Catalytic wet peroxide oxidation on solid catalysts with supported or incorporated transition metals

Оvај rаd је pоsvеćеn sintеzi i ispitivаnju оsоbinа i kаtаlitičkе primеnе smеktitоm bоgаtоg mаtеriјаlа iz rudnikа Bоgоvinа, mоdifikоvаnоg pоlihidrоksi kаtјоnimа, u prоcеsimа kаtаlitičkе i еlеktrоkаtаlitičkе оksidаciје оrgаnskih zаgаđivаčа vоdа. Hidrоsеpаrаciјоm је оd pоlаznоg mаtеriјаlа dоbiјеn pоlаzni uzоrаk (PU) sа vеćim sаdržајеm smеktitа i vеličinе čеsticа mаnjе оd 2 μm. Pоlаzni uzоrаk је pоdvrgnut izmеni izmеnlјivih kаtјоnа nаtriјumоm (NaIz uzоrаk) i mоdifikаciјi Al ili mеšоvitim AlFe, AlCu ili AlCo pоlihidrоksi kаtјоnimа. Kоd AlFe mоdifikоvаnih mаtеriјаlа је оdnоs 100Fe3+/Al3+ u rаstvоru zа mоdifikаciјu biо 1, 5, 10, 15, ili 20% i dоbiјеni uzоrci su оznаčеni kао AlFe1M, AlFe5M, AlFe10M, AlFe15M i AlFe20M. Kоd AlCu i AlCo mоdifikоvаnih uzоrаkа оdgоvаrајući оdnоs је biо 10% i оni su оznаčеni kао AlCu10M i AlCo10M. Fаzni i hеmiјski sаstаv, hеmiјskа strukturа, tеksturаlnа i mоrfоlоškа svојstvа PU, NaIz i mоdifikоvаnih uzоrаkа оdrеđеni su kоrišćеnjеm XRPD аnаlizе, ICP-OES spеktrоmеtriје, mеtоdоm аdsоrpciје i dеsоrpciје N2 i SEM mikrоskоpiје. AlFeM uzоrci su dоdаtnо аnаlizirаni FTIR spеktrоmеtriјоm, DRUV-Vis spеktrоfоtоmеtriјоm i Mössbauer spеktrоmеtriјоm...This dissertation is dedicated to the synthesis and investigation of the properties and catalytic application of pillared clays based on smectite rich bentonite material from Bogovina mines in Serbia. The obtained pillared clays were tested as catalysts in catalytic and electrocatalytic oxidation of organic water pollutants. The fraction of particles with diameters smaller than 2 μm, richer in smectite, was obtained by hydroseparation. It was referred to as PU. PU was submitted to Na-exchange procedure, resulting in Na-enriched material denoted NaIz, followed by pillaring with Al or mixed Al,Fe, Al,Cu and Al,Co polyhydroxi cations. A series of Al,Fe modified samples was obtained using pillaring solutions with the following 100Fe3+/Al3+ ratios: 1, 5, 10, 15 and 20%. The obtained materials were denoted AlFe1M, AlFe5M, AlFe10M, AlFe15M and AlFe20M. Corresponding ratio in AlCu and AlCo modified samples was 10% and they were denoted AlCu10M and AlCo10M. Phase and chemical composition, chemical structure, textural and morphological properties of PU, NaIz and PILC samples were determined by XRPD analysis, ICP-OES spectrometry, N2 adsorption-desorption method and SEM microscopy. AlFe PILCs were additionally analyzed by FTIR spectrometry, DRUV-Vis spectrophotometry and Mössbauer spectrometry..

Calcium oxide on coal fly ash cancrinite-type zeolite as a catalyst for biodiesel production

This paper discloses the synthesis of new supported catalyst in which the main components of the catalyst, catalyst support and active component, derived from waste material, and its catalytic properties tested in the reaction of the production of biodiesel. Cancrinite-type zeolite catalyst support was synthesized from coal fly ash using hydrothermal technique with NaOH as the activation reagent in a rotating PTFE autoclave reactor. The active component, CaO, was derived from waste chicken eggshells by calcination at 900 °C. Supported catalytic material was synthesized by impregnation. The content of CaO in the prepared catalysts was varied from 5 to 20 wt%. The catalysts were characterized using XRD, FT-IR, SEM, N2-physisorption, and Hg-porosimetry. The methanolysis of sunflower oil was carried out in a batch reactor at 60 °C, with methanol to oil molar ratio of 12:1, and catalyst concentration of 4 wt.%. The fatty acid methyl ester content (% FAME) was analyzed using HPLC method. Structural information related to phase identification and vibration of chemical bonds in molecular units indicates that a multiphase zeolitic structure was obtained. The structure of cancrinite-type zeolite was found to be dominantly present. It was found that the catalyst impregnated with 20% of CaO gave the highest FAME percentage of 96.46 for the reaction time of 2 h

The electrochemical behavior of ion-exchange cu-alumina

The aim of this study was to investigate the response of different alumina types modified by cooper. Two alumina oxyhydrates with different water content, 3mol H2O/ mol Al2O3 (gibbsite) 0.6 mol H2O/ mol Al2O3 (α,γ-alumina phase), were used in this study. Copper modified alumina samples were prepared by ion exchange with a solution of CuSO4*5H2O. Cu-alumina samples were dried at at 110 o C overnight. The obtained samples were used as modifiers of the carbon paste electrode. Their electrochemical response toward ferricyanide/ferrocyanide redox probe was evaluated by cyclic voltammetry and correlated with the type of alumina and the amount of copper in impregnated alumina. The possibility of the application of Cu-alumina as an electrochemical sensor was tested

The influence of short thermal treatment on structure, morphology and optical properties of Er and Pr doped ceria pigments: Comparative study

Potential non-toxic pink and red ceramic pigments based on CeO2 were successfully synthesized by selfpropagating room temperaturemethod and thermally treated at 600, 900 and 1200°C for 15min. The structure, morphology and optical properties, as well as thermal stability of Ce1-xErxO2-δ and Ce1-xPrxO2-δ(x = 0.05) were examined. Single-phase composition of all obtained CeO2 pigments was confirmed using XRPD method and Raman spectroscopy and it was not dependent on temperature. The mechanism of structural behaviour was thoroughly examined using Raman and FTIR spectroscopy. Nanometric dimensions of the crystallites of all pigments were confirmed using XRPD, TEM and FE-SEM analysis. Colour properties were dependent on the temperature treatment, and their position in the chromaticity diagram was studied using UV/VIS spectrophotometry. Colour efficiency measurements were supplemented by colorimetric analysis. It is proved that all samples are thermally stable in the investigated temperature range (up to 1200°C), and their potential application as environmentally friendly pigments of desired colour is confirmed

Supplementary data for the article: Ilić, I.; Milutinović-Nikolić, A.; Mojović, Z.; Vuković, Z.; Vulić, P.; Gržetić, I.; Banković, P.; Jović-Jovičić, N. Oxidative Degradation of Aromatic N-Compounds Using Cobalt Containing Montmorillonite-Based Catalysts. Applied Clay Science 2020, 193, 105668. https://doi.org/10.1016/j.clay.2020.105668

Supplementary material for: [https://doi.org/10.1016/j.clay.2020.105668]Related to published version: [http://cherry.chem.bg.ac.rs/handle/123456789/4045

Adsorption of nicotine from aqueous solutions on montmorillonite and acid – modified montmorillonite

Montmorillonite (Mt) and acid modified montmorillonite (MtA) were tested as nicotine adsorbents. The samples were characterized using FT-IR spectroscopy and low temperature nitrogen physisorption. Nicotine adsorption was performed with respect to contact time, pH and initial nicotine concentration. The kinetics of adsorption obeyed the pseudo-second-order kinetics. The optimal pH values for nicotine adsorption were 6 and 9 for Mt and MtA, respectively. The isotherms related to adsorption on Mt at pH = 6 and 9 as well as for MtA at pH=6 were best fitted with Sips isotherm model, while adsorption onto MtA at pH=9 obeyed Langmuir isotherm model.Монморијонит (Mt) и кисело модификован монморијонит (MtA) су испитани као адсорбенси никотина. Узорци су окарактерисани FT-IR спектроскопијом и нискотемпературном физисорпцијом азота. Адсорпција никотина испитивана је у зависности од времена контакта, pH и почетне концентрације никотина. Псеудодруги ред добро описује кинетику адсорпције. Оптимална pH вредност за адсорпцију никотина на Mt је 6 док је за MtA 9. Сипсов модел најбоље описује адсорпцију никотина на Mt на pH = 6 и 9 као и на MtA на pH = 6, док се aдсорпција на MtA на pH = 9 одвија по Лангмировом моделу

Risk factors for the appearance of minimal pathologic lesions on vocal folds in vocal professionals

Background/Aim. An excessive use or misuse of voice by vocal professionals may result in symptoms such are husky voice, hoarse voice, total loss of voice, or even organic changes taking place on vocal folds - minimal pathological lesions - MAPLs. The purpose of this study was to identify the type of MAPLs which affects vocal professionals, as well as to identify the risk factors that bring about these changes. Methods. There were 94 vocal professionals who were examined altogether, out of whom 46 were affected by MAPLs, whereas 48 of them were diagnosed with no MAPLs, so that they served as the control group. All these patients were clinically examined (anamnesis, clinical examination, bacteoriological examination of nose and pharynx, radiography of paranasal cavities, allergological processing, phoniatric examination, endo-video-stroboscopic examination, as well as gastroenterologic examination, and finally endocrinological and pulmological analyses). Results. The changes that occurred most often were identified as nodules (50%; n = 23/46) and polyps (24%; n = 11/46). Risk factors causing MAPLs in vocal professionals were as follows: age, which reduced the risk by 23.9% [OR 0.861 (0.786-0.942)] whereas the years of career increase the risk [OR 1.114 (1.000-1.241)], as well as the presence of a chronic respiratory disease [OR 7.310 (1.712- 31.218)], and the presence of gastro-oesophageal reflux disease [OR 4.542 (1.263-16.334)]. The following factors did not contribute to development of MAPLs in vocal professionals: sex, a place of residence, irritation, smoking, endocrinologic disease and the presence of poly-sinusitis. Conclusion. It is necessary to introduce comprehensive procedures for prevention of MAPLs, particularly in high-risk groups. Identification of the risk factors for MAPLs and prevention of their influence on vocal professionals (given that their income depends on their vocal ability) is of the highest importance

Insights into the effect of aluminum oxyhydrates properties on their electrochemical behavior

Alumina oxyhydrates have different structural and textural properties, as well as different density of surface functional groups. Three alumina oxyhydrates with different water content, 3mol H2O/ mol Al2O3 (gibbsite), 1mol H2O/ mol Al2O3 (boehmite) and 0.6 mol H2O/ mol Al2O3 (α,γ-alumina phase), were used in this study. The samples were used as modifiers of carbon paste electrode. Their electrochemical behavior toward ferricyanide/ferrocyanide redox probe was evaluated by electrochemical impedance spectroscopy and cyclic voltammetry. Ferricyanide/ferrocyanide redox system has a well-known electrochemical behavior and is sensitive to the changes occurring at the electrode surface. The lowest charge transfer resistance was obtained for α,γ-alumina phase. The redox process of ferri/ferro redox probe on investigated electrodes exhibited a quasi-reversible behavior, since the obtained values of peak-to-peak separation are greater than 59 mV value expected for a reversible process. The response toward quinone/hydroquinone redox probe was evaluated by cyclic voltammetry in buffered solutions at various pH. Gibbsite and boehmite showed expected response, while the surface groups of α,γ-alumina phase enabled quinone oxidation to proceed through two pathways simultaneously. The surface chemistry of investigated samples influenced their electrochemical properties.Belgrade, Serbia, 20-21. September 202

Kinetic study of glucose oxidation reaction on carbon paste electrode modified with pillared clay-supported cobalt

This work investigated the kinetics of the glucose oxidation reaction on the carbon paste electrode modified with aluminum pillared clay-supported cobalt (CP-CoAP) in alkaline solution. Cyclic voltammetry and double-step chronoamperometry methods were employed for determining the kinetic parameters such as the charge transfer coefficient, the catalytic rate constant, and the diffusion coefficient. The obtained results confirm that the CP-CoAP can be considered as a competitive electrode material for glucose oxidation

Carbonized chitosan-bentonite as electrode material

Bentonite clay has shown to be a versatile material that can be easily modified and applied as an adsorbent, (electro)catalyst, or as a support for (electro)catalyst. The carbon-clay composites combine a relatively high specific surface area of the clay with a good electrical conductivity of carbon.In this paper, the effect of the applied carbonization procedure on the electrochemical properties of bentonite-carbon composite was investigated. Chitosan-modified bentonite was carbonized by conventional thermal degradation and by the hydrothermal procedure. The electrochemical characterization was performed by cyclic voltammetry and electrochemical impedance spectroscopy. The response to Fe(CN)63-/4- and Ru(NH3)62+/3+ redox probe showed that the thermally treated sample shows somewhat higher electrochemical activity and lower charge-transfer resistance. However, an investigation of composites activity toward minophenazone, performed in the pH range 3-9 showed that the hydrothermally obtained sample shows higher activity at pH above 5, while the thermally obtained sample was more active at pH below 5