Study of CuO and V2O5 Effect on IR Spectra of Polycrystalline Bismuth Niobate

Bismuth niobate (BiNbO4) ceramics were fabricated by mixed oxide method and sintered by presureless sintering method. BiNbO4 ceramics doped with V2 O5 additive in amount 0.125 wt%, 0.250 wt% and 1 wt% of was sintered at T = 910°C whereas BiNbO4 ceramics doped with 2 wt% of CuO additive was sintered at T = 890°C and T = 910°C. It was found that V2 O5 additive improved morphology of the ceramic samples. However, the chemical composition of BiNbO4 ceramics in relation to bismuth oxide and niobium oxide manifested a tendency of lack of Bi2 O3 component. Absorption bands for the BiNbO4 compound were identified. FTIR band positions associated with NbO6 octahedra suggested that the crystal structure changes after V2 O5 incorporation

X-Ray Diffraction Study of Bismuth Layer-Structured Multiferroic Ceramics

Goal of the present research was to apply a solid state reaction route to fabricate bismuth layer-structured multiferroic ceramics described with the formula Bi5FeTi3O15 and reveal the influence of processing conditions on its crystal structure and phase composition. Simple oxide powders Bi2O3, TiO2 and Fe2O3 were used to fabricate Aurivillius-type bismuth layer-structured ferroelectrics. Pressureless sintering in ambient air was employed and the sintering temperature was TS = 900°C, TS = 1000°C and TS = 1040°C. The phase composition as well as crystal structure of ceramics sintered at various processing conditions was examined with powder X-ray diffraction method at room temperature. The Rietveld refinement method was applied for analysis of X-ray diffraction data. It was found that ceramics adopted orthorhombic structure Cmc21. The unit cell parameters of bismuth layer-structured multiferroic ceramics increased slightly with an increase in sintering temperature

Norbornene oxidation by chiral complexes encapsulated in NaY Zeolite

The preparation of chiral metal complexes in NaY zeolite is reported. The guests, chiral metal complexes, were entrapped in the supercages of NaY zeolite (host) by a two-step process in the liquid phase: (i) inclusion of the selected transition metal (rhodium(III) and manganese(II)) by ion-exchange in the porous structure and (ii) introduction of the chiral ligand, an D-erythrose amino derivative, namely (2R,4S,5R)-4-[(N-methylamino)methyl]-2-phenyl-1,3-dioxan-5-ol, followed by assembly of the complex inside the void space of the zeolite. Structural (FTIR and XRD), surface studies (SEM) and chemical analyses were used to characterize the new host guest catalysts and the results indicated that chiral metal complexes were successfully encapsulated in supercages of the NaY zeolite. Catalytic studies were performed in liquid phase for norbornene oxidation using tert-butyl hydroperoxide as the oxygen source. The catalytic results were compared with styrene and cyclohexanol oxidation as model reactions. The prepared chiral catalysts exhibited catalytic activity for all oxidation reactions. The stability of the catalysts before and after reaction was confirmed by cyclic voltammetry and FTIR studies.The authors thank Dr. M. F. R. Pereira for support in the TGA analysis. I.K.B., A.R.S., and C.O. thank the Foundation for the Science and Technology (FCT, Portugal), for the contract under "Programa Ciencia 2007 e 2008". A.R.S. also thanks FCT for the contract under "Investigador FCT 2012" and I.K.B. also is thankful for the contract under the project NORTE-07-0124-FEDER-000039. The authors thank the FCT and FEDER-COMPETE-QREN-EU for financial support to the Research Centers, CQ/UM, PEst-C/QUI/UI0686/2013 (F-COMP-01-0124-FEDER-037302), the project NORTE-07-0124-FEDER-000039, the NMR Portuguese network (PTNMR, Bruker Avance III 400-University Minho), and CICECO/UA (Pest-C/CTM/LA0011/2013).info:eu-repo/semantics/publishedVersio

Graphene-Type Materials for the Dispersive Solid-Phase Extraction Step in the QuEChERS Method for the Extraction of Brominated Flame Retardants from Capsicum Cultivars

A new application of graphene-type materials as an alternative cleanup sorbent in a quick, easy, cheap, effective, rugged, and safe (QuEChERS) procedure combined with GC-ECD/GC-MS/GC-MS/MS detection was successfully used for the simultaneous analysis of 12 brominated flame retardants in Capsicum cultivar samples. The chemical, structural, and morphological properties of the graphene-type materials were evaluated. The materials exhibited good adsorption capability of matrix interferents without compromising the extraction efficiency of target analytes when compared with other cleanups using commercial sorbents. Under optimal conditions, excellent recoveries were obtained, ranging from 90 to 108% with relative standard deviations of <14%. The developed method showed good linearity with a correlation coefficient above 0.9927, and the limits of quantification were in the range of 0.35-0.82 μg/kg. The developed QuEChERS procedure using reduced graphite oxide (rGO) combined with GC/MS was successfully applied in 20 samples, and the pentabromotoluene residues were quantified in two samples. © 2023 The Authors. Published by American Chemical Society.This work was funded by Fundação para a Ciência e aTecnologia (FCT)/MCTES through national funds (projectsUIDB/50006/2020, UIDP/50006/2020, UIDB/04683/2020,UIDP/04683/2020, and LA/P/0008/2020). Virgínia CruzFernandes has FCT financial support with a Postdoc fellowship(SFRH/BPD/109153/2015). M. S. Nunes thanks FOAM4-ENER project (PTDC/QUI-ELT/28299/2017, funded byFCT/MCTES through national funds and FEDER (POCI-01-0145-FEDER-28299)) by her work contract. I. Kuźniarska-Biernacka thanks FCT for funding through program DL 57/2016�Norma transitória REQUIMTE/EEC2018/14. DianaM. Fernandes thanks FCT for her assistant researcher position(2021.00771.CEECIND)The Supporting Information is available free of charge athttps://pubs.acs.org/doi/10.1021/acs.jafc.2c07873.Material characterization; analytical study; and compar-ing methods with the literaturePeer reviewe