H2O Crystals Research Articles

Quantitative Estimation of Effective Brønsted Acid Sites of Silica-Supported H4SiW12O40 Heteropoly Acid for Adsorption of Various Molecules.

The amount of incorporation of linear alcohols and ethers in H4SiW12O40·6H2O (HSiW·6H2O, 50 wt %) supported on silica (SiO2) was estimated by a conventional volumetric method and infrared (IR) spectroscopy, and the state of involved molecules was elucidated. First, the attribution of the key IR band at 2200 cm-1, which was observed for the water of crystallization of HSiW·6H2O, to H5O2+ species (protons) was verified by coincident observation of thermogravimetric-differential thermal analysis, X-ray diffraction (XRD), and IR spectroscopy during thermal treatment in addition to the isotope exchange with D2O. The 2200 cm-1 band was gradually decreased in intensity by increasing the amount of adsorption of pyridine and was totally consumed at saturation, while the volumetric method provided the accurate number of included pyridine molecules. Thus, the decrease of the integrated intensity of the 2200 cm-1 band was employed to evaluate the extent of interaction of linear alcohols and ethers with H5O2+ species in equilibrium and irreversible conditions at room temperature. Linear alcohols (C1-C5) consumed almost all protons in equilibrium and about 50% in evacuation at room temperature, while about a half of protons were interacted in equilibrium and a quarter in evacuation in the case of dimethyl and diethyl ethers. Knowing the number of molecules incorporated and the amount of H5O2+ species consumed, the ratio of interacted molecules and H5O2+ species was estimated as H5O2+:molecules = 1:2-3. XRD patterns indicated the copresence of molecule-incorporated and molecule-free domains under irreversible conditions. Therefore, the incorporated molecules were concentrated around the H5O2+ species in HSiW·6H2O crystals. The state of absorbed molecules in HSiW·6H2O crystals was presumed by IR spectra: the presence of Fermi resonance of the hydrogen-bonded OH stretching band of H5O2+ species with CH deformation bands of interacted molecules implied the equilibrium state of as-interacted molecules and protonated species (transition state) at room temperature.

Research on the technology and mechanism of direct acidification of phosphogypsum and deeply solidify impurities with lime

Research on the technology and mechanism of direct acidification of phosphogypsum and deeply solidify impurities with lime

Growth, structure and optical properties of Rb2CоCl4·2H2O crystals

Growth, structure and optical properties of Rb2CоCl4·2H2O crystals

Synthesis, structure and characterizations of the first alkali-metal/alkaline-earth-metal oxalatophosphate Na4Mg3(HPO4)4(C2O4)·2H2O

Synthesis, structure and characterizations of the first alkali-metal/alkaline-earth-metal oxalatophosphate Na4Mg3(HPO4)4(C2O4)·2H2O

Effect of temperature and pH value on the stability of magnesium potassium phosphate hexahydrate

AbstractMagnesium potassium phosphate hexahydrate (MgKPO4·6H2O) was used as solidification matrix to immobilize some radioactive element and some heavy metal ions, the stability of MgKPO4·6H2O under different conditions had become the focus. This work gives new insights on the stability of synthesized MgKPO4·6H2O in the different temperatures and pH values solutions. The solid phase transformed from synthesized MgKPO4·6H2O was characterized by X‐ray diffractometer (XRD), thermal gravity analysis (TG/DSC), Fourier‐transform infrared spectrum (FTIR) and scanning electron microscope (SEM) at different temperature and pH values solution. Results indicated MgKPO4·6H2O had almost no phase transition at the temperature of 50°C and 60°C. Mg3(PO4)2·22H2O appears with the increase of solution temperature. The main phase is MgKPO4·6H2O at the pH of 9 and 12, minor MgHPO4·3H2O formed at the pH of 6, next Mg3(PO4)2·22H2O formed at the pH of 3 and 6. High pH value environment is beneficial for the maintenance of MgKPO4·6H2O. This study is an important guidance for the application of MgKPO4·6H2O crystal.

In Search of Covalency Measure of Gd(III)-Ligand Interactions.

Experimental electron density distribution of the [C(NH2)3]3[Gd(EDTA)F2]·H2O crystal was determined. The derived experimental and theoretical (DFT) topological parameters such as ∇2ρc, ρc, bond degree (BD), kinetics, and potential energy were used to study the nature of Gd-O, Gd-F, and Gd-N interactions. The natural charge of the Gd is 1.86; the natural configuration of the cation is [Xe]6s0.134f7.105d0.83, and the covalency of the Gd-L bond is mainly connected with the transfer of charge from the spx ligand orbitals onto the 5d orbitals of the Gd cation. Simultaneously, the donation of charge onto the 6s and 4f orbitals occurs to a lesser extent. Moreover it was found that the donation of the ligand charges onto the Gd(III) is larger for compounds with a lower coordination number. The obtained topological parameters were analyzed in the context of the Gd(III) f-f transition properties, i.e., energy of the excited 2S+1LJ states, Judd-Ofelt intensity parameters, and luminescence lifetimes, of 18 Gd(III) compounds with various O, N, and F donor ligands (DOTA, EDTA, CDTA, DTPA, NTA, EGTA, ODA, F-, H2O, and CO32-). The calculated nephelauxetic β parameter may reflect the penetration degree of electron lone pairs of ligands inside the metal basin. Finally, it was found for the first time that the sum of the Gd(III)-L bond energy (∑EGdL) is correlated with the position of the gravity center of the 8S7/2 → 2S+1LJ transitions and increase of covalency of the Gd(III)-L bonds is associated with decrease of their bond energy. The obtained results may shed light on chemical bonding in systems containing f-elements. Such subtle differences in the covalent contribution to the Ln-L or An-L bond may tune the selectivity of the partitioning processes of lanthanides and actinides.

Enantiomer Recognition by the Difference in Adsorption Rates on the Surfaces of Chiral Crystals.

The chirality of biopolymers remains one of the mysteries of Life. For such objects, the phenomenon of supramolecular chirality (SMC) is vital. Enantiomers can be recognized by the adsorption on surfaces with SMC. However, the mechanisms of such chiral recognition are still unknown. In this work, the adsorption kinetics of menthol test enantiomers on the surfaces of γ-glycine and NiSO4•6H2O chiral crystals was studied. It was found that the difference in adsorption was observed in nonequilibrium state more often than in equilibrium. If the enantioselectivity in equilibrium state was observed, the enantioselectivity coefficient α at nonequilibrium conditions was higher. The maximum α in nonequilibrium state was 2.44 for γ-glycine crystals and 2.12 for NiSO4•6H2O crystals. Even if no differences in adsorption were observed under adsorption-desorption equilibrium conditions, a significant enantioselectivity at nonequilibrium conditions was found. This has proved the possibility of chiral recognition on surfaces with SMC by the differences in adsorption rates. Such novel chiral recognition mechanism can provide enhanced enantioselectivity in adsorption, catalysis, chromatographic separation, and chemical sensing.

Adsorption/desorption of H2O and phase transition in crystals of cobalt(II) bis(tolylterpyridine) nitrate

Adsorption/desorption of H2O and phase transition in crystals of cobalt(II) bis(tolylterpyridine) nitrate

High-Efficiency Purification and Morphology Regulation of CaSO4·2H2O Crystals from Phosphogypsum.

Phosphogypsum is a solid waste with great environmental stockpile pressure produced by the wet production of phosphoric acid. Although there are various methods to purify and utilize phosphogypsum, the means for environmentally friendly, low energy consumption, and high value-added utilization still need to be further explored. Here, CaSO4·2H2O crystal was directly purified and regulated from phosphogypsum by using the anti-solvent method. The antisolvent can be adsorbed in the c-axis direction of the crystal and further inhibit the growth rate in this direction, resulting in a change in the morphology of the crystal. By adjusting the polarity and chain length of the anti-solvent, the morphology of CaSO4·2H2O crystal can change from butterfly-like flake crystals to hexagonal prism-like crystals. When n-propanol with long chain was used as the anti-solvent, the morphology of the CaSO4·2H2O crystal showed a hexagonal prism with a specific surface area of 19.98 m2/g and a Cu2+ loading efficiency of 52.67%. The encouraging results open up new possibilities for the application of phosphogypsum.

Microscopic analysis of mechanical anisotropy and damage evolution of 3D printed rock-like samples under uniaxial compressive tests

Microscopic analysis of mechanical anisotropy and damage evolution of 3D printed rock-like samples under uniaxial compressive tests

High value-added utilization of desulfurized building gypsum as self-leveling mortar: the comprehensive effect of cement.

The utilization of desulfurized building gypsum as raw material for gypsum-based self-leveling mortar (GSL) is limited by its low strength and poor water resistance. The objective of this study is to enhance comprehensive properties of GSL and prepare qualified desulfurized building gypsum-based self-leveling mortar that can be effectively applied in practical engineering projects. The influence of cement on water consumption rate of initial fluidity (W/M ratio), fluidity, setting time, mechanical strength, and water resistance of GSL were evaluated. Additionally, rheological parameter, heat of hydration, crystal morphology, and pore structure were also analyzed. Cement significantly improved the fluidity of slurry. Moreover, the compressive strength and softening coefficient of GSL reached 20.6MPa and 0.56 at 10% cement, respectively. Furthermore, cement reduced the 30-min-fluidity loss and improved fludity by reducing the yield stress and increasing the plastic viscosity of screed. The transformation of hydration kinetics of GSL could be due to Ca2+ and OH- released by cement, thus resulting in the shortening of initial setting time and the prolongation of the interval between initial and final setting time. Scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS) showed that CSH gel and AFt crystal would generate on the surface of CaSO4·2H2O crystal, making the structure more compact. Mercury intrusion porosimetry (MIP) indicated that cement greatly reduced the porosity through the water reduction effect in the early stage and continuous hydration in the later stage. The continuous hydration of cement also increased the shrinkage rate. This work was expected to provide reference for promoting the application of desulfurized building gypsum as the high value-added screed.

4-Carboxyanilinium dihydrogen phosphate monohydrate, an organophosphate adducts of 4-amino benzoic acid: Structural, vibrational, thermal, and computational studies

4-Carboxyanilinium dihydrogen phosphate monohydrate (4-CAH2PO4·H2O), an organophosphate adduct, was synthesized and characterized by single-crystal X-ray diffraction, Fourier transform infrared (FTIR), Differential scanning calorimetry (DSC) and computational analysis performed using CrystalExplorer 21, Gaussian 09W and Multiwfn 3.7 software. The complex 4-CAH2PO4·H2O crystallized in the triclinic space group, P-1, with two molecules each of 4-carboxyanilinium (4-CA) cations, H2PO4– anions, and water, respectively, in an asymmetric unit. Crystal data for C7H12NO7P: triclinic, space group P-1, a = 8.5238(2) Å, b = 8.9068(2) Å, c = 14.4976(4) Å, α = 106.456(2)°, β = 90.195(2)°, γ = 92.811(2)°, V = 1054.13(5) Å3, Z = 4, T = 293 K, μ(Cu Kα) = 2.587 mm-1, Dcalc = 1.595 g/cm3, 18182 reflections measured (6.358° ≤ 2Θ ≤ 146.396°), 4149 unique (Rint = 0.1018, Rsigma = 0.0521) which were used in all calculations. The final R1 was 0.0584 (I > 2σ(I)) and wR2 was 0.1712 (all data). The organic layer containing 4-CA cations and the inorganic layer containing phosphate anions and water molecules in 4-CAH2PO4·H2O crystals are connected through a three-dimensional network of strong charge-assisted N–H···O and C-OH···O hydrogen bonds. The fingerprint plot of 4-CAH2PO4·H2O obtained indicated that the most prominent interaction corresponds to the short O···H contact, followed by the H···H and H···C contacts. The intermolecular interaction topology of 4-CAH2PO4·H2O has been quantitatively analyzed. The 4-CAH2PO4·H2O complex was optimized by density functional theory (DFT) with B3LYP/6-31G basis set and the theoretical IR vibrational spectra determined. The noncovalent interaction (NCI) and quantum theory of the atom in the molecule (QTAIM) analysis were done using Multiwfn 3.7 software. 4-CAH2PO4·H2O complex structure and its computational analysis are also compared with that of 4-carboxyanilinium dihydrogen phosphate (4-CAH2PO4).

Bipolar membrane crystallization enables near zero-waste production of high-purity oxalic acid crystals

Bipolar membrane crystallization enables near zero-waste production of high-purity oxalic acid crystals

Bio-sorption capacity of cadmium and zinc by Pseudomonas monteilii with heavy-metal resistance isolated from the compost of pig manure

The tolerance of Pseudomonas monteilii X1, isolated from pig manure compost, to Cd and Zn, as well as its capacity for biosorption, were investigated. The minimum inhibitory concentrations (MIC) of Cd and Zn for the strain were 550mg/L and 800mg/L, respectively. Untargeted metabolomics analysis revealed that organic acids and derivatives, lipids and lipid-like molecules, and organic heterocyclic compounds were the main metabolites. The glyoxylate and dicarboxylate metabolism pathway were significantly enriched under Cd2+ stress. The isothermal adsorption and adsorption kinetics experiments determined that the strain had adsorption capacities of 9.96mg/g for Cd2+ and 23.4mg/g for Zn2+. Active groups, such as hydroxyl, carboxyl, and amino groups on the cell surface, were found to participate in metal adsorption. The strain was able to convert Zn2+ into Zn3(PO4)2·4H2O crystal. Overall, this study suggested that Pseudomonas monteilii has potential as a remediation material for heavy metals.

Efficient Single-Phase Tunable Dual-Color Luminescence with High Quantum Yield Greater than 100% for Information Encryption and LED Applications.

In modern society, the investigation of highly efficient photoluminescent bulk materials with excitation-induced tunable multicolor luminescence and multiexciton generation (MEG) is of great significance to information security and the application of optoelectronic devices. In this study, two bulk Cu-based halide crystals of (C4H10NO)4Cu2Br5·Br and (C4H10NO)4Cu2I5·I·H2O, respectively, with one-dimensional structures were grown by a solvent evaporation method. Unexpectedly, (C4H10NO)4Cu2I5·I·H2O displayed excitation-induced tunable dual-color luminescence; one band is a brilliant green-yellow emission centered at 547 nm with a high photoluminescence quantum yield (PLQY) of up to 169.67%, and the other is a red emission at 695 nm with a PLQY of 75.76%. Just as importantly, (C4H10NO)4Cu2Br5·Br exhibits a strong broadband green-yellow emission at 561 nm under broad band excitation ranging from 252 to 350 nm, a long PL decay lifetime of 106.9 μs, and an ultrahigh PLQY of 198.22%. These materials represent the first two examples of 1D bulk crystals and Cu(I)-based halides that have a PLQY exceeding 100%. Combining the unusual luminescence characteristics with theoretical calculations reveals that MEG contributes to the green-yellow emission with ultrahigh PLQY > 100%, and that the red emission can be ascribed to [Cu2I5]3- cluster-centered emission. Additionally, an information encryption method was designed based on the Morse Code. The high luminescence characteristics of LED devices fabricated using the (C4H10NO)4Cu2Br5·Br and (C4H10NO)4Cu2I5·I·H2O crystals appear to lead to promising applications in solid-state lighting. This work extends the catalog of high-performance luminescent materials and also promotes application prospects of low-dimensional copper-based halides in optoelectronics.

The Birefringence Modulation in Short‐Wave Ultraviolet Sulfates with Functional π‐Conjugated Cations and Polymerized Heteroleptic Tetrahedral Anions

AbstractSulfates with a large bandgap are always promising optical candidates. However, due to insufficient birefringence, their applications are restricted. Here, in terms of this deficiency, two strategies are proposed to rationally modulate the optical anisotropy of sulfates by cations and anions, respectively. For the cation modulation, the [C(NH2)3]Al(SO4)2·6H2O crystal is investigated, which exhibits an unprecedented birefringence (0.098 @ 546 nm) compared with other deep‐ultraviolet transparent sulfates, resulting from the synergy of π‐conjugated [C(NH2)3]+ and non‐π‐conjugated [SO4]2− groups. For the anion modulation, a novel functional group, [S3O6]2−, with a large polarizability anisotropy, is designed. Thus, a new crystal, NaKS3O6, is obtained, which exhibits a large birefringence of 0.130 @ 546 nm with a short ultraviolet absorption cutoff edge of 215 nm. These results confirm the validity of the strategies. Therefore, the strategies play an important role in improving sulfate's birefringence and then promoting their potential applications in advanced optical systems.

Upward vibrational frequency shift due to electron–phonon polar-coupling interaction in C12H17ClN4OS·HCl·H2O crystals

Upward vibrational frequency shift due to electron–phonon polar-coupling interaction in C12H17ClN4OS·HCl·H2O crystals

Achieving great optical anisotropy with the well-directed alignment of π-conjugated groups due to hydrogen bonds

Achieving great optical anisotropy with the well-directed alignment of π-conjugated groups due to hydrogen bonds

Recovery of tungsten from spent selective catalytic reduction catalyst by sulfuric acid precipitation and evaporation crystallization method

AbstractBACKGROUNDSelective catalytic reduction (SCR) can effectively handle NOx from flue gas in coal‐fired power plants. However, as the core part of the SCR method, V2O5–WO3/TiO2 catalyst has a limited operational life in the complex flue gas environment. The recovery of rare metals from spent catalyst would not only bring economic benefits but also solve environmental problems. The process of reducing acid leaching and further roasting‐water leaching could realize the efficient recycling of vanadium, tungsten and titanium.RESULTSAfter reducing acid leaching and roasting‐water leaching to treat spent SCR catalyst, the obtained solution containing tungsten was used as the raw material in this study. The optimal pH value of solution for removal of silicon and aluminum impurities was 9.2–9.5. The best tungsten precipitation conditions were shown as follows: a tungsten concentration of 30 g L−1, a sulfuric acid concentration of 8 mol L−1, reaction temperature of 70 °C and reaction time of 2 h. Under the optimal tungsten precipitation conditions, the tungsten precipitation efficiency can reach 92.53%. Finally, in order to further improve the purity of the crude H2WO4, the crude H2WO4 was fully dissolved in ammonia, followed by filtration and evaporation crystallization to obtain 5(NH4)2O.12WO3.5H2O (APT) crystals with a purity of 93.05 wt%. The crystallization efficiency of APT was 73.37% at 60 °C for 2 h with a rotor speed of 400 rpm.CONCLUSIONThese results indicated that a higher purity of APT crystals can be obtained by the steps of removing silicon and aluminum, precipitation of tungsten by sulfuric acid, ammonia dissolution and evaporation crystallization. © 2023 Society of Chemical Industry (SCI).

Antimony Doping Enabled Photoluminescence Quantum Yield Enhancement in 0D Inorganic Bismuth Halide Crystals.

Owing to the exterior self-trapped excitons (STEs) with adjustable fluorescence beams, low-dimensional ns2-metal halides have recently received considerable attention in solid-state light-emitting applications. However, the photoluminescence (PL) mechanism in metal halides remains a major challenge in achieving high efficiency and controllable PL properties because the excited-state energy of ns2 conformational ions varies inhomogeneously with their coordination environments. Here, a novel zero-dimensional (0D) lead-free bismuth-based Rb3BiCl6·0.5H2O crystal was reported as a pristine crystal to modulate the optical properties. By doping Sb3+ ions with 5s2 electrons into Rb3BiCl6·0.5H2O crystals, bright orange emission at room temperature was obtained with a photoluminescence quantum yield of 39.7%. Optical characterizations and theoretical studies show that the Sb3+ doping can suppress the strong exciton-phonon coupling, optimize the electronic energy band structure, improve the thermal activation energy, soften the structural lattice of the host crystals, deepen the STE states, and ultimately lead to strong photoluminescence. This work manifests a fruitful manipulation in ripening bismuth-based halides with high-efficiency PL properties, and the PL enhancement mechanisms will guide future research in the exploration of emerging luminescent materials.