Analytical & Bioanalytical Electrochemistry
Volume:15 Issue: 3, Mar 2023

Wastewater laden with toxic pollutants, such as chromium (Cr), can hurt humans, the environment, and aquatic life if not properly treated. The present work proposes to study the elimination of 100 mg/l of Cr(VI) ions from a synthetic wastewater effluent using a dynamic electrocoagulation process employing aluminum electrodes. The influences of several parameters are explored for the electrocoagulation process effectiveness in terms of Cr removal yield. This was done within the following ranges:  current density (5-22 mA/cm2), initial pH (2-7), and chromium concentration (25-150 mg/l). A settling step was followed to determine the total suspended solids content and the sludge volume index after electrocoagulation treatment. Depending on the operating conditions, the data of specific electrical energy consumption were employed to determine the best operating parameters of the process efficiency. Furthermore, data analysis (Scanning Electron Microscope, Fourier Transform Infrared spectroscopy, X-ray diffraction analysis, and X-ray fluorescence) of sludge formed after electrocoagulation showed an amorphous nature with a high content of aluminum and function groups that should have a potential to be utilized as coagulant/sorbent in wastewater treatment.

The present work is devoted to the electrochemical reduction study of presumably biologically active 2-substituted quinoxaline derivatives. In this work, two new quinoxaline derivatives are presented. The electrochemical behavior of this compound in an aprotic medium and while its protonating was investigated via a voltammetric method. Using computational methods, the localization of the reduction centres depending on the compound’s structure was determined. The EPR spectra data obtained by electrochemical generation reduction product proved that the studied quinoxaline’s electroconversion occurs with radical anion formation. The linear correlation between the reduction potential of studied compounds and energy of their affinity to the electron was found (R2 = 0.933). This confirms the single reduction mechanism of radical nature for the entire series of studied 2-substituted quinoxaline derivatives. Based on that, the electron-accepting ability of these compounds was compared in order to evaluate their possible bioactivity and to select the most perspective ones among them for further research.

Eucalyptus essential oil offers numerous benefits for the immune system through its antioxidant constituents. In this investigation, we attempted to explore another field of application, in which we exploit the corrosion inhibition potential of Eucalyptus Sideroxylon (ES) essential oil to protect C38 steel in an acidic solution of HCl. To uncover the facts, careful research was designed using fundamental measurements of gravimetric and electrochemical techniques, combined with scanning electron microscopy and energy dispersive spectroscopy analysis. The finding measurements showed that ES reduces the rate of corrosion that shows up on polarization curves as a mixed inhibitor. Furthermore, the impedance data acquisition revealed that the amount of charge transfer resistance has a high value when the ES concentration increases, we found 169.40 Ω cm2 for 2.4 g/L of ES giving an efficiency of 80%. Moreover, the thermodynamic parameters showed that the interaction of ES with the metal surface is endothermic, characterized by physical adsorption.

In the present work, HCl doped polyaniline (Pani-Cl) was chemically synthesized. Chemical structure of Pani-Cl powder was confirmed using UV-visible, infrared spectroscopy and electrical conductivity measurements. Synthesized Pani was added to commercial zinc phosphate primer paint (ZP) to enhance its anticorrosion properties. The anticorrosion performance of coatings containing 0.1- 0.4 wt% polyaniline on carbon steel was evaluated in 3.0 wt% NaCl solution by open circuit potential (OCP), polarization curves and electrochemical impedance spectroscopy (EIS) measurements. The experimental results showed that the coating with 0.2 wt% of Pani-Cl (ZP-Pani0.2) provides higher anticorrosion properties and offers better barrier characteristics in the paint film, as compared with original primer. After a period of 600 hours, carbon steel coated with ZP-Pani0.2 showed good resistance against corrosion (low corrosion rate and high resistance). Besides, the OCP value was higher than that of ZP-coated steel due to the barrier effects of Pani-Cl. However, the use of more than 0.2 wt% Pani-Cl additives reduced the coating's protection efficiency. Paints adhesion was evaluated by cross cut test. It was found that paints containing 0.3 and 0.4 wt% of polyaniline present lower adhesion, as compared with the reference paint.

In this work, a potentiometric sensor was developed based on polyvinyl chloride (PVC), duloxetine tetraphenylborate ion pair, various plasticizers of dioctyl phthalate (DOP), benzyl butyl phthalate (BBP), di(2-ethylhexyl)phthalate (DEPH), tris(2-ethylhexyl) phosphate (TEPH), dibutyl butyl phosphonate (DBBPh), dibutyl phthalate (DBP), dioctyl sebacate (DOS), dibutyl sebacate (DBS), 2-nitrophenyl octyl ether (NPOE) and di-octyl phthalate (DOPH)) and THF as membrane solvent. The electrode responses at various contents of PVC and plasticizer were recorded to optimize their percentage compositions, and the best Nernst response (59.7) was obtained. The linear concentration range for this electrode made by optimal composition is 0.7 µM to 0.1 M with a detection limit of 0.3 µM.  The response time of the ion-selective electrode based on the duloxetine-tetraphenylborate ion pair was determined. The effect of pH on the potential of duloxetine hydrochloride (DHCl) solution with a concentration of 1.0 mM was studied. Moreover, the performance of the prepared electrode was studied over two months to investigate the constructed membrane electrode’s stability. The selectivity coefficients of the electrode for determination of DHCl in the presence of some ions and molecules including Na+, K+, Li+, Ni+, Mg2+, Cd2+, Zn2+, Mn2+, Fe2+, Ca2+, Cu2+, Co2+, Cr2+, ascorbic acid, D-fructose, sucrose, aspartic acid, L-H-histidine, dopamine, glucose, uric acid, propranolol, dexamethasone and melatonin were determined using a separate solution method (SSM) and an adapted potential method. The application of the proposed sensor to determine DHCl in two biological matrices, including blood serum and urine samples, was also investigated.

Ranitidine ion-selective membrane electrodes were fabricated from PVC matrix and ranitidine hydrochloride (RNH-HCl)-phosphotungestic acid (PTA) as the detecting components in the existence of di-n-octyl phthalate (DOPH), di-n-butyl phthalate (DBPH) and dibutyl phosphate (DBP) as the solvent mediator and plasticizing the PVC membrane. The electrodes were prepared with DOPH (electrode 1), and DBPH (electrode 2) gave a Nernstian, stable, and rapid response, which displayed linear response in the concentration range of 1.0×10-6-1.0×10-2 mol.L-1 and 2.03×10-6-1.0×10-2 mol.L-1, with Nernstian slope of 58.73, and 52.50 mV.decade-1 for electrode 1 and electrode 2 respectively. Limits of detection 9.30×10-7 and 3.70×10-7 mol.L-1 for electrodes 1 and 2, respectively were also obtained. Individual electrodes were operative at the pH range of 3.0-5.5 and 3.5-5.5. The membrane electrodes showed excellent selectivity for the drug ranitidine in comparison with various inorganic cations. The electrodes showed a cycle of 55,50 days not including major variations in the parameters of the electrodes. Sensor 3 was given a non-Nernstian response equal to 28.76 mV.decade-1 and the range of concentration was   2.0×10-6-1.0×10-2 mol.L-1 with a limit of detection near 3.68×10-7 mol.L-1. Ranitidine can be determined effectively in unmixed and pharmaceutical formulations using these designated methods.