Production of Copper and Cobalt Aluminate Spinels and Their Application As Supports for Inulinase Immobilization

Abaide, Ederson R.; Anchieta, Chayene G.; Foletto, Vitória Segabinazzi; Reinehr, Beatriz; Nunes, Lucielle F.; Kuhn, Raquel C.; Mazutti, Márcio A.; Foletto, Edson Luiz

doi:10.1590/1516-1439.031415

Cited by 30 publications

(11 citation statements)

References 80 publications

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“…72,79,85 The isomers differ in oxygen content and have significantly different geometries for each cluster composition (see Figure 3(b)).The XANES spectra in this case are intensely dependent on the cluster isomers. First of all, since in this case the support itself contains oxygen, and there is a known tendency of copper to mix with alumina to form copper aluminate, [86][87][88] the oxygen content of the cluster might be vague to define. In other words, Cu binds to the support and may partially dissolve in it, making it hard to define the stoichiometry of the supported cluster itself.…”

Section: Methodsmentioning

confidence: 99%

Interpreting the Operando XANES of Surface-Supported Subnanometer Clusters: When Fluxionality, Oxidation State, and Size Effect Fight

et al. 2020

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X-ray absorption near edge structure (XANES) spectroscopy is widely used for operando catalyst characterization. We show that, for highly fluxional supported nanoclusters, the customary extraction of the oxidation state of the metal from the XANES data by fitting to the bulk standards is highly questionable. The XANES signatures, as well as the apparent oxidation state for such clusters arise from a complex combination of many factors, and not only from the chemical composition in reaction conditions (e.g. oxygen content in oxidizing astrosphere). The thermallyaccessible isomerization and population of several structurally distinct cluster forms, clustersupport interaction, and intrinsic size effects all impact the metal oxidation state and XANES signal. We demonstrate this on copper oxide clusters with different compositions, Cu4Ox(x = 2-5) and Cu5Oy (y = 3, 5), deposited on amorphous alumina and ultrananocrystalline diamond (UNCD), for which we computed the XANES spectra and compare the results to the experiment. We show in addition that fitting the experimental spectrum to calculated spectra of supported clusters can in contrast provide good agreement and insight on the spectrum-composition-structure relation. Experimental XANES interpreted using the proposed fitting scheme shows the partial reduction of Cu oxide clusters at rising temperatures, and pinpoints the specific stoichiometries that dominate in the ensemble of cluster states as the temperature changes.

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Section: Methodsmentioning

confidence: 99%

Interpreting the Operando XANES of Surface-Supported Subnanometer Clusters: When Fluxionality, Oxidation State, and Size Effect Fight

et al. 2020

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“…The fact that nearly all of the main group and transition metals can be synthesized in a stable spinel structure makes it a relatively large family of compounds with manifold compositions, cation ordering, electron configurations, and valence states 9 . Owing to this large synthetic flexibility and a wide range of atomic and electronic configurations accessible within this chemical space, spinels exhibit interesting magnetic 5,10,11 , electronic 12,13 , optical 14 , and catalytic 15,16 properties useful for a diverse range of applications, including data storage 17 , high frequency electronic devices 18 , dielectrics 19 , transparent conducting oxides [20][21][22][23] , lasers 24,25 , sensing 2 , energy storage 26,27 , superconductivity 28 , and biotechnology 29 .…”

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confidence: 99%

Prediction of structure and cation ordering in an ordered normal-inverse double spinel

et al. 2020

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Spinels represent an important class of technologically relevant materials, used in diverse applications ranging from dielectrics, sensors and energy materials. While solid solutions combining two “single spinels” have been explored in a number of past studies, no ordered “double” spinels have been reported. Based on our first principles computations, here we predict the existence of such a double spinel compound MgAlGaO4, formed by an equimolar mixing of MgAl2O4 normal and MgGa2O4 inverse spinels. After studying the details of its atomic and electronic structure, we use a cluster expansion based effective Hamiltonian approach with Monte Carlo simulations to study the thermodynamic behavior and cation distribution as a function of temperature. Our simulations provide strong evidence for short-ranged cation order in the double spinel structure, even at significantly elevated temperatures. Finally, an attempt was made to synthesize the predicted double spinel compound. Energy Dispersive X-ray Spectrometry and X-ray diffraction Rietveld refinements were performed to characterize the single-phase chemical composition and local configurational environments, which showed a favorable agreement with the theoretical predictions. These findings suggest that a much larger number of compounds can potentially be realized within this chemical space, opening new avenues for the design of spinel-structured materials with tailored functionality.

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“…For comparison purposes, ZnAl 2 O 4 surface area values of 17.3, 86, 99 and 58 m 2 g −1 were obtained by combustion, co‐precipitation, hydrothermal and sol‐gel techniques (respectively), whereas CuAl 2 O 4 surface area values found in the literature were of 10, 41 and 87 (respectively) for sol‐gel, modified sol‐gel and microwave combustion techniques. Therefore, the results revealed that the route presented in this work generates materials with a high surface area by a technically easier and simpler method, without the need for sophisticated procedures such as microwave or expensive precursors …”

Section: Resultsmentioning

confidence: 99%

Reactive oxygen species‐induced heterogeneous photocatalytic degradation of organic pollutant Rhodamine B by copper and zinc aluminate spinels

Vieira

Leichtweis

Foletto

et al. 2019

J of Chemical Tech & Biotech

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BACKGROUND: The importance of potable water is immeasurable and its contamination by pollutants is a serious environmental problem. Rhodamine B (RhB), one such pollutant, is highly toxic to various organisms and may cause long-term undesirable effects when improperly disposed of. Thus, development of an efficient treatment technique is necessary. Among the new oxidation methods, heterogeneous photocatalysis is an emerging pollutant destructive technology. RESULTS: The photocatalytic activities of copper (Cu) and zinc (Zn) aluminate spinels (CuAl 2 O 4 and ZnAl 2 O 4 ) was evaluated.Chemical and physical properties were considered, and ZnAl 2 O 4 showed higher RhB degradation efficiency (73.90% in only 10 min) than CuAl 2 O 4 (51.95% in 10 min), reaching up to 100% in 30 min. According to results, a further RhB catalytic degradation pathway by ZnAl 2 O 4 was monitored by UV-visible spectrometry and ultra-high performance liquid chromatography coupled to diode array detection (UHPLC-DAD) analysis. When applied to wastewater from gemstone beneficiation, containing elevated RhB concentration, the ZnAl 2 O 4 caused 88% color removal in 120 min and its pollutant removal rate was 18 times greater than the commonly used ZnO.CONCLUSION: The superior performance of ZnAl 2 O 4 can be attributed to better pore properties, responsible for providing more active sites. These identified reactive oxygen species (ROS)-induced interactions and the species demonstrated that degradation occurs due to generation of O 2•and h + . Thus, ZnAl 2 O 4 proved to be an efficient photocatalyst for quick RhB pollutant degradation with promising potential for real wastewater treatment applications. CONCLUSIONBoth Cu and Zn aluminate spinels presented elevated catalytic performance, but when compared, ZnAl 2 O 4 presented higher J Chem Technol Biotechnol 2020; 95: 791-797

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Production of Copper and Cobalt Aluminate Spinels and Their Application As Supports for Inulinase Immobilization

Cited by 30 publications

References 80 publications

Interpreting the Operando XANES of Surface-Supported Subnanometer Clusters: When Fluxionality, Oxidation State, and Size Effect Fight

Interpreting the Operando XANES of Surface-Supported Subnanometer Clusters: When Fluxionality, Oxidation State, and Size Effect Fight

Prediction of structure and cation ordering in an ordered normal-inverse double spinel

Reactive oxygen species‐induced heterogeneous photocatalytic degradation of organic pollutant Rhodamine B by copper and zinc aluminate spinels

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