Inhibition Effect of N-(Pyridin-2-yl-Carbamothioyl) Benzamide on the Corrosion of C-Steel in Sulfuric Acid Solutions

N-(Pyridin-2-yl-carbamothioyl)benzamide (PCMB) was newly synthesized and tested as a corrosion inhibitor for C-steel in 0.5 M H₂SO₄ using chemical and electrochemical techniques. Polarization measurements showed that the synthesized compound acted as a mixed inhibitor. The inhibition efficiencies obtained from the different methods were in good agreement. The inhibitive action of this compound is discussed in terms of blocking the electrode surface by adsorption of the inhibitor according to the Langmuir isotherm. The effect of temperature on the corrosion behavior in the absence and presence of 2.5 × 10^?5 M of PCMB was studied (283–308 K). The associated activation energies (E _a) and the thermodynamic parameters (ΔH*, ΔS*, K _ads, ΔG°_ads) for the adsorption process were determined. The ΔG°_ads value is ?36.55 kJ/mol, which indicated that the adsorption mechanism of PCMB on C-steel in 0.5 M H₂SO₄ solution was combined between physisorption and chemisorption processes.     

Adsorption and Corrosion Inhibition Behavior of Schiff Base-Based Cationic Gemini Surfactant on Mild Steel in Formic Acid

The adsorption and corrosion inhibition behavior of synthesized Schiff base-based cationic gemini surfactant bis[p-(N,N,N-tetradecyldimethylammonium bromide)benzylidene]thiourea (14-S-14) on mild steel in 20% formic acid in the temperature range of 30°C to 60°C was evaluated using weight loss measurements, solvent analysis of iron ions and potentiodynamic polarization measurements. The synthesized inhibitor was characterized using Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance spectroscopy (NMR), and thin layer chromatography (TLC). The surface morphology of the corroded mild steel specimen was evaluated using scanning electron microscopy (SEM), energy dispersive x-ray analysis (EDAX), and atomic force microscopy (AFM). Thermodynamic/kinetic parameters were calculated to elaborate the adsorption and corrosion inhibition mechanism of the inhibitor. The inhibition efficiency of the compound was found to vary with inhibitor concentration, immersion time, and temperature. The adsorption of the compound on the steel surface was found to obey Langmuir adsorption isotherm.      

Surface Activity of Novel Polymerizable Anionic Polyoxyethylene 4-Nonyl-2-Prpylene-Phenyl Ether Ammonium Sulfate Succinate Surfactants

Novel polymerizable surface-active monomers were synthesized by successive treatment of polyoxyethylene 4-nonyl-2-prpylene-phenyl ether ammonium sulfate with maleic anhydride in the presence of hydroquinone at temperature of 180°C. The molecular structures of the polymerizable surfactants were confirmed by ¹H and ¹³C NMR spectroscopy. The surface tension isotherms on the air-water solution interface were obtained. The critical micelle concentrations (cmc) as well as the surface tension at the cmc were determined for these substances. The micellization and adsorption of the prepared anionic surfactants have been investigated by surface tension, and cloud point measurements. Surface parameters such as surface excess concentration (Γ _max), the area per molecule at interface (A _min) and the effectiveness of surface tension reduction (π_CMC) were determined from the adsorption isotherms of the prepared surfactants.      

Sur les carbonates basiques de fer (III): III. Préparation,radiocristallographie et spectres IR. du (NH4)4Fe2(OH)4(CO3)3·3H2O

The obtention of the crystalline basic carbonate of iron (III) and ammonium, (NH₄)₄Fe₂(OH)₄(CO₃)₃ · 3 H₂O, is described, and its formula is established by chemical analysis and infrared spectroscopy. The compound is probably monoclinic, but it was not possible to index with certainty all X-ray reflections. The compound is similar to (NH₄)₂Fe₂(OH)₄(CO₃)₂ · H₂O and its infrared spectrum leads to the assumption that in both the CO group is linked in the same fashion.     

Interaction Between Two Similar Plane Parallel Double Layers for (NH4)2Fe(SO4)2 or (NH4)2Cu(SO4)2 Type Complex Salt Electrolytes at Positive Surface Potential

Interaction energies between two similar plane parallel double layers for (NH₄)₂Fe(SO₄)₂ or (NH₄)₂Cu(SO₄)₂ type complex salt electrolytes at positive surface potential were expanded in a power series and accurate numeral results were given for 0.1 ≤ y _e  < y ₀ ≤ 20. The general expressions were given for the interaction energies of A _ν +B _ν′ +C_ν? type complex salt electrolytes at y > 0. The interaction energies for simple salts NaCl, CaCl₂, Na₂SO₄, FeCl₃, Na₃PO₄, Mg₃(PO₄)₂, Al₂(SO₄)₃, and complex salts (NH₄)₂Fe(SO₄)₂ or (NH₄)₂Cu(SO₄)₂ at y ₀ = 1 were compared. There was hardly difference between these simple salts and this complex salt for the interaction energies. The interaction energy for complex salt (NH₄)₂Fe(SO₄)₂ was close to that for simple salt Na₃PO₄.

Supplemental files are available for this article. Go to the publisher's online edition of the Journal of Dispersion Science and Technology to view the free supplemental file.     

Corrosion Inhibition of Mild Steel by Safflower (Carthamus tinctorius) Extract: Polarization,EIS, AFM,SEM, EDS,and Artificial Neural Network Modeling

Inhibitory action of safflower (Carthamus tinctorius) extract (SE) was investigated in hydrochloric acid solution through electrochemical (polarization, EIS), and surface analysis (optical microscopy/atomic force microscopy (AFM)/scanning electron microscopy (SEM)/energy dispersive spectroscopy (EDS)) techniques. In addition, Inhibition efficiency was predicted by neural network (NN) modeling in elevated temperatures and different acid concentrations. The thermodynamic adsorption parameters propose that this inhibitor retard both cathodic and anodic processes through physical adsorption and blocking the active corrosion sites. Surface analysis techniques confirm the inhibitor adsorption on the metal surface, which is in accordance with the variation of apparent activation energy of corrosion. Finally, inhibition efficiency is discussed in terms of protective film formation.     

Synthesis and Crystal Structure of (Z)-Ethyl 5-(phenylamino)-3-(phenylimino)-3H-1,2-dithiole-4-carboxylate

The compound (Z)-ethyl 5-(phenylamino)-3-(phenylimino)-3H-1,2-dithiole-4-carboxylate 3 has been synthesized by the reaction of ethylacetoacetate 1 and phenylisothiocyanate 2. Its structure has been established by ¹H NMR, ¹³C NMR, infrared, mass spectra, and x-ray crystallography.      

Spectroscopic characterization,X-ray structure and DFT studies on 4-[3-(2,5-dimethylphenyl)-3-methylcyclobutyl]-N-methylthiazol-2-amine

The titled molecule 4-[3-(2,5-dimethylphenyl)-3-methylcyclobutyl]-N-methylthiazol-2-amine (C₁₇H₂₂N₂S) is synthesized and characterized by ¹H NMR, ¹³C NMR, IR, and X-ray single crystal determination. The compound crystallizes in the monoclinic space group P2_1/c with a = 6.3972(4) Å, b = 9.4988(6) Å, c = 26.016(2) Å and β = 93.496(7)°. In addition to the molecular geometry from the X-ray determination, vibrational frequencies and gauge, including the atomic orbital (GIAO), ¹H and ¹³C NMR chemical shift values of the titled compound in the ground state are calculated using the density functional (B3LYP) method with 6-31G(d), 6-31++G(d,p) and 6-311+G(2d,p) basis sets. The calculated results show that the optimized geometries can well reproduce the crystal structure. Moreover, the theoretical vibrational frequencies and chemical shift values show good agreement with the experimental values. The predicted nonlinear optical properties of the titled compound are greater than those of urea. DFT calculations of the molecular electrostatic potentials and frontier molecular orbitals of the titled compound are carried out at the B3LYP/6-31G(d) level of theory.     

Viskosimetrische Bestimmung der Hemmkonstante (K I) von β-1,4-Glucan-4-glucanohydrolase (EC 3.2.1.4)—[C x -Cellulasen-Enzyme] in Anwesenheit eines kompetitiven Hemmstoffs Lactose

Zusammenfassung Nach der entwickelten Theorie⁵ bestimmt man viskosimetrisch die HemmkonstanteK _I=2,78·10^–2 mMol/ml der hydrolytischen Reaktion der Natriumcarboxymethylcellulose (Na-CMC) unter der katalytischen Wirkung vonC _x-Cellulasenenzym [(EC 3.2.1.4), (-1,4-Glucan-4-glucanohydrolase)], aus Aspergillus oryzae isoliert, und unter der Hemmwirkung des kompetitiven Hemmstoffs Lactose.

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Viscosimetric determination of the inhibition constant (K _I ) of -1,4-glucan-4-glucano hydrolase (EC 3.2.1.4)-[C_x-cellulase enzyme] in presence of a competitive inhibitor (Lactose)

According to a recently developed theory⁵, an inhibition constantK _I=2,78·10^–2 mMol/ml was determined viscosimetrically for the hydrolase reaction of sodium carboxymethyl cellulose (Na-CMC) withC _x-cellulase enzyme (EC 3.2.1.4, -1,4-glucan-4-glucanohydrolase), isolated from Aspergillus oryzae. Lactose was used as a competitive inhibitor.

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Co(II), Ni(II) and Cu(II) Complexes with 1-(4-Hydroxyphenyl)-1H-1,2,4-Triazole

New complexes of Co(II), Ni(II), and Cu(II) with 1-(4-hydroxyphenyl)-1H-1,2,4-triazole (L) of the composition ML₂(H₂O)₂(NO₃)₂ · nH₂O (M = Co(II), n = 3; M = Ni(II), n = 0; M = Cu(II), n = 0) were synthesized and studied by photoelectron and IR spectroscopy, magnetochemistry, thermogravimetry, and X-ray powder diffraction analysis. The type of _eff(T) relationship suggests that paramagnetic centers in the Co(II) chloride and Cu(II) nitrate and bromide complexes are involved in antiferromagnetic exchange interactions. The exchange energy values were estimated by the molecular field method.     

Ligational behaviour of thiosemicarbazide and thiosemicarbazone-(III): Tetragonal complexes of cobalt(II) derived from 4-benzylamidothiosemicarbazide and 1-(α-) furyl-4-benzylamidothiosemicarbazone

Zusammenfassung Es wurden eine Anzahl von neuen Kobalt(II)-Komplexen von 4-Benzylamidothiosemicarbazid (BTSC) und 1-(-)Furyl-4-benzylamidothiosemicarbazon (FBTS) von der allgemeinen Zusammensetzung CoL ₂ X ₂ (L=BTSC, FBTS;X=Cl, Br, I, NO₃ and NCS) synthetisiert. Die Untersuchugen erfolgten mittels Elementaranalyse, magnetischer Messungen, Elektronenanregungsspektroskopie und IR-Spektroskopie (einschließlich des fernen IR); aus diesen Messungen ließ sich eine im wesentlichen tetragonale Symmetrie für alle Komplexe dieser Reihe ableiten.

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Ligational behaviour of thiosemicarbazide and thiosemicarbazone-(III): Tetragonal complexes of cobalt(II) derived from 4-benzylamidothiosemicarbazide and 1-(-) furyl-4-benzylamidothiosemicarbazone

A number of new complexes of cobalt(II) have been prepared with 4-benzylamidothiosemicarbazide (BTSC) and 1-(-)furyl-4-benzylamidothiosemicarbazone (FBTS) which conform to the general formula CoL ₂ X ₂ (whereL=BTSC andFBTS andX=Cl, Br, I, NO₃ and NCS). These have been characterized by chemical analyses and physical measurements. The tetragonal symmetry has been proposed on the basis of electronic spectral studies for all these complexes. The explanation for the slightly lower magnetic moments for cobalt(II) complexes has been sought in the possible presence of low symmetry component. The tetragonal radial parametersDq(E),Dq(A),Dt andDs and molecular orbital parameters d and d have been evaluated. The S–N, bidentate nature of the ligands and the presence of the various anions in the coordination sphere have been confirmed on the basis of additional Co–N, Co–S and Co–X frequencies in the far infrared spectra of the complexes. The nitrato and thiocyanato groups act as monodentate and are coordinated through oxygen and nitrogen atoms, respectively.