconium phosphates deposited on the granulated silica gel as adsorbents for the extraction of cesium, strontium radioisotope ions

ABSTRACT A preliminary study of a lot of adsorbents for the adsorption of radioisotopes of cesium, strontium and yttrium from the drain waters of the Chernobyl nuclear power plant showed that granular zirconium phosphate had the best adsorption properties. The aim of this work was the synthesis and study of the adsorption of cesium and strontium ions onto zirconium phosphates deposited on granular silica gel. In the synthesis of these adsorbents, zirconium phosphates were converted into metal-substituted derivatives using alkaline earth metal compounds. The Mg, Ca, Ba, and (Mg+Ba) substituted derivatives were synthesized and investigated. It was found that, in the series of metal-substituted zirconium phosphates which were deposited on granular silica gel, the magnesium substituted ion-exchangers exhibited the best adsorption properties at cesium adsorption, and especially at strontium adsorption.

Mechanochemistry of fluoride solids: from mechanical activation to mechanically stimulated synthesis

This lecture text is focused on the comparatively young field of mechanochemistry of fluoride solids, considering both their mechanical activation and their mechanochemical synthesis. Beside a literature survey, the mechanochemical synthesis of binary fluorides MF2, MF3, of complex fluorides MMgF4, of solid solutions MaxMb1−xF2 or M1−xLnxF2+x (Ln: Y, Eu) and of fluorine-containing coordination polymers is presented. Owing to their interesting potential applications in the field of fluoride ion conductivity or luminescence properties when doped, most of the given examples are alkaline earth metal compounds. A short historical survey, remarks on peculiarities and consequences of mechanical activation as well as the necessary technical equipment for mechanochemical reactions precede the section.Graphic abstract

Ibuprofen as linker for calcium(II) in a 1D-coordination polymer: A solid state investigation complemented with solution studies

The ibuprofen alkaline-earth compounds Ibuprofen-Mg and Ibuprofen-Ca were investigated by using combined solid state and solution studies. The molecular and crystal structures of the calcium (Ca_Ibu_Hy, a 1D-coordination polymer based on ibuprofen) and magnesium (Mg_Ibu_Hy_RT and Mg_Ibu_Hy_LT) ibuprofen dihydrate salts have been analyzed in depth by using X-ray diffraction (both single crystal and powder) and in-silico tools. Differential scanning calorimetry (DSC), thermal gravimetric analysis (TGA), variable temperature X-ray diffraction experiments were carried out to study the stability of the solid forms under different temperature conditions.The Mg_Ibu_Hy_LT → Mg_Ibu_Hy_RT transition, which occurs between 250 and 300 K, is fully reversible and consists of a mild rearrangement of the crystal structure. Upon raising the temperature, dehydration of the Mg_Ibu_Hy_RT phase occurs, which leads to a completely amorphous phase at T > 340 K. As a consequence, the RT phase of the MgII compound is stable in a quite narrow temperature range. The calcium salt, in turn, gives a partially crystalline anhydrous phase with rising temperature.The coordination behavior of ibuprofen towards MgII, CaII and SrII in a water–ethanol mixture has been studied by means of potentiometric titrations. Based on the almost identical formation constants for CaII- and MgII-Ibuprofen complexes and on the well-known great affinity of MgII-for water molecules, we speculated the formation of solvent-shared ion pairs in the latter case, where the MgII-carboxylate interaction is of the outer-sphere type.

Chemical looping combustion-adsorption of HCl-containing syngas using alkaline-earth coated iron ore composites for simultaneous purification and combustion enhancement

• A novel three-stage CLCA process for HCl-containing syngas is proposed. • IO-Ba and IO-Sr can be used as oxygen carrier-HCl sorbent composites for CLCA. • Ba/Sr/Ca sorbents improve reactivity of iron ore in syngas combustion. • High temperature (950 °C) and H 2 O are required for the sorbent regeneration. • SR stage enhances syngas combustion owing to mitigation of OCS sintering. For high temperature purification of HCl-containing syngas, chemical looping combustion-adsorption (CLCA) was developed using Ba-, Sr- and Ca-coated iron ore (IO) as bifunctional oxygen carrier-HCl sorbent (OCS) composites. The behavior of OCS at fuel reaction (FR), air reaction (AR) and sorbent regeneration (SR) stages was studied. It was found that compared with conventional chemical looping combustion (CLC), CLCA could maintain high dechlorination performance at FR stage, without any deterioration after multiple cycles. Among the OCS composites, Ba and Sr-coated IO showed extraordinary performance as OCS for CLCA process of HCl-containing syngas, whereas Ca-coated IO exhibited low HCl removal ability. During 5-cycle test of Ba and Sr-coated IO, the HCl concentration in flue gas from fuel reactor was 20–30 ppmv, corresponding to approx. 95% dechlorination efficiency. For the selection of SR conditions, high temperature (950 °C) was required to achieve stable and high regeneration performance, while H 2 O was the effective regenerating gas for Ba-coated IO, instead of CO 2 . Regarding syngas combustibility, the coating with alkaline-earth metal compounds improved the oxidizing ability of IO leading to higher combustion efficiency compared to pure IO. Ba- and Sr-coated IO showed greater performance in syngas combustion than Ca-coated IO due to the greater electron donating ability and base strength. The addition of SR stage was also found to promote the syngas combustion performance, due to the mitigation of sintering problem from molten metal chlorides. The results suggest that the CLCA process could be an efficient solution for processing HCl-containing syngas.

Na1.7Li0.3BaZn7(TeO6)3: The first mixed alkali metal and alkaline earth metal zinc tellurate

The first mixed alkali metal and alkaline earth metal compound with 3D anion framework consists of zinc-oxygen and tellurium-oxygen polyhedron, Na1.7Li0.3BaZn7(TeO6)3, has been synthesized by high-temperature solution method, which crystallizes in the centrosymmetric hexagonal space group P63/m (No. 176). The [Te6Zn13O57] units in Na1.7Li0.3BaZn7(TeO6)3 is very similar to that of in classic polyoxometalate, Keggin. The UV–vis-NIR diffuse reflectance spectrum, thermal gravimetric results, differential scanning calorimetry curves and infrared spectrum of Na1.7Li0.3BaZn7(TeO6)3 were studied. In addition, the band structures, and the partial density of states have been discussed through first-principles calculations.

Dust mitigation by rolling water droplets from hydrophobic surfaces

Environmental dust mitigation from hydrophobic surfaces by rolling water droplets is considered and the dust particle removal mechanism by rolling droplet fluid is examined. The dust particles are analyzed evaluating elemental composition, shapes, and sizes. The solubility of some dust compounds in the droplet fluid is also assessed. Glass surfaces are hydrophobized through deposition of the functionalized nano-size silica particles using the dip coating method. A high speed recording system is utilized monitoring and tracking of the droplet liquid infusion (cloaking) on the dust particle surfaces. Similarly, the droplet motion on the inclined dusty hydrophobic surface is monitored and tracked. The findings reveal that dust possess various elements and alkaline and alkaline earth metal compounds can dissolve in water while forming a chemically active solution, which can damage the dusty surfaces. The droplet liquid infusion (cloaking) on the surface of the dust particles remains essential for removing dust from the hydrophobic surfaces by rolling water droplets. The droplet liquid spreading ceases for low surface energy dust particles. This prevents the droplet fluid spreading onto the surface of the dust particles; hence, these particles remain as dust residues on the surface. Rolling water droplet cleans the dusty hydrophobic surface and improves the optical transmittance of the surface.