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Electrochemical detection of n-propanol on Au and Pt electrodes modified with polyaniline-based composites
Pejzlová, Michaela ; Fischer, Jan (advisor) ; Vyskočil, Vlastimil (referee)
The electrochemical oxidation of aliphatic alcohols is problematic on conventional electrode materials and to develop methods for their detection, the catalytic properties of electrode surfaces need to be exploited. This thesis is concerned with the study of the electrochemical deposition of polyaniline (PANI) in acidic media on three different electrodes, platinum, gold and glassy carbon electrode. The properties of the PANI modified electrodes were tested in comparison to the unmodified electrodes. The electrooxidation of aliphatic alcohols n-propanol and 2-propanol in alkaline medium was studied by cyclic voltammetry. Subsequently, the effect of electrodeposited noble metals (palladium and gold) on the surfaces of unmodified and PANI modified electrodes on the electrooxidation of propanol was investigated by using the same procedures. From the linear part of the concentration dependence of n-propanol on the chosen electrodes, the limit of detection was determined. The lowest value was calculated for the platinum electrode with electrodeposited gold (LOD = 0.2 mmol l−1 ). PANI modified electrodes showed wider linear dynamic range than electrodes without this modification. Keywords: cyclic voltammetry, electrooxidation, glassy carbon electrode, gold electrode, metal electrodeposition, n-propanol,...
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Optimization of electrodeposition of polyaniline on platinum electrode for propanol oxidation
Dobiášová, Klára ; Schwarzová, Karolina (advisor) ; Coufal, Pavel (referee)
Optimization of electrodeposition of polyaniline on platinum electrode for propanol oxidation Dobiášová Klára 2023 Abstract Composites of polyaniline (PANI) with rare metal nanoparticles (metal/PANI) are a promising material for the oxidation of aliphatic alcohols. In this work, the deposition of a polyaniline (PANI) film on a platinum electrode (Pt-PANI electrode) was performed potentiostatically and using cyclic voltammetry (CV). For both methods, the parameters influencing the deposition were optimized. For cyclic voltammetry, electrodeposition in aniline solution is significantly influenced by the final potential Efin of the scan. The PANI film with the highest current response during the deposition itself, which correlates with the thickness of the formed film, was created in the case of Efin + 1.1 V; i.e. the peak potential of the aniline oxidation peak. However, this method proved unreliable due to the poor reproducibility of the current response corresponding to PANI formation. For the PANI film formed by the CV method, its color change related to its oxidation state was investigated, with the color change being imperceptible to the naked eye in a basic environment and the most visible colour change occurring between + 0.05 V and + 0.2 V in an acidic environment. Potentiostatic deposition of...
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Electrochemical oxidation of selected bile acids in acetonitrile
Habániková, Shannelle Diana ; Schwarzová, Karolina (advisor) ; Fischer, Jan (referee)
The concentration of bile acids is an important parameter in hepatobiliary tract diseases. This work deals with the electrochemical oxidation of the chenodeoxycholic (CDCA) and cholic acid (CA) at boron dopped diamond (BDD) electrode in comparison with the oxidation at glassy carbon (GCE) and platinum electrode (PtE), in a mixed environment of acetonitrile and water (0.26 % from 0.1 mol·l-1 HClO4, supporting electrolyte). The measurement was carried out in an electrochemical cell with salt bridge containing 0.5 mol·l-1 NaClO4 separating the working and the Pleskov's reference electrode (0.01 mol·l-1 AgNO3 and 1 mol·l-1 NaClO4 in acetonitrile). Cyclic voltammetry (CV) characterization of BDD electrode by a redox pair [Fe(CN)6]4-/3- (c = 0.1 mmol·l-1) in 1 mol·l-1 KCl was performed. Quasi-reversible behaviour was observed and the difference of the anodic and the cathodic peak potential ranged from 80 to 200 mV, depending on the scan rate. Alumina polishing (4 min) of the BDD electrode was identified as the most appropriate method of activating the surface and it was applied between consecutive voltammetric scans in the presence of CA and CDCA. Irreversible anodic peaks of CDCA and CA in acetonitrile-water (0.26 %) were observed at the relatively high potentials of about +1100 ± 100 mV, depending on...
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Electrochemical Oxidation of Selected Bille Acids in Acetonitrile
Klouda, Jan ; Nesměrák, Karel (advisor) ; Rychlovský, Petr (referee)
The use of voltammetry for determining bile acids and similar compounds is described in literature, but in most cases separation precedes. The goal of this bachelor's thesis was to develop a method for direct determination and identification of seven selected bile acids. The experiments were carried out in non-aqueous medium of acetonitrile using DC voltammetry. As the working electrode a rotating disc platinum electrode and a rotating disc glassy carbon electrode were employed. Platinum electrode proved not to be suitable for this kind of use. The GCE on the other hand showed some potential, but the chemical properties of the bile acids exclude its use in terms of identification.
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