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A new iron-phosphate compound (Fe₇P₁₁O₃₈) obtained by pyrophosphate stoichiometric glass devitrification.

ABSTRACT: Iron phosphates are a wide group of compounds that possess versatile applications. Their properties are strongly dependent on the role and position of iron in their structure. Iron, because of its chemical character, is able to easily change its redox state and accommodate different chemical surroundings. Thus, iron-phosphate crystallography is relatively complex. In addition, the compounds possess intriguing magnetic and electric properties. In this paper, we present crystal structure properties of a newly developed iron-phosphate compound that was obtained by devitrification from iron-phosphate glass of pyrophosphate stoichiometry. Based on X-ray diffraction (XRD) studies, the new compound (Fe₇P₁₁O₃₈) was shown to adopt the hexagonal space group P6₃ (No. 173) in which iron is present as Fe³⁺ in two inequivalent octahedral and one tetrahedral positions. The results were confirmed by Raman and Mössbauer spectroscopies, and appropriate band positions, as well as hyperfine interaction parameters, are assigned and discussed. The magnetic and electric properties of the compound were predicted by ab initio simulations. It was observed that iron magnetic moments are coupled antiferromagnetically and that the total magnetic moment of the unit cell has an integer value of 2 µ_B. Electronic band structure calculations showed that the material has half-metallic properties.

SUBMITTER: Goj P

PROVIDER: S-EPMC8617057 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:We synthesized and characterized a novel iron(II) aceto EMIM coordination compound, which has a simplified empirical formula Fe4(OAc)10[EMIM]2, in two different hydration forms: as anhydrous monoclinic compound and triclinic dihydrate Fe4(OAc)10[EMIM]2·2H2O. The dihydrate compound is isostructural with recently reported Mn4(OAc)10[EMIM]2·2H2O, while the anhydrate is a superstructure of the Mn counterpart, suggesting the existence of solid solutions. Both new Fe compounds contain chains of Fe2+ octahedrally coordinated exclusively by acetate groups. The EMIM moieties do not interact directly with the Fe2+ and contribute to the structural framework of the compound through van der Waals forces and C-H···O hydrogen bonds with the acetate anions. The compounds have a melting temperature of ∼94 °C; therefore, they can be considered metal-containing ionic liquids. Differential thermal analysis indicates three endothermic transitions associated with melting, structural rearrangement in the molten state at about 157 °C, and finally, thermal decomposition of the Fe4(OAc)10[EMIM]2. Thermogravimetric analyses indicate an ∼72 wt % mass loss during the decomposition at 280-325 °C. The Fe4(OAc)10[EMIM]2 compounds have higher thermal stability than their Mn counterparts and [EMIM][OAc] but lower compared to iron(II) acetate. Temperature-programmed desorption coupled with mass spectrometry shows that the decomposition pathway of the Fe4(OAc)10[EMIM]2 involves four distinct regimes with peak temperatures at 88, 200, 267, and 345 °C. The main species observed in the decomposition of the compound are CH3, H2O, N2, CO, OC-CH3, OH-CO, H3C-CO-CH3, and H3C-O-CO-CH3. Variable-temperature infrared vibrational spectroscopy indicates that the phase transition at 160-180 °C is associated with a reorientation of the acetate ions, which may lead to a lower interaction with the [EMIM]+ before the decomposition of the Fe4(OAc)10[EMIM]2 upon further heating. The Fe4(OAc)10[EMIM]2 compounds are porous, plausibly capable of accommodating other types of molecules.

Project description:Plastics contribute a magnificent role to modern civilization, but the waste becomes a huge burden to ecology and remains intact for a thousand years. Hence, the recent movement is shifted to biodegradable plastic. In this study, an attempt was made to introduce an added value to the environment where the bio-plasticized materials were used for phosphate removal. A G-plasticized magnetic starch-based Fe3O4 clay polymer nanocomposite (PNC) was synthesized to remove phosphate from the aqueous solution. It was synthesized from activated carbon (AC), coated iron oxide nanoparticles (CIONP), nanoclay (NC), and glycerol (G) as a plasticizer. The synthesized adsorbents were characterized with UV-Vis, SEM, XRD, and FTIR. The PNC and constituent (CIONP) were tested for phosphate removal through batch adsorption experiments. The adsorption capacity increases with increasing the adsorbent dose and decreases with an increase in phosphate concentration. The synthesized PNC effectively raised the constituent optimum phosphate ion adsorption pH from acidic (pH = 3) to slightly acidic (pH = 6). At the optimal pH, the CIONP and PNC maximum phosphate adsorption capacity (MPAC) was 3.12 and 2.31 mg P/g, respectively. In addition, the phosphate removal efficiency of PNC (45-95% at pH 6) was comparable to CIONP (58-97% at pH 3) under an initial 2-100 mg P/L. The adsorbents adsorption kinetics and isotherm study best described by the pseudo-second-order and Freundlich model, in turn. The SEM images support the conclusion, in which the PNC shows a heterogenous porous surface. Therefore, the adsorption mechanisms were mainly described by multilayer and chemical adsorption, such as electrostatic and ion exchange. It can be concluded that there is a positive synergistic effect between the biopolymer (starch) and nanomaterials that form the PNC. This study results propose the multiple added values of modified bio-plasticized material (with adsorbent) for environmental (phosphate) remediation.

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A new iron-phosphate compound (Fe₇P₁₁O₃₈) obtained by pyrophosphate stoichiometric glass devitrification.

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A new iron-phosphate compound (Fe₇P₁₁O₃₈) obtained by pyrophosphate stoichiometric glass devitrification.