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The purpose of this paper is to understand corrosion behavior of copper and aluminum in monopropylene glycol-based heat transfer fluid by using synthetic and green inhibitors.

Weight loss, potentiodynamic and impedance measurements were applied to specimens to obtain their electrochemical characteristics and corrosion behaviors. Ageing test was applied to the fluids that contain different corrosion inhibitors to see the effect of inhibitors on fluid structure, and surface morphologies were examined by scanning electron microscopy (SEM).

The corrosion tests showed that synthetic inhibitors have better anti-corrosion potential than green inhibitors.

Like the synthetic corrosion inhibitors, there is growing interest in green inhibitors. Synthetic corrosion inhibitors are expensive and toxic for live beings, but green inhibitors from naturel sources are easy to reach and non-toxic for live beings and environment.

For solar heating systems, there is a need to select the correct heat transfer fluid; corrosion behavior of fluid plays a major role in the operation because the big part of the heating system consists of copper and aluminum close to ferrius metals and stainless steel.

The paper reports an investigation into the use of aqueous extracts of rice bran as a green inhibitor for corrosion of carbon steel in hydrochloric acid (HCl) solution.

Extracts from the rice bran were used as the main component of an environmentally friendly corrosion inhibitor for use in HCl pickling processes. Inhibition behavior on carbon steel in HCl was investigated by means of mass‐loss tests, polarization curves, electrochemical impedance spectroscopy and atomic force microscopy.

The results show that the extract exhibited good inhibition performance in 1 M HCl. The inhibition efficiency increased with increase in the concentration of the inhibitor and was only moderately affected by temperature variations in the range 303‐363 K. The inhibitive action was due to adsorption on the A3 steel and the adsorption process was consistent with the Langmuir isotherm. The free energy of adsorption (ΔG_ads.) was −4.192 kJ/mol. The negative value of ΔG_ads. indicated spontaneous adsorption of the inhibitor occurred on the surface of A3 steel.

Rice bran extract is an effective inhibitor and can be used to protect carbon steel from corrosion in HCl solution.

The rice bran extracts are an effective green inhibitor and can be widely used in the pickling of metals.

Plant development and use as green corrosion inhibitors are already recognized as one of the most environmentally friendly and effective protocols. In recent years, efforts have been made to find green corrosion inhibitors as an alternative to synthetic inhibitors for metals in acid medium. This paper aims to report the investigation of use of aqueous extracts of Tamarindus Indica as green inhibitors for corrosion of metals within different circumstances.

The use of Tamarindus Indica extracts (leaves, stem, fruit pulp and fruit husk) as corrosion inhibitors for mild steel and aluminum in different mediums (HCl, H2SO4, formic acid and citric acid) at different temperatures was investigated.

The inhibitory efficiency of Tamarindus Indica extracts increases with increasing concentration and decreases with increasing temperature. Langmuir is the adsorption isotherm, and the extract (inhibitor) is a mixed-type inhibitor (physisorption and chemisorption).

Tamarindus extracts (leaves, stem, fruit pulp and fruit husk) are effective inhibitors and can be used to protect metals from corrosion at different circumstances.

To the best of the authors’ knowledge, this is the first review that discusses the use of Tamarindus Indica extracts as corrosion inhibitors for metals.

This paper aims to investigate the stability of passive oxide film formed on the surface of 316L stainless steel in 3.5 Wt.% NaCl in the presence of two environmentally non-toxic inhibitors, i.e. leaf extracts of Musa spp. (MS) and Jatropha curcas (JC).

Current transients and potentiodynamic polarization curves were used to explain the stability of the passive film on Current transients and potentiodynamic polarization curves were used to explain the stability of the passive film on 316L stainless steel at both ambient temperature (25 °C) and 70 °C. For the potentiostatic tests, the coupons underwent cathodic stripping to remove the native oxide on their surfaces at −850 mV for 600 s, and a potential of 50 mV was imposed to observe the repassivation for 200 s. For the potentiodynamic tests, the pitting potential measured at 100 μA/cm2, corrosion potential and cathodic current density were obtained for analysis.

The current transients perfectly fitted into the exponential decay curve; i = i_s + i_peak exp(−t/τ), where the decay constant, τ measures the repassivating speed and extent to which the newly formed film heals and stabilizes. The current transients showed that MS and JC help in the repassivating process, especially at 300 ppm and 200 ppm, respectively, both at the lower temperature. The potentiodynamic curves mostly correlated with the current transients except for the hybrid inhibitor. The inhibitors increased the pitting potentials at concentrations that are correlated to their scanning electron micrograph images.

Because they are cheap and environmentally friendly, plant extracts that are proven corrosion inhibitors could be used to aid the formation of passive film on passive alloys in not-so-aggressive environments.

Both MS and JC improve the film stability mostly at intermediate concentrations of 200 and 300 ppm, respectively, at ambient temperature and 70° C.

Using leaf extracts of plants as green inhibitors is considered an environmentally friendly engineering solution.

The leaf extracts are a convenient resource of green inhibitors because their plants are readily available or could be easily naturalized, the processing technique to obtain the extracts is very cheap and the inhibitors are environmentally friendly. In addition, cathodic stripping exposes a relatively larger surface area than that obtained using the most common forms of depassivation; hence, the efficiency of the inhibitor in aiding the formation of the new oxide film to cover the bare surface would be better measured. There is very lean research data on the combined use of green inhibitors and cathodic stripping to study repassivating kinetics of passive alloys.

The purpose of this study is to develop green/natural corrosion inhibitors. Adina cordifolia leaves extract (ACLE) was screened for its corrosion inhibition potential for mild steel (MS) corrosion in 0.5 M H₂SO₄ medium.

Adina cordifolia (AC) leaves were subjected to cold ethanol extraction and concentrated after refluxed with double distilled water. The resultant concentrate was screened for corrosion inhibition studies using sequence of standard corrosion monitoring techniques, namely, gravimetric analysis, electrochemical studies and scanning electron microscopy (SEM).

Gravimetric analysis provided evidence that the prepared ACLE showed dose dependent corrosion inhibition; impedance study revealed that the ACLE increases the charge transfer resistance and decreases double layer capacitance while polarization curves indicated that ACLE acts as a mixed-type inhibitor. Further studies over MS surface/test solutions through SEM and Fourier-Transform Infrared spectroscopy evident the formation of ACLE protective film protects MS.

AC’s methanol extract developed in this work can be used as a green corrosion inhibitor over industrial applications.

For the first time, AC leaves were tested as corrosion inhibitors for MS corrosion in 0.5 M H₂SO₄ medium. The results evidenced that ACLE will be a promising corrosion inhibitor, which could be usable in industries as a green corrosion inhibitor.

Corrosion is a major concern for many industries that use metals as structural or functional materials, and the use of corrosion inhibitors is a widely accepted strategy to protect metals from deterioration in corrosive environments. Moreover, the toxic nature, non-biodegradability and price of most conventional corrosion inhibitors have encouraged the application of greener and more sustainable options, with natural and synthetic drugs being major actors. Hence, this paper aims to stress the capability of natural and synthetic drugs as manageable and sustainable, environmentally friendly solutions to the problem of metal corrosion.

In this review, the recent developments in the use of natural and synthetic drugs as corrosion inhibitors are explored in detail to highlight the key advancements and drawbacks towards the advantageous utilization of drugs as corrosion inhibitors.

Corrosion is a critical issue in numerous modern applications, and conventional strategies of corrosion inhibition include the use of toxic and environmentally harmful chemicals. As greener alternatives, natural compounds like plant extracts, essential oils and biopolymers, as well as synthetic drugs, are highlighted in this review. In addition, the advantages and disadvantages of these compounds, as well as their effectiveness in preventing corrosion, are discussed in the review.

This survey stresses on the most recent abilities of natural and synthetic drugs as viable and sustainable, environmentally friendly solutions to the problem of metal corrosion, thus expanding the general knowledge of green corrosion inhibitors.

The purpose of this study was to investigate the inhibitive action of some green leaves on Monel 400 alloy in acidic media.

Green leaves of Mespilus japonica, Ricinus communis L and Vitis vinifera were immersed in methanol solutions, separately, and filtrated after 48 h of immersion; the obtained filtrates were examined as corrosion inhibitors of Monel 400 alloy in hydrochloric acid solution (1.0M HCl). The performance of these inhibitors was evaluated using electrochemical impedance spectroscopy and potentiodynamic polarization. The effect of temperature on corrosion behavior of Monel 400 was also studied.

The results obtained showed that all tested inhibitors performed as good corrosion inhibitors. The inhibition process is attributed to the adsorption of the inhibitors on Monel surface. The adsorption behavior was found to follow Langmiur isotherm. The inhibition efficiencies of extracts increased with increasing the concentration of each inhibitor and deceased with increasing the temperature.

Practical implication These inhibitors could have application in industries where hydrochloric solutions were used to remove the surface impurities of Monel 400.

This paper helps to find new corrosion inhibitors that are safe and eco-friendly.

This study aims to investigate the inhibition performance of an aqueous extract of Matricaria recutita chamomile on the corrosion of S235JR steel in 0.5 M NaCl by using electrochemical impedance spectroscopy (EIS) and polarization measurements.

The inhibition performance was investigated using EIS and polarization measurements. Surface analysis demonstrates the presence of a protective layer on the steel surface in the presence of the extract. Quantum chemical parameters calculated for the molecules contained in the aqueous extract are interpreted to predict the corrosion inhibition efficiency of the considered extract.

The inhibition efficiency of chamomile aqueous extract for S235JR steel increases with increasing amounts of plant concentration and with an increase in the immersion time. The optimal inhibition efficiency of chamomile extract, 98.90 per cent, was achieved for S235JR steel when immersed in 15 per cent v/v of extract concentration for 2 h. The surface analysis in the absence and presence of the chamomile extract confirmed the formation of a protective layer on steel surface. The quantum chemical calculations allowed to explain the great inhibition efficiency values by interpreting the calculated quantum parameters.

This is the first study carrying out an experimental and theoretical investigation on M. recutita chamomile as a green corrosion inhibitor, with interesting potential industrial applications.

The purpose of this paper is to develop an eco-friendly corrosion inhibitor for mild steel in 1 M HCl.

A pharmaceutical drug acetyl G was investigated for its corrosion inhibition efficiency using weight loss method, potentiodynamic polarisation and electrochemical impedance spectroscopy.

The inhibition efficiency increased with increase in inhibitor concentration. Results from polarisation studies revealed mixed type of inhibition. Impedance studies, scanning electron microscopy and Fourier transform spectroscopy confirm the adsorption of inhibitor on the mild steel surface.

The drug acetyl G has sulphur and nitrogen atoms which effectively block the corrosion of mild steel and is non-toxic and has good inhibition efficiency.

This method provides an excellent, non-toxic and cost-effective material as a corrosion inhibitor for mild steel in acid medium.

Application of this drug as a corrosion inhibitor has not been reported yet in the literature. Replacing the organic inhibitors, this green inhibitor shows excellent inhibition efficiency. This is adsorbed excellently on the mild steel surface due to the presence of long chain and hetero atoms. Thus, the drug retards the corrosion reaction.

This paper aims to appraise the inhibitory effect of saponins extracted from Gongronema latifolium (SEGL) on mild steel in acid media. This is in a bid to conserve our environment and maintain the integrity of engineering structures and materials.

The corrosion inhibition of SEGL and ethanolic extracts of the leaves of G. latifolium (EEGL) on mild steel was studied by hydrogen evolution technique within a temperature range of 30-60°C in tetraoxosulphate (VI) acid solutions.

The extracts inhibit the corrosion of mild steel, and the inhibition efficiency depends on the concentration of the plant extract, temperature and the period of immersion. SEGL was comparatively more efficient than EEGL. Optimum values of the inhibition efficiency for both the EEGL and SEGL (93.7 and 96.5 per cent, respectively) were obtained at extract concentration of 10 g/L, whereas the least values were obtained at extract concentration of 0.5 g/L.

This paper provides new information on the possible application of isolated SEGL as an environmentally friendly corrosion inhibitor. The possible mechanism of the inhibitive action is also given.