TGA DTA Research Articles

C18‐DABCO‐AA: A Novel Brønsted Acidic Gemini Surfactant for the Environmental Benign Synthesis of 2,3‑Dihydroquinazolin‑4(1H)‑ones in Water at Ambient Temperature

AbstractWe have successfully synthesized a new acidic surfactant named C18‐DABCO‐AA, which contains octadecyl and acetic acid substituent on DABCO (1,4‐diazabicyclo [2.2.2] octane) unit, with an excellent yield. The synthesized surfactant was analyzed using FT‐IR, 1H NMR, and 13C NMR spectroscopic techniques. Its thermal behavior was analyzed by using the TGA–DTA technique. Our analysis indicates that the synthesized surfactant has excellent surfactant properties. Its critical micelle concentration (CMC) is 0.80 mM as determined by the conductivity method and UV–vis absorption measurement at 298.15 K. Surfactant also showed strong acidic properties with a pKa of 3.3. It is the best catalyst for the synthesis of 2,3‑dihydroquinazolin‑4(1H)‐ones (DHQs) in water at 40 °C. The synthesis is achieved via two‐component reactions of various aromatic aldehydes and anthranilamide in water at a CMC concentration of C18‐DABCO‐AA. The method was also extended for synthesizing DHQs via two‐component reactions of different ketones and anthranilamide under similar reaction conditions. The products were achieved in with yields ranging from good to excellent within 60–90 min. Additionally, the aqueous solution with C18‐DABCO‐AA was reused up to five times with a minor decrease in product yield. The present protocol is fast, energy‐efficient, and can be used on a large scale for synthetic purposes. Additionally, it boasts impressive environmentally friendly credentials.

The structural, mechanical, optical and dielectric properties of aminated PMMA-Ag-GO nanocomposite for coatings

The present study reports the synthesis and characteristics of an aminated PMMA-Ag-GO polymer nanocomposite (PNGAg) for coatings. The XRD diffractogram data indicated the presence of crystallinity in samples. The lattice strain of (002) planes and crystallite size were computed to estimate the number of graphene oxide (GO) layers. The homogenous dispersion of GO with silver (Ag) nanoparticles over the surface of the samples was verified by the SEM and EDAX tests. The thermal stability and interaction of fillers with aminated PMMA is confirmed by of TGA–DTA and FTIR analysis. Moreover, the substantial shift of FTIR bands supports the bonding of functional groups with Ag decorated GO and the stability of nanocomposite. The estimated mechanical properties like flexural strength and composite modulus (> 90 MPa) supported the applicability of PNGAg as coatings. The UV–Vis spectroscopy evidenced the characteristic absorption peaks of GO in line with range of UVC radiation in aminated PMMA. Along with high values of relative permittivity, the shift of loss tangent maxima to higher end with increase in GO concentration is attributed to greater number of interfaces. Owing to the functionalisation by naproxen along with dispersion of GO, contributed to MWS polarisation and hence strengthen the dielectric properties. As the concentration of GO rises from 0.1 mol% to 0.7 mol%, substantial shift of AC conductivity (i.e. 2.49 × 10−6 Scm−1 to 37.9 × 10−6 Scm−1) is observed. The high conductivity of PNGAg5 at 0.9 mol% GO suggests the presence of numerous layers, leading to increased interfacial polarization and a higher dielectric constant. In addition to that, the semi-circle in impedance plot and bulk resistance also supported the optimal dielectric properties of samples. As a whole, the results have shown that PNGAg nanocomposites are good coating materials for wide variety of devices.

The influence of catalyst structure on acidic strength of –SO3H groups for alkyl levulinate synthesis from biomass–derived feedstocks using sulfonic acid functionalized flexible MOF catalyst

A Brönsted acidic BUT−8(Cr)–SO3H metal–organic framework was used for the synthesis of ethyl levulinate from two different biomass–derived platform chemicals viz. furfuryl alcohol and levulinic acid. The catalyst was well characterized using various methods such as PXRD, FTIR spectroscopy, acid–base titration, NH3–TPD, TGA–DTA, SEM, TEM as well as the computational density functional theory (DFT) method. The performance of BUT–8(Cr)–SO3H catalysts was found to be superior to other catalysts (HZSM–5, H–Beta, and amberlyst –15) taken in this study. The sulfonic acid moieties bound to the aromatic naphthalene structure of BUT–8(Cr)–SO3H MOF were found to have a much stronger influence on the catalytic performance than the sulfonic acid moieties bound to the styrene framework of amberlyst–15. The key discoveries regarding the Brönsted acidic characteristics were computed via DFT incorporating the hydrogen removal energy, molecular electrostatic potential maps, and stability of the conjugate base of –SO3H moieties. The trend in the DFT–derived values was in the following order: BUT–8(Cr)–SO3H > Linker–naph –SO3H > Amberlyst–15. The results also indicate the influence of Cr metal on MOF structure to increase the acidic strength of the –SO3H group. The reaction optimization using DOE, recyclability, leaching study, and substrate scope study for both pathways using BUT–8(Cr)–SO3H were obtained.

Combined Potential of Quarry Waste Fines and Eggshells for the Hydrothermal Synthesis of Tobermorite at Varying Cement Content

Quarry waste fines and eggshells are unavoidable wastes which relentlessly contribute to environmental loads and pollution. Although many studies have suggested various methods for recycling, these wastes remain underutilized due to some technical constraints. In addition, no study has yet explored the possibility of combining quarry waste fines (QWF) and eggshell powder (ESP) for tobermorite synthesis. Tobermorite is the main component which primarily provides strength to autoclaved aerated concrete products. With this in mind, this study seeks to evaluate the potential of QWF-ESP mix at 10%, 15%, and 20% amounts of cement, respectively. The XRF, XRD, and TGA–DTA techniques were used to characterize the waste materials, while physical and mechanical property tests and XRD analysis were performed on the autoclaved samples. It was found that QWF contains 53.77% SiO2 and ESP contains 97.8% CaO which are key components for tobermorite synthesis. This study also revealed that the mixture with only 10% cement has the highest compressive strength among the QWF-ESP samples. Furthermore, the formation of tobermorite in the samples was confirmed through XRD analysis. Hence, the hydrothermal curing of QWF-ESP can be further developed to produce functional tobermorite-bearing materials.

Morphology, Crystal Structure and Thermal Properties of Nano-Sized Amorphous Colemanite Synthesis

It is important to utilize the raw colemanite (RC) mineral, which has abundant reserves in the world, and to reduce its particles to smaller sizes for nanotechnology. However, not only the particle size of the produced colemanite powder but also its other properties need to be elucidated. By using the Taguchi design, the RC mineral was ground in a high-energy ball mill. From signal-to-noise (S/N) ratio, the smallest average particle size was found to be 3.10 µm for the experiment E04/nano-sized amorphous colemanite (NAC) powder. The characteristics of as-received RC mineral and synthesized NAC material were investigated using laser particle size analyzer, optical microscopes, SEM–EDS, XRD, TEM, HRTEM, and TGA–DTA devices. It was found that the NAC powder was not homogeneous, a small peak within the 300–20 nm range appeared, and d90, d50, d10, and dmin values were, respectively, 14.6 µm, 3.08 µm, 232 nm, and 26 nm. In the XRD analysis, the pure colemanite, calcite, and silica minerals were determined. The crystal structure of the NAC powder almost turned amorphous, and the crystallite size of (031) peak was reduced to 7.3 nm. It was deduced that the average particle size was 8.29 nm (R2 = 0.86), and the d-spacing value was 0.307 nm. This significant finding was attributed to the mobility of balls and moreover it was interpreted with an equation. An unknown transition in TGA–DTA was referred to the calcite mineral. Finally, it is believed that the synthesized NAC material will be beneficial to engineering studies as a natural/mineral additive.

Optimizing the Fly Ash/Activator Ratio for a Fly Ash-Based Geopolymer through a Study of Microstructure, Thermal Stability, and Electrical Properties

Fly ash (FA)-based geopolymer was prepared using sodium hydroxide and sodium silicate (in 2.5ratio) as an alkali activator liquid (AL). The condition of FA/AL was optimized for achieving 1.00, 1.25, 1.5, and 1.75 ratios by varying the alkali concentrations, which are referred to as GP1, GP2, GP3, and GP4, respectively. The influence of slight variations in the FA/AL ratio on microstructure, morphology, functional groups, and composition was investigated by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), X-ray fluorescence (XRF), and Fourier transform infrared spectroscopy (FTIR). FESEM detected a homogeneous fused matrix of fly ash and alkali activator solution up to 1.5 ratios; GP3 showed a dense morphology. FTIR confirmed that the formation of aluminosilicate gel induced a shift in the T–O (T = Si or Al) asymmetric stretching band, nearing a lower frequency. XRD showed an amorphous structure with phases, including quartz, mullite, hematite, and sodalite. The thermogravimetry and differential thermal analysis (TGA–DTA) indicated that the geopolymer samples were thermally stable. The electrical study concluded that the geopolymer possessed insulating properties.

Synthesis, growth, and optical applications of N, N′-bis (2-aminophenyl) ethane-1,2-diammonium picrate: An organic crystal

Futuristic organic nonlinear optical single AEDP crystal bearing the IUPAC nomenclature of N, N′-Bis(2-Aminoethyl) Ethane-1,2-Diammonium Picrate was grown via slow evaporation approach in aqueous solvent. The single crystal X-ray diffraction studies were employed for resolving lattice parameters of AEDP single crystal. The data regarding triclinic crystalline structure, bonds vibrations and symmetries of molecular vibrations of the prepared single crystal were realized adopting XRD, FT-IR and vibrational measurements techniques respectively. Evidences regarding excellent crystal optical transparency and maximum crystal non-linear optical properties for the prepared AEDP crystal in the range 200–2000 nm were revealed by Optical absorbance spectrum documented in the UV–vis–NIR wavelength range enhances the scope of unearthing and evolving potential nonlinear systems. Thermal stability and nonlinear optical (NLO) nature of AEDP crystal were inspected by applying differential thermal-thermo gravimetric analysis (DTA–TGA) and second harmonic generation test respectively. The promising features of the crystal leads towards application in the design of nonlinear optical devices and light-controlled electrical switches.

Crystal Chemistry, Optic and Magnetic Characterizations of a New Copper Based Material Templated by Hexahydrodiazepine.

Crystals of the new organic-inorganic material (DAP-H2)[CuBr4] (1); (DAP = hexahydrodiazepine (C5H14N2)) were successfully synthesized by slow evaporation and characterized by single-crystal X-ray diffraction, infrared spectroscopy, thermal analysis, UV-Vis-NIR diffuse reflectance spectroscopy, and magnetic measurements. X-ray investigation demonstrates that 1 crystallizes in the monoclinic space group C2/c. The supramolecular crystal structure of 1 is guided by several types of hydrogen bonding which connect anions and cations together into a three-dimensional network. The optical band gap was determined by diffuse reflectance spectroscopy to be 1.78 eV for a direct allowed transition, implying that it is suitable for light harvesting in solar cells. The vibrational properties of this compound were studied by infrared spectroscopy, while its thermal stability was established by simultaneous TGA-DTA from ambient temperature to 600 °C. The study of the photoresponse behavior of an optoelectronic device, based on (C5H14N2)[CuBr4], has shown a power conversion efficiency (PCE) of 0.0017%, with J sc = 0.0208 mA/cm2, V oc = 313.7 mV, and FF = 25.46. Temperature dependent magnetic susceptibility measurements in the temperature range 1.8-310 K reveal weak antiferromagnetic interactions via the two-halide superexchange pathway [2J/k B = -8.4(3) K].

Chitosan-Biopolymer-Entrapped Activated Charcoal for Adsorption of Reactive Orange Dye from Aqueous Phase and CO2 from Gaseous Phase

Polymers have been proven to be an interesting class of adsorbents applied in water treatment. Biopolymers are of special interest due to their unique properties such as biocompatibility, biodegradability, and reusability. This work reports a composite formed by a chitosan biopolymer and activated charcoal using sodium citrate as a crosslinking agent. The chitosan–citrate-activated charcoal composite (CCA) was characterized using FT–IR, SEM, EDAX, XRD, TGA–DTA and BET surface area analysis. The material was found to be microporous in nature with a surface area of 165.83 m2/g that led to high adsorption capacities toward both the targeted pollutants. In an aqueous phase, the dye adsorption studies were carried out with reactive orange 16 (R-16) dye, while in a gaseous phase, CO2 adsorption capacity was evaluated. Under optimum solution conditions, maximum R-16 dye removal capacity was found to be 34.62 mg g−1, while in the gas phase the CO2 adsorption capacity was found to be 13.15 cm3g−1. Intrinsic microporosity of CCA resulted in an enhanced capture capacity for R-16 dye and carbon dioxide in the respective phases. Material sustainability studies were carried out to evaluate various sustainability parameters.

CeFeO3-CeO2-Fe2O3 Systems: Synthesis by Solution Combustion Method and Catalytic Performance in CO2 Hydrogenation.

Rare-earth orthoferrites have found wide application in thermocatalytic reduction-oxidation processes. Much less attention has been paid, however, to the production of CeFeO3, as well as to the study of its physicochemical and catalytic properties, in particular, in the promising process of CO2 utilization by hydrogenation to CO and hydrocarbons. This study presents the results of a study on the synthesis of CeFeO3 by solution combustion synthesis (SCS) using various fuels, fuel-to-oxidizer ratios, and additives. The SCS products were characterized by XRD, FTIR, N2-physisorption, SEM, DTA-TGA, and H2-TPR. It has been established that glycine provides the best yield of CeFeO3, while the addition of NH4NO3 promotes an increase in the amount of CeFeO3 by 7-12 wt%. In addition, the synthesis of CeFeO3 with the participation of NH4NO3 makes it possible to surpass the activity of the CeO2-Fe2O3 system at low temperatures (300-400 °C), as well as to increase selectivity to hydrocarbons. The observed effects are due to the increased gas evolution and ejection of reactive FeOx nanoparticles on the surface of crystallites, and an increase in the surface defects. CeFeO3 obtained in this study allows for achieving higher CO2 conversion compared to LaFeO3 at 600 °C.

Electronic, magnetic, optical properties, and morphological characteristics of nanocrystalline based on zinc–cobalt molybdate prepared by soft chemistry route

We report on a simple technique for the preparation of nanocrystalline metal molybdate Zn1-xCoxMoO4 (0 ≤ x ≤ 1) using the polymeric route. The formation mechanism, homogeneity, and structure of the obtained powders were investigated with thermal analysis (TGA–DTA), X-ray powder diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR). The morphology was examined by scanning electron microscopy (SEM), field emission scanning electron microscopy (SEM–FEG) and Brunauer–Emmett–Teller analysis (BET). The particle size was determined by transmission electron microscopy (TEM). UV–Visible spectroscopy and CIE L*a*b* colorimetric parameters were used for color characterization and measurement. According to the XRD analysis of the obtained compounds, for cobalt content greater than or equal to 45 %, the phase formed after grinding is isomorphic to α-CoMoO4. A triclinicphaseof zinc molybdate α-ZnMoO4 polycrystals compound is observed for the cobalt content less than or equal to 30 %. A triclinicstructure of α-ZnMoO4 and monoclinic symmetry of CoMoO4 coexist for cobalt contents between 30 % and 45 %. The solid solution Zn0.7Co0.3MoO4(ZnCoMo-0.3–600), which was obtained in an acidic environment, was formed of grains of quasi-spherical shape with nanometric sizes between 30 and 100 nm. The specific surface area (BET) of the nanocrystalline powders decrease as a function of the substitution of Co2+ in the ZnMoO4, the highest value recorded for the ZnCoMo-0.3–600 powder was about 56.7 m2g−1. As a result, we can claim clearly from the analysis of the diffuse reflection spectra that the thermochromism occurs from the shift of the O2–→Mo6+charge transfer band towards high energies. According to the optical band-gap energy (Eg = 2.153 eV), the monoclinic ZnCoMo-1–700 (CoMoO4) was classified as a semiconductor nanomaterial. The theoretical magnetic moment of this sample is approximately μtheorical = 5.00049 μB.

Effect of Adding Monohydrocalcite on the Microstructural Change in Cement Hydration.

This study explored the application of mineral carbonation products in the form of monohydrocalcite (MHC) as a Portland cement additive. This work studied the effect of adding monohydrocalcite on the microstructural change in cement hydration. We investigated the hydration and microstructure development of MHC–cement at different aging times and different MHC mass % values. Chemical composition changes over time were investigated using X-ray diffraction (XRD) and scanning electron microscopy (SEM). The hydration behaviors of MHC blended with cement were monitored using thermogravimetric analysis and differential thermal analysis (TGA–DTA). The results indicated that the role of MHC in the hydrated cement was enhancing the cement hydration process with may increase the long term strength gain. We also discovered the effect of MHC in term of the long-term chemical reaction and forming the new phase formation of tilleyite in the hydrated MHC cement at long curing ages that was not present in the ordinary Portland cement (OPC) system.

Photoluminescence properties of Eu3+-doped Na2CaSiO4 phosphor prepared by wet-chemical synthesis route

The present investigation focuses on the development of Eu3+ activated phosphors for near ultraviolet (NUV) excited light emitting diode (LED) applications. In this investigation, we have synthesized a series of Na2CaSiO4:Eu3+phosphors via wet-chemical method and characteristic of synthesized phosphors have been analyzed by X-ray diffraction (XRD), Scanning electron microscopy (SEM), Thermo gravimetric analysis– Differential thermal analysis (TGA–DTA) and photoluminescence (PL) techniques. The recorded excitation band indicates a broad excitation band centered at 262 nm due to charge transfer (CT) band and sharp peaks at 395 nm and 466 nm due to 7F0→5L6 and 7F0→5D2 transition of Eu3+ ions. The highest excitation intensity was observed at 396 nm wavelength. Therefore under 396 nm excitation, the emission spectrum showed characteristics peaks located at 595 nm and 615 nm, which are attributed due to the 5D0→7F1 and 5D0→7F2 transition of Eu3+ ions. Emission spectra shows dominant emission peak at orange region around 595 nm due to the magnetic dipole transition of5D0→7F1. In addition, the effects of the Eu3+ ions on the emission intensity were investigated, it was found that the emission intensity increases as the concentration of Eu3+ ions increases up to 0.5 mol%. Thereafter, PL emission intensity was decreased due to concentration quenching. The CIE Chromaticity coordinate of the prepared phosphor was located in the orange region around (0.584, 0.421) with high color purity. As per the investigation of prepared Na2CaSiO4:Eu3+phosphors, it was concluded that it is a promising candidate for lighting and display applications.

Renewable hydrogen production via glycerol steam reforming over Ni/CeO2 catalysts obtained by solution combustion method: The effect of Ni loading

A series of nanocrystalline Ni/CeO2 catalysts with various Ni content was prepared by urea-nitrate combustion synthesis and evaluated in glycerol steam reforming for renewable H2 production. The as-prepared, reduced and spent catalysts were characterized by various analytical techniques such as XRD, N2-physisorption, SEM–EDX, TEM–HAADF and SAED, H2-TPR, XPS, Raman, and DTA–TGA. NiO is predominantly in the X-ray amorphous state (particle size 2–4 nm regardless of the Ni amount), which is retained for Ni0 particles after reduction by H2. Significant fraction of NiO(Ni0) is localized between CeO2 aggregates. An increase in the Ni content leads to inhibition of the agglomeration of CeO2 crystallites and increase in CeO2 defectiveness up to 6.8 wt% Ni; formation of CeO2(Ni2+) solid solution at 8.7 wt% Ni, which decomposes upon reduction. The sample containing 6.8 wt% Ni exhibits the best combination of Ni content and dispersion, CeO2 defectiveness, glycerol conversion, H2 yield, selectivity to H2 and CO2 and has low selectivity to hydrocarbons. TEM and DTA–TGA revealed the formation of amorphous, graphite-like, and fibrous coke depending on the Ni amount. This formation leads to accelerated deactivation due to partial agglomeration of Ni0 particles and encapsulation of amorphous nickel.

Synergistic sorption performance of karaya gum crosslink poly(acrylamide-co-acrylonitrile) @ metal nanoparticle for organic pollutants

In this work, we tailor facile hydrogels nanocomposite (HNC) based on sustainable karaya gum for water treatment. Karaya gum crosslink poly(acrylamide-co-acrylonitrile) @ silver nanoparticle (KG-cl-P(AAm-co-AN)@AgNPs) HNC were made by an aqueous free radical in situ crosslink copolymerization of acrylamide (AAm) and acrylic acid (AA) in aqueous solution of KG-stabilized AgNPs. FTIR, XRD, DTA–TGA, SEM, and TEM were used to characterize HNC. The hydrogels' swelling, diffusion, and network characteristics were investigated. The removal efficiency of HNC was found to be 99% at pH 8 for a crystal violet (CV), dose of 0.02 g after 1 h. Dye adsorption by these hydrogels was also investigated in terms of isotherms, and kinetics. The dye's exceptionally high adsorption capacity on HNC for CV removal is explained by H-bonding interactions, as well as dipole-dipole and electrostatic interactions between anionic adsorbent and cationic dye molecules (Qmax, 1000 mg/g). The HNC can be regenerated with 0.1 M HCl and reused at least 10 times maintaining over 68% dye removal. The loading of AgNPs into the polymeric matrix of KG-cl-P(AAm-co-AN) significantly increases the removal percentage of CV dye from its aqueous solution, according to this study.

Synthesis, structural characterization, antibacterial activity, DFT computational studies and thermal analysis of two new thiocyanate compounds based on 1-phenylpiperazine

Two hybrid materials, (HPhPip)2[Co(NCS)4] (I) and (HPhPip)(NCS)•PhPip (II), were grown using the slow evaporation method. The characterization of both compounds was accomplished by means of different analytical techniques such as IR, TGA–DTA, and single X-ray diffraction. XRD showed that compounds (I) and (II) crystallized into triclinic and noncentrosymmetric orthorhombic systems, respectively. In Compound (I), the Co(II) ion is surrounded by four NCS−anions and shows a distorted tetrahedral coordination geometry. Crystal packing analysis indicates that the [Co(NCS)4]2−anion and 1-phenylpiperazinium cation are linked together through N–H…S to form a graph set. Compound (II) presents an interesting 3-D network via N–H…N, C–H…S, and C–H•••π intermolecular interactions between HPhPip+, NCS−, and PhPip, consolidating the stacking of the crystal. FT-IR was used to explore the modes of vibration of the different functional groups present in two compounds. A theoretical investigation has also been performed via DFT on the molecular structure of compounds, allowing the determination of the Mulliken charge distribution, the Molecular Electrostatic Potential maps, and the HOMO–LUMO diagrams. The Hirshfeld surface, two-dimensional fingerprint plots and enrichment ratio were investigated to indicate the important role of intermolecular interactions. The robust thermal stability of the two crystals was ensured by thermogravimetric–differential thermal analysis. Finally, the bacterial potency of two compounds has been surveyed.

THE EFFECT OF PH AND CALCINATION TEMPERATURE ON THE ZrO2 PHASE FORMATION FROM NATURAL ZIRCON SAND OF KERENG PANGI

In this research ZrO2 has been synthesized from Kereng Pangi zircon sand in Central Kalimantan through alkali fusion-coprecipitation method. Firstly, zircon sand (ZrSiO4) was purified to reduce impurities by magnetic separation, cleaned using an ultrasonic cleaner, soaked/leached with HCl 2 M for 12 hours and leached with HCl at 60 ºC for 3 hours. Secondly, alkali fusion was done with KOH as an alkali. This product was then washed by water and dried before leached with HCl 30% at 90 ºC for 30 minutes to precipitate and seperate Silica from Zircon. ZrO2 filtrate (ZrOCl2) precipitated with NH4OH at pH 4, pH 7, and pH 10 forms Zr(OH)4 gel. Zr(OH)4 gel was dried and characterized by DTA-TGA, which was then followed by calcination based on DTA TGA results at temperature ranges of 550 ºC - 700 ºC to produce ZrO2. XRD results show that single tetragonal phase of ZrO2 is formed in all variations of pH precipitation and calcination temperature. An analysis using MAUD software show that crystal size reduces as the increase in precipitation of pH. The crystal size results are 110 nm, 66 nm and 48 nm at pH 4, pH 7 dan pH 10 at 700 ºC, respectively. Moreover, XRF results show that ZrO2 with purity is at around 95.8 % at pH 4 and 96.3 % at pH 7 and pH 10.

Influence of synthetic parameters on the enhanced photocatalytic properties of ZnO nanoparticles for the degradation of organic dyes: a green approach

Herein, we report a green synthetic strategy using aqueous leaves extract of Actinodaphne madraspatna Bedd (AMB) for the synthesis of ZnO NPs. The physical shape, size, thermal stability, surface area, surface composition and chemical state, morphological and optical properties of the synthesized ZnO NPs are well characterized through UV–Visible diffuse reflectance spectroscopy (DRS UV), Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), Raman spectroscopy, thermal gravimetric analysis–differential thermal analysis (TGA–DTA), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), Brunauer–Emmett–Teller (BET) and X-ray photon spectroscopy (XPS). FT-IR spectrum of ZnO NPs showed a characteristic peak at 416.62 cm−1. Optical studies of prepared ZnO NPs showed the bandgap values are reduced in the range of 3.05 to 2.96 eV. The XRD and TEM data revealed the synthesized ZnO NPs exist in wurtzite crystal structure with crystallite sizes of 18 nm to 68 nm range. The variation in bandgap, surface area and crystallite structure of ZnO NPs would be achieved by changing the experimental parameters. FESEM showed spherical-shaped structure. XPS result confirmed the atomic states of Zn and O. The green synthesized ZnO NPs were examined for the photocatalytic degradation of methylene blue (MB) and acid violet 17 (AV17) dyes under UV light and the rate constants ‘k’ was calculated. It is found that the green synthesized ZnO NPs with reduced bandgap showed enhanced photocatalytic activity with higher rate constant.

Tungstic acid (H4WO5) immobilized on magnetic‐based zirconium amino acid metal–organic framework: An efficient heterogeneous Brønsted acid catalyst for l‐(4‐phenyl)‐2,4‐dihydropyrano[2,3c]pyrazole derivatives preparation

A new magnetic nanocatalyst based on the immobilization of tungstic acid onto new design robust, cost‐effective, green, and scalable zirconium‐L‐aspartate amino acid metal–organic framework (MOF)‐grafted L‐(+)‐tartaric acid stabilized magnetite nanoparticles (Fe3O4/tart‐NPs) was synthesized by two successive solvo (hydro)‐thermal methods. This catalyst was characterized by Fourier‐transform infrared (FT‐IR), energy‐dispersive X‐ray spectroscopy (EDS), X‐ray diffraction (XRD), field‐emission scanning electron microscopy (FESEM), Brunauer–Emmett–Teller (BET), Barrett–Joyner–Halenda (BJH), zeta potential, Thermogravimetry Analysis‐Differential Thermal Analysis (TGA–DTA), and vibrating sample magnetometer (VSM) analyses. This catalyst is outstanding to prepare l‐(4‐phenyl)‐2,4‐dihydropyrano[2,3‐c] pyrazole derivatives in aqueous media due to the open metal sites, high and steady proton conductivity in the zirconium‐MOF, MIP‐202(Zr), and MOF and also due to Brønsted acid properties of tungstic acid. This acidic catalyst can easily be extracted by an outward magnetic field after completion of the reaction without any deactivation or selectivity loss. The products were characterized by spectroscopic analysis (FT‐IR,1H‐NMR, and13C‐NMR). The optimized reaction conditions and a possible reaction mechanism are outlined.

Influence of Yb3+ ion incorporation in the structure of Yttrium Divanadate(V) on the properties of a new ceramic solid solution Y8-yYbyV2O17

New substitutional, limited solid solution of the formula Y8-yYbyV2O17 where 0 < y ≤ 2.0 was synthesized by the high-temperature reaction in the air from mixtures of α-Y8V2O17 with Yb8V2O17. The new Y8-yYbyV2O17 were characterized by powder XRD, DTA–TGA, IR, UV–vis-DRS and SEM methods. The structure, thermal stability, unit cell volume, band gap energies as well as the position of the IR absorption bands in the spectrum of Y8-yYbyV2O17 were determined. The solid solution was established to have the same structure as β-Y8V2O17 and it was found that with increasing concentration of Yb3+ ions in its crystal lattice the volume of its unit cell decreases along with its energy gap decreasing to 2.4 eV (for y = 2.0), while the IR absorption bands are shifted towards higher wavenumbers. The morphologies of the high temperature polymorph of Y8V2O17 and solid solution were analyzed.