Analytical & Bioanalytical Electrochemistry
Volume:14 Issue: 9, Sep 2022

The present work deals with the corrosion inhibition mechanism of mild steel in 1 M H2SO4 employing the new carbonitrile derivative viz. 2-amino-4-(4-hydroxyphenyl)-6-(p-tolyl)-4H-pyran-3-carbonitrile (HCN). A such mechanism was elicited by means of the potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy (EIS) techniques and weight loss (WL). The experimental results revealed maximal inhibition efficiency (IE) rates up to 92.4% in weight loss. WL measurement revealed a decrease in corrosion rate with increasing concentration of corrosion inhibitor and decreasing with increasing temperature up to 333 K. The Nyquist curves indicated that the corrosion inhibition was controlled by a charge transfer process whereas the PDP curves showed that the HCN behaved as a mixed-type corrosion inhibitor. The Langmuir isotherm was used to determine the adsorption thermodynamic parameters. Thermodynamic characteristics for activation and adsorption were determined and discussed. Adsorption free energy at 303 K ( = -22.26 kJ mol-1 for HCN) indicated a combination of chemisorption and physisorption. The inhibitor (HCN) formed a protective layer that acted as a barrier between the surface of the metal and the acid medium which was investigated through surface studies like Scanning Electron Microscopy (SEM) coupled with Energy dispersive X-ray analysis (EDS).  The surface studies were in coincidence with weight loss and electrochemical studies. Density functional theory (DFT) was performed to support the experimental data in an aqueous medium using the basis set 6-311G(d,p). From the Mulliken population analysis, the adsorption sites have been studied and the results of DFT were steady with the experimental studies.

In this paper, well-distributed Lanthanum-doped Superparamagnetic nanoparticles (La-Fe3O4) are reported. Nanoparticles powder has been synthesized using cathodic electrochemical deposition method. By applying a constant current density of 1 A in a two-electrode electrochemical system, nanoparticles with a diameter of approximately 11 nm with a spherical structure were prepared. The structure, morphology and magnetic properties of these nanoparticles have been systematically investigated by using TEM, XRD, VSM and FT-IR analysis. The results indicate the existence of a superparamagnetic behavior at room temperature for progressive measurements as a function of the magnetic field. The magnetic hysteresis (magnetic saturation, Coercivity and Remanence) of the sample shows the effective role of doped lanthanum in improving the magnetic properties of ferrite nanoparticles, and the magnetic saturation value is 54.23 emu/g. Based on these results, the electrochemical method can be used as an efficient and low-cost synthetic method to make iron oxide nanoparticles doped with lanthanum.

In this work, a new sensitive sensor based on application of fast Fourier transform square wave voltammetry (FFTSWV) for determination of sulfadiazine is described. The developed sensor is a modified carbon paste electrode with Eu2(CO3)3 nanoparticles. The characterization of the used materials was done through transmission electron microscopy (TEM) and FT-IR   spectroscopy. The cyclic voltammogram of sulfadiazine showed a well-resolved irreversible oxidation peak at around 0.85 V vs. Ag/AgCl.  After optimization of experimental conditions, such as pH, percentage of modifier, amplitude, number of cycle and frequency a linear calibration curve was obtained in the concentration ranges of 1.0×10-6 – 250.0×10-6 M with a limit of detection 0.4×10-7 M. The proposed sensor was successfully applied for the determination of sulfadiazine in pharmaceutical sample with the RSD range of 0.7 to 1.7.

A new Lead (II) PVC membrane sensor incorporating thiophene-2-aldehyde thiosemicarbazone (TATS) as ionophore, tetraphenylborate (NaTPB) in the form of anion excluder and dioctylphthalate (DOP) as a plasticizer was constructed. The optimum membrane prepared with composition, PVC: DOP: Ionophore: NaTPB as 33: 59: 3.4: 4.6 (w/w %), exhibits best results with linear potential response for concentration range (1.0 ×10–7 to 1.0 ×10–2 M) and a slope of 29.4 ± 0.1 mV/decade. The performance of electrode and its electrochemical response to Pb2+ were thoroughly studied and found good over a pH range of 2.4–8.0, with a short response time of < 15 s. The sensor can be used for at least 4 months with reproducibe results and is inert in non-aqueous content up to 15% (v/v). It revealed good selectivity over a wide variety of alkali, alkaline earth and other metal ions. The electrode was successfully applied by using it as an indicator electrode in potentiometric titration of Pb (II) ion with EDTA and indetermination of of Pb2+ ion in some water samples.

In the past two decades, quest of finding sustainable and environment friendly energy sources has increased enormously. Fuel cell technology has seen exciting growth for the solution of requirement of sustainable energy. Fuel cells are based on electrochemical reactions to change chemical energy into electrical energy. For this, reduction of CO2 and O2 are two of the important reactions. Despite quite stable nature of CO2, its reduction can be achieved effectively in presence of catalyst. Both the CO2RR and ORR reactions yield useful byproducts like water, formic acid, formaldehyde, methanol etc. Earlier Pt based catalysts were in use for these conversions in fuel cells. In the recent years, polyaza macrocycle-based catalysts are being applied as these being cost effective. For both above-described purposes, polyazamacrocyclic complexes, like metalloporphyrin, phthalocyanine, have been proved to be very effective. This article is focused mainly on recent advancement in Tetra, Penta and Hexaazamacrocyclic complexes for CO2 RR and ORR reactions.

Ethinylestradiol (EE2) is classified as an estrogenic pharmaceutical compound. It is an agonist of the estrogen receptors and is approved for treating estrogen deficiency and osteoporosis prophylaxis in the short term when a choice of medicines is limited. EE2 is administered for the treatment of female hypogonadism and menstrual disorders. This strong estrogen is known to cause nausea, fluid retention, and thrombosis as side effects. It is, therefore, necessary to monitor EE2 levels in biological, environmental, and pharmaceutical samples. Various ultra-sensitive analytical methods were introduced during the last decades but modified electrochemical methods have great attention due to their undeniable properties. Here, all electrochemical analytical methods used for the determination of EE2 are considered and discussed.