Analytical & Bioanalytical Electrochemistry
Volume:11 Issue: 12, Dec 2019

A simple and highly selective electrochemical method for the investigation of catechol (CC) and hydroquinone (HQ) was developed on the surface bare carbon paste electrode (BCPE) modified with electropolymerized thin film of o-Phenylenediamine (o-PD) by using cyclic voltammetric technique. Electrochemical measurements were carried by using both cyclic voltammetric (CV) and differential pulse voltammetric (DPV) techniques at poly(o-PD) modified carbon paste electrode (MCPE). The proposed modified electrode shows adsorption-controlled process and exhibited a good limit of detection for CC and HQ was 1.1 and 2.1 µM respectively. In order to study the selectivity of the electrode, interference study was carried out by using DPV technique. Therefore, poly(o-PD)/MCPE showed excellent electrocatalytic behavior for the simultaneous electrochemical investigation of CC and HQ

The aim of this work is to characterize the seed oil of Aleurites moluccana and to develop a new formulation based on this oil (noted as “ALM”), which was used as a green corrosion inhibitor for iron in acidic solution. The fatty acid composition was determined using the chromatography gas GC/MS analysis. The Electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization measurements were carried out for different concentrations of the ALM formulation, immersion times and rotation speeds. The surface analyses was performed by scanning electron microscopy (SEM) coupled with the energy dispersive X-Ray analysis (EDX). The results showed that the seeds oil of Aleurites moluccana was principally composed of unsaturated fatty acids (Oleic, Linoleic and Linoleinic acids) reached a value of 88%. The inhibition efficiency increases with increasing of concentration to attain a value of 97% at 250 ppm of the ALM formulation and acts as a mixed type inhibitor. This efficiency is reinforced by increasing immersion time and the rotation speeds values of the working electrode

The purpose of this study is to measuring the chloride ion concentration in blood serum using a pair of chloride ion-sensor and reference electrode at integrating single strip (ISS). The chloride ion-sensor is offered through the chlorination process of the Ag surface on the strip to form an Ag/AgCl layers are sensitive over of chloride ion. The reference electrodes have been fabricated using three membrane layers with different roles and compositions. The first layer is a mixture of Chitosan/Cellulose Acetate (CA) membrane doped with 3 M KCl salt, where the first layer is placed above the surface of the Ag/AgCl electrode that has been previously provided. The first layer acts as an inner layer. While the second layer is a mixture of Chitosan/CA membrane doped with 0.1 M KNO3 salt which acts as an outer layer. While the third layer is a CA membrane that acts as a protective layer. Chitosan/CA membrane mixture uses a ratio of 20:80. The ISS showed a good performance by generating range measurement 1 M–10-3 M and had selectivity towards H2PO4-=-3.40 to -3.64, HPO42-=-3.67 to -3.83, NO3-=-1.42 to -1.65, HCO3-=-2.29 to -2.35 and SO42-=-3.84 until -4.25. The measurement of chloride ion on blood serum gave results equivalent to the ISE commercial and the ion analyzer equipment

Benserazide (BZ), a dopadecarboxylase inhibitor, is the most widely prescribed drug in treatment of Parkinson’s disease. Therefore, it is urgent to develop a sensitive and selective BZ sensor. We used tin oxide nanocomposite (Cu@SnS/SnO2) for developing a new electrochemical sensor for determination of BZ in human urine and pharmaceutical tablets. Morphology of the synthesized Cu@SnS/SnO2 was investigated by scanning electron microscopy (SEM). The modified electrode was characterized by electrochemical impedance spectroscopy (EIS) and voltammetric techniques. The sensitivity and limit of detection of RGO/Cu@SnS/SnO2 electrode for BZ are 0.275 µAµM−1 in the range of 1-100 µM and 0.58 µM. Moreover, the proposed electrode shows good selectivity, reproducibility and stability. The applicability of the modified electrode was demonstrated by determination of BZ in human urine and pharmaceutical formulation.

We present in this work the study of the protective effect of Benzopyridine (BP) and Benzimidazole (BZ) on the corrosion of ordinary steel in 1 M HCl. This study was carried out using gravimetric methods, potentiodynamic and electrochemical impedance measurements. The effect of structural molecule on their inhibition efficiency has been reported with a view to establishing a relationship between inhibitor efficiency and molecular structure. Both compounds inhibit the corrosion of ordinary steel to different degrees. It has been found that the molecule which comprises a pyridinum group has a higher inhibition efficiency than that of the compound which has an imidazole group, which indicate that the order of efficiency of these compounds in solution and the extent of their tendency to adsorb on ordinary steel surface is as follows: BP>BZ. The synergistic study between the studied inhibitors and potassium iodide shows that we can improve the inhibitory efficiency of our inhibitors and that these compounds act in combined forms by a competitive adsorption. The theoretical calculation by the density function theory (DFT) method confirms the experimental results.

Mercury(II) was sensitively detected in acidic solutions using chitosan (Cts) reinforced by grafting Thiourea (TU). In order to validate our developed method, the characteristics of the carbon paste electrode (CPE) modified with (TU-gt-Cts) were investigated by several electrochemical techniques, and the surface parameters were determined. Cyclic voltammetry (CV) analysis were realized in the presence of [Fe(CN)6]3−/4− and KCl as a redox probe and the effectives surfaces area (A) were calculated. Electrochemical impedance spectroscopy (EIS) measurements indicated low interfacial charge transfer resistance at the (TU-gt-Cts) modified electrode. The study of the scan rate effect denotes that the electrochemical system presented a diffusion controlled process happened in conjunction with a quasi-reversible electron transfer reaction. Electrochemical parameters of mercury on the surface of (TU-gt-Cts/CPE) were determined with a chronoamperometry (CA) method as D=2.22×10-5 cm2s-1 and k0=1.15×10-3 cms-1, for the diffusion coefficient and standard rate constant of electron transfer respectively. The square wave anodic striping voltammetry (SWASV) was checked as a sensitive detection method. Under the optimized chemical and instrumental parameters, the stripping peak current was linear to the Hg(II) concentration in  the ranges of 5.0×10-9 to 1.0×10–6 molL–1 and from 1.0×10–6 to 5.0×10–6 molL–1 with a detection limit (LOD) of 1.61×10–9 molL–1. The studied sensor was successfully applied for Hg(II) detection in tap and seawater with adequate recoveries.

Carbon steel is a well-known material and widely used in various industries. One of its major drawbacks is its corrosion in several middle and especially in acid solutions. In this work, we have studied the performance of polystyrene coating at different concentrations on E24 carbon steel against corrosion, in molar hydrochloric acid solution by gravimetric measurements, potentiodynamic polarization (PDP) and Electrochemical Impedance Spectroscopy (EIS) measurements. The effect of coating concentration, immersion time and temperature was examined. The viscosimetric molecular weight of polystyrene was investigated by measuring the intrinsic viscosity.The experimental results showed that the polystyrene coating acts as an effective anticorrosive coating of E24 carbon steel. The value of the protective efficiency reached 87,7% for 4.38 mmol/l of polystyrene coating with gravimetric tests. The stationary and the transient efficiencies reached 89.20% and 80.8% values respectively. The effect of temperature on the anticorrosion behavior of polystyrene film in the range 298-328 K, indicates that protective efficiency decreases with temperature.

Ferritic stainless steels are cheaper than austenitic stainless steels and if their behavior could be improved, both electrochemically and mechanically, they are able to rival and be substituted by a few austenitic grades in some specific usages. Numerous approaches have been utilized to produce the bulk fine-grained (FG) stainless steels so far. There are just two mechanical methods to get FG structures: procedures of advanced thermomechanical and severe plastic deformation techniques. The literature review clearly reveals the semiconducting properties of ferritic stainless steel (especially FG structures) that have been rarely investigated. So, the first aim of this paper is to review the semiconducting behaviors of the passive layers being formed on this type of stainless steels. In the following, we study influence of grain refinement on the semiconducting properties of produced passive films on FG ferritic stainless steels have been evaluated using Mott–Schottky analysis.

In the present work, the corrosion of carbon steel in 1.0 molL–1 HCl was investigated in the presence of new synthesized inhibitor, 2-methyl-N'-(di(thiophen-2yl)methylene)benzohydrazide (DTBH) by Potentiodynamic polarization (PDP), Electrochemical Impedance Spectroscopy (EIS) and Weight Loss (WL) measurements. Polarization studies showed that DTBH acted as a mixed-type corrosion inhibitor with predominantly anodic inhibition effect. EIS results confirmed the adsorptive type of the inhibitor, which increased the polarization resistance of the corrosion reaction. Based on the weight loss results, maximum inhibition efficiency was obtained 92.0% at the concentration of 300 ppm of DTBH. It was also shown that the adsorption of DTBH obeys Langmuir isotherm with mainly chemisorption.

An electroanalytical sensor amplified with ZnO nanoparticle (ZnO NPs) and 1butyl-2,3-dimethylimidazolium hexafluorophosphate (1B23DIPF6) was fabricated as new analytical approach for determination of sulfapyridine in different real samples. The ZnO NPs was synthesized by a simple precipitation method with low calcination temperature (⁓ 300 °C) and characterized by XRD and FESEM methods and results confirm a particle size ⁓45.2 nm for ZnO NPs. In addition, the two-fold amplification of paste electrode (PE) with ZnO NPs and 1B23DIBr (PE-ZnO NPs-1B23DIPF6) created a new tool for determination of sulfapyridine in the concentration range of 0.09-400 µM with detection limit 30.1 nM. On the other hand, the PE-ZnO NPs-1B23DIPF6 showed recovery data between 99.4%-104.1% for determination of sulfapyridine in some different real samples such as urine and tablet.