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Effect of pH on the Oxide Film Formation on a Pristine Zr Electrode
Hromadová, Magdaléna; Kocábová, Jana; Kolivoška, Viliam; Pospíšil, Lubomír
2017 - English
Effect of pH on the oxidation of zirconium metal was studied by cyclic voltammetry in\naqueous borate buffer solutions as a function of the potential scan rate and pH from 4.80 to\n9.17. The results show that the oxide growth kinetics depends on pH of the electrolyte\nsolution and the total amount of irreversibly formed oxide under the potentiodynamic\nconditions decreases with decreasing buffer pH in accord with thermodynamic considerations.\nCathodic current corresponding to hydrogen evolution reaction diminishes in the presence of\nanodically modified electrode compared to bare zirconium.
Keywords:
zirconium; oxide film; hydrogen evolution
Available on request at various institutes of the ASCR
Effect of pH on the Oxide Film Formation on a Pristine Zr Electrode
Effect of pH on the oxidation of zirconium metal was studied by cyclic voltammetry in\naqueous borate buffer solutions as a function of the potential scan rate and pH from 4.80 to\n9.17. The results ...
Photocatalytic active coatings-environmental way to improve quality and durability of buildings
Sázavská, T.; Jakubičková, M.; Jirkovský, Jaromír; Šubrt, Jan; Peterka, F.
2017 - English
Transparent coatings of TiO2-SiO2 nanocomposite were developed to be applied on building facades in order to prevent growth of microorganisms and thus to improve urban building sustainability. Structure and texture characteristics of the prepared nanocomposites were determined by electron microscopy (SEM, TEM + EDS), their photocatalytic activity was quantified by testing self-cleaning ability and antimicrobial activity. The self-cleaning properties were evaluated according to the standard ISO method based on photocatalytic degradation of methylene blue. The TiO2-SiO2 nanocomposite coatings were applied on various types of substrates commonly used in building industry. The antimicrobial activity was mainly investigated for algae because these microorganisms are often responsible for facades ageing. According to the laboratory tests the prepared TiO2-SiO2 nanocomposites are highly efficient. This fact was already proved by first applications in real conditions. The transparent SiO2-TiO2 nanocomposites represent an ecological and noninvasive way how to keep nice appearance of buildings for a long time. It is due to their permanent photocatalytic activity causing self-cleaning and algicidal effects. Such coatings may significantly reduce ageing processes on facades of buildings that are caused by microbiological pollution and smog exhalations.
Keywords:
Photocatalysis; Photocatalytic algae degradation; Photocatalytic paint
Available at various institutes of the ASCR
Photocatalytic active coatings-environmental way to improve quality and durability of buildings
Transparent coatings of TiO2-SiO2 nanocomposite were developed to be applied on building facades in order to prevent growth of microorganisms and thus to improve urban building sustainability. ...
Mystery of Ageing of „Zero-Valent Iron“ (ZVI)
Wouafo, M. T.; Donkeng Dazie, Joel; Tchatchueng, J. B.; Noubactep, Ch.; Ludvík, Jiří
2017 - English
So called „zero-valent iron“, (ZVI), is used for water treatment, or, more generally for\nenvironmental remediation. In fact, the surface of the metallic iron powder in the presence of\nwater and oxygen cannot be considered as pure Fe0 but as a mixture of its corrosion products.\nThe remediation process occurs on the surface of these iron particles, hence, the degree of\n„corrosion“ is crucial for the process itself. Therefore, investigation of „aging“ of ZVI is an\nimportant prerequisite for deeper understanding of its activity.\nIn this work, the first results of the systematic study of aging of iron metal powder are\npresented. The investigation was performed in batch conditions in aqueous buffered solutions\npH 4, 4.7, 5.5 and in the presence of air oxygen. Increasing and then decreasing concentration\nof the Fe2+ ion in the solution appeared to be the important marker of aging process.\nIn the second part of the work, removal of Zn2+ ions using ZVI was investigated.\nElectrochemical techniques, namely polarography and its differential pulse form (DPP) were\nused for permanent monitoring of the presence of Fe2+ and Zn2+ ions in the studied solution.\nChanging concentrations of both ions revealed that at pH 5.5 the optimum aging time of ZVI\nfor removal of Zn2+ from aqueous solution is 6 hours.
Keywords:
zero-valent iron; aging effect; zinc ion removal
Available on request at various institutes of the ASCR
Mystery of Ageing of „Zero-Valent Iron“ (ZVI)
So called „zero-valent iron“, (ZVI), is used for water treatment, or, more generally for\nenvironmental remediation. In fact, the surface of the metallic iron powder in the presence of\nwater and ...
Redox Properties of Quasi Dimer of 1,3-diphenylisobenzofuran for Singlet Fission
Šimková, Ludmila; Ludvík, Jiří
2017 - English
Molecules on the base of 1,3-diphenylisobenzofuran attract an interest because of their\npossible efficiency for singlet fission This study is focused on electrochemical behaviour of\nthe „quasi dimer“ of 1,3-diphenylisobenzofuran. For characterization of reduction mechanism\nin situ UV-vis and EPR spectroscopy were used. The monomer 1,3-diphenylisobenzofuran\nand its CH2 dimer were added to this study for comparison. The redox properties of both\ncompared molecules are similar. The location and the nature of the covalent bridging unit in\nCH2dimer have small effect onthe redox potentials. But the pi-conjugation in the molecule of\nquasi dimer causes approximately 0.2 V easier oxidization and reduction.
Keywords:
1,3-diphenylisobenzofuran; dimer; Singlet fission
Available on request at various institutes of the ASCR
Redox Properties of Quasi Dimer of 1,3-diphenylisobenzofuran for Singlet Fission
Molecules on the base of 1,3-diphenylisobenzofuran attract an interest because of their\npossible efficiency for singlet fission This study is focused on electrochemical behaviour of\nthe „quasi ...
Labile Lead Phytochelatin Complexes Could Enhance Transport of Lead Ions across Biological Membrane
Šestáková, Ivana; Navrátil, Tomáš
2017 - English
In connection with studies of hazardous metals transport across model phospholipid\nmembranes, behavior of complexes of lead with phytochelatin PC2 has been examined. Using\nstripping chronopotentiometry with different values of reducing current, the release of free\nlead ions confirms labile behavior. Similar conclusion resulted from voltammetry on silica gel\nmodified carbon paste electrode.
Keywords:
phytochelatin; lead; voltammetry
Available on request at various institutes of the ASCR
Labile Lead Phytochelatin Complexes Could Enhance Transport of Lead Ions across Biological Membrane
In connection with studies of hazardous metals transport across model phospholipid\nmembranes, behavior of complexes of lead with phytochelatin PC2 has been examined. Using\nstripping ...
Electrochemical determination of 2-nitrofluorene and investigation of its interaction with DNA
Skalová, Štěpánka; Stávková, K.; Barek, J.; Vyskočil, V.
2016 - English
2-Nitrofluorene (2-NF) belongs to the group of nitrated polycyclic aromatic hydrocarbons. These compounds are categorized as environmental pollutants and they can manifest mutagenic and carcinogenic effects. A differential pulse voltammetric method at a glassy carbon electrode (GCE) was developed for sensitive determination of 2-NF. Under the optimum conditions found, a linear calibration dependence was obtained in the concentration range of 2 x 10(-7) - 1 x 10(-5) mol L-1, with the limit of quantification of 2 x 10 mol L-1. The practical applicability of this method was verified on the direct determination of 2-NF in a model sample of sand. Moreover, the mutual interaction between 2-NF and DNA was investigated using an electrochemical DNA biosensor (DNA-modified GCE). Cyclic voltammetry, electrochemical impedance spectroscopy, and square-wave voltammetry were employed in this study, confirming the formation of a 2-NF-DNA complex.\n
Keywords:
DNA biosensors; DNA interaction; glassy carbon electrode
Available at various institutes of the ASCR
Electrochemical determination of 2-nitrofluorene and investigation of its interaction with DNA
2-Nitrofluorene (2-NF) belongs to the group of nitrated polycyclic aromatic hydrocarbons. These compounds are categorized as environmental pollutants and they can manifest mutagenic and carcinogenic ...
Charge Transport in Single Molecule Junctions of Spirobifluorene Scaffold
Hromadová, Magdaléna; Kolivoška, Viliam; Sokolová, Romana; Šebera, Jakub; Mészáros, G.; Valášek, M.; Mayor, C.
2016 - English
Single molecule conductance of two spirobifluorene molecules of different length have been studied by scanning tunneling break junction (STM–BJ) methodology. First molecule contains a tripodal spirobifluorene platform, whereas a second one contains the same platform with chemically attached p-phenyleneethynylene molecular wire. The conductance values change only slightly between these two molecules, which demonstrated that such a platform provides both highly conducting pathway and stable anchor for the future molecular electronic devices.
Keywords:
single molecule conductance; spirobifluorene; break junction
Available at various institutes of the ASCR
Charge Transport in Single Molecule Junctions of Spirobifluorene Scaffold
Single molecule conductance of two spirobifluorene molecules of different length have been studied by scanning tunneling break junction (STM–BJ) methodology. First molecule contains a tripodal ...
Fosfolipidy modifikovaná elektroda ze skelného uhlíku a její využití pro stanovení pesticidů
Švecová, H.; Sokolová, Romana; Součková, J.; Skopalová, J.; Barták, P.
2016 - Czech
Lipidové membrány jsou již mnoho let studovány jako modely biomembrán. Formování lipidových membrán na povrchu pevných elektrod poprvé popsali Tien a Salamon 1. Od té doby byly použity jako substráty pro lipidové vrstvy různé materiály jako např. stříbro 2, zlato 3, rtuť 4 nebo skelný uhlík 5. Lipidový film na povrchu elektrody je schopen akumulovat organické molekuly v závislosti na jejich náboji a na jejich hydrofilním respektive hydrofobním charakteru. Je známé, že mnoho organických látek, jako jsou pesticidy, léčiva a jiné farmakologicky významné látky, interagují s fosfolipidovou vrstvou a mastnými kyselinami v membráně a mohou být silně akumulovány v lipidové tkáni. In this article we described glassy carbon electrode modified with Asolectin (mixture of phosholipids). Properties of phospholipid layer, such as its thickness or solidity, were investigated using atomic force microscopy (AFM). The modified electrode was applied for square wave voltammetry (SWV) measurements to study interactions of pesticide paraquat with phospholipid layer and to detect paraquat selectively in real samples of river water.
Keywords:
paraquat; electrochemistry; phospholipids
Available at various institutes of the ASCR
Fosfolipidy modifikovaná elektroda ze skelného uhlíku a její využití pro stanovení pesticidů
Lipidové membrány jsou již mnoho let studovány jako modely biomembrán. Formování lipidových membrán na povrchu pevných elektrod poprvé popsali Tien a Salamon 1. Od té doby byly použity jako substráty ...
Využití voltametrické metody pro sledování obsahu antioxidantu v biopalivech
Tomášková, M.; Chýlková, J.; Navrátil, Tomáš; Šelešovská, R.
2016 - Czech
Z hlediska kvality biopaliv je hlavním problémem jejich oxidační degradace během skladování, která vede ke vzniku produktů, které mohou způsobit ucpání palivových filtrů nebo korozi kovových částí motoru. Kromě toho má oxidační stabilita běžné motorové nafty podstatný vliv na stabilitu směsí s bionaftou. Právě nestabilita bionafty v porovnání s běžně používanou naftou vede k řadě otázek a obav při skladování biopaliv. Pro zpomalení oxidace a zajištění dostatečné stability je nutné nalézt vhodná aditiva a znát jejich přesné množství. Mezi antioxidanty používané pro zvýšení oxidační stability bionafty a jejich směsí s běžnou naftou patří i propyl galát 1-4. The simple and fast method for analysis of Propyl gallate (PG) in biofuels was proposed in this paper. Voltammograms of antioxidant under study were recorded using linear sweep voltammetry method at a gold disc electrode in supporting electrolyte containing 0.18 mol L-1 H2SO4 and 10 % ethanol. For purposes to monitor effects on fuel quality caused by oxidative degradation, the proposed method was applied to samples of biodiesel and Ekodiesel® (the blend of biodiesel with fuel diesel). The analysis of PG can be performed without pretreatment of Ekodiesel samples, and after extraction using distilled water in case of biodiesel samples.
Keywords:
propyl gallate; antioxidant; voltammetry
Available at various institutes of the ASCR
Využití voltametrické metody pro sledování obsahu antioxidantu v biopalivech
Z hlediska kvality biopaliv je hlavním problémem jejich oxidační degradace během skladování, která vede ke vzniku produktů, které mohou způsobit ucpání palivových filtrů nebo korozi kovových částí ...
Graphene Field-Effect Transistor as a Probe of Doping by Adsorbed Oxygen Molecules
Blechta, Václav; Mergl, Martin; Drogowska, Karolina; Kučera, Lukáš; Valeš, Václav; Červenka, Jiří; Kalbáč, Martin
2016 - English
Graphene has high potential in chemical sensing, thus understanding adsorption and charge transfer between graphene and adsorbed molecules is essential. We show that graphene field-effect transistor exhibits a moderate sensoric response towards oxygen at temperature of 150 °C. Field-effect transistors serve as a tool to probe electronic properties of graphene. We demonstrate that adsorption of oxygen molecules onto graphene leads to an upshift of Dirac point and light changes in mobility of charge carriers.
Keywords:
graphene; sensor; transistor
Available at various institutes of the ASCR
Graphene Field-Effect Transistor as a Probe of Doping by Adsorbed Oxygen Molecules
Graphene has high potential in chemical sensing, thus understanding adsorption and charge transfer between graphene and adsorbed molecules is essential. We show that graphene field-effect transistor ...
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