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The corrosion inhibition of mild steel in 1 M HCl by 1,1-bis(3-ethoxycarbonyl-5-methylpyrazolyl)-methane (P1) and 1,4-bis(3-ethoxycarbonyl-5-methylpyrazolyl)-butane (P2) has been studied at 308 K using electrochemical and weight loss measurements. Polarization curves reveal that the used compounds are mixed type inhibitors. Results show that inhibition efficiency increases when the inhibitor concentration increases. The comparative study of inhibitive performance of the two bipyrazolic derivatives revealed that P2 is more effective than P1. The adsorption of P2 on steel surface obeyed Langmuir’s adsorption isotherm. The kinetic and thermodynamic parameters for mild steel corrosion and inhibitor adsorption, respectively, were determined and discussed. Obvious correlation was found between corrosion inhibition efficiency and quantum chemical parameters, using the Density Functional Theory method (DFT). The obtained theoretical results have been compared with the experimental results.

2-[Bis-(3,5-dimethyl-pyrazol-1-ylmethyl)-amino]-4-[bis-(3,5-dimethyl-pyrazol-1-ylmethyl) carbamoyl]-butyric acid (Pyr1-1) has been evaluated as a corrosion inhibitor for carbon steel using weight loss and electrochemical polarization (EIS). The study was also complemented by scanning electron microscopy (SEM) and quantum chemical calculations. The inhibition efficiency ( η %) increased with increasing Pyr1-1 concentration, showing a maximum IE of 93.5% at 298 K at 10 −3 M and decreased with increasing temperature. The electrochemical studies showed that Pyr1-1 inhibitor retards both cathodic and anodic processes through the inhibitor adsorption on the metal surface and blocking the active corrosion sites. The corrosion current density is the order 165.8 μA/cm 2 of Pyr1-1 at the optimum concentration. EIS results show that the change in the impedance parameters ( R ct and C dl ) with concentration of Pyr1-1 is indicative of the adsorption of molecules leading to the formation of a protective layer on the surface of carbon steel. A good fit to Langmuir adsorption isotherm was obtained between surface coverage degree and inhibitor concentration. The results obtained by weight loss measurements are consistent with the results of the electrochemical study. Quantum chemical approach used to calculate electronic properties of the molecule to ascertain the relation between inhibitive effect and molecular structure. The equilibrium adsorption behavior of this molecule on Fe (1 1 0) surface was investigated using molecular dynamics simulation.

This work is devoted to examine the effectiveness of the aqueous extracts of olive (Olea europaea L.) leaves, roots, and stems on corrosion of mild steel in 1 M HCl solution using the weight loss measurement at various temperature and concentration effects. Polarization curves and electrochemical impedance spectroscopy (EIS) methods were employed to evaluate corrosion rate and inhibition efficiency. Corrosion inhibition efficiencies of 89.24, 88.84, and 89.83 % were achieved in 1 M HCl for olive root extract (ORE), olive stem extract (OSE), and olive leaf extract (OLE), respectively. It was found that the different extracts act as a good corrosion inhibitor for the tested system. The inhibitive action of the extract is discussed with a view to the adsorption of its components onto the steel surface which made a barrier to mass and charge transfer. The adsorption of extract components onto the steel surface was found to be a spontaneous process and increases the activation energy of the corrosion process. The inhibition efficiency is greatly reduced as the temperature increased. Experimental results show that corrosion inhibition efficiency increases with concentration of the sample extract. Polarization studies show that olive leaf, root, and stem extracts act as a mixed inhibitor.

The inhibition ability of diethylenetriaminepentakis(methylphosphonic) acid (DTMP) against carbon steel corrosion in 1 M HCl at 30 °C was evaluated by weight loss, ac impedance and electron probe microanalyser (EPMA) methods. The experimental results showed that DTMP was a good inhibitor for the steel corrosion in 1 M HCl medium and its inhibition efficiency increased with the inhibitor concentration. Data, obtained from ac impedance measurements, were analysed to model the corrosion inhibition process through appropriate equivalent circuit models. Adsorption of DTMP on the carbon steel surface followed the Langmuir adsorption isotherm. Surface analysis supported the formation of a protective inhibitor film on the carbon steel surface.

A new benzoxazin derivative, namely methyl 3-(2-oxo-2H-1,4-benzoxazin-3-yl) propanoate (1,4-MBXP), was synthesized under mild conditions from 2-aminophenols and dimethyl-2-oxoglutarate. The prepared compound was identified by FT-IR, 1H NMR, 13C NMR spectroscopies, elementary analysis and MS. Its inhibitive action against the corrosion of carbon steel in 1M H2SO4 solution was investigated by weight-loss and hydrogen evolution measurements. 1,4-MBXP is a good corrosion inhibitor and its inhibition efficiency increases with the increase of concentration to attain 75.08 % at 180 ppm. The temperature effect on the corrosion behaviour of carbon steel in 1M H2SO4 with and without the inhibitor at 180 ppm was studied in the temperature range from 298 to 338 K. The synergistic action caused by iodide ions on the corrosion inhibition of carbon steel in 1M H2SO4 by 1,4-MBXP at 180 ppm was studied using weight methods at 298 K. The inhibition efficiency synergistically increased on addition of potassium iodide.

The corrosion inhibition potentials of Mentha rotundifolia oil on carbon steel in 1 M HCl was studied at different concentrations via gravimetric, electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization techniques. Polarization curves reveal that Mentha rotundifolia oil is a mixed-type inhibitor. Changes in impedance parameters (charge transfer resistance Rt, and double-layer capacitance Cdl) were indicative of adsorption of Mentha rotundifolia on the metal surface, leading to the formation of a protective film. The effect of the temperature on the corrosion behavior with addition of the optimal concentration of Mentha rotundifolia oil was studied in the temperature range 308 and 338 K. Adsorption of oil on the carbon steel surface is found to obey the Langmuir adsorption isotherm. Attempts to explain the inhibitory action were carried out using density functional theory (DFT) at B3LYP/6-31G(d,p) level. Quantum chemical parameters most relevant to its potential action as corrosion in...

The corrosion inhibition properties of 2-hydroxy-1-(2-hydroxy-4-sulfo-1-naphthylazo)-3-naphthoic acid (HHSNNA) for C38 steel in HCl 1 M solution were analyzed by electrochemical impedance spectroscopy (EIS), potentiodynamic polarization and gravimetric methods. It was found that the presence of HHSNNA hugely decreases the corrosion rate, while its inhibition efficiency (E%) increases with concentration to attain 93.8 % at 10−3 M. The high inhibitory efficiency of HHSNNA was related with the adsorption of HHSNNA molecules at the metal/solution interface and a protective film formation. Adsorption behavior of the inhibitor on the surface followed the Langmuir adsorption isotherm. This compound is classified as the mixed type corrosion inhibitor with predominant control of the cathodic reaction. Data, obtained from EIS measurements, were analyzed to model the corrosion inhibition process through an appropriate equivalent circuit model.

2-Allyl-p-mentha-6,8-dien-2-ols P1−P3 synthesized from carvone P are tested as corrosion inhibitors of steel in 1 M HCl using weight loss measurements, potentiodynamic polarisation and impedance spectroscopy (EIS) methods. The addition of 2-allyl-p-mentha-6,8-dien-2-ols reduced the corrosion rate. Potentiodynamic polarisation studies clearly reveal that the presence of inhibitors does not change the mechanism of hydrogen evolution and that they act essentially as cathodic inhibitors. 2-Allyl-p-mentha-6,8-dien-2-ols tested adsorb on the steel surface according to Langmuir isotherm. From the adsorption isotherm some thermodynamic data for the adsorption process are calculated and discussed. EIS measurements show the increase of the charge-transfer resistance with the inhibitor concentration. The highest inhibition efficiency (92%) is obtained for P1 at 3 g/L. The corrosion rate decreases with the rise of temperature. The corresponding activation energies are determined.

Quantum chemical calculations based on DFT method were performed on three quinoxalines compounds namely ethyl 2-(4-(2-ethoxy-2-oxoethyl)-2- p -tolylquinoxalin-1(4 H )-yl)acetate ( Q 1), 1-[4-acetyl-2-(4-chlorophenyl)quinoxalin-1(4 H )-yl]acetone ( Q 2) and 2-(4-methylphenyl)-1,4-dihydroquinoxaline ( Q 3), used as corrosion inhibitors for copper in nitric acid media to determine the relationship between the molecular structure of quinoxalines and inhibition efficiency. Quantum chemical parameters such as the highest occupied molecular orbital energy ( E HOMO ), the lowest unoccupied molecular orbital energy ( E LUMO ), energy gap (Δ E ), dipole moment ( μ ), electronegativity ( χ ), electron affinity ( A ), global hardness ( η ), softness ( σ ), ionization potential ( I ), the fraction of electrons transferred (Δ N ), and the total energy (TE), were calculated. The theoretically obtained results were found to be consistent with the experimental data reported.

We report (time-dependent) density functional theory calculations characterizing the changes in the electronic and optical properties of oligothiophene dyes when grafted on a titania surface via a carboxylic acid or catechol moiety as anchoring group, in relation to their use in dye-sensitized solar cells. The broadening of the LUMO level of the compounds upon adsorption has been extracted from the computed electronic structures and used to estimate electron injection times into the conduction band of the oxide. The strongly coupled carboxylic-containing dyes lead to faster electron injection times compared to catechol-substituted dyes. This difference is ascribed to the electron-donating character of the catechol moiety that polarizes the dye LUMO away from the dye@titania interface. The absorption spectra simulated at the TD-DFT level indicate that the grafted carboxylic-thiophene dyes undergo an indirect injection mechanism (type I) in which an intramolecular excitation is created before the charge is transferred to titania. In contrast, catechol dyes with a short conjugation length for the thiophene backbone are type II sensitizers exhibiting a direct injection mechanism leading to a direct photoexcitation from the dye HOMO to the titania conduction band. A mixed character prevails for the injection in the case of catechol dyes containing a longer oligothiophene chain.

This work ultimately pays careful consideration to a method that respects the environment, and that can be developed across the accumulation of research to reduce the corrosion of metals in sea water. Extracts of Ziziphus lotus (wild jujube) were tested as a corrosion inhibitor of copper in sea water, using polarization methods and weight loss measurements. We also present by SEM the morphology of copper surface analyzed after immersion in inhibited and uninhibited electrolytes. The inhibition efficiency of Ziziphus lotus extracts was calculated and compared. We note good agreement between these methods. The obtained results revealed that the tested inhibitor significantly reduced the kinetics of the corrosion process of copper. Its efficiency increases with the concentration, and attained 93% at 5 g/L. The effect of temperature on the corrosion behavior of copper in natural sea water was also studied in the range of 293 K and 323 K, to determine thermodynamic data of activation.

This work is devoted to examine the effectiveness of pyrazoles 4-(4,5-dihydro-1Hpyrazol- 5-yl)-N,N-dimethylaniline (D) on corrosion of mild steel in a 1 M HCl solution, using weight loss measurement at concentration effects. The inhibitor (D) was synthesized in our laboratory. The formation of this pyrazole was carried out with hydrazine and α-unsaturated aldehydes, and the structure was checked by spectroscopic means, such as FT-IR, 1H NMR and 13C NMR. Polarization curves and electrochemical impedance spectroscopy (EIS) methods were used to assess both the corrosion rate and inhibition efficiency. Potentiodynamic polarization showed that D behaved as a mixed-type inhibitor. The Nyquist plots showed that, while D concentrations increased, charge-transfer resistance increased and double-layer capacitance decreased, involving increased inhibition efficiency. Adsorption of the inhibitor molecules corresponds to Langmuir adsorption isotherm. Quantum chemical calculations showed that the inhibitor was prone to be protonated in the acid, and the results were in full agreement with experimental observations.

The inhibition effect of quince pulp extract (QPE) on the adsorption and corrosion of carbon steel in 1M HCl solution was investigated using the weight loss method, potentiodynamic polarization and impedance spectroscopy measurements. At first, the quince extract was characterized, its polyphenolic content was qualitatively and quantitatively determined and its anti-oxidant activity was assessed. The HPLC–DAD–MS showed that the quince extract contained a high quantity of polyphenols with the main compounds being neochlorogenic acid, rutin and chlorogenic acid (7.68, 9.05 and 18.57 mg/g fw, respectively), which represent together about 84 % of total phenolics. The extract exhibited a strong antioxidant potential as it inhibited 87 % of the DPPH· anionic radical. The polarization measurements indicate that the extract acts as a mixed inhibitor. The values of inhibition efficiency increase with inhibitor concentration reaching a maximum value (88 %) at 5 × 10−1 g/L. The presence of QPE enhances the values of R t and reduces the C dl values. The adsorption of QPE under consideration on a steel/acidic solution interface at all temperatures follows the Langmuir adsorption isotherm. The QPE inhibitor efficiency was temperature-independent.

The influence of natural occurring extract of Chenopodium Ambrosioides (CAE) on the corrosion inhibition of carbon steel in sulfuric acid solution is studied by the weight loss method, potentiodynamic polarization and impedance spectroscopy (EIS) measurements. The experimental results reveal that extract has a good inhibiting effect on the metal tested in 0.5 M H2SO4 solution. The protection efficiency increases with increasing inhibitor concentration to attain 94% at 4 g/l. Potentiodynamic polarization studies clearly reveal that it acts essentially as a cathodic inhibitor. EIS results show that the change in the impedance parameters (Rt and Cdl) with concentration of extract of Chenopodium Ambrosioides is indicative of the adsorption of molecules leading to the formation of a protective layer on the surface of carbon steel. The efficiency decreases with temperature. The adsorption of Chenopodium Ambrosioides extract is found to obey the Langmuir adsorption isotherm. The activation energies and enthalpies of the corrosion process of carbon steel in acidic medium were determined.

An efficient green ultrasound-assisted procedure for the preparation of five new functionalized 1-alkyl-3-butylimidazolium ionic liquids (ILs) 2–6 is described. Their structures were characterized by FT-IR, 1H NMR, and 13C NMR spectroscopy and mass spectrometry. The newly synthesized compounds were screened for their antimicrobial and anticancer activities. The former revealed that the ILs exhibited promising activity compared with standard drugs. Moreover, IL 4 was found to be a very promising antiproliferative agent against the human hepatocellular carcinoma (HEPG2), human breast adenocarcinoma (MCF7), and colon carcinoma (HCT116) cell lines and consistently produced low IC50 values.

In view of the emerging importance of the ILs as “green” materials with wide applications and our general interests in green processes, a series of a twenty five new 1-alkyl-3-(4-phenoxybutyl) imidazolium-based ionic liquids (ILs) derivatives is synthesized using a facile and green ultrasound-assisted procedure. Their structures were characterized by FT-IR, 1H-NMR, 13C-NMR, 11B, 19F, 31P, and mass spectrometry. Antimicrobial screens of some selected ILs were conducted against a panel of Gram-positive and Gram-negative bacteria. The antimicrobial activity of each compound was measured by determination of the minimal inhibitory concentration (MIC) yielding very interesting and promising results. Their antibacterial activities are reported, and, on the basis of the experimental and virtual POM screening data available, attempt is also made to elucidate the structure activity relationship.

The inhibition effect of curcumin on the corrosion of mild steel in 1.0 M HCl solution was studied by weight loss, potentiodynamic polarization curves and electrochemical impedance spectroscopy (EIS) methods. The experimental results suggest that this compound is an efficient corrosion inhibitor and the inhibition efficiency increases with the increase in inhibitor concentration. Adsorption of this compound on mild steel surface obeys Langmuir isotherm. Also the objective of this work is to attempt to find relationships between electronic structure and inhibition efficiency. The structural parameters, such as the frontier molecular orbital energies (E HOMO and E LUMO), gap of energy ΔE, from the molecule to iron as well as electronic parameters such as Mulliken atomic populations were calculated and discussed using the Density Functional Theory method (DFT).

A series of novel Cd(II) complexes incorporating ligand, di(2-pyridinyl)methanone N-(2-pyridinyl)hydrazone (DPMNPH), has been investigated. The ligand, DPMNPH, and its corresponding complexes have been characterized with the help of a number of techniques: microanalysis, FT-IR, 1H and 13C NMR, UV/vis spectroscopy, thermal studies and MS–FAB mass spectrometry. In addition, single crystal X-ray diffraction measurement studies are also employed in one of the complexes showing a distorted trigonal bipyramidal geometry. Furthermore, the existence of NH⋯Npy intramolecular hydrogen bonding interactions in the ligand and its corresponding complexes has also been reported.

2,5-Bis(n-methylphenyl)-1,3,4-oxadiazole with (n = 2,3,4), denoted n-MPOX, have been investigated by using potentiodynamic polarization (PP) and electrochemical impedance spectroscopy (EIS) methods, to evaluate the electrochemical behavior of brass in simulated cooling water system. The PP study revealed that oxadiazole inhibited both cathodic and anodic reactions, indicating a mixed type control of inhibition. It was shown that, 3-MPOX as well as 4-MPOX, were the best inhibitors and the inhibition efficiency followed the sequence: 3-MPOX ⩾ 4-MPOX ≫ 2-MPOX. The interference between non-oxidizing biocide CTAB and 3-MPOX and 4-MPOX against corrosion and biocorrosion has also been studied.

Based on potentiodynamic polarization measurements and electrochemical impedance spectroscopy, 5-phenyl-1,2,4-triazole-3-thione (PTT) was investigated as a corrosion inhibitor for C38 steel in 1 M HCl solution. The effects of temperature and immersion time were also studied. The corrosion inhibition efficiencies as measured by all the above techniques were in good agreement with each other. The results showed that PTT is a very good inhibitor for C38 steel in acidic media. It acts as a mixed inhibitor. The inhibition efficiency increases with increasing inhibitor concentration and decreases with increasing temperature and immersion time. Thermodynamic and activation parameters are discussed. Adsorption of PTT was found to follow the Langmuir adsorption isotherm. A physisorption mechanism is proposed.

Corrosion inhibition effect of Argan oil (AO) on corrosion of C38 steel in 1 M HCl solution was investigated using weight loss measurements, electrochemical polarization and EIS methods. Results obtained reveal that Argan oil acts as a mixed inhibitor without modifying the hydrogen reduction mechanism. The inhibition efficiency increases with increased Argan oil concentration to attain a maximum value of 81% at 3 g/L. The inhibition efficiency of Argan oil decreases with the rise of temperature. Argan oil is adsorbed on the steel surface according to Langmuir isotherm model. The parameters ( E a ∗ , Δ H a ∗ , Δ G ∗ and Δ S a ∗ ) were estimated and discussed. The fundamental thermodynamic functions were used to glean important information about Argan oil’s inhibitory behavior.

The corrosion inhibition and adsorption of ethanol extracts of leaves (LV), stems (ST) and roots (RT) of Rotula aquatica plant for mild steel in H 2SO 4 solutions were investigated using conventional weight loss, gasometric techniques, electrochemical polarizations and electrochemical impedance spectroscopy. The results showed that all the three extracts of Rotula aquatica plant performed well as inhibitor for the corrosion of steel in sulphuric acid media and the inhibition efficiencies of the extract follow the trend RT > LV > ST. Inhibition efficiencies increased with increasing concentration of the plant extracts but decreased with the temperature rise for all cases. Both the cathodic hydrogen evolution and the anodic dissolution of mild steel were inhibited, hence the active molecules of all the extracts studied acted as mixed type corrosion inhibitors.

Three complexes of the general formula trans/cis-[Ru((II))(dppme)(N-N)Cl2] {dppme is H2C=C(CH2PPh2)2 and N-N is 1,2-diaminocyclohexane (trans/cis-(1)) and 1-methyl-1,2-diaminopropane (trans-(2)} were obtained by reacting trans-[RuCl2(dppme)2] with an excess amount of corresponding diamine in CH2Cl2 as a solvent. The complexes were characterized by an elemental analysis, IR, (1)H, (13)C and (31)P{1H} NMR, FAB-MS and UV-visible. The trans-(1) (kinetic product) readily isomerizes to the cis-(1) (thermodynamic product) and this process was followed by using (31)P{(1)H} NMR, cyclic voltammetry and UV-vis spectroscopy. The electrochemical studies on complex (1) reveal that the Ru(III)/Ru(II) couples are sensitive to the isomer (trans/cis) formed. The cis-(1) was confirmed by X-ray structure and (31)P{(1)H} NMR. Transfer-hydrogenation reactions for reduction of trans-4-phenyl-3-butene-2-one were conducted using complexes trans/cis-(1) and trans-(2). The electronic spectra of cis/trans-(1) in dichloromethane were calculated with the use of time-dependent DFT methods.

The inhibition effect of Mentha pulegium extract (MPE) on the acid corrosion of carbon steel in 1 M HCl solution was investigated using weight loss, potentiodynamic polarisation, and electrochemical impedance spectroscopy. The results show that the Mentha pulegium extract is a good inhibitor, and that the inhibition efficiency depends on the concentration of the plant extract. Efficiency is higher than 88 % for 33% Mentha pulegium extract. Polarization measurements also show that Mentha pulegium extract is a good mixed inhibitor. The remarkable inhibition efficiency of MPE was discussed in terms of blocking of the electrode surface by adsorption of inhibitor molecules through active centres. Mentha pulegium extract is adsorbed on the carbon steel surface according to the Temkin adsorption model. The effect of temperature on the corrosion behaviour of carbon steel in 1 M HCl with addition of 33% MPE was studied in the temperature range 308-338 K. SEM also confirmed the adsorption of MPE on carbon steel surface.

A polyethylene terephthalate membrane electrode based on clinoptilolite as the ionophore was prepared and was deposited on a gold electrode. This one was characterised with electrochemical impedance spectroscopy and modelled with an equivalent electric circuit. The detection of ammonium at low concentrations and the interaction with the other cations were made by impedance measurements. The study of the interaction of ammonium ions in presence with the cations such as Na+, Ca2+ and K+ in the same concentration showed that the electrode is selective and sensitive for very low concentrations 10−7 mol/l, but the membrane is saturated for concentrations greater than 10−2 M. The life expectancy of the membrane exceeded 50 days when we changed the PBS solution after 44 days.

The novel trans -[RuCl 2 (dpme)(L)] complexes ( 1L 1 – 1L 4 ) {dpme is H 2 C C(CH 2 PPh 2 ) 2 and L is 1,2-ethanediamine ( L 1 ), 1,3-propanediamine ( L 2 ), 2,2-dimethyl-1,3-propanediamine ( L 3 ) and 1,4-butanediamine ( L 4 )} were obtained by reacting trans -[RuCl2(dpme) 2 ] with an excess amount of the corresponding diamine in CH 2 Cl 2 as the solvent. One of the diphosphine ligands was quantitatively replaced by the corresponding diamine, even when excess diamine was added. In solution the trans -[RuCl 2 (dpme)(diamine)] isomer configuration was confirmed by NMR spectroscopy and the X-ray crystal structure of 1L 2 was also determined. These diphosphine complexes ( 1L 1 – 1L 4 ) have exhibited significant activity and selectivity as hydrogenation catalysts for α,β-unsaturated ketones. Increasing the chelating ring of the diamine ligands from five and six to seven decreases the turnover frequencies (TOFs). The catalytic activities were compared to the analogous trans -[RuCl 2 (dppp)(L)] ( 2L 1 – 2L 4 ) {dppp is H 2 C(CH 2 PPh 2 ) 2 }. Complexes 1L 1 – 1L 4 catalyzed the hydrogenation of α,β-unsaturated ketones faster than the previously reported complexes 2L 1 – 2L 4 . Density functional theory (DFT) calculations have been carried out to study the shift in the Ru(III)/Ru(II) couple and the catalytic activity for two representative complexes, 1L 2 and 2L 2 .

The corrosion inhibition of 2-(benzylthio)-1,4,5-triphenyl-1H-imidazole (BTI) for carbon steel in a 1 M HCl solution was studied by means of weight loss, potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), and scanning electron microscopy (SEM) methods. Quantum chemical calculations based on the DFT method were performed on BTI. Molecular dynamics simulations were carried out to establish the mechanism of corrosion inhibition for carbon steel with BTI in HCl. Kinetic and thermodynamic parameters of activation using a statistical model were calculated. Polarization curves revealed that BTI is a mixed-type inhibitor. The results showed that BTI is a good inhibitor for the corrosion of carbon steel in 1.0 M HCl solution and that its inhibition efficiency is higher than 88% at 1 × 10–3 M BTI. Adsorption of the inhibitor on the carbon steel surface follows the Langmuir adsorption isotherm, and the value of the free energy of adsorption, ΔGads, indicates that the adsorption of BTI is a s...

The one-pot, three-component reaction of aromatic nitriles, hydroxylamine hydrochloride, and sodium carbonate in ethylene glycol provided 3,5-disubstituted 1,2,4-oxadiazoles. These 1,2,4-oxadiazole derivatives are quickly prepared under microwave irradiation (2 h) in high yields and excellent state of purity. The synthesized compounds were characterized by means of their 1H, 13C NMR, mass spectroscopy data and elemental analysis.

Inhibition of the corrosion of C38 steel in 1 M HCl by 6-bromo-3-nitroso-2-phenylimidazol[1,2-α]pyridine (BNPP) has been studied by use of electrochemical impedance spectroscopy and potentiodynamic polarization. BNPP inhibited the corrosion of C38 steel in 1 M HCl solution. Polarization curves show that BNPP acts as mixed-type inhibitor. Changes in impedance (charge-transfer resistance, Rt, and double layer capacitance, Cdl) were indicative of adsorption of BNPP on the metal surface, leading to formation of a protective film. The extent of surface coverage by the inhibitor was determined by measurement of weight loss; it was found that adsorption of this inhibitor on the C38 steel surface obeys the Langmuir adsorption isotherm. The effect of temperature on the corrosion behaviour was studied in the range 289–328 K. The results showed that the rate of corrosion of C38 steel increased with increasing temperature both in the presence of 10−3 M BNPP and in its absence. Activation energies in the presence and absence of BNPP were obtained by measuring the temperature dependence of charge-transfer resistance.

This study evaluates solid-phase micro-extraction (SPME) coupled with gas chromatography–mass spectrometry (GC–MS) to determine trace levels of bis-phenol A in water and leached from plastic containers. In our study, we used very thin composite membranes prepared in the laboratory. The extraction using headspace post-derivatization with bis(trimethylsilyl) trifluoroacetamide (BSTFA), containing 1 % trimethylchlorosilane (TMCS) vapor, following SPME was compared with extraction without derivatization. The SPME experimental procedures to extract bis-phenol A in water were optimized with a relatively polar polyacrylate (PA)-coated fiber, an extraction time of 50 min, and desorption at 300 °C for 2 min. Headspace derivatization following SPME was performed using 7 μL of BSTFA with 1 % TMCS at 65 °C for 30 s. The precision was 5.2 % without derivatization and 9.0 % headspace derivatization. The detection limit was determined to be at the nanogram per liter level. When SPME was used following headspace derivatization, the detection limit was one order of magnitude better than that achieved without derivatization. The results of this study reveal the adequacy of the SPME–GC–MS method for analyzing bisphenol A leached from plastic containers. The concentrations of bisphenol A leached from plastic containers into water ranged from 0.7 to 78.5 μg L−1.

Inhibition performance of purpald (4-amino-3-hydrazino-5-mercapto-1,2,4-triazole (AHMT)) was investigated as a corrosion inhibitor for a copper surface in 2 M HNO3 at 303 K by weight loss, ac impedance, and dc polarization techniques. The obtained results indicate that AHMT is a good inhibitor and its inhibition efficiency attains 94.7% at 10–2 M. Polarization studies showed that AHMT acts as a mixed type inhibitor. The inhibitor adsorption process in the Cu/AHMT/2 M HNO3 system was studied at different temperatures (303–343 K). The adsorption of AHMT on the copper surface obeyed Langmuir’s adsorption isotherm. The kinetic and adsorption parameters for copper/acid in the presence and absence of AHMT were evaluated and discussed.

This work reports results from potentiodynamic polarisation and impedance investigation, with a rotating disc electrode, of inhibition of corrosion of A106 steel in aerated, unstirred 3.0 % NaCl solutions using di-n-butyl bis(thiophene-2-carboxylato-O,O′)tin(IV) as inhibitor. These studies showed that it is a mixed-type inhibitor. Inhibition efficiency increased with increasing di-n-butyl bis(thiophene-2-carboxylato-O,O′)tin(IV) concentration and decreases with increasing solution temperature. Maximum efficiency of inhibition of the inhibitor of approximately 78 % is observed at a concentration at 10−2 M. The inhibition process was attributed to formation of an adsorbed film on the metal surface that protects the metal against corrosive agents. The adsorption isotherm confirms the applicability of Langmuir equation to describe the adsorption process. Thermodynamic functions for the adsorption process were determined. The efficiency of corrosion inhibitors and global chemical reactivity depend on such properties as energy of the highest occupied molecular orbital (E HOMO), energy of the lowest unoccupied molecular orbital (E LUMO), energy gap (ΔE), which were calculated. All calculation was been performed by density functional theory (DFT) using the Gaussian03W suite of software. Calculated results were usually in agreement with the experimental data.

The inhibitory effect of some new synthesized benzamide compounds on corrosion of mild steel in 1 M HCl solution has been studied by use of weight loss measurements and the electrochemical techniques potentiodynamic polarization and electrochemical impedance spectroscopy. The inhibiting action is more pronounced with increasing concentration. Inhibition efficiency is maximum (approximately 99 %) at 10−3 M. Polarization measurements also show that the compounds act as mixed inhibitors. The cathodic curves indicate that reduction of protons at the mild steel surface occurs as a result of a pure activating mechanism. EIS measurements reveal increased transfer resistance with increasing inhibitor concentration. The presence of heteroatoms increases inhibition efficiency without causing a drastic change in adsorption mechanism, which follows the Langmuir isotherm model. Significant correlations were obtained between inhibition efficiency with the chemical indexes calculated, by use of the standard software Gaussian03, on the basis of density functional theory (DFT) at the B3LYP/6-31G** level of theory, indicating that variation of inhibition with inhibitor structure may be explained in terms of electronic properties. The effect of temperature on the corrosion behaviour of steel in 1 M HCl without and with inhibitors at 10−3 M was studied in the temperature range from 308 to 333 K, and the associated activation energy was determined.

Inhibition of corrosion of copper in 1M HNO3 solution by four amino acids, proline (Pro), phenylalanine (Phe), tyrosine (Tyr), and tryptophan (Try), has been studied by use of gravimetric and electrochemical polarization measurements. The results obtained the from two different techniques are comparable, and show that Tyr and Try act as good inhibitors of corrosion of copper in 1 mol L−1 HNO3. Correlation between inhibition efficiency and quantum chemical calculations, performed using semi empirical (AM1 and MNDO) and ab-initio methods, is discussed.

The present study describes the inhibition effect of 4-benzyl piperidine (P1), 1,6-bis(4-benzylpiperidine-1-carboxamide)hexane (P2) and bis(4-benzylpiperidine)thiuram disulfide (P3) towards the corrosion of mild steel in 5.5 M H3PO4 solution using weight loss measurements and polarization technique. The influence of inhibitor concentration and temperature on the inhibitory behavior of P2 and P3 was investigated. Meanwhile, the inhibition efficiency (IE) was found to depend on the molecule structure and the concentration of piperidine derivatives. The IE for 10−3 M P2 and P2 in 5.5 M H3PO4 is around 90 %. Polarization studies clearly revealed that all the compounds used act as mixed-type inhibitors. Adsorption isotherms were fitted by the Langmuir isotherm. Adsorption energies ( $$ \Updelta {\text{G}}^\circ_{\text{ads}} $$ and $$ \Updelta {\text{H}}^\circ_{\text{ads}} $$ ) and kinetic parameters were evaluated. Significant correlations are obtained between inhibition efficiency with the calculated chemical indexes, indicating that the variation of inhibition with structure of the inhibitor may be explained in terms of electronic properties.

Inhibition of corrosion of carbon steel in phosphoric acid solution by use of l-cysteine methyl ester hydrochloride has been investigated by measurement of weight loss and use of electrochemical methods. The efficiency of inhibition was increased by increasing the concentration of the inhibitor and reduced by increasing the temperature. Polarization studies revealed that this compound behaves as mixed-type inhibitor. Electrochemical impedance spectroscopy showed that dissolution of the steel occurs as a result of charge-transfer. Adsorption of the inhibitor obeyed the Langmuir adsorption isotherm. Kinetic and thermodynamic data were calculated and are discussed.

A binuclear nickel(II) chloride complex with dimethyl-1,10-phenanthroline, di-μ-chloro-bis[chloro(2,9-dimethyl-1,10-phenanthroline)nickel(II)] dimer, has been prepared and its molecular structure determined by X-ray diffraction. The crystal is triclinic, space group P−1, with the Ni(II) in [NiCl2(C14H12N2)]2 coordinated to two N of the phen ligand and three Cl−, one terminal and two bridging. A center of inversion lies midway between two Ni(II). Overall Ni(II) coordination is distorted triangular bipyramidal. The dimer complex was also characterized by elemental analysis, FAB-MS, IR and UV–visible spectroscopy, and thermogravimetric analysis.

Argania spinosa press cake, kernels and hulls extracts are excellent corrosion inhibitors for steel. In this work electrochemical methods are used to study the inhibition of corrosion on steel in 1 M HCl. It has shown that Argan press cake, kernels and hulls extracts suppress both the anodic and cathodic process and they behave as mixed-type inhibitors. The inhibition efficiency was found to increase with inhibitors content. Data obtained from EIS measurements, were analyzed to model the corrosion inhibition process through appropriate equivalent circuit model; a constant phase element has been used. The values of the inhibition efficiency calculated from these techniques are in reasonably good agreement. The adsorption isotherm of natural compounds on the steel surface was found to obey Langmuir’s adsorption isotherm.

In this work, the effect of potassium ferrocyanide (Pf) on the corrosion of mild steel in solutions of phosphoric acid (H3PO4) has been investigated in relation to the concentration of the inhibitor by weight loss, potentiodynamic polarization and AC impedance (EIS) measurements. The results obtained revealed that this compound is good a mixed-type inhibitor. The effect of temperature on the corrosion behavior with the addition of optimal concentration of Pf was studied in the temperature range 298–328 K. The value of inhibition efficiency decreases slightly with the increase in temperature. Changes in impedance parameters (charge transfer resistance, R t, and double layer capacitance, C dl) were indicative of adsorption of Pf on the metal surface, leading to the formation of a protective film. Adsorption of Pf on the C38 steel surface was found to obey the Langmuir adsorption isotherm. Some thermodynamic functions of dissolution and adsorption processes were also determined.

Inhibition of the corrosion of mild steel in molar hydrochloric acid by two calixarenes, including the effect of inhibitor concentration and temperature, has been investigated by use of weight loss and electrochemical measurements (polarisation and impedance). The results obtained showed that the rate of corrosion decreased substantially in the presence of the compounds, with maximum inhibition of 98.2 % by one of the compounds at a concentration of 10−3 M. The effect of temperature on corrosion behaviour in the presence of different concentrations of the two new calixarenes was studied in the range 45–75 °C. The efficiency of inhibition by the compounds increased with increasing inhibitor concentration and was independent of temperature. Polarisation curves revealed that the calixarenes are mixed-type inhibitors. Adsorption of the inhibitors by the carbon steel surface obeyed the Langmuir adsorption isotherm. Some thermodynamic data for the dissolution and adsorption processes were also determined.

The corrosion inhibition properties of purpald (4-amino-3-hydrazino-5-mercapto-1,2,4-triazole (AHMT)) on carbon steel in phosphoric acid (2 M H 3 PO 4 ) solution has been examined and characterized by weight loss, Tafel polarization, electrochemical impedance spectroscopy (EIS) and X-ray photoelectron spectroscopy (XPS) methods. The experimental results reveal that the compound has a good inhibiting effect on the carbon steel in 2 M H 3 PO 4 solution. The protection efficiency increases with increasing inhibitor concentration, but the temperature has hardly effect on the inhibition efficiency of AHMT. The adsorption of AHMT is found to obey the Langmuir adsorption isotherm. Thermodynamic data and XPS analysis clearly show that the adsorption mechanism of AHMT on carbon steel surface in 2 M H 3 PO 4 solution is mainly electrostatic-adsorption. Potentiodynamic polarization studies have shown that AHMT acts as a mixed-type of inhibitor. Data obtained from EIS studies were analyzed to model inhibition process through appropriate equivalent circuit model.

In this paper, a new natural lignocellulosic material based on Luffa Cylindrica, (LC), to adsorb the Ni (II) in the water. The Luffa Cylindrica powder (LCP) is characterized using different techniques. The effect of different operating parameters on the adsorption of Ni (II) ions is investigated. Batch adsorption experiments are performed as a function of adsorbent dose, pH, Nickel concentration, contact time and temperature. The optimum conditions for maximum adsorption were attained at pH 6 and LC dose of 1 g/L. The results show that the increase in the temperature leads to decrease the adsorption quantity of Ni (II) on LCP up to the maximum in the range of 6.84-7.87 mg/g. On the other hand, the results of the adsorption isotherms follow the Freundlich model and the kinetic adsorption and the pseudo-second order reaction. Moreover, the thermodynamic study indicates that the adsorption process, which depends on the solution pH, is an exothermic and spontaneous phenomenon. Overall, the results show the adsorption behavior of this raw material that can be used as a low-cost alternative to commercial materials., Moroccan Journal of Chemistry, Vol. 4, No 4 (2016)

International audience; The extract (E) and oil of Melissa Officinalis leaves (EO) have been evaluated as a corrosion inhibitors for carbon steel in 1.0 M HCl solution by means of weight loss measurements, potentio dynamic polarization, and electro chemical impedance spectroscopy (EIS). Tafel polarization study revealed that extract (E) and oil of Melissa Officinalis (EO) act as a mixed type inhibitors. The Nyquist plots showed that with increasing the inhibitors concentrations, the charge-transfer resistance increased and the double-layer capacitance decreased, involving increased inhibition efficiency. The inhibition was found to increase with increasing the concentration of the extract (E) and oil of Melissa Officinalis (EO). The values of inhibition efficiency calculated from weight loss, Tafel polarization curves, and EIS were in good agreement. The effect of temperature on the corrosion behaviour of mild steel in 1.0 M HCl with addition of both extract (E) and oil of Melissa Officinalis (EO) was also studied and thermodynamic parameters were determined and discussed.

Methyl 2-(bis((3,5-dimethyl-1H-pyrazol-1-yl)methyl)amino) acetate, BT36, and methyl 2-(bis((3,5-dimethyl-1H-pyrazol-1-yl)methyl)amino)-3-(1H-indol-3-yl)propanoate, BT 43, have been synthesized. Investigation by weight-loss measurement and use of electrochemical techniques revealed the compounds are very effective inhibitors of corrosion of C38 steel in 1 M HCl solutions—percentage protection exceeded 95 % for BT43 at concentrations as low as 10−2 M. An impedance study in the absence and presence of these compounds revealed the mechanism of protection was cathodic inhibition by polarization and charge-transfer. The Langmuir adsorption isotherm was obeyed. Quantum chemical data calculated by use of DFT at the B3LYP/6-31G* level of theory revealed a good correlation between inhibition efficiency and the molecular structure of BT36 and BT43. The highest occupied molecular orbital, the lowest unoccupied molecular orbital, the separation energy (ΔE), and the dipole moment (μ) from the inhibitor to the metal surface explain the experimental data well.

A fast, simple and inexpensive sample preparation method based on the matrix solid-phase extraction (SPE) technique is proposed for the isolation of cypermethrin and its metabolite residues from soils. Both the extraction and clean-up procedures were carried out in two steps and target compounds were determined by gas chromatography coupled with electron-impact mass spectrometry (GC-EI/MS). The characteristic ions and fragmentation mechanism of cypermethrin were evaluated by electron impact ionization mass spectrometry (EI/MS). After the optimization of different parameters, such as the extraction solvent, the pesticide was extracted from the matrix with methanol/acetone in a Soxhlet extractor, cleaned up on a Florisil column by elution with a mixture of 30% ethyl acetate in n-hexane and analyzed by gas chromatography-electron impact ionization mass spectrometry (GC-EI/MS) in the selected ion-monitoring mode (SIM) with permethrin as internal standard. Recovery was in the range 77–118% with relative standa...

The corrosion inhibition properties of horehound (Marrubium vulgare L.) extract (HE) in 1 M hydrochloric acid medium was carried out using electrochemical methods (polarization curve and electrochemical impedance spectroscopy). Experiments were performed by concentration of the inhibitor and temperature effect. The results showed variation in inhibition performance of this plant extract. The Langmuir model was tested to describe the adsorption behavior of the inhibitor on the C38 steel surface. Some thermodynamic functions of dissolution processes were also determined.

The main objective of this study is to understand the setting mechanism of a zinc phosphate cement and the development of its mechanical hardness. This cement is widely used in dentistry and is composed of solid phase cement containing zinc oxide (ZnO) and aluminium phosphate AlPO4 ·nH2O, and then liquid phase cement which is composed of phosphoric acid and water. The setting of the cement is due to a mixture of both phases together. In this optic, the control of the effect of different compounds in setting mechanism and hardness is carried out by using several investigation methods such as ESM, XRD, IR, TGA, and DTA. For this study, we explain in detail each phase of the cement process, such as the preparation of raw materials, their mixing, the introduction of the solid phase of cement to the liquid phase, and then the hardening of the cement. The results obtained show the effect of powder size on the setting reaction of the cement and show that aluminium phosphate had an interesting effect on the hardening and setting time of the cement. The X-ray diffraction showed that the principal phase of the hydratation product, which is Hopeite, is available in the mixture of initial reactants and other secondary products, which are zinc phosphate salts in primary and secondary forms.

International audience; Essential oil of aerial parts of Salvia aucheri Boiss. var. mesatlantica was obtained by hydrodistillation and analyzed by GC and GC/MS. The oil was predominated by camphor (49.8%). The inhibitory effect of this essential oil was estimated on the corrosion of steel in 0.5M H2SO4 using electrochemical polarisation and weight loss measurements. The corrosion rate of steel is decreased in the presence of natural oil. The inhibition efficiency was found to increase with oil content to attain 86.12% at 2g/L. Polarisation curves revealed that this oil of Salvia aucheri var. mesatlantica act as mixed type inhibitor with a strong predominance of anodic character. The temperature effect on the corrosion behaviour of steel in 0.5M H2SO4 without and with the inhibitor at 2 g/L was studied in the temperature range from 303and 343 K, the associated activation energy have been determined. The adsorption of oil on the steel surface was found to obey Langmuir's adsorption isotherm.