X-ray Powder Diffraction Patterns Research Articles

Discreditation of Borishanskiite as a Mineral Species (= Polarite, PdPb)

Abstract A re-examination by electron probe microanalysis of the holotype sample of the platinum-group mineral borishanskiite, previously defined as Pd1+x(As,Pb)2 with x = 0–0.2, reveals that the mineral contains no detectable As. The new data also show the mineral to be stoichiometric, i.e., vacancy-free, with the average chemical composition (based on 2 apfu) of Pd0.99(Pb0.72Bi0.28)Σ1.00 (n = 3) or ideally, PdPb. A comparison of the powder X-ray diffraction patterns for borishanskiite (PDF 00-029-0960) and polarite (PDF 00-023; ideally PdPb) show that, within error, the two are same. Further, the refined unit-cell parameters of borishanskiite, a = 7.18(2), b = 8.62(2), c = 10.66(2) Å, agree well with those of polarite, a = 7.140, b = 8.563, c =10.501 Å. Given the new chemical data for borishanskiite, which suggest the ideal chemical formula PdPb, along with its crystallographic similarity to polarite, it is concluded that borishanskiite is equivalent to polarite. Discussion of the extent of the PdBi–PdPb solid-solution series and confusion concerning the ideal formula for polarite is also presented.

Synthesis and photoluminescence characterisation of Ca2La2O5:Eu3+, a novel red-emitting phosphor: a comprehensive study

ABSTRACT A novel low-melting-temperature chemical flux method was used to synthesise a Ca2La2O5 lattice doped with Eu3+ ions in the range of 0.5-2.5 mol-%. The phosphors were characterised by powder X-ray diffraction (PXRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy, particle size distribution, photoluminescence (PL), and Fourier transform infrared spectroscopy, respectively. The PXRD pattern revealed the hexagonal crystal structure with the space group P63/m. The microstrain (ϵ) was found to not vary with different concentrations of dopant and the negative means compression in the lattice. Particles of varying sizes and irregular shapes were observed from the SEM micrographs. The EDAX mapping revealed that all the constituent elements were found to be in appropriate ratios. Interestingly, the Ca2La2O5:xEu3+ (x = 0.5-2.5 mol-%) phosphor samples were excited at 590 nm, showing a Stokes-shifted red-PL with significant intensities at 615 and 627 nm. Unconventionally, when the phosphor is excited at 590 nm, the Eu3+ ion-characteristic luminescence owing to 5D0→7FJ (J = 0, 1, 2, 3, 4) transitions are manifested. Another remarkable observation is that the PL at 627 nm corresponding to 5D0→7F3 transition was much stronger than the 615 nm emission of Eu3+ corresponding to 5D0→7F3 transition, indicating high colour purity among the available red-emitting phosphors.

Green production and analysis of silver nanoparticles utilizing Pathor Kuchi Leaf

Silver nanoparticles (Ag NPs) were manufactured utilizing Pathor Kuchi Leaf (PKL) extract in an environmentally, cost-effective green way. X-Ray Powder Diffraction (XRD), Fourier Transform Infrared (FTIR), Ultraviolet–Visible Spectroscopy (UV–Vis), and Scanning Electron Microscopy (SEM) have been used to look into Ag NPs generation. The crystalline structure was shown by the XRD pattern investigation, and its typical size is 19 nm. Its biological molecules composites are in charge of the diminishment and also the capping of Ag NPs, according to FTIR spectra. The UV–Vis spectra of silver NPs expressed a noticeably large absorption peak centered at ∼400 nm, which denoted the production of Ag0 from Ag+. After the distribution of sizes analysis, it must have been discovered that the mean dimension of the particles of the spherical silver nanoparticles in the SEM pictures was 5.33 µm. Ag NPs have been shown to potentially improve the power generation, short circuit current, and open circuit voltage of PKL bio-electrochemical cells. This work exhibits a straightforward, economical, and ecologically friendly way of manufacturing. The uniqueness of this work is that it is the first-ever comparative analysis of Ag NPs’ production utilizing PKL extract. The majority of the conclusions have been grouped and visually explained.

Local Structural Investigation of Near-Infrared-Reflective Black Ca2(Mn,Ti)O4 Pigments Using Synchrotron Radiation X-Ray and Density Functional Theory Calculations.

Layered perovskite black Ca2(Mn,Ti)O4 ceramics were studied by using synchrotron radiation X-rays (SRX) and density functional theory (DFT) calculations to investigate the valence states of the cations, average/local structures, and electronic states. The crystallographic data were obtained by the Rietveld refinement of the obtained synchrotron radiation X-ray powder diffraction patterns. X-ray absorption near edge structure (XANES) spectroscopy measurements revealed that the ratios of Mn4+ and Ti4+ were about 82 and 95%, respectively, in all samples, and the Mn/Ti valences were not affected by the introduction of Ti4+. In addition, two pre-edge peaks were observed in the Mn-XANES spectra, but their peak positions and intensities were affected by doping with Ti4+, indicating that the symmetry of the MnO6 octahedra was changed. A comparison of the atomic distances estimated from the Rietveld analysis and radial distribution function (RDF) revealed that there were large differences between the M-M distances (M = Mn, Ti). Therefore, XANES simulations were carried out to obtain models of the local structure. The experimental and theoretical data indicate that the Mn atoms were configured in a zigzagging arrangement, and the distortion of the MnO6 octahedra increased with the increase in the degree of Ti4+ doping. The origin of the changes to the pre-edge peaks was not only the crystal field strength around Mn but also the symmetry of the MnO6 octahedra.

Investigation of vapochromism of 3,3′,5,5′-tetramethylbenzidine-tetrasilicicfluormica intercalation compounds through visible diffuse reflection and powder X-ray diffraction

In this study, we synthesized intercalation compounds of 3,3′,5,5′-tetramethylbenzidine (TMB) and tetrasilicicfluormica (TSFM) via a commonly used cation exchange method with TMB2+/TSFM cation exchange capacity (CEC) ratios of 1.0, 2.0, 2.7, and 5.4. These materials were characterized using powder X-ray diffraction (XRD), X-ray fluorescence, thermogravimetric-differential thermal analysis, scanning electron microscopy, and visible absorption spectroscopy. The vapochromism of each sample was assessed directly from the exterior of the glass sample tube using diffuse reflectance spectroscopy. All specimens vacuum-dried at 50 °C appeared yellow but turned green under water vapor at TMB/CEC = 2.0, 2.7, and 5.4, and blue under acetonitrile vapor at all TMB/CEC ratios. The sample with TMB/CEC = 2.0, in particular, exhibited clear vapochromic effects towards water and acetonitrile. Methanol and formic acid induced color changes similar to that of water vapor but less intense, except at TMB/CEC = 2.0. The color of each sample faded upon exposure to gaseous ammonia, whereas ethanol, acetone, iodomethane, and nonpolar solvents did not induce any color changes. The powder XRD pattern suggested changes in the array structures of TMB in the interlayer spaces due to vapor exposure.

The influence of Fe loading on the optical and gas sensing characteristics of SnO2/ZnO heterostructures

In the present study, SnO2/ZnO heterostructures and iron (Fe) loaded SnO2/ZnO heterostructures were prepared using a simple two-step hydrothermal route by varying the Fe loading concentration in the range of 0.02–1.00 wt%. The effect of loading different concentrations of Fe on the surface of the SnO2/ZnO heterostructure was analyzed and discussed. X-ray powder diffraction patterns revealed rutile tetragonal and hexagonal wurtzite crystal structures. Scanning electron microscopic images showed spherical nanospheres and hierarchical nanostructures with an average diameter of 22 and 20 nm, for the SnO2/ZnO and 0.02–0.8 wt%/Fe/SnO2/ZnO respectively. Nonetheless, a 1.0 wt% Fe/SnO2/ZnO displayed platelets-like structures surrounded by hierarchical nanostructures. The optical band gap of the SnO2/ZnO heterostructure reduced from 3.1 eV to 1.9 eV upon loading Fe content. The photoluminescence spectra showed that all the materials contained a higher amount of surface defects. The 1.0 wt% Fe/SnO2/ZnO heterostructure-based sensor displayed enhanced response toward 100 ppm xylene. This improvement could be linked to the porous behaviour observed in the heterostructure of 1.0 wt% Fe/SnO2/ZnO nanoplatelets, which allowed more xylene gas adsorption.

Structural and magnetic properties of nanoparticles of La3Ni2NbO9 double perovskite

The nanoparticles of La3Ni2NbO9 (LNNO) have been produced via the glycine-nitrate combustion technique followed by a process of calcination with an average crystallite size of ∼ 25 nm. The powder X-ray diffraction (XRD) pattern was analyzed for structure analysis by Rietveld structure refinement. Study on the XRD pattern reveals that LNNO crystallizes in the single phase of monoclinic crystal structure with P21/n space group. Analysis of temperature-dependent magnetization reveals that nanoparticles of LNNO undergo paramagnetic to antiferromagnetic phase transition at Neel temperature TN ∼ 43 K and antiferromagnetic to spin glass transition at Tg ∼ 31.45 K. Analysis of magnetic ac-susceptibility reveals that the LNNO nanoparticles follow Vogel-Fulcher and dynamic scaling power laws in the low-temperature region.

Unveiling room temperature ferromagnetism in Zinc(II)-picoline complex modified TiO2 for spintronic applications

Ferromagnetic materials have long been a focal point of research due to their potential applications in spintronics, data storage, and magnetic sensors. In recent years, metal oxide semiconductors have garnered attention as promising candidates for ferromagnetism, thanks to their tunable properties and compatibility with existing semiconductor technologies. In this study, we present an organo-metallic complex of [Zn(pic)2Cl2] grafted onto TiO2 core-shell nanoparticles (NPs), resulting in the generation of ferromagnetic properties at room temperature. Additionally, we explore the affinity of the organo-metallic complex over the surface of nanocrystalline anatase TiO2 through adsorption analyses in an aqueous solution. The powder X-ray diffraction patterns confirm the crystallization of the samples in a typical anatase structure, exhibiting phase purity without any impurity phases. UV–visible studies reveal a slight decrease in the band gap due to the formation of a core-shell structure (Zn-TiO2 complex). Photoluminescence spectroscopic study demonstrates the presence of oxygen defect-related emission peaks in Zn-modified TiO2 NPs. Remarkably, all Zn-TiO2 samples exhibit room temperature ferromagnetic behavior, prepared with various contact time intervals. The results unequivocally demonstrate that even a small amount of surface substitution of the Zn-based organometallic complex on the TiO2 surface significantly enhances the room temperature ferromagnetic ordering. Understanding the unique characteristics of this material is vital to unlocking its potential applications and exploring its capabilities in the field of spintronics.

Zinc(II)-Based Ring-and-Rod Coordination Layer as an Excitation-Wavelength-dependent Dual-Emissive Chemosensor for Discriminating Fe3+, Cr3+, and Al3+ in Water.

The reactions of Zn(NO3)2, 3,6-bis(pyridin-3-yl)-9H-carbazole (bpycz), and 2,5-dihydroxyterephthalic acid (H4dhbdc) or 2-bromoterephthalic acid (Br-1,4-H2bdc) under hydro(solvo)thermal conditions yielded corresponding coordination polymers (CPs) {[Zn(H2dhbdc)(bpycz)]•0.5H2O}n (1) and [Zn(Br-1,4-bdc)(bpycz)]•2DMAc•H2O (2), respectively, with high thermal stability approaching 350 °C. CP 1 adopts a ring-and-rod layer structure, which is topologically described as a 4-connected net with the point symbol of 2•65. Two layers are interpenetrated in parallel interlocking mode to form a double 2D → 2D polyrotaxane entanglement with extra-framework void space of 19.6%. CP 2 has a non-interpenetrating ring-and-rod layer structure of 4-connected 2•65 net topology, with extra-framework void space of 16.6%. Thermally activated 1 and 2 revealed CO2 uptakes of 101.1 and 98.6 cm3 g-1, respectively, at P/P0 = 1 and 195 K. X-ray powder diffraction (XRPD) patterns confirmed that 1 and 2 both possessed high chemical stability in H2O, CH3OH, acetone, and DMF, and framework stability during gas adsorption-desorption. The H2O suspension of 1 displayed excitation-dependent dual-emissive properties, appearing at 432 nm upon excitation at 300 nm and at 528 nm upon excitation at 365 nm. Of note, 1 was capable of detection of Fe3+, Cr3+, and Al3+ ions in H2O, showing good anti-interference ability, excellent selectivity, and high sensitivity. More interesting, the dual-emissive properties make 1 to be an excellent luminescence chemosensor to screen Fe3+, Cr3+, and Al3+ from a pool of metal ions in H2O upon excitation at 300 nm via luminescence quenching effect and then discriminate Fe3+, Cr3+, and Al3+ upon excitation at 365 nm via luminescence quenching, unaltered, and enhancement responses, respectively. On the other hand, the H2O suspension of 2 demonstrated an excitation-independent emission appearing at around 430 nm, which could be utilized to sensitively detect Fe3+ and Cr3+ ions with good anti-interference ability and excellent selectivity via luminescence quenching effect. Further, 1 and 2 were recyclability and possessed cycling stability. The plausible sensing mechanisms for 1 and 2 toward Fe3+, Cr3+, and Al3+ were also explored in detail.

Nucleation & growth of α-Ti(HPO4)2·H2O single-crystal and its structure determination from X-ray single–crystal data

α-titanium phosphate phase [α-Ti(HPO4)2·H2O; abbreviated as α-TiP] is a nanolayered metal phosphate with several industrial and recent biotechnological applications related to their nanolayered morphology and ion exchange capabilities. Structural wise, α-TiP is a tetravalent metal phosphate that tends to crystallize into microcrystalline powder. Here we report that the crystallization of single α-TiP crystals with suitable dimensions (>50 μm) for single-crystal X-ray diffraction could be effectuated using a prolonged hydrothermal treatment of a metallic titanium alloy (Ti–6Al–4V) in a highly concentrated phosphoric acid aqueous solution. Accordingly, the single-crystal X-ray diffraction analysis revealed the crystalline structure in a monoclinic space group, P21/c, with a = 8.6288(5) Å, b = 5.00546(17) Å, c = 19.1468(11) Å, and β = 127.555(9)°. Although the space group is the same crystallographic space group that was previously reported from the microcrystalline powder relying on powder X-ray diffraction (PXRD) and neutron powder diffraction, the obtained unit cell volume is slightly larger. Bulk of the obtained crystals were also subjected to detailed analyses using polarization optical microscopy (POM), scanning electron microscopy combined with energy dispersive X-ray microanalysis (SEM-EDX), Fourier transform Infrared Spectroscopy (FTIR) and thermal analysis (TG/SDTA). The single crystals are hexagonally shaped and exhibit the exact titanium to phosphorus ratio expected for α-TiP. The bulk sample PXRD pattern resembles perfectly that reported for the α-TiP polycrystalline powder with clearly sharper peaks. TGA-SDTA analysis revealed the expected thermal behaviour for α-TiP phase and demonstrated their higher thermal stability when compared to the polycrystalline powder.

Interaction of SiC with Al2O3−(t + m)ZrO2(Y2O3) Oxide Composition

We employed contact alloying in the range 1000–1860°С to study the reaction specifics between SiC and Al2O3−(t + m)ZrO2(Y2O3) oxide composition. Real-time experiments with photographic recording of the changing size and shape of the Al2O3−(t + m)ZrO2(Y2O3) sample on a SiC ceramic substrate showed that Al2O3−(t + m)ZrO2(Y2O3) compositions react with the silicon carbide substrate in the range 1720–1860°С to melt and penetrate into (impregnate) the substrate. X-ray powder diffraction patterns were measured for samples taken from the contact area of the oxide composition with SiC directly on the substrate and in a chipped-off 1-mm-deep near-surface layer. ZrС, Al2Y4O9, and Al3.21Si0.47 were formed in the contact area via redox reactions involving oxide melt, in addition to 6H-SiC, Si and Al2O3, t-ZrO2 phases, which are the initial components of the substrate and oxide composition, respectively.

Effect of sintering temperature on the structural, morphological and humidity sensing properties of ZnO nanostructure

ZnO metal oxide powder was prepared using co-precipitation method and the effect of sintering temperature was studied. Powder X-ray diffraction (PXRD) technique has been used to investigate the crystal structure and phase analysis. The wurtzite hexagonal crystal structure of the ZnO powder has been clearly seen in the PXRD pattern. Using the Scherer’s formula, the average crystallite size of ZnO powder was determined to be between 27 and 37 nm. The surface has grown spherical nanoparticles with size varying from ~100 nm to ~200 nm, as shown in the scanning electron microscopy (SEM) photograph.

Structural, magnetic, antimicrobial and hemolysis properties of sol–gel derived iron manganese tri oxide (FeMnO3) nanostructures

Nanocrystalline Iron Manganese Tri Oxide (FeMnO3, abbreviation name IMTO) material was attempted via colloidal solution followed by gel formation and subsequent processing at a calcined temperature of 480 °C. The above-mentioned compound was investigated for its structural characteristics, magnetic behavior, antibacterial response, and hemolysis experiment for spintronics and biomedical applications. The cubic crystal structure and weak ferromagnetic behaviour were noticed for the synthesized material from the powder X-ray diffraction (XRD) pattern and Vibrating Sample Magnetometer (VSM) studies. The surface structure of the title compound is noticed in aggregated spherical particles using Scanning Electron Microscopy (SEM) analysis. The antimicrobial activity of IMTO samples against gram-positive strains such as Streptococcus mutans (S. mutans) and Staphylococcus aureus (S. aureus) and gram-negative strains like Escherichia coli (E. coli) and Pseudomonas aeruginosa (P. aeruginosa) has been performed, followed by measurements of the zone of inhibition and their values are elucidated in detail. The hemolysis assay was carried out by taking human blood with the synthesized compound at various concentrations (5, 10, and 15 mg/mL), and the results showed its biocompatible nature.

Crystal structure and luminescence dynamics of highly pure LiM(PO3)3:Eu3+ (M = Sr, Ca) red phosphors for white light emitting diodes

Highly pure red phosphors LiM(PO3)3:Eu3+ (M = Sr, Ca) doped with Eu3+ (1 mol%) were synthesized via solution combustion method and their crystal structure and luminescence dynamics were studied to explore its suitability in white light emitting diodes. The Rietveld refinement analysis of the powder X-ray diffraction patterns reveals that the phosphors belong to the pure triclinic phase of LiSr(PO3)3 and LiCa(PO3) with space group P-1¯ (2). The scanning electron microscopy images showed the agglomerated morphology. The photoluminescence emission spectra under 393 nm show an orange band at 594 nm and a red band at 613 nm ascribed to 5D0 → 7F1, 5D0 → 7F2 transitions of Eu3+ ion in both the phosphors. Moreover, the spectroscopic properties such as luminescence behaviour, and Stark splitting were used to examine the symmetry of Eu3+ ions in LiM(PO3)3:Eu3+ (M = Sr, Ca) phosphors in terms of distortion induced upon doping. The Stark splitting shows that the actual site symmetry for Eu3+ ion was estimated to be D2 type for both phosphors. The photometric properties of LiCa(PO3)3:Eu3+ such as Commission International de l’Eclairage coordinates (x = 0.64, y = 0.36) near to the standard one (red), high color purity (95%) and higher brightness reveal that the phosphor has the capability of acting as a red component in n-UV white light emitting diodes.

Design and Study of Nanoceria Modified by 5-Fluorouracil for Gel and Polymer Dermal Film Preparation.

In this work we studied nanoceria (CeO2NPs) and nanoceria modified by 5-fluorouracil (5FU) as potential APIs. Nanoceria were synthesized by precipitation in a matrix of hydroxyethyl cellulose or hydroxypropylmethyl cellulose, using cerium (III) nitrate and meglumine. Nanoceria properties were estimated by UV, FTIR and X-ray photoelectron spectra; scanning electron and atomic force microscopy; powder X-ray diffraction patterns and energy dispersive X-ray microanalysis. The cytotoxicity of nanoceria and polymer-protected nanoparticles was evaluated using the established cell line NCTC clone 929 (C3H/An mouse, subcutaneous connective tissue, clone of L. line). The morphology and metabolic activity of nanoparticles at 10 μg∙mL-1 of cells was not significant. In addition, the cytotoxic effects of nanoceria were assessed on two human colorectal cancer cell lines (HT29 and HCT116), murine melanoma B16 cells and normal human skin fibroblasts. An inhibitory effect was shown for HCT116 human colorectal cancer cells. The IC50 values for pure CeO2NPs and CeO2NPs-5FU were 219.0 ± 45.6 μg∙mL-1 and 89.2 ± 14.0 μg∙mL-1, respectively. On the other hand, the IC50 of 5FU in the combination of CeO2NPs-5FU was 2-fold higher than that of pure 5FU, amounting to 5.0 nmol∙mL-1. New compositions of nanoceria modified by 5-fluorouracil in a polymer matrix were designed as a dermal polymer film and gel. The permeability of the components was studied using a Franz cell.

High-Pressure Vibrational and Structural Studies of the Chemically Engineered Ferroelectric Phase of Sodium Niobate

Pure NaNbO3 has an antiferroelectric phase at ambient pressure. The structural behaviour of the chemically engineered ferroelectric phase of sodium niobate, NNBT05: [(0.95) NaNbO3-(0.05) BaTiO3], under high-pressure has been studied using Raman scattering and angle-dispersive synchrotron X-ray diffraction techniques. At pressure > 1 GPa, noticeable changes in the Raman spectra can be seen in the low wavenumber modes (150–300 cm−1). Large changes in the positions and intensities of the Raman bands as a function of pressure provide evidence for structural phase transition. The results indicate significant changes in the bond-lengths and the orientation of the NbO6 octahedra at ~1 GPa, and a transition to the paraelectric phase at ~5 GPa, which are at lower pressures than previously found in pure NaNbO3. The powder X-ray diffraction pattern shows an appreciable change in the peak profile in terms of position and width on increasing pressure. The pressure dependences of the structural parameters show that the response of the lattice parameters to pressure is strongly anisotropic. By fitting the pressure–volume data using the Birch–Murnaghan equation of state, the isothermal bulk modulus was estimated. The experimental results suggest that on doping BaTiO3 in NaNbO3, the bulk modulus increases. The bulk modulus of NNBT05 has been estimated to be 164.5 GPa, which is fairly close to 157.5 GPa, as previously observed in NaNbO3.

Nickel-Manganese bimetallic Selenide as an electrode for supercapcitor applications

Evolving efficient electrochemically active nanostructures from earth-abundant transition metals have procured remarkable interest in recent years. In comparison with different transition metals, nickel (Ni) and manganese (Mn) are generous electrocatalysts for the energy storage applications. Herein, for the first-time Ni-Mn diselenide nanoparticles with spherical morphology were prepared by simple hydrothermal method with different concentrations of Ni and Mn. Powder X-ray diffraction (XRD) patterns confirmed the cubic phase of NiMnSe2. High resolution scanning electron microscopy (HR-SEM) confirmed the spherical morphology of synthesized NiMnSe2 nanoparticles. As a result, the Ni0.75Mn0.25Se2 exhibited an excellent electrochemical behaviour with specific capacitance of 1490F/g.

Kaolinite-titanium nanocomposite applied to the photodegradation of the genotoxic compound cisplatin and the terephthalic acid hydroxylation reaction

In this study, we synthesized and characterized kaolinite-titanium photocatalysts via functionalization of kaolinite with titanium (IV) isopropoxide through the sol-gel route to obtain Kaol-TiO2-400 nanocomposites for photodegradation of cisplatin. We characterized these materials by X-ray powder diffraction (XRD), Fourier-transform infrared (FTIR) spectroscopy, and scanning electron microscopy (SEM). We then applied the Kaol-TiO2-400 solid in photodegradation studies after heat treatment at 400 °C and evaluated the genotoxicity of cisplatin photodegradation products. XRD results showed that the basal spacing of the Kaol solid remained unchanged at 7.14 Å, which is characteristic of pure kaolinite, indicating that only the surfaces and edges of the kaolinite lamellae were altered. The FTIR spectra of the materials displayed typical bands of Ti-OH groups and kaolinite, confirming clay surface bonding. The photodegradation studies of cisplatin by UV–visible spectroscopy and high-performance liquid chromatography (HPLC) showed that the Kaol-TiO2-400 nanocomposite had the best degradation profile, reducing the concentration of cisplatin from 15.0 mg L−1 to 5 mg L−1 within 90 min. This fast degradation profile was attributed to the well-dispersed presence of anatase on the layered clay, as observed in the XRD pattern of Kaol-TiO2-400. Additionally, the photocatalytic activity was confirmed using terephthalic acid solution as a typical model to detect the presence of hydroxyl radicals. The typical fluorescent compound 2-hydroxyterephtalyc acid was obtained within 5 min of UV light exposure. The experiment was conducted over 6 cycles, and the same profile was obtained, confirming the stability of the heterogeneous photocatalyst based on kaolinite and that no leaching of the active phase occurred during the hydroxylation reaction. Thus, the higher photodegradation profile was attributed to the presence of anatase dispersed on layered kaolinite, which was efficient in reducing the mutagenicity of cisplatin, as confirmed by biological assays.

Acetalization of Alkyl Alcohols with Benzaldehyde over Cesium Phosphomolybdovanadate Salts

In this work, vanadium-substituted cesium phosphomolybdate salts with general formulae Cs3+nPMo12−nVnO40 (n = 0, 1, 2, and 3) were synthesized and evaluated in the acetalization of benzaldehyde with alkyl alcohols. All the catalysts were characterized through Raman, infrared, and ultraviolet–visible spectroscopies, powder X-ray diffraction patterns, isotherms of N2 desorption/adsorption, and measurements of acidity strength. The catalytic activity of cesium phosphomolybdovanadate salts was evaluated in the acetalization reactions of benzaldehyde with alkyl alcohols. Among the salts tested, the Cs4PMo11V1O40 was the most active and selective catalyst in the conversion of benzaldehyde to methyl benzyl acetal and benzoic acid, which was obtained without the use of an oxidant agent. The impact of the main reaction parameters on the conversion and selectivity was evaluated by varying the content of vanadium per heteropolyanion, catalyst load, temperature, and alkyl alcohols. The greatest activity of the Cs4PMo11V1O40 salt was assigned to the highest Brønsted acidity strength, as demonstrated by the acidity measurements and analysis of their surface properties. This solid catalyst has advantages over traditional liquid homogenous catalysts, such as low corrosiveness, a minimum generation of residues and effluents, and easy recovery/reuse. In addition, its synthesis route is easier and quicker than solid-supported catalysts and comprises a potential alternative route to synthesize acetals.

CO2-Induced Gate-Opening Adsorption on a Chabazite/Phillipsite Composite Zeolite Transformed from a Faujasite Zeolite Using Organic Structure-Directing Agent-Free Steam-Assisted Conversion.

Organic structure-directing agent-free steam-assisted conversion and Cs+ ion exchange were used to transform the faujasite (FAU)-type zeolite to the Cs+-type chabazite/phillipsite (CHA/PHI) composite zeolite. Compared with the pure PHI-type zeolite, the Cs+-type CHA/PHI zeolite showed gate-opening CO2 adsorption behavior and good thermal stability. In situ powder X-ray diffraction (PXRD) of the CO2 adsorption was measured to elucidate the mechanism for the gate-opening adsorption on the CHA/PHI zeolite. The Na+-type CHA/PHI zeolite did not show such adsorption behavior, and the PXRD pattern of the Na+-type CHA/PHI zeolite did not change with increasing CO2 partial pressure, which suggests that this unique adsorption behavior was caused by the PHI framework transition or Cs+ ions moving in both the CHA and PHI frameworks. Furthermore, in situ Fourier-transform infrared spectra of CO2 adsorption and CO2 breakthrough measurement on the Cs+-type CHA/PHI zeolite suggest that the CHA and PHI frameworks in the CHA/PHI zeolite shared eight-membered-ring windows and that CO2 molecules could easily diffuse from a CHA cage to a PHI framework. The ideal adsorbed solution theory was used to calculate the CO2/N2 separation selectivity for the Cs+-type CHA/PHI zeolite. At 298 and 318 K, the Cs+-type CHA/PHI composite zeolite showed a high CO2/N2 separation coefficient of >10,000 compared with other zeolites with high CO2 adsorption capacity. Furthermore, the CO2 working capacity was calculated for the Cs+-type CHA/PHI zeolite in both the pressure- and temperature-swing processes, and the results showed that the CHA/PHI composite zeolite could selectively separate CO2 from the CO2/N2 gas mixtures released from power generation plants operating using these processes.