scholarly journals Polarographic Performance of Some Azo Derivatives Derived from 2-amino-4-hydroxy Pyridine and Its Inhibitory Effect on C-steel Corrosion in Hydrochloric acid

2019 ◽  
Vol 35 (1) ◽  
pp. 98-109 ◽  
Author(s):  
M. Abdallah ◽  
M. M. Alfakeer ◽  
N. F. Hasan ◽  
E. M. Mabrouk ◽  
Ahmed. M. Alharbi
Keyword(s):  
Dissociation Constants ◽  
Steel Corrosion ◽  
Transition Metal Ions ◽  
Electrode Reaction ◽  
Formation Constants ◽  
Inhibitory Effect ◽  
Azo Compounds ◽  
Alkaline Solutions ◽  
Acidic Solutions ◽  
Mechanistic Pathway

The polarographic performance of five azo compounds derived from 2-amino-4-hydroxypyridine was studied in BR buffer series of pH 2-12. The polarograms of all azo compounds in strong acidic solutions gave a single irreversible diffusion-controlled 4-electron wave representing the splitting of the N=N group to the amine stage but in alkaline solutions 2-electron irreversible wave is obtained corresponding to the reduction of the azo center to the hydrazo stage. For NO2 substituted derivative, approximately two equal waves were observed in the acidic solutions, , but in the alkali, the rise of the second wave is approximately twice that of the first wave. The effect of substituents on electrode reaction was investigated and the kinetic parameters were calculated. The mechanistic pathway was proposed and interpreted. The dissociation constants of the tested azo compounds were examined by potentiometric methods and the M-L formation constants of their complexes with some transition metal ions were computed. Application of the investigated azo compounds as inhibitors of dissolution of carbon steel in in 1MHCl solutions was inspected using potentiodynamic polarization technique. The results indicated that these compounds inhibit C-steel corrosion in HCl solutions and the inhibition efficiency reached 81% in presence of 1x10-3 M of the inhibitors. The efficiency of the inhibitors follows the following sequence: III> II > I > IV > V This arrangement is consistent with the sequence of the E1/2 and the pka values of these azo compounds.

scholarly journals Electrochemical and Spectrastudies of Some Sulfa Drug Azodyes and Their Metal Complexes in Aqueous Solution

2017 ◽  
Vol 14 (1) ◽  
pp. 6021-6032 ◽  
Author(s):  
E.M. Mabrouk ◽  
Kh.A.Al Omary ◽  
A.S.Al- Omary ◽  
E.H. El-Mossalamy
Keyword(s):  
Dissociation Constants ◽  
Mercury Electrode ◽  
Reduction Process ◽  
Electrode Reaction ◽  
Formation Constants ◽  
Azo Compounds ◽  
Alkaline Solutions ◽  
Sulfa Drugs ◽  
Sulfa Drug ◽  
Buffer Solutions

The electrochemical behavior of some azo compounds derived from sulfa drugs derivatives in B.R. buffer solutions of different pH containing 20 (v/v) ethanol was investigated at the mercury  electrode using different techniques (DC,DPP,CV and Coulometry) to investigate the effect of medium on the electro reduction process and suggestion the electrode reaction mechanism. The obtained results denoted that these compounds were reduced undergo a single irreversible 4- electron polarographic wave in acid and neutral solutions which represent the cleavage of the N=N center to the amine stage, whereas in alkaline solution, two wave are obtained the second is 2-electron irreversible wave corresponding to the reduction ofCHO group to CH2OH. The DPP and CV data showed a single peak in solutions of pH< 8, whereas three peaks are in alkaline solutions. The dissociation constants of the investigated compounds were determined by using spectrophotometric and potentiometric methods. Also the metal – ligand formation constants were determined potentiometrically and found in the order Cu˃ Co˃ Ni ˃Zn.

scholarly journals The Effect of pH, Ionic Strength and the Presence of PbII on the Formation of Calcium Carbonate from Homogenous Alkaline Solutions at Room Temperature

Minerals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 783
Author(s):  
Fulvio Di Lorenzo ◽  
Kay Steiner ◽  
Sergey V. Churakov
Keyword(s):  
Ionic Strength ◽  
Deep Understanding ◽  
Inhibitory Effect ◽  
Alkaline Solutions ◽  
Nucleation Kinetics ◽  
Experimental Conditions ◽  
Calcium Carbonates ◽  
Natural Systems ◽  
Geological Processes ◽  
System Variables

Precipitation of calcium carbonates in aqueous systems is an important factor controlling various industrial, biological, and geological processes. In the first part of this study, the well-known titration approach introduced by Gebauer and coworkers in 2008 s used to obtain reliable experimental dataset for the deep understanding of CaCO3 nucleation kinetics in supersaturated solutions over a broad range of pH and ionic strength conditions. In the second part, the effect of impurities, i.e., 1 mol% of Pb2+, was assessed in the same range of experimental conditions. Divalent lead has been shown to have an inhibitory effect in all ranges of the conditions tested except for pH 8 and low ionic strength (≤0.15 mol/L). Future investigations might take advantage of the methodology and the data provided in this work to investigate the effect of other system variables. The investigation of all the major variables and the assessment of eventual synergic effects could improve our ability to predict the formation of CaCO3 in complex natural systems.

scholarly journals Electrocatalysis of the HER in acid and alkaline media

2013 ◽  
Vol 78 (12) ◽  
pp. 2007-2015 ◽  
Author(s):  
Nemanja Danilovic ◽  
Ram Subbaraman ◽  
Dusan Strmcnik ◽  
Vojislav Stamenkovic ◽  
Nenad Markovic
Keyword(s):  
Catalytic Decomposition ◽  
Alkaline Media ◽  
Alkaline Solutions ◽  
Water Molecules ◽  
Bifunctional Catalysts ◽  
High Coverage ◽  
Acidic Solutions ◽  
Noble Metal Catalysts ◽  
Alkaline Environments ◽  
Decomposition Of Water

Trends in the HER are studied on selected metals (M= Cu, Ag, Au, Pt, Ru, Ir, Ti) in acid and alkaline environments. We found that with the exception of Pt, Ir and Au, due to high coverage by spectator species on non-noble metal catalysts, experimentally established positions of Cu , Ag, Ru and Ti in the observed volcano relations are still uncertain. We also found that while in acidic solutions the M-Hupd binding energy most likely is controlling the activity trends, the trends in activity in alkaline solutions are controlled by a delicate balance between two descriptors: the M-Had interaction as well as the energetics required to dissociate water molecules. The importance of the second descriptor is confirmed by introducing bifunctional catalysts such as M modified by Ni(OH); e.g. while the latter serves to enhance catalytic decomposition of water, the metal sites are required for collecting and recombining the produced hydrogen intermediates.

On the quantitative relations between structure and antiaggregation activity of ω-aryl-ω-oxoalkanoic acids

1986 ◽  
Vol 51 (11) ◽  
pp. 2617-2625 ◽  
Author(s):  
Miroslav Kuchař ◽  
Bohumila Brunová ◽  
Jaroslava Grimová ◽  
Václav Rejholec ◽  
Václav Čepelák
Keyword(s):  
Partition Coefficients ◽  
Dissociation Constants ◽  
Inhibitory Effect ◽  
Partition Chromatography ◽  
Linear Quadratic ◽  
Marked Influence ◽  
Methyl Group ◽  
Retention Characteristics ◽  
Anti Inflammatory

A series of ω-aryl-ω-oxoalkanoic acids, I-IV, has been prepared and investigated for dissociation constants in 80% methylcellosolve, retention characteristics in thin-layer partition chromatography and partition coefficients P in the system octanol-water. Also evaluated were their anti-inflammatory efficacy and inhibitory effect on the platelet aggregation induced by collagen. Analysing the relations between structure and antiaggregation effect, we obtained a non-linear, quadratic dependence of this effect on lipophilicity, the optimum being at log P = 3. The antiaggregation effect increased with shortening the chain between the carbonyl and the carboxyl, and with increasing acidity. It was also diminished by the presence of a methyl group on the interlinking chain. To assess the role of lipophilicity we used the RM values of partition chromatography. The relation between anti-inflammatory efficacy and structure was assessed only qualitatively. In this aspect, too, the nature of the chain between the carbonyl and carboxyl proved to have a marked influence. The anti-inflammatory activity proved considerably enhanced by the presence of another aromatic ring in ω-oxoalkanoic acids derived from biphenyl.

Inhibition Effect of Sodium Nitrite and Silicate on Carbon Steel Corrosion in Chloride-Contaminated Alkaline Solutions

CORROSION ◽  
2011 ◽  
Vol 67 (12) ◽  
pp. 125001-1-125001-12 ◽  
Author(s):  
O. Girčienė ◽  
R. Ramanauskas ◽  
L. Gudavičiūtė ◽  
A. Martušienė
Keyword(s):  
Carbon Steel ◽  
Sodium Nitrite ◽  
Steel Corrosion ◽  
Alkaline Solutions ◽  
Inhibition Effect ◽  
Chloride Contaminated

Electrochemical studies of Schiff base compounds derived from antipyrine nucleus in ethanolic buffer solutions

2000 ◽  
Vol 78 (9) ◽  
pp. 1170-1177 ◽  
Author(s):  
Ibrahim S El-Hallag ◽  
Gad B El-Hefnawy ◽  
Youssef I Moharram ◽  
Enass M Ghoneim
Keyword(s):  
Schiff Base ◽  
Electrochemical Behaviour ◽  
Electrochemical Techniques ◽  
Mercury Electrode ◽  
Electrode Reaction ◽  
Limiting Current ◽  
Electron Transfer Process ◽  
Buffer Solutions ◽  
Mechanistic Pathway ◽  
Electrochemical Parameters

The electrochemical behaviour of Schiff base compounds derived from an antipyrine nucleus was investigated in 30% (v/v) ethanolic buffer solutions (pH 3-11) using various electrochemical techniques at mercury electrode. The results showed that, the total limiting current of each of the studied compounds corresponds to 2-electron transfer process. The mechanistic pathway of the electrode reaction of the investigated compounds at mercury electrode, the effect of the medium, and the evaluation of the electrode reaction parameters were illustrated and discussed.Key words: Schiff base, antipyrine nucleus, electrode reaction, electrochemical parameters, cyclic voltammetry.

Mild electrochemical oxidation of zeolite templated carbon in acidic solutions, as a way to boost its charge storage properties in alkaline solutions

Carbon ◽  
2018 ◽  
Vol 138 ◽  
pp. 369-378 ◽  
Author(s):  
Milica Vujković ◽  
Danica Bajuk-Bogdanović ◽  
Ljiljana Matović ◽  
Marija Stojmenović ◽  
Slavko Mentus
Keyword(s):  
Electrochemical Oxidation ◽  
Alkaline Solutions ◽  
Charge Storage ◽  
Acidic Solutions ◽  
Storage Properties ◽  
Templated Carbon

scholarly journals Exchange of Some Divalent Metal Cations and Their Effect on the Dissociation of Iron(III) Phosphate

1996 ◽  
Vol 13 (4) ◽  
pp. 241-260 ◽  
Author(s):  
S. Mustafa ◽  
A. Naeem ◽  
N. Rehana ◽  
T. Hussain
Keyword(s):  
Transition Metal ◽  
Thermodynamic Parameters ◽  
Alkaline Earth ◽  
Dissociation Constants ◽  
Ph Value ◽  
Transition Metal Ions ◽  
Divalent Metal ◽  
Solution Ph ◽  
Divalent Metal Cations ◽  
Titration Data

Potentiometric titrations of iron(III) phosphate have shown an apparently weak monobasic acid behaviour towards alkali, alkaline earth and divalent transition metal ions. The selectivity sequence and dissociation of the exchanger was found to increase in the order Cu2+ > Zn2+ > Ni2+ > Ca2+ > K+. The dissociation constants of iron(III) phosphate have been determined from Potentiometric titration data in the temperature range 303–323 K. In addition, the exchange of Cu2+, Zn2+ and Co2+ on iron(III) phosphate and the effect of these ions on dissociation were also studied as a function of concentration, temperature and solution pH value. The thermodynamic parameters ΔH0, ΔS0 and ΔG0 for the dissociation of iron(III) phosphate are also presented.

scholarly journals The inhibition of mild steel corrosion in 0.5 M H2SO4 solution by radish leaf extract

RSC Advances ◽  
2019 ◽  
Vol 9 (70) ◽  
pp. 40997-41009 ◽  
Author(s):  
Dongyi Li ◽  
Panpan Zhang ◽  
Xinyu Guo ◽  
Xiaowei Zhao ◽  
Ying Xu
Keyword(s):  
Weight Loss ◽  
Mild Steel ◽  
Electrochemical Method ◽  
Leaf Extract ◽  
Steel Corrosion ◽  
Inhibitory Effect ◽  
H2so4 Solution ◽  
Mild Steel Corrosion ◽  
Weight Loss Method ◽  
Loss Method

The inhibitory effect of radish leaf extract (RLE) on mild steel corrosion in 0.5 M H2SO4 was studied by the weight loss method and the electrochemical method.

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