Application of Some Natural Plants Extracts as Green Inhibitors for Corrosion Protection of steel in 1 M HCl

International Journal of Scientific & Engineering Research Volume 9, Issue 5, May-2018 ISSN 2229-5518 1542 Application of Some Natural Plants Extracts as Green Inhibitors for Corrosion Protection of steel in 1 M HCl R.M. Abou shahba1 , A.S. Fouda2, A.E. El-Shenawy1 and Taghreed J. A. Seyam3 1 2 Department of Chemistry, Faculty of Science, Al-Azhar University, Nasr city, Egypt. Department of Chemistry, Faculty of Science, El-Mansoura University, El-Mansoura-35516, Egypt, Fax: +2 0502246254 3 Ministry of Education and Higher Education, Gaza, Palestine. Abstract The inhibitive action of Costus speciosus (Crep ginger) and Lawsonia alba (Henna) on mild steel corrosion in 1 M HCl solution was investigated using potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) techniques. Surface analysis such as scanning electron microscope (SEM), Atomic Force Microscopy (AFM) techniques confirmed the formation of protective layer on mild steel surface in the presence of plants extract. Results obtained showed that these investigated compounds are functioned as good inhibitors for mild steel corrosion in 1 M HCl solution. Polarization data revealed that the plants extract act as mixed type inhibitors .The inhibition efficiencies increase with increasing inhibitor concentration. The results obtained from different tested techniques were in good agreement. IJSER Keywords Crep ginger , Henna, mild steel, HCl 1- Introduction Corrosion of metals is a major industrial problem that has attracted much investigations and researches. This is because some industrial processes such as acid cleaning, pickling and etching facilitate contact between metal and aggressive medium (such as acid, base or salt), consequently the metal is prone to corrosion. A corrosion inhibitor is a substance which, when added in small concentration to an environment, effectively reduces the corrosion rate of a metal exposed to that environment. Thus, inhibitors are one of the most practical methods for protection from corrosion ,especially in acid solutions to prenent unexpected metal dissolution and acid consumption [1,2]. A common classification of inhibitors is based on their effects on the electrochemical reactions involved in the corrosion process [3,4]. Organic compounds used as inhibitors, occasionally, they act as cathodic, anodic or as cathodic and anodic inhibitors, nevertheless, as a general rule, act through a process of surface adsorption, designated as a film - forming. These inhibitors build up a protective hydrophobic film adsorbed molecules on the metal surface, which provides a barrier to the dissolution of the metal in the electrolyte. They must be soluble or dispersible in the medium surrounding the metal [5]. The researchers have been focused on the use of eco- IJSER © 2018 http://www.ijser.org International Journal of Scientific & Engineering Research Volume 9, Issue 5, May-2018 ISSN 2229-5518 1543 friendly compounds such as plant extracts which extracts as green inhibitors in 1 M HCl solution. contain many organic compounds. Amino acids, The application of extracts of henna, thyme, alkaloids, pigments and tannins are used as green bgugaine and inriine was investigated for their alternatives for toxic and hazardous compounds, anticorrosion activity due to biodegradability, eco-friendliness, low addition of bgugaine on steel corrosion in HCl is cost and easy availability the extracts of some patented [14].The common plants and plant products have been effects of studied as corrosion inhibitors for various metals paradisica (Banana) peels and environmental corrosion in 1 M HCl as well as change in conditions[6]. Mild steel (MS), X80, J55 steel inhibition efficiency with ripening of the peels are commonly used in construction of oilfield are investigated [15]. The corrosion inhibition line pipes, casing and storage facilities. Their effect of red apple (Malus domestica) fruit corrosion behavior was investigated in 1 M HCl extract for mild steel in HCl was investigated by solution in absence and presence of seed extracts gravimetric and electrochemical methods at 30 – of Griffonia simplicifolia(SEGS) at 303 K [7]. 60 oC [16]. The inhibition efficiency of acid The inhibition efficiency of Tinospora crispa extract of Nicotiana leaves on mild steelin 1 M extracts as corrosion inhibitor of mild steel in 1 HCl has been evaluated by weight loss method M HCl was determined using weight loss, [17]. Ibrahim et al [18] using traditional weight potentiodynamic polarization and EIS [8]. Abou loss measurements and various electrochemical Shahba et al [9] investigated the corrosion techniques to investigate the inhibition effect of inhibition of mild steel by Catharanthus roseus Fig leaves extract on corrosion of mild steel in 2 (Vince rosea) and Turmeric (Curcuma longa) M HCl solution. alloys under different [10-13]. The effect of inhibition and adsorption the aqueous extracts of Musa on mild steel IJSER This work focuses on the inhibitory effect of Costus speciosus (Crep ginger) and Lawsonia alba (Henna) extracts as green inhibitors for mild steel in 1 M HCl solutions at room temperature using different techniques. 2- Experimental. 2.1. Materials and solutions 2.1.1. Composition of material sample Table (1): Chemical composition (wt%) of the mild steel Element Weight (%) Fe C Si Mn P Ni Al Cu S Ti Co Mo Cr 99.66 0.068 0.022 0.169 0.004 0.011 0.033 0.045 0.006 0.001 0.005 0.005 0.004 2.1.2. Test solutions with bidistilled water. The concentration range of The solution of 1M hydrochloric acid (Test solution) experiment hydrochloric were using acid prepared analytical (37%) for grade and inhibitor was 50 to 300 ppm. each of 2.2. Preparation of plants extracts diluting concentrated HCl to a required concentration IJSER © 2018 http://www.ijser.org International Journal of Scientific & Engineering Research Volume 9, Issue 5, May-2018 ISSN 2229-5518 1544 Costus speciosus (Crep ginger) leaves and finally dried. The polarization curves were flowers and Lawsonia alba (Henna) leaves plants determined by changing the electrode potential were purchased from the local market and automatically from – 0.1 to 0.2 V with respect to ground into a fine powder to give 200 gm of the free corrosion potential (E vs. SCE) at a scan powdered materials which extracted separately rate of 1 mV/s. Stern-Geary method [20] used for by soaking in 70 % methanol (300 ml) for 48 hr. the determination of corrosion current is at room temperature. Then the methanolic extract performed by extrapolation of anodic and of the sample was concentrated to nearly dryness cathodic Tafel lines to a point which gives log icorr under reduced pressure by using the rotary and the corresponding corrosion potential (Ecorr) evaporator at 45 oC to achieve the crude for inhibitor free acid and for each concentration methanolic extract which kept for further of inhibitor. Then icorr was used for calculation of investigation [19]. inhibition efficiency (%IE) and surface coverage (θ) as in equation 4 [21]: % IE = θ x 100 = [1 – (icorr(inh.)/ icorr(free)] x 100 (1) 2.3. Preparation of mild steel specimens where icorr(free) and icorr(inh) are the corrosion All specimens were mechanically cut into current densities in the absence and presence of IJSER sizes with 2 cm x 2 cm x 2 cm dimensions and inhibitor, respectively. Electrochemical abraded by emery paper of different grads, then washing with acetone and bidistilled water and finally dried. impedance spectroscopy measurements EIS were carried out in a frequency range of 1 Hz to 100 kHz with amplitude of 10 mV peak-to-peak. . The experimental impedance was analyzed and 2.4. Measurements Techniques interpreted based on the equivalent circuit. The Electrochemical measurements main parameters deduced from the analysis of A three-electrode cell including a Nyquist diagrams, are the charge transfer working electrode, an auxiliary electrode and a resistance Rct (diameter of high-frequency loop) reference the and the double layer capacity Cdl. The inhibition electrochemical measurements. The working efficiencies and the surface coverage (θ) electrodes were made of mild steel.The auxiliary obtained from the impedance measurements are electrode was a platinum foil, the reference calculated from equation 5 [22]: electrode was used for electrode was a saturated calomel electrode %IE = θx100 = [1-(R°ct/Rct)] × 100 (SCE) with a fine Luggin capillary tube (2) positioned close to the working electrode surface o in order to minimize ohmic potential drop. Each where R ct and Rct are the charge transfer specimen was successive abraded by using SiC resistance in the absence and presence of emery papers up to 1200 grit size, washed with inhibitor, respectively bidistilled water and degreased in acetone and IJSER © 2018 http://www.ijser.org International Journal of Scientific & Engineering Research Volume 9, Issue 5, May-2018 ISSN 2229-5518 2.5. Surface Investigation Techniques 2.5.1. Scanning Electron Microscopy (SEM) 1545 concentration (50- 300) ppm of inhibitors in 1 M HCl solution at room temperature were studied and the polarization curves are shown in Figures The mild steel specimens were immersed for 24 hr. in 100ml 1M HCl solution containing optimum concentrations (300 ppm of inhibitors). After 24 hr., the specimens were taken out and dried. Examination of mild steel (1-2). The inhibition efficiency (% IE) of the used inhibitors values and the degree of surface coverage (ϴ) were calculated using the equation (1). The important electrochemical corrosion parameters such as corrosion potential (Ecorr), surface after 24 hr. exposure to 1 M HCl solution corrosion current density(icorr), anodic (βa) and without and with inhibitors was carried by using cathodic (βc) Tafel plots and the inhibition (JEOL JSM-5500,JAPAN) scanning electron microscope. efficiencies (% IE) are given in Tables (2-3). Inspection the data of these Tables it is shown 2.5.2. Atomic Force Microscopy (AFM) that: i. The cathodic and anodic curves obtained The mild steel specimens were exhibited Tafel-type behavior. immersed for 24 hr. in 100ml 1M HCl solution containing optimum concentrations (300 ppm of ii. The cathodic and anodic potential values IJSER inhibitors) at room temperature. After 24 hr., the slightly specimens were taken out and dried. The nature negative and positive direction in the of the protective film formed on the surface of presence of different concentration mild steel surface after 24 hr. exposure to 1 M of the compounds extracts in 1 M HCl solution without and with inhibitor was HCl, indicating the inhibitors acted carried by using a Pico SPM2100 AFM device as a mixed type inhibitor [23, 24] as operating in contact mode in air at it shown from Figures (4-6) where Nanotechnology Laboratory, Faculty of both Engineering Mansoura University. polarization curves are influenced by the shifted cathodic presence towards both and of anodic the inhibitive compounds in the corrosive media. 3. Results and Discussion iii. The corrosion current density (icorr) 3.1. Potentiodynamic polarization values are decreased, while the Potentiodynamic polarization inhibition measurements are depend on the nature of increased inhibitor such as anodic or cathodic or mixed- on the of (% increase the in IE) the inhibitors, indicating that these compounds the inhibitor reaction. The inhibition action of extracts with concentration type inhibitor, mode of action and mechanism of compound efficiency retard the dissolution of mild steel in electrochemical 1 M HCl solution and degree of corrosion behavior of mild steel in 1 M HCl inhibition solution in the absence and presence of various IJSER © 2018 http://www.ijser.org depends on the International Journal of Scientific & Engineering Research Volume 9, Issue 5, May-2018 ISSN 2229-5518 concentration and type of the 1546 vi. The order of inhibition efficiency for the inhibitor. This implies that these additives is: compounds were acting as good Costus speciosus > Lawsonia alba adsorption inhibitors. iv. The inhibitive action of these compounds was discussed in terms 0.1 of blocking the electrode surface by adsorption the inhibitors molecules 0.01 log i , mA cm-2 through the active centers. v. The values of anodic (βa) and cathodic (βc) Tafel plots for the inhibitors variation in Tafel slope suggested 1E-6 -1.0 that the inhibitors is blocking the changing the mild steel dissolution blank 50ppm 100ppm 150ppm 200ppm 250ppm 300ppm 1E-4 1E-5 were shifted slightly, the slightly cathodic and anodic sites without 1E-3 -0.8 -0.6 -0.4 E, mv (vs SCE) Figure (1): Potentiodynamic polarization curves for the corrosion of mild steel in 1 M HCl in the absence and presence of various concentrations of Costus speciosus at 25oC. IJSER mechanism [25,26]. Table (2): potentiodynamic data for mild steel in 1M HCl in the absence and presence of different concentrations of Costus speciosus extract at 25oC. [inh.] ppm - Ecorr, mV vs. SCE 0 50 icorr, μA cm-2 βc mV dec-1 βa mV dec-1 C.R, Mpy θ % IE 528 1250 132 94 445 - - 498 388 98 70 110 0.690 69 501 335 102 67 90 0.732 73.2 150 492 258 108 65 87 0.794 79.4 200 488 220 110 72 81 0.824 82.4 250 475 192 115 75 76 0.846 84.6 300 490 157 118 63 71 0.874 87.4 100 IJSER © 2018 http://www.ijser.org -0.2 0.0 International Journal of Scientific & Engineering Research Volume 9, Issue 5, May-2018 ISSN 2229-5518 1547 Table (3): potentiodynamic data of mild steel in 1M HCl in the absence and presence of different concentrations of Lawsonia alba extract at 25oC. [inh.] ppm - Ecorr, mV vs. SCE icorr, μA cm-2 βc mV dec-1 βa mV dec-1 C.R, mpy θ % IE 0 528 1250 132 94 445 - - 5 507 698 122 85 130 0.442 44.2 498 644 123 80 124 0.485 48.5 15 488 367 126 87 118 0.706 70.6 20 492 332 111 78 112 0.734 73.4 25 505 305 118 73 105 0.756 75.6 300 492 217 120 70 98 0.826 82.6 10 IJSER 3.2. Electrochemical Impedance Spectroscopy (EIS) Measurements records the real (resistance) and imaginary Impedance measurement is a good impedance response of the system. Study technique in monitoring corrosion process. It is a systems in which multiple electrochemical non-destructive test because the magnitude of reactions are occurring gives some insight into potential surface the capacitive nature of electrochemical cells and modification and errors associated with large has been proven to be powerful and accurate deviations from electrochemical equilibrium are method for measuring corrosion rate. applied is small. Also, (capacitance and inductance) components of the also reduced [27]. Information derived can be related to the kinetics of the electrode process, mechanism and surface properties at the metal/solution interface. Therefore, EIS tests were conducted. Electrochemical impedance is usually measured by applying an AC potential to The impedance spectra obtained for mild steel in 1 M HCl solution in the absence and presence of various concentrations of tested inhibitors at room temperature are presented as Nyquist plots (a) in Figures (3-4). an electrochemical cell and measuring the current through the cell. The EIS instrument IJSER © 2018 http://www.ijser.org International Journal of Scientific & Engineering Research Volume 9, Issue 5, May-2018 ISSN 2229-5518 Upon the shape of the Nyquist plots (a) 1548 layer (adsorbed protective film) [32- the diameter of the capacitive loops in the 34]. presence of inhibitors is bigger than in the iii. The absence of inhibitor and increases with the (%IE) obtained from EIS measurements are nearly closed to inhibitor concentration. This indicate that the those obtained from polarization and impedance of inhibited substrate increases with weight loss methods. the inhibitor concentration. Noticeably, these iv. The order of the inhibition efficiency capacitive loops are not perfect semicircles obtained from EIS measurements is which can be attributed to the frequency as follows: dispersion effect. In general, this imperfections behavior is attributed to surface roughness and Costus speciosus > Lawsonia alba inhomogeneity of the mild steel [28-30]. The impedance spectra of the different Nyquist and Bode plots Figures (3-4) were analyzed by fitting the experimental data to a simple equivalent circuit model. IJSER The corrosion parameters from impedance measurements are shown in Tables (4-5). The obtained results show that: 90 value of Rct increases with increasing the concentration of the inhibitors and hence, the increase in the corrosion inhibition efficiency in acidic solution. This is due to the formation of protective film on the metal surface [31]. ii. The values of Cdl decrease on addition of inhibitor. This decrease could have been caused by an increase in the thickness of electrical double 80 a 70 -Zimag, Ohm cm-2 i. The 60 Figure (3): The 50 40 blank 50ppm 100ppm 150ppm 200ppm 250ppm 300ppm 30 20 10 0 -10 0 40 80 120 160 200 240 Nyquist (a) plots Zreal ,Ohm cm-2 for the corrosion of mild steel in 1M HCl in the absence and presence of different concentrations of Costus speciosus extract at 25oC Table (4): EIS parameters for the corrosion of mild steel in 1 M HCl in the absence and presence of different concentrations of Costus speciosus at 25oC. IJSER © 2018 http://www.ijser.org International Journal of Scientific & Engineering Research Volume 9, Issue 5, May-2018 ISSN 2229-5518 [inh.] ppm 1549 Rct, Ω cm2 Cdl, µFcm−2 θ %IE 0.0 12.3 47.16 - - 50 29.4 34.4 0.592 59.2 40.9 29.2 0.699 69.9 150 54.5 27.9 0.774 77.4 200 60.1 26.3 0.795 79.5 250 64.3 24.7 0.808 80.8 300 77.9 22.1 0.842 84.2 100 Table (5): EIS parameters for the corrosion of mild steel in 1 M HCl in the absence and presence of different concentrations of Lawsonia alba at 25oC. IJSER [inh.] ppm Rct, Ω cm2 Cdl, µFcm−2 θ %IE 0.0 12.3 47 - - 50 20.2 30.3 0.391 39.1 100 0 22.2 23.6 0.446 44.6 150 35.0 21.2 0.648 64.8 200 36.7 19.9 0.664 66.4 250 44.5 16.2 0.723 72.3 300 64.8 14.8 0.810 81.0 surface analysis was carried out by using 3.3. Surface Examinations 3.3.1. Scanning Electron Microscopy (SEM) Scanning Electron Microscopy after the corrosion tests as shown in Figures (5-7). The In order to evaluate the surface Inspections of the SEM images reveal that there morphology of the mild steel after exposure to 1 is severe damage and cavities on the surface of M HCl solution for 24 h immersion in the mild steel in the absence of compound extracts absence and presence of investigated compound Figures (5), because the metallic material is extracts at optimum concentration (300ppm), a affected by the corrosive environment. However IJSER © 2018 http://www.ijser.org International Journal of Scientific & Engineering Research Volume 9, Issue 5, May-2018 ISSN 2229-5518 1550 in the presence of the compound extracts there are very few pits and cracks observed in the inhibited mild steel surface Figure (6-7). The SEM studies confirm that a good protective film formation by the adsorbed inhibitor molecules on the mild steel surfaces [35]. Figure (7): SEM micrographs for mild steel surface after 24 h of immersion in 1 M HCl + 300 ppm of Lawsonia alba extract at 25oC. 3.3.2. Atomic Force Microscopy (AFM) AFM is a powerful tool to investigate Figure (5): SEM micrographs of mild steel surface after 24 h of immersion in 1 M HCl the surface topography at nano-to-micro scale. It IJSER has become a new choice of study to influence the inhibitor on the generation and the progress of the corrosion at the metal or glass/solution interface [36, 37]. AFM is becoming an accepted method for investigation of the roughness of metals, alloys and glasses [38]. The three- dimensional (3D) surface topography of the polished mild steel in 1 M HCl solution in the absence and presence of investigated compounds extracts at optimum concentrations (300ppm) are shown in the Figures (8-11). The scanning area of all the AFM images like polished mild steel, blank and inhibited mild steel is 4 µm × 4 µm. As analyzed from the inhibited sample Figure (6): SEM micrographs for mild steel Figure(10-11), there are very less pits, cracks and surface after 24 h of immersion in 1 M HCl + damage on the surface of mild steel with the o 300 ppm of Costus speciosus extract at 25 C. optimum concentrations (300ppm) of compound extracts. The average roughness value of polished mild steel Figure (8) surface is 33.431nm. The slight roughness observed on the surface of polished mild steel is due to IJSER © 2018 http://www.ijser.org International Journal of Scientific & Engineering Research Volume 9, Issue 5, May-2018 ISSN 2229-5518 1551 atmospheric corrosion and some streaks made on considerable pores structure with deep cracks. the surface of mild steel during polishing with However, emery papers. The average roughness value of concentrations mild steel surface in 1M HCl solution Figure (9) compound extracts the average roughness's are in the absence investigated compound extracts reduced to 102.64, 91.724, 118.64, 103.65, and are 667.5 nm. The greater roughness is due to the 107.97, respectively. The lower value of acid attack on the surface of mild steel in the roughness corrosion test period 24 h. therefore, the surface compound extracts protects the surface of mild of mild steel in 1 M HCl solution had a steel effectively. in the presence (300ppm) reveals that of the IJSER Figure (8): AEM micrographs of mild steel surface before immersion in 1M HCl IJSER © 2018 http://www.ijser.org of optimum investigated investigated International Journal of Scientific & Engineering Research Volume 9, Issue 5, May-2018 ISSN 2229-5518 1552 Figure (9): AEM micrographs of mild steel surface after 24 h of immersion in 1M HCl IJSER Figure (10): AFM micrographs for mild steel surface after 24 h of immersion in 1 M HCl + 300 ppm of Costus speciosus extract IJSER © 2018 http://www.ijser.org International Journal of Scientific & Engineering Research Volume 9, Issue 5, May-2018 ISSN 2229-5518 1553 Figure (11): AFM micrographs for mild steel surface after 24 h of immersion in 1 M HCl + 300 ppm of Lawsonia alba extract (4) The corrosion inhibition is probably due to Conclusions On the basis of this study the following conclusions can be drawn: surface and blocking its active sites by IJSER (1) Costus speciosus and Lawsonia alba extracts acts as inhibitors for mild steel corrosion in acidic medium. the adsorption of the plant extracts on the metal (2) Inhibition efficiency of Costus speciosus and Lawsonia alba extracts increases with increase in concentration of the inhibitors. (3) The values of inhibition efficiency indicate that, Costus speciosus extract more effective than Lawsonia alba extracts. phenomenon of physical and chemical adsorption. (5) SEM reveals the formation of a smooth surface on mild steel in presence of Costus speciosus and Lawsonia alba extracts probably due to the formation of an adsorptive film of electrostatic character. (6) Also the results indicate that, Costus speciosus and Lawsonia alba extracts acts as mixed type inhibitors. References [1] H. Ashassi-Sorkhabi, D. Seifzadeh and M. G. Hosseini; Corrosion Science 50 (12), pp. 3363, 2008. [2] A. K. Satapathy, G. Gunasekaran, S. C.Sahoo,K. Amit and P.V. Rodrigues; Corrosion Science 51 (12), pp. 2848, 2009. [3] V. S. Sastri, P. R. Roberge and J. R. Perumareddi; Selection of Inhibitors Based on Theoretical Considerations, Canadian Institute of Mining, Metallurgy and Petroleum, 1992. [4] M. Ash and I. Ash, Handbook of Corrosion Inhibitors, NACE,Teexas: Houston, USA, 2001. [5] A. S. 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