KHALSA PUBLICATIONS

The inhibition effect of Cassia alata leaves extract on corrosion of mild steel in 1N HCl was investigated through mass loss measurements with various time and temperature. The observed result indicated that the corrosion inhibition efï¬ciency and degree of surface coverage were increased with increase of inhibitor concentration and temperature. The thermodynamic parameters (Ea, âˆ†Hads, âˆ†Gads, âˆ†Sads) were evaluated for corrosion inhibition process which suggests that the adsorption is endothermic, spontaneous and chemisorptions and also the inhibitor follows Langmuir adsorption isotherm. The protective ï¬lm formed on metal surface was analyzed using spectroscopic studies viz, UV, FT-IR and EDX techniques

A.p, Petchiammal

Rani, P.Deepa

laks, S.Seetha

Selvaraj, S.

ISSN 2321-807X 
82 | P a g e                              J u l y  1 5 ,  2 0 1 3  
Anti-corrosive effect of Cassia alata leaves extract on 
Mild steel in 1.0N Hydrochloric acid  
A. Petchiammal, P.Deepa Rani, S.Seetha lakshmi and S.Selvaraj. 
Post graduate and Research Department of chemistry, 
Sri Paramakalyani College, Alwarkurichi-627412, Tamil Nadu, India. 
Mail id: ap_mscchem@yahoo.in 
Phone No. 9442064252 
Fax no: 04634-283530. 
ABSTRACT 
The inhibition effect of Cassia alata leaves extract on corrosion of mild steel in 1N HCl was investigated through mass loss 
measurements with various time and temperature. The observed result indicated that the corrosion inhibition efficiency 
and degree of surface coverage were increased with increase of inhibitor concentration and temperature. The 
thermodynamic parameters (Ea, ∆Hads, ∆Gads, ∆Sads) were evaluated for corrosion inhibition process which suggests that 
the adsorption is endothermic, spontaneous and chemisorptions and also the inhibitor follows Langmuir adsorption 
isotherm. The protective film formed on metal surface was analyzed using spectroscopic studies viz, UV, FT-IR and EDX 
techniques.  
KEYWORDS: Mild steel, Corrosion, Cassia alata leaves, Mass loss, Adsorption isotherm 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Council for Innovative Research 
Peer Review Research Publishing System 
Journal: Journal of Advances in Chemistry 
Vol 2, No. 2 
editor@cirworld.com 
www.cirworld.com, member.cirworld.com 
 
ISSN 2321-807X 
83 | P a g e                              J u l y  1 5 ,  2 0 1 3  
INTRODUCTION 
Mild steel is the material of choice almost all the field in Worldwide due to its low cost and easy availability. It has been 
extensively used under different condition in chemical and allied industries in handling alkaline, acid and salt solution. 
Chloride, sulphate and nitrate ions in aqueous media are particularly aggressive and accelerate the corrosion. One of the 
best way of protecting mild steel from corrosion is the use of inhibitors [1]. But the use of chemical inhibitor has been found 
to be more expensive, toxic, non bio-degradable and harmful to living things. Hence there is a big problem for researchers 
to search the non-toxic, eco-friendly corrosion inhibitors. Recent years, several green inhibitors have been used for the 
prevention of corrosion by most of the investigators. Few examples are Allium Cepa [2], Eucalyptus globulus [3], 
Phyllanthus amarus [4], bitter leaf powder [5], Carob seed oil [6], Bacopa monnieri [7], Citrullus Vulgaris peel [8], Albizia 
lebbeck seed [9], Hibiscus Esculenta leaves [10], Jatropha curcas [11], Eugenia Jambolana [12]. In continuous of our 
research work, our present investigation is an anti-corrosive effect of Cassia alata leaves on mild steel in 1N Hydrochloric 
acid have been investigated with various period of contact and temperature using the mass loss measurements and the 
corrosion product on metal surface is analysed by UV, FT-IR, EDX spectral studies.  
EXPERIMENTAL 
Specimen preparation 
Mild steel  specimen were mechanically pressed to cut different coupons, each of dimension exactly 20cm
2 
(5x2x2cm), 
polished with emery wheel of 80 and 120, and degreased with trichloroethylene, then washed with distilled water cleaned, 
dried and then stored in desiccator and used throughout our present study.  
Preparation of Cassia alata leaves (CAL) extract 
Freshly available Cassia alata leaves were dried well, grinded and soaked in required alcohol for about 48hrs, and then 
filtered, followed by evaporation in order to remove the excess of alcohol completely and the pure plant alcoholic extract 
was collected. From this extract the different concentration (0-1000ppm) of stock solution was prepared and used 
throughout the present investigation.  
Mass loss measurement 
In mass loss measurement, the specimen of mild steel is immersed exactly in 100ml of the test solution in the presence 
and absence of the inhibitor. The specimens were withdrawn from the test solutions after 24 to 360hrs at room 
temperature and one hour at the temperature range of 303K to 323K. From this observed data, the corrosion rate (mmpy), 
percentage of inhibition efficiency (%I.E) and surface coverage (θ) was calculated using the following formulae (1-3).  
                      
87.6×W
Corrosion Rate mmpy =
DAT               
(1)                                             
 Where, mmpy = millimeter per year, W = Mass loss (mg), D = Density (gm/cm
3
), A = Area of specimen (cm
2
), T = time in 
hours. 
                                         
1 2
1
W - W
%IE = ×100
W
               (2) 
                                             
1 2
1
W - W
θ=
W
                    (3) 
Where W1 and W2 are the corrosion rates in the absence and presence of the inhibitor respectively.   
SURFACE CHARACTERIZATION  
The predominant elements present in the corrosion products was recorded by an EDX detector using a model Oxford 
Instrument Model - INCA Penta xFET. The stretching frequency of functional groups in the corrosion product was 
analysed by FT-IR spectrum using the model Jasco/Japan. The absorption maximum of the corrosion product was 
analysed by UV spectra using  the Model Jasco V670. 
RESULTS AND DISCUSSION 
Table 1 reflects that the variation of corrosion parameters with concentration of CAL extract on mild steel at different 
period of contact in 1N Hydrochloric acid. It revealed that the corrosion rate was decreased gradually with the addition of 
inhibitor. The maximum of 73.62% inhibition efficiency was achieved at 1000 ppm of inhibitor concentration after 360 hrs 
exposure time. The almost greater than 73% of surface coverage (θ) was achieved due to the co-ordination between the 
mild steel metal and the hetero atom (oxygen, nitrogen) present in the inhibitor. 
 
 
ISSN 2321-807X 
84 | P a g e                              J u l y  1 5 ,  2 0 1 3  
Table 1: Variation of corrosion parameters with Concentration of CAL extract on mild steel at different period of 
contact in 1N Hydrochloric acid 
Conc.of 
inhibitor 
(ppm) 
24hrs 72hrs 120hrs 168hrs 216hrs 360hrs 
C.R %I.E C.R %I.E C.R %I.E C.R %I.E C.R %I.E C.R %I.E 
0 5.3635 ---- 3.1113 --- 2.3405 ---- 2.2987 ---- 2.1615 --- 2.0123 ---- 
10 4.1097 23.3 2.3451 24.6 1.5185 35.1 1.2804 44.2 0.9668 55.2 0.6780 66.3 
50 3.7615 34.9 2.2445 27.8 1.4674 37.3 1.2074 47.4 0.8422 61.0 0.5960 70.3 
100 3.5989 32.9 1.8575 40.3 1.4489 38.0 1.1278 50.9 0.7809 63.8 0.5789 71.2 
500 3.4828 35.0 1.6718 46.2 1.4135 39.6 1.1046 51.9 0.7493 65.3 0.5665 71.8 
1000 3.3203 38.0 1.1919 61.6 1.3560 42.0 1.0348 54.9 0.7367 65.9 0.5309 73.6 
 
Variation of corrosion parameters with various concentration of CAL extract on mild steel at different temperature in 1N 
Hydrochloric acid is shown in Table-2. As can be seen from Table-2 that the corrosion rate was decreased and the 
percentage of inhibition efficiency increased with increase of inhibitor concentration with rise in temperature from 303 to 
323K. It suggested that the adsorbed layer retards the corrosion rate when rise in temperature from 303 to 323K. The 
maximum of 75.00% inhibition efficiency was achieved at 323K. The value of inhibition efficiency was increased with rise 
in temperature. Thus, the inhibitor efficiencies were temperature dependent and it being chemically adsorbed at all 
temperatures. This was due to the adsorption of active molecules on the metal surface is higher than the desorption 
process.  
Table 2: Variation of corrosion parameters with Concentration of CAL extract on mild steel at different 
temperature in 1N Hydrochloric acid 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Temperature 
(K) 
Concentration 
of inhibitor 
(ppm) 
Mass loss 
(mg) 
 
Corrosion 
rate (mmpy) 
Inhibition 
efficiency 
(%) 
 
 
303 
0 372 207.29 -- 
10 211 117.58 43.27 
50 200 111.45 46.23 
100 183 101.97 50.80 
500 147 081.92 60.48 
1000 135 075.23 63.70 
 
 
313 
0 502 279.74 --- 
10 289 161.04 42.43 
50 200 111.45 60.15 
100 187 104.20 62.74 
500 175 097.52 65.13 
1000 152 084.70 69.72 
 
 
323 
0 572 318.74 ---- 
10 298 166.06 47.90 
50 208 115.90 63.63 
100 198 110.33 65.38 
500 147 094.73 70.27 
1000 135 079.68 75.00 
ISSN 2321-807X 
85 | P a g e                              J u l y  1 5 ,  2 0 1 3  
Adsorption isotherm 
The adsorption process was influenced by the chemical structures of molecule present in CAL, the distribution of charge in 
molecule, the nature and surface charge of metal and the type of aggressive media. The surface coverage values (θ) were 
tested graphically for fitting a suitable adsorption isotherm. In those cases, the plot of log C versus log C/ θ yield a straight 
line, clearly proving that the adsorption of the used inhibitors from 1N HCl solutions on the metal surface obeys the 
Langmuir adsorption isotherm (Fig.1) which is represented by equation (7). 
  log C/   = log C – log K                                -----------------------(7)            
Where  is the degree of surface coverage, C is the concentration of the inhibitor solution and K is the equilibrium constant 
from which the free energy of adsorption (∆Gads) is calculated by the following Equation (8) and the corresponding values 
are shown in Table-2. The negative values of ∆G ads suggested that the adsorption of CAL extract onto the metal surface is 
a spontaneous process and the adsorbed layer is more stable.  
                 ∆G ads = -2.303 RT log (55.5 K)                             ------------------------- (8) 
Where R is the gas constant, T is the temperature. The above adsorption isotherm reveals that there is no interaction 
between the adsorbate and adsorbent 
1.0 1.5 2.0 2.5 3.0
1.0
1.5
2.0
2.5
3.0
3.5
lo
g
(C
/d
e
ta
)
323K
log C
303K
313K
 
Figure 1 Langmuir isotherm for the adsorption of CAL inhibitor on mild steel in 1N Hydrochloric acid. 
 
Table 3: Langmuir adsorption parameters for the adsorption of CAL extract on Mild steel  in 1N Hydrochloric acid 
Adsorption 
Isotherms 
Temperature 
(Kelvin) 
∆Gads 
kJ/mol 
 
 
Langmuir 
303 -1.914 
313 -2.222 
323 -2.522 
 
Thermodynamics parameters 
A plot of log CR vs. 1000/T gave straight lines as shown in Fig.2. The apparent activation energy (Ea) was calculated by 
using following relationship. 
                   CR= Aexp (-Ea/RT)       
                 log CR= log A-Ea /RT                                  
Where Ea is the apparent activation energy for the corrosion of mild steel in 1N HCl solution, R the gas constant, A the 
Arrhenius pre-exponential factor and T is the absolute temperature. The values of Ea obtained from the slope of the lines 
are given in Table-4 
ISSN 2321-807X 
86 | P a g e                              J u l y  1 5 ,  2 0 1 3  
3.10 3.15 3.20 3.25 3.30
1.85
1.90
1.95
2.00
2.05
2.10
2.15
2.20
2.25
2.30
2.35
2.40
2.45
2.50
2.55
1000ppm
0ppm
10ppm
50ppm
1000/T(K
-1
)
100ppmlo
g
(C
R
)
500ppm
 
Figure 2 Arrhenius plots of mild steel in acid with and without different concentrations of CAL 
An alternative formula of the Arrhenius equation is the transition state equation 
              CR=RT/Nh exp (∆S/R) exp (-∆H/RT)  
where h is the Planck’s constant, N the Avogadro’s number, ∆S the entropy of activation, and ∆H the enthalpy of 
activation. A plot of log (CR/T) vs. 1000/T should give a straight line (Fig.3) with a slope of (−∆H/R) and an intercept of 
[log(R/Nh)) + (∆S/R)], from which the values of ∆S and ∆H were calculated and listed in Table-4. The data shows that the 
thermodynamic parameters (Ea and ∆H) of the corrosion of mild steel in 1N HCl solution in the presence of the inhibitors 
are lower than those in the free acid solution indicating less energy barrier for the reaction in the presence of the inhibitor 
is attained. The positive value of enthalpy of activation reflects the endothermic nature of metal dissolution process 
meaning that dissolution of metal is difficult. The increase of ∆S is generally interpreted by increase in disorder taking 
place on going from reactants to the activated complex [13] 
Table 4: Thermodynamic parameters for mild steel in 1N HCl solution obtained from weight loss measurements. 
         
S.No 
Concentration 
of CAL (ppm) 
Ea 
(kJ mol−1) 
∆H (kJ 
mol−1) 
∆S (J K−1 
mol−1) 
1 0 7.63142 6.5022 8.5795 
2 10 6.15111 5.0219 9.4771 
3 50 0.68416 0.4450 11.8856 
4 100 1.38511 0.2559 11.6249 
5 500 2.60444 1.4752 11.1840 
6 1000 1.04889 0.8230 11.8972 
 
ISSN 2321-807X 
87 | P a g e                              J u l y  1 5 ,  2 0 1 3  
3.10 3.15 3.20 3.25 3.30
-0.60
-0.55
-0.50
-0.45
-0.40
-0.35
-0.30
-0.25
-0.20
-0.15
-0.10
-0.05
0.00
1000ppm
0ppm
10ppm
lo
g
(C
R
/T
)
50ppm
100ppm
1000/T(K
-1
)
500ppm
 
Figure 3 The relation between log(CR/T) and 1/T for different concentrations of CAL extract 
MORPHOLOGY EXAMINATION OF MILD STEEL  
UV spectrum: 
   
(a)                                                                        (b) 
Figure 4 UV spectrum of ethanolic extract of CAL (a), the corrosion product on  mild steel  in 1N HCl  in the 
presence of CAL extract (b). 
              Fig.4(a) and (b) shows that the UV visible spectrum of ethanolic extract of CAL and the corrosion product on the 
surface of Mild steel in the presence of CAL extract in 1N Hydrochloric acid respectively. In the UV spectrum, the two 
absorption bands around 260 and 362nm and bands around 260 and 525nm were noticed in Fig.4(a) and (b) respectively. 
In the presence of inhibitor one band (260nm) remains unchanged and another band (362nm) shifted to higher wavelength 
region.  The change of absorption band from the above may confirmed the strong co-ordination between the active group 
present in the inhibitor molecules and the metal surface.  
FT-IR analysis        
The Fig.5 and 6 reflects that the FT-IR spectrum of the ethanolic extract of CAL inhibitor and the corrosion 
product on mild steel in the presence of inhibitor in 1N Hydrochloric acid. On comparing these spectra, the prominent peak 
is shifted from 3317.34 to 3355.88cm
-1 
for –OH group, the frequency at 1119.93cm
-1 
is attributed to –C-N stretching in 
amine is shifted to 1149.38cm
-1
 indicates that the binding between metal and inhibitor takes place through amino group. 
Thus the FT-IR spectra support the fact that the corrosion inhibition of CAL inhibitor on mild steel in 1N Hydrochloric acid 
may be the adsorption of active molecule in the inhibitor and surface of the metal.   
 
ISSN 2321-807X 
88 | P a g e                              J u l y  1 5 ,  2 0 1 3  
 
Figure 5 FT-IR spectrum of ethanolic extact of Cassia Alata leaves (CAL) 
 
Figure 6 FT-IR spectrum for the corrosion product on mild steel in the presence of CAL extract with 1N 
Hydrochloric acid 
EDX spectrum 
EDX spectroscopy was used to determine the elements present on the mild steel surface in the absence and 
presence of inhibitor. Fig.7 and 8 represents the EDX spectra for the corrosion product on metal surface in the absence 
and presence of optimum concentrations of CAL extract in 1N Hydrochloric acid. In the absence of inhibitor molecules, the 
spectrum may concluded that the existence of chlorine due to the formation of metal chloride and in addition to this, 
spectrum consists of iron, silicon, carbon which is the part of composition of mild steel. However, in the presence of the 
optimum concentrations of the inhibitors, nitrogen and oxygen atoms are found to be present in the corrosion product on 
the metal surface. It clearly indicates that these hetero atoms present in the inhibitor molecules may involve the complex 
formation with metal atom during the adsorption process and prevent the further dissolution of metal against corrosion. 
ISSN 2321-807X 
89 | P a g e                              J u l y  1 5 ,  2 0 1 3  
 
Figure 7 EDX spectrum of the corrosion product on mild steel surface in 1N HCl 
 
Figure 8 EDX spectrum of the corrosion product on mild steel in the presence of CAL  extract in 1N HCl 
CONCLUSION 
On the basis of the above results, it can be seen that Cassia alata leaves is a good inhibitor for mild steel in 1N HCl. The 
inhibition efficiency of CAL attains a maximum value of 73.62%.  This inhibition effect increases with the increase of 
inhibitor concentration. The inhibition efficiency of CAL is dependent on temperature. CAL shows an adsorption on the 
metal surface according to the Langmuir adsorption isotherm model. The value of activation energy (Ea), enthalpy of 
adsorption (∆Hads) and free energy changes (∆Gads) indicates that the adsorption of inhibitor on metal surface follows 
chemical, endothermic and spontaneous process respectively. The corrosion product over the surface of mild steel is 
characterized by UV, FT-IR and EDX studies also confirm protective film completely shielded the entire metal surface and 
reduce the further dissolution of metal against corrosion.        
REFERENCE 
[1]. Anand B, Balasubramanian, V. 2011. Corrosion Behaviour of Mild Steel in Acidic Medium in Presence of  
      Aqueous Extract of Allamanda Blanchetii, E-J.of Chem. 8, 226-230.   
[2]. Sulaiman S, Nor-Anuar A, Abd-Razak A.S, Chelliapan S. 2012. A study of using  Allium Cepa (onion) as natural  
     corrosion inhibitor in industrial chill wastewater system,  Res.j.chem.sci, 2, 10-16 
[3]. Rekkab S. et.al, 2012. Green corrosion inhibitor from essential oil of Eucalyptus globulus (myrtaceae) for C38  
      steel  in sulfuricacid solution, j. Mater. Environ. Sci, 3, 613-627.   
ISSN 2321-807X 
90 | P a g e                              J u l y  1 5 ,  2 0 1 3  
[4].Sribharathya V, Susai Rajendran and Sathiyabama, J. (2013). Inhibitory action of Phyllanthus amarus extracts on  
     the corrosion 2-thiophene carboxaldehyde as corrosion inhibitor for zinc in phosphoric acid solution of mild steel in  
     seawater, Chem. Sci Trans, 2, 315-321. 
 [5]. Ayeni F.A, et.al, (2012). Effect of aqueous extracts of bitter leaf powder on the corrosion inhibition of Al-Si alloy in   
      0.5 M caustic soda solution, Advanced Mater. Res, 367: 319-325. 
[6]. Dris Ben Hmamou et.al, (2012). Carob seed oil: an efficient inhibitor of C38 steel corrosion in Hydrochloric acid,  
      Inter. J. of Industrial Chem, 3:25 
[7]. Ambrish Singh et.al, (2012). Stem extract of brahmi (Bacopa Monnieri) as green corrosion inhibitor for aluminum  
      in NaOH solution, Int. J. Electrochem. Sci, 7: 3409 – 3419. 
[8]. Petchiammal A, Deepa Rani P, Selvaraj S, and Kalirajan K 2012. Corrosion Protection of Zinc in Natural Sea  
       Water using Citrullus Vulgaris peel as an Inhibitor, Res. J. of Chem. Sci, 2, 24-34. 
[9]. Petchiammal A, Selvaraj S, and Kalirajan K. 2013. Albizia lebbeck seed extract as effective corrosion inhibitor for  
      Mild steel in acid medium. Bio interface res. in App. Chem, 3, 498-506 
[10]. Petchiammal A, Selvaraj S, and Kalirajan K. 2013. Influence of Hibiscus Esculenta leaves on the corrosion of  
        stainless steel in acid medium, Inter. J. of Univ. Pharm. and Bio Sci, 2, 242-252 
[11]. Deepa Rani P and Selvaraj S. 2011. Comparitive account of Jatropha curcas on Brass(Cu- 40Zn) in   acid and  
         Natural sea water environment, Pacific J. of Sci. and Technol, 12, 38- 49. 
[12]. Deepa Rani P et al.  2013. Eugenia Jambolana Used as Corrosion Inhibitor on Mild Steel in 1N Hydrochloric 
        Acid Medium, 2, 215-225 
[13]. Ayatia N.S et al. 2011. Inhibitive effect of synthesized 2-(3-pyridyl)-3,4-dihydro-4- quinazolinone as a corrosion  
       inhibitor for mild steel in hydrochloric acid, Mater. Chem. and Phy, 126, 873–879 
 


English

Anti-corrosive effect of Cassia alata leaves extract on Mild steel in 1.0N Hydrochloric acid

Compared with the traditional methods of removal SO2 from flue gas, the organic solvent absorption has some advantages as low investment, high SO2 absorption efficiency and desorption efficiency. For the industrial application of organic solvent absorption as soon as possible, some laboratory research on selectively removing SO2 and NOx from flue gas in the presence of CO2 and an enlarged experiment has been done with a novel absorbent of Mn(II)+ DMSO. The effect on desulfurization selectivity for absorbents is studied. And the regeneration capacities for absorbent are researched. The result shows that the novel absorbent has not only strong desulfurization efficiency, but also good selectivity for SO2 and CO2, the feasibility of desulfurization absorbent has been proved

KHALSA PUBLICATIONS

Not a member yet

Anti-corrosive effect of Cassia alata leaves extract on Mild steel in 1.0N Hydrochloric acid

Research on selectivity removing SO2 from flue gas with a novel absorbent

0

0