Analytical & Bioanalytical Electrochemistry
Volume:11 Issue: 10, Oct 2019

In this work, we are interested in studying the effect of the addition Lepidium sativum seeds (LSS) on the inhibition of the corrosion of carbon steel in acidic medium 1.0 M HCl. The inhibition of the corrosion reaction of carbon steel (CS) was performed using (LSS) in a 1.0 M hydrochloric acid medium using impedance spectroscopy (EIS) and potentiodynamic polarization (PDP). The phytochemical study revealed the existence of flavonoids, saponosides, tannins, alkaloids, sterols and polyterpenoids compounds. Inhibitory efficiency increases with increasing inhibitor concentration and decreases with increasing temperature. The experimental results show that Lepidium sativum seeds (LSS) is a good corrosion inhibitor where the maximum inhibition is around 90% at 2 g/L. PDP studies show that the Lepidium sativum seeds (LSS) act as mixed inhibitor. Corrosion current density decreased from 729 µAcm-2 (blank) to 125 µAcm-2 at 2 g/L (LSS). The studied inhibitor is adsorbed on the metal surface according to the model of the Langmuir adsorption isotherm

Corrosion inhibition of mild steel in an acidic environment using several concentrations of DNA from Manihot esculenta leaf (Cassava leaf) (MANIHOT ESCULENTA LEAFDNA) at different temperatures was examined using gravimetric analysis and linear polarization techniques. Three different isotherms (Langmuir, Freundlich and Flory-Huggins) were evaluated for their fitness to the experimental data. Based on the results, thermodynamic parameters regarding the DNA behaviour were calculated using the Freundlich adsorption isotherm because it gave the best
isotherm shows that the adsorption of the DNA inhibitor to the surface of mild steel is by physisorption and the data obtained from the thermodynamic assessment illustrates a spontaneous and exothermic corrosion process. The morphologies of the mild steel surfaces with and without inhibitor were assessed by scanning electron microscopy (SEM). The SEM results showed that the presence of the DNA inhibitor slowed down the corrosion process. The micrograph for MANIHOT ESCULENTA LEAFDNA inhibitor showed a near smoother surface at 10 °C and 20 mg/L and 25 °C and 20 mg/L thus confirming their provision of more active surfaces. However, it was observed that the DNA inhibitor efficiency increased with increased DNA concentration, with the best inhibitor efficiency (74.2%) obtained at 10 °C for 20 mg/L DNA concentration. A mechanism of adsorption was also proposed which was validated by the data obtained from XRD analysis.description of the DNA inhibitor. The Freundlich adsorption

The acetanilide AC and the para-hydroxy acetanilide PHA are used in this work as corrosion inhibitors of the carbon steel (UNS G10260) in a solution of NaCl 3%. In this research using potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) techniques. The set of the results shows that the studied compounds have varied inhibition efficiencies and the adsorption of composed on the surface the metal is made according to the isotherm of Langmuir. The compound PHA presented the best power of inhibition to a concentration of 60ppm (R˃89%). The results showed that the adsorption of AC and PHA is connected to the concentration of every inhibitor and strongly influenced by the temperature. The study thermodynamics showed that the process of adsorption is spontaneous (the negative free energy), physical type of the PHA and chemical for the AC. The effect of synergy between both inhibitors (AC+PHA) was also examined in the chlorinated environment. With different mixtures concentrations of both inhibitors, an efficiency maximum attaint 99.15% for 20 ppm of AC+60 ppm. Cooperative adsorption for all the mixtures.

Grain size effect on corrosion general trends was clarified by Ralston and Birbiliś ́s review by sorting them with three different corrosion status (active, passive, and active/passive) having diverse potentiodynamic polarization curves. The active type made them realize that finer grain size showed an acceleration in corrosion currents whereas the passive type had a totally opposite trend. A mixed type of the prior two types being lower in the passive zone and the active zone of higher was indicated within the active/passive type. There is a big problem whether these attitudes retain in submicron size- or nano-scale grain size. Ultrafine–grained (UFG) materials have drawn remarkable attention through twenty years ago. Several severe plastic deformation (SPD) processes have been applied in order to make UFG materials in which the accumulative roll bonding (ARB) procedure is the most effective one among them. Structure of UFG divulges an advancement in mechanical properties along with distinct corrosion behavior, but not always resulting in better corrosion resistance. Diverse relevant work is reviewed in this paper in order to date the studied passive behavior of UFG aluminum, copper, and titanium, having produced utilizing ARB procedure. In this study, the grain size effect using ARB procedure on passive behavior of aluminum, copper, and titanium has been evaluated in related passive environments using potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) methods.

The present work is very simple and sensitive method for cyclic voltammetry, differential pulse voltammetry and chrono amperometry (CA). Uric acid sensor was developed at (DBCMAT-CoPcs) 2,4-dibromo-6-{[cyclohexyl(methyl)amino]methyl}aniline-tetra substituted on cobalt phthalocyanine modified GCE. The novel synthesized catalyst confirmed with various spectroscopic techniques. The modified DBCMAT-CoPc/GCE showed a high electrocatalytic activity and lower potential towards the oxidation of uric acid (UA). The response of UA was linear over the concentration ranging from (CV 0.1–1.8; DPV 0.2–2.8; CA 0.05–0.8 μmol/L), sensitivity for (CV 131.85; DPV 22.634; CA 2.509 μAμM-1cm-2) and detection limit for (CV 0.03; DPV 0.066; CA 0.016 μM) (S/N=3). The CVs and DPV techniques shows the same peak potential (+370 mV) and fabricated sensor exhibited its special advantages such as low working potential, sensitivity along with good repeatability and reproducibility for the determination of uric acid.

The aim of this work is to optimize the conditions for the preparation of activated carbon based from date’s stones by phosphoric acid activation using the surface response methodology of experimental design, which allowed us to predict the optimal conditions. In order to achieve our objective, we studied the influence of three key parameters (Pyrolysis temperature (Pyrol. T), Pyrolysis time (Pyrol. Tim) and Impregnation ratio (Impr. ratio)) on the responses studied (Zn2+ and Cu2+). A second-degree polynomial model was therefore used to model the influence of two key parameters. The concerned results, especially the theoretical operating parameters, allowed us to give a better condition for the preparation of activated carbon are (Pyrol. T about 600 °C, Pyrol. Tim equals180 min and Impr. ratio is 1.2). The characteristics of activated carbon obtained under these experimental conditions were determined by Fourier transform infrared spectroscopy (FTIR) and polarizing optical microscope (POM). The produced activated carbon had a well-developed porous structure. The FTIR analysis indicates presence of variety of functional groups on the surface of activated carbon

 Quantum chemical calculations using the Density Functional Theory (DFT) method were performed on three triazole derivatives, namely (1-(4-aminophenyl)-1H-1,2,3-triazol-4yl)methanol (ATM), 1-(1-(4-aminophenyl)-5-methyl-1H-1,2,3-triazol-4-yl)ethanol (ATE) and ethyl 1-(4-aminophenyl)-5-methyl-1H-1,2,3-triazole-4-carboxylate (ATC). The theoretical studies involved the correlation between experimental results and semi-empirical parameters; the analysis of the sites for electrophilic and nucleophilic attacks carried out using Fukui function and the derivation of equations for the theoretical inhibition efficiencies of the inhibitors using the quantitative structure activity relation (QSAR). The result showed that the highest occupied molecular orbital energy (EHOMO) increases as the percentage inhibition efficiency (%IE) increases, global nucleophilicity (ω) and hydrophobicity (log P) decreases with increasing %IE, while lowest occupied molecular orbital energy (ELUMO), band gap (BG) and dipole moment (DM), did not show any correlation with %IE. The analysis of the condensed fukui functions suggests that similiar centers (N4) would be preferred for electrophilic attack for all the inhibitors. The QSAR model developed reproduced the observed %IE of these compounds well with a CV.R2 value of 0.999947436) and R2adj value of 0.99993

The essential oil from the seeds of Anethum graveolens (AGEO) was studied by Gas Chromatography (GC) and Gas Chromatography-Mass Spectrometry (GC/MS). 12 components were identified accounting 98% of the total oil, which Carvone (43.5%), Dillapiol (26.7%) and Limonene (15.4%) were the major compounds. The use of AGEO as a C38 steel corrosion inhibitor in 1 M HCl solution was studied by weight loss measurements, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) methods. AGEO acted as a highly efficient mixed-type inhibitor. Adsorption of the inhibitor on the steel surface followed Langmuir adsorption isotherm. The calculated adsorption thermodynamic parameters were calculated and discussed. Quantum chemical calculations and molecular dynamic simulations were also carried out in order to correlate the inhibitory effect of AGEO and the electronic properties of its major constituents, and to provide some indications into the nature of their interaction with the metal surface at a molecular level.

In the present study, a highly sensitive electrochemical sensor was developed for the trace analysis of paracetamol using voltammetric techniques. The electrochemical redox behavior of paracetamol was investigated by Fe3O4@SiO2 on surface of GCE using drop casting technique. It showed a supreme electrocatalytic activity at pH 5.5 in 0.1 M PBS. The surface morphology of Fe3O4@SiO2 was studied using SEM and FT-IR. The effect of sweep rate, pH and concentration of paracetamol were investigated. The oxidative peak current of paracetamol was increased linearly while increasing its concentration from 0.8-24 nM and the LOD and LOQ were found to be as low as 4.88 nM (S/N=3) and 19 nM respectively, which is found to be much sensitive than many methods reported in the literature. DPV technique was used for the simultaneous detection of paracetamol in presence of etilefrine and dopamine.

A potentiometric sensor was made using a non-covalent imprinted nano-polymer for analysis of furosemide pharmaceutical compound. Furosemide is a diuretic drug which is also categorized among the doping agent. The nano-molecularly imprinted polymer (nanoMIP) was prepared through precipitation polymerization, where furosemide was used as a template molecule, acryl amid (AA) as a functional monomer and ethylene glycol dimethacrylat (EGDMA) as a cross-linking agent. The sensor showed a selective and sensitive response to the analyte (the template molecule) in aqueous solutions. The MIP-based sensor responded Nernstian (51.8±0.3 mV decade−1) in a concentration range of 7.5×10-6 to 1.0×10-1 mol L-1 with a lower detection limit of 5.0×10-6 mol L-1. The response time of the sensor was ∼20 s, a high performance and a satisfactory long-term stability (more than 2 months). The proposed sensor has acceptable accuracy, sensitivity and precision to be used for furosemide assay in some pharmaceutical preparations.