Kamal Shalabi

The inhibitive effect of the Euphorbia Helioscopia linn. extract (EHE) on the corrosion of copper
in 1 M HNO3 has been evaluated by means of potentiodynamic polarization, electrochemical impedance
spectroscopy (EIS) and electrochemical frequency modulation (EFM) techniques. The calculated adsorp
tion thermodynamic parameters indicated that the adsorption was a spontaneous, exothermic process
accompanied by an increase in entropy. The inhibition efficiency increases with increasing the concentration
of the inhibitor in the medium and decrease with increasing the temperature. The maximum inhibition
approached to 91% in the presence of 500 ppm EHE using Tafel polarization technique. The results show that
EHE is an effective corrosion inhibitor for protecting the corrosion of copper in 1 M HNO3 medium even at
stimulated conditions.

The corrosion behavior of aluminum in 0.5 M HCl solution in the absence and presence of (E)-3,6-dibromo-
2-((4-methoxyphenylimino)methyl)phenol(I),(E)-3,6-dibromo-2-((4-chlorophenylimino) methyl) phenol (II)
and (E)-4-(3,6-dibromo-2-hydroxybenzylideneamino)benzoic acid(III)was investigated using potentiodynamic
polarization, electrochemical impedance spectroscopy (EIS) and electrochemical frequency
modulation (EFM) techniques. The inhibitive action of the investigated compounds was discussed in terms
of blocking the electrode surface by adsorption of the molecules through the active centers contained in
their structures. The adsorption of these derivatives on aluminum surface is consistent with Freundlich
adsorption isotherm. The effect of temperature on the rate of corrosion in the absence and presence of these
compounds were also studied. Physical adsorption mechanism is proposed from the calculated
thermodynamic parameters for all investigated compounds. Quantum chemical parameters such as the
highest occupied molecular orbital energy (EHOMO), the lowest unoccupied molecular orbital energy
(ELUMO), energy gap (ΔE), dipole moment (μ), electronegativity (χ), chemical potential (Pi), global hardness
() and softness (σ), were calculated. Quantum chemical studies indicate that the inhibition potentials of
these compounds correlate well with EHOMO, ΔE,, σ, Pi, χand ΔN. A good correlation was found between
the theoretical data and the experimental results.

The inhibition efficiency of alcoholic extract of Phoenix dactylifera plant on aluminum and aluminum
silicon in 0.5 M hydrochloric acid solution have been evaluated by potentiodynamic polarization, electrochemical
impedance spectroscopy (EIS) and electrochemical frequency modulation (EFM). Values of inhibition efficiency
obtained are dependent upon the plant extract concentration and temperature. Generally, inhibition was found to
increase with increasing the inhibitor concentration, but decreased with increasing the temperature. The effect of
temperature on the corrosion behavior of Al and Al–Si alloy in 0.5M HCl with and without addition of plant
extract was studied in the temperature range 20–60°C. Thermodynamic functions of dissolution processes were
calculated from experimental EFM data and the interpretation of the results are given. Physical adsorption mech
anism has been proposed for the inhibition and Temkin adsorption isotherm was obeyed for Al and Al–Si alloy.

Corrosion of aluminum in 0.1 M HCl solution in the absence and presence of β-blocker inhibitors (atenolol,
propranolol, timolol and nadolol) was investigated using weight loss, potentiodynamic polarization and electrochemical
impedance spectroscopy (EIS) techniques. The inhibition efficiency increased with inhibitor concentration and decreased with
rise of temperature. Potentiodynamic polarization curves revealed that they acted as cathodic inhibitors. Some thermodynamic
parameters were calculated and discussed. All inhibitors were adsorbed on Al surface obeying Frumkin isotherm. All EIS tests
exhibited one capacitive loop which indicates that the corrosion reaction is controlled by charge transfer process. The
inhibition efficiencies of all test methods were in good agreement.

The effect of some chalcone derivatives on the dissolution of carbon steel in 1.0 M HCl solution was studied using weight loss, potentiodynamic polarization measurements, electrochemical impedance spectroscopy (EIS) and electrochemical frequency modulation (EFM) techniques. The inhibition efficiency was found to increase with increasing concentration of the inhibitors and decrease with raising temperature. The adsorption of chalcone derivatives on the carbon steel surface obeys the Langmuir adsorption isotherm. Polarization studies indicate that these investigated compounds are mixed type inhibitors. The thermodynamic functions of adsorption processes were calculated from weight loss at different temperatures data and were used to analyse the inhibitor mechanism. The surface morphology of the carbon steel specimens was evaluated using scanning electron microscope (SEM) and energy dispersive X-ray (EDX) analysis.

The efficiency of Thymus vulgarise extract (TVE) as a nontoxic corrosion inhibitor for copper and α-brass in 1 M HNO3 has been tested by weight loss and electrochemical techniques such as potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) and electrochemical frequency modulation (EFM) techniques. The calculated adsorption thermodynamic parameters indicated that the adsorption was a spontaneous, exothermic process accompanied by a decrease in entropy. The inhibition efficiency increases with increasing the concentration of the extract in HNO3 solution and decreases with increasing the temperature. The adsorption of the extract on the copper and α-brass surfaces in the acid solution was found to obey Langmuir’s adsorption isotherm. Scanning electron microscope (SEM) results showed the formation of a protective film on the copper and α-brass surfaces in the presence of TVE. The results obtained from different techniques were in good agreement.

The corrosion inhibition of Cu10Ni alloy by Arctostaphylos uva-ursi extract (AUUE) in 1 M HNO3 has been investigated by potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), electrochemical frequency modulation (EFM) and scanning electron microscope (SEM) techniques. Potentiodynamic polarization indicated that AUUE acted as mixed type inhibitor but mainly cathodic. The calculated adsorption thermodynamic parameters indicated that the adsorption was a spontaneous, exothermic process accompanied by an increase in entropy and obey Langmuir adsorption. The inhibition efficiency increases with increasing the concentration of the inhibitor and decreases with increasing the temperature. The SEM results showed the formation of a protective film on the alloy surface in the presence of AUUE. The results obtained from different electrochemical techniques were in good agreement.

The inhibition effect of Atropa Belladonna extract (ABE) on the corrosion of carbon steel in 1 M HCl solution was investigated by potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) and electrochemical frequency modulation (EFM) techniques. The adsorption process obeyed a Langmuir adsorption isotherm. ABE acts as a mixed-type but mainly anodic inhibitor in 1 M HCl. The calculated adsorption thermodynamic parameters indicated that the adsorption was a spontaneous, exothermic process accompanied by an increase in entropy. The maximum inhibition approached 96.6% in the presence of 500 ppm ABE using Tafel polarization technique. Quantum chemical parameters were also calculated, which provided reasonable theoretical explanation for the adsorption and inhibition behavior of ABE on C-steel. ABE constituents have been simulated as adsorbate on Fe (1 1 0) substrate and the adsorption energy have been identified on iron surface. The results obtained from different electrochemical techniques and theoretical calculations were in good agreement.

Recent studies on the surface modification by alkali
and heat treatments in Titanium metal are reviewed. Previous
laboratory studies investigated the effects of different alkali and
heat treatments on properties of Ti implant material. It seems
hopeful that this type of treatments is a suitable technique for
dental implants. In the present study, heat treatments applied
above700cᵒ that may seem hopeful to apply change in the limit of
temperature range that all previous researches decide. Apply
physical studies to correlate with other properties for
development of high bioactive materials.

The inhibitive action of the aqueous extract of tobacco towards the corrosion of C-steel in HCl solution was investigated. The inhibition efficiency was measured using weight loss, potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) and electrochemical frequency modulation (EFM) techniques. The surface morphology of carbon steel was also studied. It was found that the addition of the extract reduces the corrosion rate of C-steel and hence increases the inhibition efficiency. The inhibitive effect of the tested extract was discussed in view of adsorption of its components on the steel surface. The adsorption of the extract components on the C-steel surface follows Langmuir adsorption isotherm. The thermodynamic functions of dissolution and adsorption processes were calculated and discussed. The inhibition efficiency increases as the temperature is increased. The presence of extract decreases the activation energy of the corrosion process.

The effect of the addition of some aryl azo- thiazolin 4-one derivatives on the corrosion of α-brass in nitric acid investigated using weight loss, potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) and electrochemical frequency modulation (EFM) measurements. It was found that the investigated compounds behave as inhibitors. The inhibition efficiency increases with increasing the inhibitor concentration, but decreases with increasing the temperature. The adsorption of these compounds on the α-brass surface follows Temkin’s adsorption isotherm. The effect of the temperature on the corrosion of α-brass in 1 M nitric acid was studied. Potentiodynamic polarization studies showed that these compounds are mixed-type inhibitors and the results obtained from the techniques are in good agreement.

The inhibitive action of Gibberellic acid on the corrosion of carbon steel in 1 M HCl solution was investigated by weight loss, potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) and electrochemical frequency modulations (EFM) techniques. Potentiodynamic polarization studies clearly reveal that Gibberellic acid acts essentially as mixed inhibitor. The inhibition efficiency was found to increase with inhibitor concentration. The adsorption of Gibberellic acid on carbon steel surface is found to obey Langmuir adsorption isotherm. The morphology of inhibited carbon steel was analyzed by scanning electron microscope (SEM) and energy dispersive X-ray spectroscopy (EDX). The mechanism of inhibition process was discussed in terms of the adsorption of Gibberellic acid on the metal surface.

Anise extract, was investigated as green corrosion inhibitor of carbon steel in 1 M HCl solution using weight
loss, potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) and electrochemical frequency
modulation (EFM) techniques. Surface morphology was tested using scanning electron microscope (SEM) and energy
dispersive X-ray (EDX). The adsorption of the inhibitors on carbon steel surface was found to obey the Langmuir’s
adsorption isotherm. The activation and adsorption parameters were calculated and discussed.

The inhibition effect of some phenyl sulfonylacetophenoneazo derivatives
(PSAAD) on the corrosion of Al in 0.5 M HCl solutions was studied by
potentiodynamic polarization, electrochemical impedance spectroscopy, and electrochemical
frequency modulation. The results obtained showed that the addition of
the PSAAD inhibits the hydrochloric acid corrosion of Al. Potentiodynamic
polarization measurements showed that the PSAAD act as mixed type inhibitors but
predominately act as cathodic inhibitors. The inhibition efficiency increases with
increasing the PSAAD concentration, but decreases with increasing temperature. A
kinetic model and the Langmuir adsorption isotherm fit the experimental data well.
A good correlation was found between the theoretical data and the experimental
results.

The corrosion inhibition of carbon-steel in 1 M HCl by some (Z)-N'-(1-phenylethylidene) benzohydrazide
derivatives (PEBH) has been investigated using weight loss method, potentiodynamic polarization, electrochemical
impedance spectroscopy (EIS) and electrochemical frequency modulation (EFM) techniques. Results obtained showed
that these investigated compounds are good inhibitors and their inhibition efficiencies increase with increasing inhibitor
concentration and decrease with increase in temperature. Moreover, polarization studies clearly revealed that the
presence of inhibitors changes the mechanism of hydrogen evolution and the metal dissolution i.e. they act as mixed
type inhibitors. EIS study showed that charge transfer resistance increases with the increase of inhibitor concentration
but the capacitance of double layer decreases. The adsorption of investigated compounds obeys Langmuir’s adsorption
isotherm. The activation parameters were determined and discussed. The mechanism of adsorption had been explained
on the basis of chemical structure of the investigated inhibitors. It was found that there is a good agreement between the
different tested techniques.

The inhibition effect of some Chalcone derivatives [3-(4-hydroxyphenyl)-1-phenylprop-2-en-1-one as an
inhibitor (1) and 3-(4-hydroxyphenyl)-1-(4-nitrophenyl)prop-2-en-1-one as an inhibitor (2)] on the corrosion of
aluminum in 0.5 M HCl solution was studied using potentiodynamic polarization, electrochemical impedance
spectroscopy (EIS), electrochemical frequency modulation (EFM) and weight loss measurements. The results drawn
from the different techniques are comparable and exhibit small discrepancy. Results for weight loss indicated that
inhibitor efficiency (% IE) increased with increasing inhibitor concentration, reaching a maximum inhibiting power of
85.9 , 95.7 % at 21 x 10-6 M for inhibitors 1 and 2, respectively and decreased with increasing the temperature.
Polarization studies clearly revealed that the presence of inhibitors changes the mechanism of hydrogen evolution and
the metal dissolution i.e. they act as mixed type inhibitors. Some activation and adsorption thermodynamic parameters
were calculated and discussed. The surface coverage of the inhibitors obeyed Langmuir adsorption isotherm.

This study examined the effect of different organized media such as β-cyclodextrin and micelle surfactants, either anionic
(sodium dodecyl sulphate), cationic (cetrimide) or non-ionic (tween-20 and tween-80), on the potentiometric properties of propranolol polyvinyl chloride selective electrode based on tetraphenyl borate (PRO-TPB) ion-exchanger as an electroactive material. It was found that the Nernstian slope for propranolol over the concentration range of 1 × 10-5 to 10-2 M was unaffected by non ionic surfactant, whereas cationic surfactant significantly decreased the Nernstian slope. However, anionic surfactant significantly increased the Nernstian slope. The electrode basic analytical parameters such as measurement range, slope characteristics, detection limit, response time, and selectivity coefficients in relation to some inorganic cations, sugars, amino acids and some β-blockers were
investigated in presence or absence of organized media. Electrode was used for the potentiometric determination of propranolol in pharmaceutical preparations with and without organised compounds. The results were consistent with those obtained using a reference method.