Electrochemical Behavior of Hybrid Films Composed of Copper Hexacyanoferrate and Conducting Polymer

Hybrid organic / inorganic films, composed of poly 4-aminoquinolidine (PAQ) matrix and Prussian blue – like copper hexacyanoferrate (CuHCFe) redox centers were prepared. Platinum disk (Pt) was used as a conductive substrate onto which the hybrid films (Pt/PAQ/CuHCFe) were electrodeposited by potential cycling. Electrochemical behavior of the modified electrode was well characterized using cyclic voltammetry technique. The hybrid film modified electrode showed improvement in the electrochemical response in aqueous and non aqueous media compared with the polymer film (PAQ) single layer. Moreover a good electrocatalytic activity towards the oxidation of hydroquinone (H2Q) was observed. In addition, the electrode exhibited a distinct advantage of good chemical and mechanical stability. (doi: 10.5562/cca1920

Electrooxidation of Iodide Ion at Poly 8-(3-acetylimino-6-methyl-2,4- dioxopyran)-1-aminonaphthalene Modified Electrode in Aqueous Solution

Poly 8-(3-acetylimino-6-methyl-2,4-dioxopyran)-1-aminonaphthalene (PAMDAN) films were electrodeposited on platinum electrode (Pt), forming PAMDAN/Pt modified electrode, to study its utility in electrooxidation of iodide ion. The electrooxidation process was investigated by cyclic voltammetry. The effects of different factors e.g. scan rate, iodide ion concentration, film thickness and acid concentration have been studied to improve the redox response of PAMDAN/Pt modified electrode during the oxidation process. (doi: 10.5562/cca1843

Ceftriaxone as an Inhibitor for Corrosion of Al in Formic Acid Solutions

The inhibiting effect of ceftriaxone on the corrosion of Al in HCOOH solution was studied by means of weight loss, thermometry, hydrogen evolution and potentiodynamic polarization techniques, complemented with surface examination using scanning electron microscopy (SEM). The obtained results showed that ceftriaxone are excellent inhibitor in HCOOH solution. The inhibition efficiency increases with inhibitor concentration. Polarization curves indicate that ceftriaxone was acted as a mixed-type inhibitor. The adsorption of the inhibitor on Al surface was found to obey Langmuir isotherm and showed a physisorption mechanism. The thermodynamic activation and adsorption parameters were calculated and discussed. Keywords: Ceftriaxone, aluminum, corrosion inhibitor, potentiodynamic polarization, adsorption, gravimetry and gasometr

Inhibitive Effect of Urea and Urea Derivatives on the Corrosion of Silver in Acetic Acid Solutions

The corrosion of silver in acetic acid was studied using potentiodynamic polarization technique in absence and presence of different concentrations of urea, thiourea and N-allylthiourea. The inhibition efficiency was found to depend on both the inhibitor type and concentration. The inhibitive action of these compounds is based on the formation of salt complex and/or the adsorption of the protonated species on the metal surface according to Temkin's isotherm. The thermodynamic parameters Kads and ΔG°ads for the adsorption process are calculated and discussed

Electropolymerization of diaminofluorene and its electrochemical properties

AbstractPoly 2,7-diaminofluorene (PDAF)/Au modified electrode was prepared using 2,7-diamino fluorene (DAF) dissolved in acetonitrile (ACN) containing 0.1M LiClO4 using consecutive multisweep cyclic voltammetry (CV) and controlled potential electrolysis (CPE) techniques. Factors affecting the film formation, such as limits of potential cycling, sweep rate, number of sweeping cycles, monomer concentration, and also polymerization techniques were examined in detail. It was found that the optimum conditions, using a potentiodynamic technique on Au electrode as the working electrode, are by sweeping the potential between –200mV and 800mV at a sweep rate of 50mV/s for 10 cycles using 5mM DAF monomer solution. The obtained modified electrode was active only in acidic aqueous solutions (pH range from 0 to 2) and its activity was found to be pH dependent. PDAF was isolated and characterized using UV–vis, 1HNMR and SEM analyses. The electrical conductivity was found to be 1.5×10−5Scm−1. An electropolymerization mechanism was proposed and discussed based on the obtained experimental data and molecular orbital calculations. The obtained modified electrode has been found to improve the electrochemical reversibility and decrease the overpotential of hydroquinone. PDAF/Au was stable chemically and electrochemically both in aqueous and organic solutions, making it an excellent candidate for sensing and/ or electrocatalytic applications

Voltammetric and impedimetric determinations of selenium(iv) by an innovative gold-free poly(1-aminoanthraquinone)/multiwall carbon nanotube-modified carbon paste electrode

Selenite (Se4+), a significant source of water pollution above the permissible limits, is considered a valuable metal by environmentalists. In this study, we described a novel electrochemical sensor that utilized a carbon paste electrode (CPE) that was modified using multiwall carbon nanotubes (MWCNTs) and poly(1-aminoanthraquinone) (p-AAQ) for finding Se4+ in water samples. Electrochemical quantification of Se4+ depends on the formation of a selective complex (piaselenol) with p-AAQ. In this work, we prepared a CPE modified by physical embedding of MWCNTs and 1-aminoanthraquione (AAQ), while the polymer film was formed by anodic polymerization of AAQ by applying a constant potential of 0.75 V in 0.1 M HCl for 20 s followed by cyclic voltammetry (CV) from -0.2 to 1.4 V for 20 cycles. The modified CPE was used for differential pulse voltammetry (DPV) of Se4+ in 0.1 M H2SO4 from 0 to 0.4 V with a characteristic peak at 0.27 V. Further, the proposed sensor was characterized by scanning electron microscopy, energy-dispersive X-ray spectroscopy, and electrochemical impedance spectroscopy (EIS). The analytical conditions regarding the electrode performance and voltammetric measurements were optimized, with the accumulation time and potential, supporting electrolyte, differential-pulse period/time, and amplitude. The EIS results indicated that the p-AAQ/MWCNTs-modified CPE sensor (p-AAQ/MWCNTs/CPE) that also exhibited low charge-transfer resistance (R-ct) toward the anodic stripping of Se4+, exhibited good analytical performance toward different concentrations of Se4+ in a linear range of 5-50 mu g L-1 Se4+ with a limit of determination (LOD) of 1.5 mu g L-1 (3 sigma). Furthermore, differential-pulse voltammetry was employed to determine different concentrations of Se4+ in a linear range of 1-50 mu g L-1 Se4+, and an LOD value of 0.289 mu g L-1 was obtained. The proposed sensor demonstrated good precision (relative standard deviation = 4.02%) at a Se4+ concentration of 5 mu g L-1. Moreover, the proposed sensor was applied to analyze Se4+ in wastewater samples that were spiked with Se, and it achieved good recovery values