IBN AL- HAITHAM J. FOR PURE & APPL. S CI. VOL. 24 (2) 2011 Potentiostatic Study for the effect Of LAS on the Corrosion Of pure Zinc in 0.01 M HCl so lutions K. A. AL-Saadi , S. A-J. Al-Safi Departme nt of Chemistry, College of Science , Unive rsity of Baghdad Received in : 22 December 2010 Accepte d in :28 February 2011 Abstract A p otentiost atic st udy for the corrosion of p ure zinc in 0.01 M HCl was achieved in absence and p resence of (linear alky lbenzene solfonate LAS) detergents in a range of concentrations (0-50) mg/L. The electrochemical st udies included anodic, cathodic p olarization by using p otentiost at over temp erature rang (293- 323) K. The mechanism of corrosion rate of p ure zinc was suggested by evaluating of αa , αc , ba , bc , i0 , Rp and the kinetic p arameters also calculated ( Ea , A) at t he above temp erature rang, The thermody namic of corrosion, corrosion accelerating and corrosion p rotecting were invest igated by calculating (∆G, ∆H and ∆s) values. Keyword: zinc corrosion, p otentiostat, linear alkylbenzene solfonate LAS. Introduction " corrosion is t he deterioration of substance or its p rop erties because of the reaction with its environment. In the water works industry , the "subst ance" that deteriorates may be metal pipe or fixture, the cement in a p ipe lining or an asbestos-cement (A-C) p ipe" (AWWA 1990, Aly et at 1998). This normal and natural p rocess may result in failure of comp onent and can seldom be totally p revented. The effect of corrotion is imp ortant in water utility industry [1]. Electrochemical theory is one way to understand the st ructure of metals on the basic of p articles by imagining an array of p ositively charged ions sitting in negatively - charged "y as" of free electrons, coulombic att raction holds these op p ositely -charged p articles together, but the p ositively-charged ions are att racted to negatively charged p articles outside the metal as well, such as the negative ions (anions) in an electrolyte. For a given ion at the surface of a metal, there is a certain amount of energy to be gained or lost by dissolving into the electrolyte or becoming a p art of the metal, which reflects an atom scale tug-of-war between the electron gas and dissolved anions. The quantity of energy then strongly depends on a host of variables, including the ty p es of ions in a solution and their concentrations, and the number of electrons p resent at the metals surface[2]. Zinc is a metal with numerous industrial app lications and is mainly used for the corrosion p rotection of steel. Zinc is an indust rially imp ortant metal and is corroded by many agents, of which aqueous acids are the most dangerous[3]. Surfactants are the active cleaning ingredients in sy nthetic detergents used for all kinds of washing. They consist of a water-soluble (hy drop hilic) and a water-insoluble (hy drop hobic) comp onent. As a result of t his st ructure, the molecules of surfactants align themselves t o form micelles able to sep arate dirt and oily st ains[4]. Organic substances as well as inorganic ones affect the corrosion rate. It is claimed that if organic molecules have group s like -OH, -CHO, -COOH, -CN, -SCN, -CO, -NH2, -SO3, double or triple bonds or unp aired electrons, the subst ance and the metals interact easily, and charging the zero charge p otential, an effective p rotection is p rovided [5]. IBN AL- HAITHAM J. FOR PURE & APPL. S CI. VOL. 24 (2) 2011 In this st udy , the effects of the organic molecules like linear alky lbenzene solfonate LAS (which is a raw material of detergents and has surface active p rop erties) on zinc were invest igated. Experime ntal procedure Ap ure zinc (99.99%) p ieces of 1cm² were served in the corrosion cell as a working electrode. Platinum was served as the counter electrode while saturated calomel electrode (SCE) was used as a reference electrode. The corrosion cell were conducted with advanced p otentiost at winking M Lab-200(2007) [Bank Elektronik – Intelligent controls GmbH with all accessories] Cell + Electrode + working electrode holder (Germany ). The open circuit p otential (OCP) was measured and the polarization curves were scanned between (-1.1 to - 0.2) V. The 0.01M HCl solutions were p repared by using HCl (37% Aldrich) and diluted with DI water (with a measure conductivity less than 2 µs ⁄cm). LAS, Fw=362.498 g.mole -1 . Where m+n =10 A dilute solution (500 p p m) of LAS (98% p ure) was p repared using DI water and then used for p reparation of all acid electrolytes solutions (by addition of the desired amount of LAS solution (500 mg/L)) in the concentration ranges of st udy (0-50) mg/L. Re sults and Discussion (I) Polarization curve Figs (1– 4) show t y p ical p olarization curves for Zn in 0.01M HCl in presence and absent of different concentration of LAS ranging between (2.5-50) mg/L, at temp erature range (293- 323) K. Table 1. shows the resulting data (the corrosion p otential Ec and corrosion current densities( ic) which have been derived from the polarization curves. The data of table 1 show that the corrosion current density (ic) increased while the corrosion p otential Ec generally decreased with the increase of temp erature in absence and p resence of LAS. The corrosion current densities (ic) and corrosion p otential (Ec) have been obtained by extrapolation of the linear logarithmic sections of cathodic and anodic Tafel lines to the p oint of intersection. The rate of an electrochemical reaction is limited by various p hy sical and chemical factors. The behavior of electrochemical sy st em depends on the charge transfer reactions which occur at the interface. The basic law of charge –transfer reaction has been exp ressed through the Butler-Volmer electrodic equation [6] as i = i0 [е (1- β) ηF/RT – е - β η F/RT ] ------- (1) In which, i0, is the equilibrium exchange current density , β, is the sy mmetry factor, the term η=E-Ec measures how much the p otential E has dep arted from the equilibrium value Ec. The following equation p rovides a simple way of understanding non-p olarizable and p olarizable interface [7]:- i = i0 Fη / RT -------------- (2) CH3 - (CH2)m - CH SO3 – Na + ( CH2 )n – CH3 IBN AL- HAITHAM J. FOR PURE & APPL. S CI. VOL. 24 (2) 2011 where η is about 0.01V or less for one electron transfer reaction. By rearrangement of this equation, one obtains [5]. η / I = RT/ i0F=Rp -------------- (3) so t he term η / i corresp onding to the resist ance Rp of interface at an electrode to the charge transfer reaction and is termed the p olarization resist ance. The higher the value of i0, the less does the p otential difference across an interface depart from the equilibrium value on p assage of a current [6]. (II) The Tafel sl opes and Transfe r coefficie nts The cathodic (bc) and anodic (ba) Tafel slop es which were obtained from the slop es of cathodic and anodic Tafel regions of the p olarization curves are given in table 1. The data of the table show that the cathodic and anodic Tafel slop es shifted slightly with increasing temp erature at all LAS concentration. Values of transfer coefficients for the cathodic (αc) and anodic (αa), p rocesses have been calculated from the corresp onding cathodic (bc) and anodi (ba) Tafel slop es using the relationship [6]: αc = 2.303RT / bcF -------------- (4) αa = 2.303RT /baF --------------- (5) Where R is the gas constant and F is the faraday constant. The results obt ained are given in table 2. A values of αc of ~ 0.5 could be diagnost ic of a p roton discharge-chemical desorp tion mechanism in which the p roton discharge is the rate-determining st ep (r.d.s). Values of αa are shown in table 2, and in most cases αa were close to 0.5 in absence of LAS at t he temp erature range (303-323)K, indicating the metal dissolution reaction to be the rate-determining st ep for the reactions taking p lace at t he anode. The variation of αa could be interp reted in terms of the variation of the rate-determining st ep from charge transfer p rocess to either chemical-desorp tion or to electrochemical desorp tion, in p resence of LAS and in absent LAS at 293K. The variation of (ba) and (αa) may be attributed to the variation of the rate-determining st ep in the metal dissolution reaction. A change in mechanism as well as in the rate-determining st ep cannot be ignored throughout the anodic p rocesses. (iii) The exchange current desities and polariz ation resi stances. The polarization resist ance (Rp) was determined from Stern-Geary equation [6]: Rp = [d(∆E)/di] ∆E→0 = babc / 2.303(ba + bc)ic --- (6) Values of Rp are p resented in table 2. Values of exchange current density were calculated from equation (3) and the i0 values p resented in table 2. The i0 for a metal electrode determines the extent of the p olarization of the interface adjacent to the electrode; a nonp olarizable interface corresp onds t o one at which the potential difference does not change easily with the p assage of current. The higher the value of i0 is, the less does the p otential difference across an interface depart from the equilibrium value on the p assage of a current. Similarly , the case of i0→0 or Rp →∞ means that the p otential departs from the equilibrium values even with a very small current density leaking across the interface. The value of i0→0 is the idealized extreme of a p olarizable interface; i0→∞ is idealized extreme of a non- p olarized interface. IBN AL- HAITHAM J. FOR PURE & APPL. S CI. VOL. 24 (2) 2011 Values of i0 in absence of LAS are higher than corresp onding i0 values in p resence of LAS at all temperature and LAS concentrations, indicating the variation of interface p olarization, that means LAS led to increase the interface polarization. The maximum LAS concentration effect i0 was at 323K by using 5 mg/L LAS. (iv) The protection e fficie ncy (P%) The p rotection efficiency (P%) of an inhibitor or of a p rotection mean was calculated by [7,8]: P% = 100[1- (ic)2 / (ic)1] ------------- (7) where (ic)1 and (ic)2 are resp ectively the corrosion current densities of the Zn in the absence and presence of the LAS at t he same temperature; (ic)1 and (ic)2 refer also t he corrosion rate of unp rotected and p rotected metal by any p rotection methods. Values of p rotection efficiency which were calculated for various concentration of LAS at temp erature range (293-323) K are given in table 2. LAS concentration led to accelerate the corrosion rate of Zn in 0.01 M HCl at (293 – 303)K while at 313 and 323 K it lead to p rotect the zinc from corrosion where LAS used in concentrations (5 and 25) mg/L. Using 50 p p m LAS led to inhibit the zinc corrosion at the four temp eratures above, but using 2.5 p p m LAS at 313 accelerate corrosion of Zinc. Fig. 5 shows the variation of P% with temp eratures for the different LAS concentration, while Fig. 6 shows the variation of P% with LAS concentrations for the different temp eratures. Fig.7 shows t he variation of corrosion rate (ic) against temp erature for different LAS concentrations, while Fi g.8 shows t he variation of corrosion rate against LAS concentrations at different temp eratures. (v) Kinetics of corrosion The effect of temp erature on the rate of corrosion has been st udied over the temp erature range from 293 to 323K. The rate(r) of corrosion may be exp ressed as [9]. r = 0.13 (e / ρ) icor r --------------- (8) where (e) is the best chemical equivalent of the metal, (ρ) its density and icor r is the corrosion current density , the value of icor r may b taken to be prop ortional with the rate of corrosion (r). Fig.9 shows log icor r p lott ed against the recip rocal of the absolute temp erature (1/T) for the Zn in 0.01HCl. The result is shown to be almost a linear dependence on the corrosion rate (log icor r) on (1/T) which can be exp ressed as [10]: Log icor r = log A – Ea /2.303RT ---------- (9) Which is similar to the well-known Arrhenius equation with: r = A exp (-Ea / RT) ----------- (10) Ea represents the activation energy of the corrosion and A is the p re-exp onential factor in the rate equation. Values of Ea and A are then derived from the slop and the intercep t of log icor r versus 1/T p lot. T able 3 presents the values of Ea and log A for p ure zinc in 0.01M HCl. Fig.10 shows t he resulting values of Ea as a function of LAS concentration in 0.01M HCl. IBN AL- HAITHAM J. FOR PURE & APPL. S CI. VOL. 24 (2) 2011 There was non-linear decrease in Ea values on increasing LAS concentration, up to 25 mg/L and then increased reaching to 50 mg/L thus, the p resence of LAS in the acidic media p robably lowering the energy barrier for the metal corrosion through the decrease of the app arent energy of activation resulting in the consequent increase of the surface tendency for corrosion, but a value reaches to 7.48x10 10 in absence of LAS and by adding LAS the A value be so lower that means LAS led to decrease the number of anodic corrosion sites. A liner relationship is frequently observed between the energy of activation (Ea) and the p re-exp onential factor (A) for a given reaction over a different LAS concentrations Fig.11. It is usually of the form [11]. Log A = m Ea + C ----------- (11) This relation is referred to as a "comp ensation effect" or the "Theta Rule". The former name is meaningful, since an increase in Log A at constant Ea imp lies a higher rates while an increase in Ea at a constant Log A therefore tend to comp ensate from the st andpoint of the rate. When such a compensation op erates, it is p ossible for st riking variations in Ea and LogA through a surface series to y ield only relatively small change in activity ; alternatively when the effect does not op erate (that is, when either Ea or LogA alone changes) st riking variation in activity results. The high LogA values are due to the greater concentration of corroding sites on zinc. The comparatively lower Ea values co mbined with greater values of LogA for corrosion of the metals make the corrosion mu ch easier [15]. Although that Ea with using 50 mg/L LAS is equal to 37.19 KJ.mol -1 and the Ea with absence of LAS is equal to 50.34 KJ.mol -1 but values of LogA for the first is 8.28 and for the second is equal 10.87, that means the 50 mg/L LAS led to decrease the energy barrier but in the same time it led to decrease the number of the active corrosion sites (anodic sites) and overall p rocess is reached to p rotect the corrosion of zinc. vi) Thermodynamic of corrosion Values of Ec for various LAS concentration and at different exp erimental temp eratures reflect the variation in the Gibbs free energy (ΔG) values of the corrosion, and reflect the tendency of metal for corrosion on thermodynamic grounds [12,13]. Table (1) shows the decreasing of Ec with temp erature increasing in absence and p resence of LAS. In each temp erature the addition of LAS let to increase Ec in active direction and – ΔG increased according to the following equation [14]: ΔG = - nFEc -------------- (12) ΔG = ∆H - T∆S -------------- (13) Where n is number of electron, and F is t he Faraday constant. Fig.12 shows t he variation of ∆G with t emp erature at the different LAS concentration. Table 4: shows ∆H (intercept) and ∆S (from slope) for the corrosion of Zn in HCl 0.01 M solution at different LAS concentrations. Conclusion LAS led to p rotect Zn from corrosion in 0.01M HCl solution and the best LAS concentration was 50 mg/L (P% close to 64-25 %) at 313K. The uses of 50 mg/L LAS led to lowest ΔS values for t he corrosion which is due to the decreasin g of the zinc ions eff luence as a result of LAS lay er adsorbed on zinc surface. IBN AL- HAITHAM J. FOR PURE & APPL. S CI. VOL. 24 (2) 2011 The p resence of low concentration of LAS at low temp erature, led to accelerate the corrosion of zinc because LAS act as an oxidation agent react with electrons in the cathodic regions and on increasing temp erature the LAS p articles go far from cathodic regions and act as a protected layer of anodic regions p reventing the effluence of zinc ions to the solution. Re ferences 1. Castorina ,J. ; Jegatheesan, V. (2001), " corrosion Impact on Drinking Water Dist ribution sy st em A review and Fut er research Divition". School of Engineering, James cook university , Townsville, QLD 4811, Aust ralia. 2. Wikipedia, (2009), "corrosion" the free encyclop edia. Hlm pag. (1-10). 3. Shanthamma Kampalapp a RAJAPPA, Thimmap p a V. VENKATESITA, (2003) "Inhibition studies of a few organic comp ounds and their condensation p roducts on the corrosion of Zinc in hy drochloric acid medium", Turk J. chem.. 27 : 189-196. 4. PANIZ ZA, M . ; DE(UCCHI, M . and CERISOLA, G. (2006) "Electrochemical degradation of one onic surfactants", of Ap p lred Electrochemist ry , 35:357-361. 5. ZOR, S.; YAZ JCI, B. and ERBIL, M . (1999). " The effect of Detergent Pollution on the corrosion of Iron and Alumination", Turk J. chem.., 23 : 393-400. 6. Shreir,L.L: corrosion, (1976) M etal /Environment Reactions (New nes-Butter wort hs), Bost on, vol.2. 7. Bockris ,O’M .and Reddy, A.K.N. (1970) “M odern electrochemist ry " p lenum p ress, 2: 883-910. 8. AL-Saadie,Saria, K.A.S ; AL-Safi, A.J. and Duny a Edan EL-M ammar, (2007) “Effectof(1,4-heny lenediamine) on the corrosion of lead in 1M HCL solution ”, um- salama science Journal, 4(2):290-297, 9. AL-Saadie, K.A.S (2008) “The effect of LAS on th corrosion of AL, Zn and Pb in 1M HCL”, National Journal of chemistry 29:76-86. 10. Brgül Yazici and Sabel Zor, (1999), “Electro oxidation of LAS on Pt electrodes” Turk. J. chem. 23: 73-81. 11. Ein-Eli, Y.; Auinat, M . and Starosvetsky , D. (2003), “Electrochemical and surface st udies of zinc in alkaline solution containing organic corrosion inhibitors”, Journal of p ower sources 114:330-337. 12. AL-Saadie, K.A. Ph.D. Thesis, (1997) “Electrochemist ry st udies of the corrosion, corrosion-inhibition and p rotection of some iron alloys in acidic and basic media”, university of Baghdad, college of science. 13. Zenfeld, I.L.R. (1981), “corrosion inhibitors”, 66, M c Grow-Hill, Inc. 14. At eya, B.G.; Aradouli, B.E. and El-Nizamy , F.M . (1981), “corrosion inhibition for atainless steel by thiourea” Bull. Chem. Soc.Jp n vol. 54: 3187. 15. Naema Ahmed Hikmat Ezideen, (2002) "Investigation of the surface behaviour of certain metals" Ph.D T hesis, college of science, university of Baghdad. IBN AL- HAITHAM J. FOR PURE & APPL. S CI. VOL. 24 (2) 2011 Fig.(1): Effect of LAS (0-50) mg/L on polariz ation curve for Zn i n 0.01 M HCl at 293 K. Fig.(2): Effect of LAS (0-50 ) mg/L on Polarization curve for Zn in 0.01 M HCl at 303 K. Fig.(3): Effect of LAS (0-50 ) mg/L on polarization curve for Zn in 0.01 M HCl at 313 K. Fig.(4): Effect of LAS (0-50 ) mg/L on polarization curve for Zn in 0.01 M HCl at 323 K. IBN AL- HAITHAM J. FOR PURE & APPL. S CI. VOL. 24 (2) 2011 Table (1): Variati on of corrosi on potential (Ec), corrosion current densities (i c), cathodic (bc) and anodic (ba) Tafel sl opes for Zn i n 0.01M HCl in absence and presence of LAS . ba x 10‾³ v/decad e -bc x 10‾³ v/decad e ic x 10‾ 6 A.cm‾² - Ec /v T/K Solution C/mg. L -1 62.90 138.7 59.60 1.0082 293 0 mg/L 80.10 156.2 239.16 0.9694 303 106.80 136.7 316.70 0.9886 313 107.20 138.3 449.55 0.9955 323 68.50 182.3 158.39 0.9855 293 2.5 mg/L 101.70 178.8 264.19 0.9974 303 108.90 121.6 436.28 1.0154 313 106.40 134.0 498.11 1.0157 323 105.10 146.4 165.09 0.9778 293 5 mg/L 109.30 135.6 284.15 0.9954 303 101.70 83.60 296.80 1.0156 313 90.00 91.80 359.79 1.0144 323 99.40 147.1 213.85 0.9890 293 25 mg/L 96.80 152.2 252.02 0.9991 303 99.50 130.2 246.08 0.9985 313 123.80 152.3 428.87 1.0091 323 64.80 124.5 36.99 0.9766 293 50 mg/L 105.70 162.8 106.25 0.9960 303 95.80 129.0 113.2 0.9972 313 85.50 142.2 173.07 0.9951 323 IBN AL- HAITHAM J. FOR PURE & APPL. S CI. VOL. 24 (2) 2011 Table (2): Variati on of activation ene rgy ΔG, protection e fficiencies P% and polariz ation resistances (Rp), corresponding transfe r coefficients (αa and αc) and exchange current densities (i0) for Zn at 0.01M HCl. Table(3):Values Ea, log A and A at different LAS concentration C/mg. L -1 Ea/kJ.mol -1 Log A/ molecu le.cm -2 A / molecu le.cm -2 0 50.337 10.8740 7.48 x 10 10 2.5 31.1504 7.7750 5.95 x 10 7 5 18.8788 5.6296 4.26 x 10 5 25 16.0290 5.1597 1.44 x 10 5 50 37.1875 8.2841 1.92 x 10 8 αa x 10 ‾4 -αc x 10 ‾4 i0 x 10 ‾7 A.cm‾² Rpx10 3 Ω. cm² P% -ΔG/ kJ.mol -1 T /K Solution c/ mg. L -1 9242 4191 ــــــــ 315.27 0.800 293 185.63 ــ 0 mg/L ــــــــ 96.13 2.715 3848 7505 303 187.09 ــ ــــــــ 82.19 3.281 4543 3874 313 190.79 ــ ــــــــ 58.33 4.770 4634 5978 323 192.13 ــ 8487 3189 1.849 136.49 -165.75 190.20 293 2.5 mg/L 5911 3362 2.450 106.54 -10.46 192.49 303 5702 5107 4.716 57.17 -37.73 195.97 313 6023 4782 5.382 51.70 -10.80 199.60 323 5531 3971 1.568 160.91 -176.99 188.71 293 5 mg/L 5500 4454 2.822 92.48 -18.81 192.11 303 6106 7428 4.017 67.12 +6. 29 196.01 313 7120 6981 5.073 54.84 +19. 96 1.95. 77 323 5848 3952 2.095 120.44 -258.8 190.87 293 25 mg/L 6210 3950 2.560 101.94 -5.37 192.82 303 6241 4769 2.709 99.51 +22. 31 192.71 313 5176 4210 4.026 69.12 +4. 60 194.75 323 8971 4669 0.504 500.28 +37. 93 188.48 293 50 mg/L 5687 3692 0.996 261.91 +55. 57 192.22 303 6482 4814 1.278 210.87 +64. 26 192.45 313 7495 4506 2.077 133.96 +61. 50 192.05 323 IBN AL- HAITHAM J. FOR PURE & APPL. S CI. VOL. 24 (2) 2011 Table(4):Values ΔH, and ΔS at different LAS concentration C/mg.L -1 - ΔH / kJ.mol -1 ΔS / J.K -1 .mol -1 0 202.39 360 2.5 129.08 21 5 115.90 25 25 157.28 12 50 157.6 11 IBN AL- HAITHAM J. FOR PURE & APPL. S CI. VOL. 24 (2) 2011 -30 0 -20 0 - 10 0 0 10 0 2 9 0 3 0 0 310 320 330 T / K P % 2. 5 m g/ L 5 m g/ L 25 m g / L 50 m g / L -3 00 -2 00 -100 0 100 0 10 20 30 40 50 60 C/ mg/ L P % 29 3 K 30 3 K 313 K 32 3 K 0 100 200 300 400 500 600 29 0 30 0 310 3 20 33 0T / K m 0 m g/ L 2 .5 m g/ L 5 m g/ L 2 5 m g/ L 5 0 m g/ L 0 100 20 0 30 0 40 0 500 60 0 0 20 40 60 C / mg/L m 29 8 K 30 3 K 313 K 32 3 K Fig.(5): Variation of p% with temperatures for different LAS concentration. Fig.(6): Variation of p% with LAS concentration at different temperatures. Fig.(7): Variation of corrosion rate w ith temperatures for different LAS concentration Fig.(8): Variation of corrosion rate w ith LAS concentration at different temperatures IBN AL- HAITHAM J. FOR PURE & APPL. S CI. VOL. 24 (2) 2011 1 1.5 2 2 .5 3 0 .0 03 0 .0 031 0 .0 032 0.0 033 0 .00 3 4 0 .0 0 3 5 1/ T ( K -1 ) 0 p pm 2. 5p pm 5 p pm 25 pp m 50 pp m 0 10 20 30 40 50 60 0 20 40 60 C / mg/L Fig.(10): Variation of Ea against LAS conce ntration Fig.(9): Variation log icorr against 1/T for the corrosion of Zn in abse nce and presence of LAS in 0.01 M HCl IBN AL- HAITHAM J. FOR PURE & APPL. S CI. VOL. 24 (2) 2011 0 2 4 6 8 10 12 0 2 0 4 0 6 0 Ea / KJ .mol - 1 Fig.(12): Variation of ∆G against temperature a t the different LAS c oncentration. Fig.(11): Variation of Ea against Log A - 198 - 196 - 194 - 192 - 190 - 188 - 186 290 30 0 310 320 330 T / K G / K J m o l - 1 0 m g/L 2.5 mg/L 5 m g/L 25 m g/L 50 m g/L 2011) 2( 24المجلد مجلة ابن الھیثم للعلوم الصرفة والتطبیقیة تآكل الزنك النقي في في LASإستخدام المجهاد الساكن لدراسة تأثیر مادة الـ M 0.01 تركیز يوسط حامض الهیدروكلوریك ذ ساریة عبدالجبار الصافي، خلود عبد صالح السعدي .قسم الكیمیاء ،كلیة العلوم ، جامعة بغداد 2010كانون األول 22:استلم البحث في 2011 شباط 28: قبل البحث في :الخالصة بوجـود وغیـاب المنظــف M0.01 تمـت دراسـة السـلوك الكهروكیمیـائي لتاكـل الزنـك فـي محلــول حـامض الهیـدروكلوریك - 0( mg/L مـدى مــن التراكیــز فــي ) LAS(ثیر وجـود المنظــف أدرس تــ ،اذ). LAS(سـلفونات الكیــل البنـزین الخطیــة 50 .( الكاثودي واألنودي باستخدام المجهاد الساكن في مدى حراري یتـراوح تضمنت الدراسة الكهروكیمیائیة متابعة األستقطاب K)293 – 323 .(میكانیكیة لسرعة تآكل الزنك من خالل تقدیر قیم تاقترح)αa , αc , ba , bc , i0 , Rp ( والقیم الحركیة )Ea , A (القـیم الثرمودینامیكیـة تكمــا عینـ. عنـد المـدى الحـراري أعـاله)(∆G, ∆H, ∆s لتآكـل الزنـك وتـأثیر الـــLAS .مادة مثبطة أو معجلة للتآكلبوصفها ة: الكلمات المفتاحیة تآكل الزنك، المجهاد الساكن، سلفونات الكیل البنزین الخطی