Materials decay naturally through a process called corrosion in which they react with their surroundings. It is possible to prevent mild steel from corroding in hydrochloric acid (HCl) by applying a variety of corrosion inhibitors. In this work, the novel mononuclear manganese coordination complex [Mn(Hbpz)2(NCS)2] showed promising properties that make it suitable for corrosion prevention applications. In this experiment, different experimental methods were used to evaluate its inhibitory potential. For example, weight loss (WL) showed a 96% reduction in corrosion rate at higher concentrations. EIS was evidence that the concentration effect increases Rct and reduces Cdl. Moreover, the polarization examination demonstrated that C3 is a mixed-type inhibitor. In addition, quantum mechanical and statistical methods were also used, and the effect of temperature was also determined. Besides, thermodynamic equations were used and calculated. The adsorption follows the Langmuir isothermal model and the simulation method confirmed the spontaneous adsorption nature of the complex, which improves the surface characterization results.

The inhibition ability of a bipyrazole compound (L-1) and its complex copper [Cu (Hbpz)3] (BF4)2] (C1) towards mild steel (MS) corrosion in HCl solution was studied at various concentrations and temperatures using weight loss (WL) potentiodynamic polarization curves (PPC), electrochemical impedance spectroscopy (EIS), scanning electron microscope (SEM), and energy-dispersive X-ray spectroscopy (EDS) methods, UV-vis spectroscopy and computational approach. Results of the polarization revealed that these compounds are mixed type. The adsorption of both molecules on the MS surface is demonstrated by the EDS, SEM and UV-visible findings. Adsorption of both compounds was found to obey Langmuir adsorption isotherm. Density functional theory (DFT) and Monte Carlo Simulation (MC)) supports the experimental results.

The inhibitive effect of M. piperita and M. pulegium essential oils on the corrosion behavior of mild steel in 1M HCl was studied using the weight loss measurements, polarization curves, and electrochemical impedance spectroscopy techniques. The inhibition efficiency was found to be dependent on the concentration of the essential oil obtained from both plants. Results showed that these essential oils act as a mixed-type inhibitor. The charge transfer resistance increases, while the double layer capacitance decreases by increasing the essential oil concentration of both plants. The presence of such essential oil may have enhanced their adsorption on the metal surface and thereby blocked the surface and protected the metal from corrosion. The results of the electrochemical methods were in good agreement with the weight loss measurement results. These essential oils antibacterial activity was evaluated using the microdilution method against one gram positive and one Gram negative bacteria. M. piperita and M. pulegium essential oils showed satisfactory activities against S. epidermis, E. coli DH5α. Received 01 Dec 2016, Revised 02 Jan 2017, Accepted 04 Jan 2017

For the first time, the investigation and characterization of Benzimidazole derivatives, as a potential corrosion inhibitors for mild steel in acidic aqueous solutions has been reported. The inhibition efficiency was calculated based on the data using weight loss, surface studies and basic computational calculations. The values reported in this manuscript were 80% for P1 and 89 for P2. The adsorption of the inhibitors on the mild steel surface was found to obey the Langmuir's adsorption isotherm. The results obtained from chemical and theoretical techniques are in good agreement with each other..

The effect of addition of 1,5-di(prop-2-ynyl)-1H-pyrazolo[3,4-d]pyrimidine-4(5H)-thione (P1) on the corrosion of steel in hydrochloric acid 1M has been studied by weight loss measurements, potentiodynamic and EIS measurements. The corrosion rates of the steel decrease with the increase of the inhibitor concentration, while the inhibition efficiencies increase. The addition of 1,5-di(prop-2-ynyl)-1H-pyrazolo[3,4-d]pyrimidine-4(5H)-thione (P1) enhances the inhibition efficiency considerably. The presence of this inhibitor increases the degree of surface coverage. E (%) obtained from the various methods is in good agreement. Polarisation measurements show also that the 1,5-di(prop-2-ynyl)-1H-pyrazolo[3,4-d]pyrimidine-4(5H)-thione act as mixed type inhibitor.

The inhibitive action of Theobromine on corrosion of mild steel in 1M HCl solution has been studied using weight loss measurement, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) techniques. It was found that the inhibition efficiency of Theobromine inhibitor increases with increase in concentration of inhibitor and decreases with increase in temperature. The inhibitor show corrosion inhibition efficiency of 90% at 1g/l and 308 K. Polarization data suggested that the Theobromine inhibitor used as mixed type inhibitor. Impedance measurements indicating that the corrosion reaction is controlled by charge transfer process. The adsorption of Theobromine on the metal surface was found to obey Langmuir adsorption isotherm. The Density Functional Theory (DFT) was employed for quantum chemical calculations to correlate the experimental findings.

The inhibition effect of 3-methyl-4-(3-methylisoxazol-5-yl)isoxazol-5(2H)-one monohydrate (P1) on the corrosion of carbon steel in 1 M HCl was studied by weight loss, electrochemical impedance spectroscopy (EIS) techniques and potentiodynamic polarization methods. The results showed that isoxazole P1 was a good inhibitor in 1 M HCl and inhibition efficiency increases with isoxazole P1 concentration to attain 93% at 10-3M at 308 K. E(%) values obtained from various methods used are reasonably good agreement. The adsorption of isoxazole P1 obeyed the Langmuir adsorption isotherm. Polarization curves showed that isoxazole P1 acted as a mixed-type inhibitor in HCl. The effect of the temperature on the corrosion behavior with addition of 10-3M of the inhibitor was studied in the temperature range 313-343 K, and the thermodynamic parameters were determined and discussed. In addition, a quantum chemical study suggests isoxazole P1 inhibitor is structurally essential for the protection of metal surface

Thymus Capitatus is a shrub, which is native of the Mediterranean basin. The purpose of this study was to determine the chemical composition and inhibitory effect of essential oil of Thymus Capitatus on the corrosion of mild steel in hydrochloric acid (1M).The essential oil of Thymus Capitatus has been studied using gas chromatography (GC) and GC-mass spectrometry (GC-MS). 91.2% of the components are detected (32 components) and the major components were, p-Cymene(18.9%), carvacrol (13.4%), acetate of geranyl (12.2%), borneol (10.2%), Camphene (3.9%), α-pinene (2.9%) and trans caryophyllene (2.9%).The inhibitory effect of essential oil of Thymus Capitatus was estimated on the corrosion of mild steel in 1M in Hydrochloric acid (HCl) using weight loss, Electrochemical Impedance Spectroscopy (EIS) and Tafel polarization curves. The results of the polarization curves show that the corrosion current density decreases 698μA/cm2 to 290μA/cm2 after addition of the inhibitor (essential oil of Thymus Capitatus), the charge transfer resistance increases 49 ohm.cm2 to 101 ohm.cm2 in the electrochemical impedance spectrum after addition of the inhibitor. The inhibition of the compound effect is attributed to the formation of afilm on the surface of the steel.

This work describes the successful performance of Gracilaria bursa-pastoris as an eco-friendly corrosion inhibitor for mild steel in HCl 1M solution. This study investigated by weight loss measurement, electrochemical impedance spectroscopy (EIS) and Tafel polarization. The inhibition mechanism is discussed considering thermodynamics of adsorption and kinetics of the electrochemical reactions. Gracilaria bursa-pastoris is a mixed-type inhibitor and the mode of inhibition results from the geometric blocking effect of physisorbed inhibitive species at the metal surface.

Corrosion inhibition behaviour of (E)-4-(2,3-Dihydro-1,3-benzothiazol-2-ylidene)-3-methyl-1-phenyl-1H-pyrazol- 5(4H)-one (P1) on mild steel corrosion in 1 M HCl was investigated at various concentrations by gravimetric and electrochemical techniques. The polarization curves indicated that (E)-4-(2,3-Dihydro-1,3-benzothiazol-2-ylidene)- 3-methyl-1-phenyl-1H-pyrazol-5(4H)-one (P1) as mixed inhibitor. The adsorption of (E)-4-(2,3-Dihydro-1,3- benzothiazol-2-ylidene)-3-methyl-1-phenyl-1H-pyrazol-5(4H)-one (P1) on mild steel leading to inhibition was found to follow the Langmuir adsorption isotherm. The quantum chemical calculations were carried out to establish the mechanism of corrosion inhibition.

The inhibition of the corrosion of mild steel in 1 M HCl by the seeds essential oil of piper nigrum; extracted through microwave-assisted hydrodistillation (MHD) and conventional hydrodistillation (CHD) method; has been studied using weight loss, potentiodynamic polarization method and electrochemical impedance spectroscopy measurements at different concentrations and effect of temperature. Three amounts of essential oils obtained by classical hydrodistillation and by microwave hydrodistillation on low and high microwave power are tested on the corrosion inhibition of mild steel. The measurements show that inhibition efficiencies increase with the increasing concentration of the inhibitor. The results of weight loss studies correlated well with those of impedance and polarization studies. The maximum inhibition efficiency (95.99%) was found at 0.6g/L at 308 K, after 6 h as immersion time. This reveals that inhibitive action of the inhibitor was mainly due to adsorption on the mild steel surface and blocking of the active sites. The above results showed that inhibitor acted as a mixed-type corrosion inhibitor. The adsorption of HAS on the mild steel surface obeyed the Langmuir adsorption isotherm. This was supported by the impedance measurements which showed a change in the charge transfer resistance and double layer capacitance, indicating the adsorption of HAS on the mild steel surface.

The purpose of this study was to examine the effect of (4Z)-4-(2H-1,4-benzothiazin-3(4H)-ylidene)-5-methyl-2- phenyl-2,4-dihydro-3H-pyrazol-3-one (P1) as a corrosion inhibitor on mild steel in 1M HCl solution using the weight loss, the potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) techniques. The efficiency of inhibition of each inhibitor increases with increasing of inhibitor concentration at 308K, which leads to a significant reduction in the corrosion rate of mild steel. The adsorption of (4Z)-4-(2H-1,4-benzothiazin-3(4H)- ylidene)-5-methyl-2-phenyl-2,4-dihydro-3H-pyrazol-3-one (P1) on the surface of the mild steel has been well described by the Langmuir adsorption model and quantum chemical calculations were carried out to establish the mechanism of corrosion inhibition.

The inhibition ability of two new 1,2,4-triazolo[1,5-a]pyrimidine derivatives (P3 and P4) towards mild steel corrosion in 1 M HCl solution was studied at various concentrations and temperatures using mass loss, polarization curves, and electrochemical impedance spectroscopy (EIS)methods. The experimental results reveal that P3 and P4 are efficient mixed type corrosion inhibitorsand their inhibition efficiencies increase with increasing concentration. The adsorption of these inhibitors on mild steel surface obeys Langmuir isotherm. Quantum chemical parameters were calculated using the Density Functional Theory method (DFT). The Correlation between theoretical and experimental results was discussed. Received 22 Oct 2016, Revised 28 Nov 2016, Accepted 04 Dec 2016

This work is devoted to examine the effectiveness o f the hexane extract of Nigella Sativa L (SH NS) on corrosion of mild steel in 1 M HCl solution using the weight los s measurement at various concentration effects. Pol arization curves and electrochemical impedance spectroscopy ( EIS) methods were employed to evaluate corrosion ra te and inhibition efficiency. The inhibition efficiency wa s found to increase with inhibitors content to atta in 98% (at 0.5g/L). Data obtained from EIS studies were analyz ed to determinate the model inhibition process thro ugh appropriate equivalent circuit model. Inhibition ef ficiency E (%) obtained from the various methods is in good agreement. The associated activation energy has bee n determined. The adsorption of natural products on the steel surface was found obey to Langmuir’s adsorption iso therm.

The new series of Schiff base were synthesized from 7-methyl-2-phenylimidazo[1,2-a]pyridin-3-amine condensed with different substituted aldehydes (4-Hydroxybenzaldehyde, Vanillin, 3-Nitrobenzaldyde, 4Nitrobenzaldehyde)in presence of catalytic quantities of acetic acid. So the structure offers for this synthesis well coincide with the results obtained bydifferent spectroscopic techniques (IR, 1 H NMR, 13 C NMR and Mass spectroscopy). These new compounds were evaluated for their antibacterial, againstGram positive and Gram negative bacteria, and antifungal activityagainst yeasts and moulds, using micro-dilution tests. The biological activityof the synthesized compoundswere compared with standard drugs. The best results are observed in the amine starting (new 7-methyl-2-phenylimidazo [1,2-a]pyridin-3-amine), it showed interesting antibacterial activity of all tested strains, particularly against Proteus strain is a Gram -.

(Z)-2-benzylidene-2H-[1,4]benzothiazin-3-one (T1) h as been evaluated as a corrosion inhibitor for mild steel using weight loss and electrochemical polarization (EIS). The study was also complemented by quantum chemica l calculations. The inhibition efficiency (E%) increa sed with increasing (T1) concentration, showing a m aximum E% of 95% at 308 K at 10-3M. The electrochemical study reveals that this compound is an cathodic inhibito r and corrosion current density is the order 120 μ A/cm2 of (T1) at the optimum concentration. EIS res ults show that the change in the impedance parameters (Rct and Cdl) wi th concentration of (T1) is indicative of the adsor ption of molecules leading to the formation of a protective layer on the surface of mild steel. A good fit to L angmuir adsorption isotherm was obtained between surface co verage degree and inhibitor concentration. The resu lts obtained by weight loss measurements are consistent with the results of the electrochemical study. Qua ntum chemical approach used to calculate electronic prop erties of the molecule to ascertain the relation be tween inhibitive effect and molecular structure

The removal of toxic metal, cadmium, by using adsorption into Algerian Luffa Cylindrica, LC, was investigated. The biosorption process was studied with respect to contact time, particle size, pH and temperature. The results showed that equilibrium was reached within 1 h. The used biosorbent gave the highest adsorption capacity at pH 6. The experimental isotherm data were analysed and modelled. The maximum adsorption capacity, Langmuir’s qmax, improved from 5.46 to 7.29 mg/g as the temperature increased from 10 to 40 °C. The enthalpy ΔH0 and entropy ΔS0 values were respectively estimated at 33.92 kJ.mol-1 and 0.12 kJ mol-1.K1 for the process, which reflects the endothermic nature and the spontaneous feasibility of the present sorption system. Besides, the adsorption kinetics was found to follow the second-order model, as well as the micropore diffusion model described the Kinetic data well, suggesting therefore a possible physisorption process.

Various techniques carried out to reduce or decrease the corrosion rate of materials and metal alloys. The use of green inhibitors is one of the most practical techniques used against this phenomenon. In this work, we have studied the influence of aqueous extracts of ginger rhizomes on the corrosion of mild steel in 1M HCl acid medium by electrochemical measurements: polarization curve, electrochemical impedance spectroscopy and weight loss measurements. The results showed that the inhibition efficiency was found to increase with inhibitor content to attain 95% in the presence of the ginger concentration 10-3M at 308K. The effect of temperature on the behaviour of corrosion showed that the inhibition efficiency of deferent extracts decreased significantly with temperature. The adsorption of various extracts on the steel surface follows the Langmuir’s adsorption isotherm.

This work is devoted to examine the effectivenes of 5-methyl-1H-pyrazole-3-carbohydrazide(MPC) on corr osion of mild steel in 1 M HCl solution using the weight los s measurement at various temperature and concentrat ion effects. Polarization curves and electrochemical impedance s pectroscopy (EIS) methods were employed to evaluate corrosion rate and inhibition efficiency. Inhibitio n efficiency of 95% is reached with 10 -3 M of ( MPC ) at 308 K. Potentiodynamic polarization showed that the MPC be haves as mixed-type inhibitor. The Nyquist plots sh owed that increasing MPC concentration, charge-transfer resis tance increased and double-layer capacitance decrea sed, involving increased inhibition efficiency. Adsorpti on of the inhibitor molecules corresponds to Langmu ir adsorption isotherm. Quantum chemical calculations showed that the inhibitor has the tendency to be protonated in the acid and the results agree with experimental observation s.