Expired Chicken Egg-White Extract’s Adsorption Behavior As a Corrosion Inhibitor for Carbon Steel in 1M HCl

Laboratoire d’ingénierie des Procédés et d’environnement (LIPE), Université Hassan II, Ecole supérieure de Technologies, BP.8012 Oasis, Casablanca, Morocco Laboratoire de Chimie Appliquée, Département de Chimie, Faculté Des Sciences Semlalia, Université Cadi Ayyad Marrakech, Morocco Laboratory Materials 1ematic Research Center the Ben M’sik Faculty of sciences, Hassan II University Casablanca, Morocco


Introduction
e corrosion of carbon steel in acidic environments has become a fundamental and industrial problem because of the strong interest of scientists and engineers around the world [1]. e comprehensive use of structural and machinery building purposes renders carbon steel a metallic alloy vulnerable to corrosion degradation [2]. It is further exacerbated by its attractive mechanical and physical qualities, recyclability expense, and availability [3]. Mineral acid is often used in industry to chemically clean carbon steel, stainless steel, titanium, copper, and other alloys [4,5]. Under these conditions, the choice of inhibitor or inhibitor formulation will depend on the corrosion system involved, especially the nature of the acid, the presence of dissolved organic or inorganic compounds, as well as the temperature, etc. [6,7]. As corrosion inhibitors, the development of organic extracts has exceeded a certain level; currently, they are the first choice for inhibitors. e inhibitory action of these organic compounds is due to the development of a more or less continuous barrier that inhibits the solution for accessing the metal (or via adsorption) [8][9][10]. e organic compounds used as inhibitors must have at least one heteroatom working as an active center for their fixation on the metal such as nitrogen (amines, amides, imidazolines, and triazoles), oxygen (acetylenic alcohols, carboxylates, and oxadiazoles), sulfur (thiourea derivative, mercaptans, sulfoxides, and thiazoles), or phosphorus (phosphonates); one limitation in the application of these products may be the increase in temperature as organic molecules are often unstable at high temperatures [11][12][13]. Amino acids are effective and environment-friendly corrosion inhibitors that have been extensively researched in experiments and theory under various conditions. Almost all of these amino acids have been tested in acidic solutions against iron corrosion [14][15][16].
Inhibitors have the originality of being the only means of intervention from the corrosive medium, which makes them an easy and inexpensive method of corrosion control, provided that the products used are of moderate cost [17][18][19]. In recent years, various studies have centered on reducing the harmful effects of human life on the earth and its potential to sustain life [20,21]. us, there is increasing interest in biodegradable chemistry as there is a demand for innovative ecologically friendly products and biodegradable natural inhibitors from plant or animal origin with a lower concentration to provide greater efficacy [22,23].
Currently, many types of research are focussing on corrosion inhibition by organic extracts that give a good efficiency such as corrosion inhibition in Swertia chirata extract in an acid environment (0.5 M H 2 SO 4 ) [24], evetia peruviana (Kaner) flower extract (TPFE) [25], leaf extract of Arbutus unedo L. [26], Crotalaria pallida leaf extracts [27], which were tested for mild steel, in 1M HCl. In our work, we have chosen the expired chicken egg, especially the white part, because the yellow part contains just lipids and the other contains of organic and mineral elements; for this reason, we have chosen the white part [28][29][30][31]. Expired egg white, which is available all over the world and is less expensive as an organic (animal origin) corrosion inhibitor for carbon steel in a 1M HCl solution, has a 90% effectiveness at 298 K; we examined weight loss (WL) and electrochemical tests such as potentiodynamic polarization (PDP) curves, electrochemical impedance spectroscopy (EIS), and SEM and EDX to assess the inhibitor efficacy. e isotherm and thermodynamic adsorption characteristics, as well as the adsorption mechanism, are all investigated. Figure 1 shows the preparation of expired egg-white extract (EEW). e EEW is dried in an oven at 308 K for 120 hours to make the drying completely uniform. en, the resulting solid was crushed and sieved to obtain a fine powder. Accurate amounts were added to a concentrated 1M HCl solution (37%) to get the total solubility. en, the whole solution was adjusted with distilled water to finally obtain extract concentrations (0.1, 0.2, 0.4, and 0.8 g/L) in a 1M HCl solution.

Weight Loss Measurements.
e inhibitory effect of the EEW extract was tested on a carbon steel specimen with dimensions of 2.26-1.33-0.30 cm 2 and a chemical composition of 0.63 Cr (percent by weight) and S, 0.35-0.39% C, 0.50-0.80% Mn, Ni, and Mo, 0.015-0.035% S, 0.35-0.39% C, 0.50-0.80 Mn, and 0.40% Si, with the rest being Fe. We repeated each test three times for consistency, and the analytical balance can read up to four decimal places. e carbon steel specimen was polished with 400-, 600-, 800-, and 1200-grade abrasive paper before each experiment. Acetone was used to degrease the surface, which was then rinsed with distilled water. e samples were subsequently submerged in 100 ml of EEW extract at various concentrations. e examination lasted 6 hours. ey were weighed again after being washed with distilled water. is investigation was also carried out at various temperatures (298, 308, 318, 328 K). e rate of corrosion (CR), (θ) surface coverage, and inhibition efficiency (η%) [32,33] were put to use.
where W 0 and W t are, respectively, the carbon steel mass values before and after immersion in the corrosive solution (mg). S is the carbon steel surface area (cm 2 ), t is the corrosion time in (h), CR inh and CR int,0 are, respectively, the corrosion rate, with and without inhibitors g.cm 2 h − 1 .

Electrochemical
Measurements. An OrigaLys potentiostat was used to make the electrochemical measurements. e Origa Master 5 software controls the system is fitted with a traditional three-electrode setup. e working electrode (WE) was made of carbon steel with a diameter of 0.28 cm 2 . e platinum electrode serves as a counter electrode (CE), while the reference electrode is a calomel-saturated (Hg 2 Cl 2 /Hg) electrode (RE). e electrode potential was automatically adjusted in the range of 300 mV more or less than the E corr at 1 mV/s to evaluate potentiodynamic polarization (PDP) curves. e frequency range for the measurements was 20 kHz to 200 MHz, with a 20 point per decade amplitude. Prior to each test, the working electrode (WE) was polished using abrasive series paper (400, 600, 800, and 1200), and distilled water and acetone were used to monitor the process. All of the trials were carried out at 298 K.

FT-IR Spectroscopy Results.
e presence of functional groups and heteroatoms is the most crucial item in the adsorption of inhibitor molecules to the iron surface, as seen in the FT-IR spectrum of expired egg-white extract in Figure 2. e existence of various functional groups may be seen in the IR spectra ( Figure 2). e wide and strong bands in the range of 3500-3000 cm −1 are attributed to the OH/ N-H/CH group [34].
e bands observed at 1650 cm −1 correspond to the C�O stretch group, and the absorption bands at 1550 cm −1 correspond to N-H/C�C stretch (aromatic nucleus) [35]. e C-H2 bands are observed around 1460 cm −1 and 1396 cm −1 . e bands between 1360 and 1080 cm −1 are assigned to the C-N bands [36].

WL Measurements.
To get a better understanding of how corrosion is inhibited. e weight loss technique was used to examine the effect of different doses on the inhibitory potential of EEW at 298, 308, 318, and 328 K. Table 1 and Figure 3 demonstrate the corrosion rate (CR) and inhibition efficiency (η%); the efficacy of the inhibition rises as the inhibitor concentration increases, suggesting an increase in surface coverage and blocking the activation activity on the carbon steel surface. Furthermore, these findings revealed that, at all temperatures examined, the inhibition was efficient, the EEW lowered the CR values, and as the temperature of the solution grew, the percent values for EW dropped. is lowered corrosion rate with rising temperature may be explained further by a preexponential factor, which results from decreased desorption of inhibitor species from the carbon steel surface. e influence of temperature on the ΔH ads and ΔS ads of the corrosion process may be assessed.

Adsorption Isotherm and ermodynamic Parameters.
Adsorption isotherm investigations reveal the process by which inhibitors bind to metal surfaces. Adjusting the corrosion rate CR and the degree of inhibitor surface coverage yielded the isotherm adsorption model that best reflects the adsorption of EEW on carbon steel in a 1 M HCl medium. Different isotherm adsorption models are used (Langmuir, Temkin, El-Awady's, Freundlich, and Flory-Huggins) expressed in the linear form: Langmuir adsorption isotherm [37]: El-Awady's thermodynamic/kinetic adsorption isotherm model [38,39]:   Journal of Chemistry 3 Temkin adsorption isotherm model [40]: Freundlich adsorption isotherm [41]: Flory-Huggins adsorption isotherm [42]: is research is to find the R2 correlation coefficient for each isothermal model of Table 2. e best-fitting model was chosen based on the correlation coefficient. In this research, the Langmuir isotherm with a 0.999 corrélation coefficient value provided the greatest match to experimental data. In a hydrochloric acid medium, it explains a superior adsorption mechanism of the EEW extract on carbon steel.
To comprehend the kind of EEW adsorption in the metal/solution contact, the following formula is used to calculate the value of ΔG ads : where T is the absolute temperature (K), R is the gas constant, K a ds is the adsorption equilibrium constant calculated from the isotherm, 8.314 JK − 1 mol − 1 , and C H 2 O is the value of the concentration of water in the solution (1000g.l − 1 ) [43,44]. e negative values of ΔG a ds obtained as in Table.3, according to Figure 4, guarantee the adsorption   mechanism's spontaneity and stability on the carbon steel surface. e ΔG a ds values are between −25 and −26 kJ.mol − 1 , which are lower than −20 kJ.mol − 1 and higher than −40 kJ.mol − 1 , indicating that adsorption of inhibitor molecules on the carbon steel surface includes both physisorption and chemisorption [45]. e corrosion thermodynamic parameters were used to further analyze the adsorption behavior of EEW on the carbon steel surface. Arrhenius and transition state equations were used to calculate activation energy (Ea), entropy (ΔS a ), and activation enthalpy (ΔH a ). e activation energy (Ea) was calculated using the following equation [46]: where R is the universal gas constant, T is the absolute temperature (K), and is the frequency factor. e connection between Log (CR) and 1000/T in 1 M HCl without and with the EW inhibitor produces straight lines with slopes of E a /2.303RT, as illustrated in Figure 5.
e estimated values of the apparent activation energy using equation (8) are given in Table 4. e equation of transition states is where (N A � 6.023 × 10 23 ) is Avogadro's number, (h � 6.62607 × 10 − 34 )is Planck's constant, ΔH a ds is the enthalpy, and ΔS a ds is the entropy of adsorption. Figure 6 displays the plot of log(CR/T) versus which will give a straight line, with a slope of ΔH a ds /2.303R and an intercept of[ΔS a ds /2.303R + log(R/N A .h)]. us, giving the values of ΔS a ds and ΔH a ds , results are shown in Table 4. e values ΔH a ds are positive, indicating an endothermic corrosion process [48]. e values of E a and   Figure 4: Langmuir adsorption isotherm model for EEW on the carbon steel surface at temperatures from 298 to 328 K.   Journal of Chemistry ΔH a ds have increased in the presence of an inhibitor EEW due to the increased energy barrier of the corrosion reaction occurring at the metal surface. Because the corrosion process is a unimolecular reaction, the mean value of the difference E a − ΔH a ds is 2.60 kJ/mol, which is identical to the mean value of the product RT described by the following equation: E a − ΔH a ds � RT [49]. e activation entropy's high and negative values indicate that the complex activated in the rate-determining step is an association rather than a dissociation phase, implying that there is a decrease in disorder throughout the transition from reactants to activated complexes [50].

PDP Measurements.
Carbon steel polarization curves in a 1M HCl solution at 298 K were also produced in the absence and presence of EEW inhibitors of various doses. e entire behavior of the steel/acid/inhibitor system is depicted in Figure 7. Table 5 illustrates the inhibition efficacy of different doses of inhibitor in 1M HCl for corrosion current densities (Icorr), corrosion potential (Ecorr), Tafel slope (βa) and (βc), and EI (%). Equation (10) defines the corrosion inhibiting effectiveness (%): e current densities without and with inhibitor, as calculated by extrapolation of the Tafel lines, are I corr and I inh , respectively [51,52]. e inhibitory capacity of the inhibitor was studied using a polarization test, and the results are shown in Figure 7; it can be seen that by the successive addition of an egg-white extract to the 1 M HCl medium, in the presence of the EEW, the corrosion potential is somewhat pushed towards the cathode branch, with a fluctuation in the values of β a and β c .
is indicates that the presence of inhibitors in an acidic environment slowed both carbon steel dissolving and hydrogen reduction [53,54]. In comparison to the blank, there is no significant change in the corrosive potential readings. e E corr is displacement is less than 85 mV, indicating that it is a mixed-character inhibitor [55,56]. As the corrosion concentration of the inhibitors increases, the corrosion current density values decrease [57] according to the data given in Table 6. ese results can be ascribed to the adsorption of EEW on the carbon steel surface, which reduces the active site's surface area and can function as a corrosion barrier [58,59]. It should also be noted that a good inhibition efficiency was observed in the presence of EEW (89%) at a concentration of 800 mg. L −1 .

3.4.2.
Impedance Spectroscopy Electrochemical. Electrochemical impedance spectroscopy is widely and effectively applied in global corrosion and protection processes, addressing the use of electrochemical impedance measurements to investigate the inhibitory mechanism; it seems that this technique is particularly adapted to determine the mode of action of inhibitors; it allows evaluating the dielectric characteristics of the film formed and to follow their evolution according to many parameters [60,61]. It also makes it possible to explain the chemical or electrochemical processes developing through the films. In this study of corrosion inhibition of carbon steel in 1 M HCL acid media at 298 K, the impedance of the Nyquist and Bode diagrams is presented in Figures 8(a)and 8(b). Figure 8(a) shows the equivalent circuit, rather than using capacitors, uses stationary-phase elements (CPE) to provide a variety of heterogeneities suitable for corrosion electrodes, such as deficient polishing, grain boundary, surface contaminants, and surface roughness [62]. We utilized the parameters (n and Y 0 ) of our test to construct a mathematical model since the impedance of carbon steel is frequency dependent.
where Y 0 denotes the CPE constant, j is an imaginary number and j 2 � −1, ω represents the angular frequency in rad −1 and ω � 2πf, and n is a measure of the roughness of the carbon steel surface; 0 ≤ n ≤ 1 [63]. In addition, this is due to a variety of factors, including electrode roughness, dielectric constant, and surface heterogeneity; in our research, the n values are in a range of 0.981 < n < 0.996, indicating that inhibitors have no effect on the mechanism of corrosion and that the electron transfer reaction regulates the corrosion process both in the absence and presence of inhibitors [64]. e following equation was used to determine the doublelayer amplitude (C dl ): where f max is the maximum frequency of the imaginary component of the impedance and R p is the charge transfer resistance; it is evident from Table 5 that the C dl values decreased in the presence of the inhibitor, owing to an increase in the thickness of the protective layer on the electrode surface in the presence of an inhibitor [65]; in other words, the decrease in C dl values is attributed to the progressive replacement of water molecules adsorbed on the metal surface by larger water molecules [66].
In this work, we looked at the efficacy of inhibition η EIS (%) using the following equation [67]: where R inh p and R corr p are the charge transfer resistance values with and without EEG, respectively; furthermore, it is clear from Table 5 that the values of Rp increase significantly with the increase of the inhibitor concentration in the acid solution, the polarization resistance (Rp) is inversely related to the corrosion rate, and the creation of an insulating protective coating at the metal/solution contact is responsible for the increase in Rp values [68]. is gives a maximum inhibitor concentration efficiency of 90% at 800 mg/L of EEW; these findings support the hypothesis that EEW works via adsorption at the metal/solution contact. Figure 8(b) show the impedance data in Bode diagrams of impedance size (|Z |) and full-frequency angle of phase for the C-steel electrode obtained at various inhibitor doses; furthermore,    [69,70]. is may explain the efficacy in the current research due to the presence of these features in the EEG, as well as delocalized electron density in the majority of the molecular structure.
In the same way, the higher efficiency of EEG, in contrast to Lilium brownii leaf extract [71], camphor leaf extract [72], and Tamarindus indica extract [73], can be explained by that the EEG contains many electron sources such as oxygen atoms, nitrogen atom, and hydroxy group, confirming the benefit of using EEG as a corrosion inhibitor.

EDX Spectra and Scanning Electron Microscopy (SEM)
Surface Analysis. Figure 9 shows the surface morphology of carbon steel during 12 hours of immersion with and without an inhibitor in a 1M HCl solution at 298 K. e SEM analysis shows the surface of the steel with and without an inhibitor so that the surface with an inhibitor is at the energy 20 KV. e surface morphology was severely degraded by exposing the specimen to 1 M HCl, as seen in Figure 9 (blank). After immersion in an acidic solution containing 800 mg, the surface of the specimen was smoother and revealed fewer pits. When inhibitor molecules engage with the corroding surface of CS in the acid solution, a protective barrier layer is formed, resulting in the smoothness of the inhibited CS surface [74][75][76].

Conclusions
e inhibition behavior of the expired egg-white extract (EEW) in 1M HCl was examined using weight loss, electrochemical study, and SEM with EDX: Potentiodynamic polarization (PDP) studies show that this natural product is a mixed-type inhibitor and acts as an adsorptive inhibitor Increasing the inhibitor concentration up to 800 mg/L at 298 K, the inhibition efficiency increases to 89% for (PDP) and 90% for (EIS) e site electrochemical impedance spectroscopy indicated that the ECP, with increasing inhibitor concentrations, and the charge transfer resistance of the electrical double layer dropped and the charge transfer resistance rose e effect of temperature showed that extract adsorption occurs by physical and chemical adsorption and follows the Langmuir isotherm Scanning electron microscopy reveals the development of a protective layer on the metal surface Data Availability e data used to support the findings of this study are available from the author upon request.  Journal of Chemistry 9

Conflicts of Interest
All of the authors have no affiliation with any organization with a direct or indirect financial interest in the subject matter discussed in the manuscript.