- Email: [email protected]
Corrosion inhibition of mild steel by Capsicum annuum fruit paste
Accepted Manuscript Title: Corrosion inhibition of mild steel by Capsicum annuum fruit paste Author: Chandan M. Reddy Bhargav D. Sanketi S. Narendra Kumar PII: DOI: Reference:
S2213-0209(16)30172-0 http://dx.doi.org/doi:10.1016/j.pisc.2016.06.033 PISC 318
To appear in: Received date: Revised date: Accepted date:
20-2-2016 12-6-2016 13-6-2016
Please cite this article as: Reddy, C.M., Sanketi, B.D., Narendra Kumar, S.,Corrosion inhibition of mild steel by Capsicum annuum fruit paste, Perspectives in Science (2016), http://dx.doi.org/10.1016/j.pisc.2016.06.033 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
Corrosion inhibition of mild steel by Capsicum annuum fruit paste Chandan M Reddy1, Bhargav D Sanketi1, Narendra Kumar S1 1
Department of Biotechnology, RV College of Engineering, RV Vidyanikethan Post, Mysore
+918904885909, [email protected] Abstract
ip t
Road, Bangalore-59
cr
The anti-corrosive property of Capsicum annuum fruit paste (CFP) on mild steel was investigated. Weight loss and SEM analysis showed that the aqueous and ethanolic solutions of
us
CFP exhibits excellent corrosion inhibition in 2M HCl. Contact angle, surface atomic composition and FTIR studies verified the presence of an organic film on the mild steel surface.
an
The FTIR spectra also indicated the formation of active compound- Fe complex. CFP thus shows potential as an inexpensive environment friendly corrosion inhibitor for mild steel.
M
Key words: Capsicum annuum fruit paste, Mild steel, Capsaicinoids, Anti-corrosive coating.
d
Introduction
Protection of steel from acid corrosion has become increasingly important in various industries.
te
The toxicity of most status quo corrosion inhibitors has increased the need for environment
Ac ce p
friendly ones [1]. Plant based polar organic compounds containing hetero-atoms and ring structures have been widely explored [2-6] and have proven to be effective. Capsicum annuum (chili pepper) fruit has a high concentration of alkaloids called capsaicinoids [7] and other polar molecules like ascorbic acid [8] hence making it a strong candidate in anticorrosion studies.
In this study, we explored the corrosion inhibitory properties of CFP as a solution and as dried coat in acid. Weight loss method and SEM were used to study the inhibition efficiency. Contact angle, EDS and FTIR studies were done to analyze the protective film. Materials and Methods Preparation of the corrosion inhibitor solution
Page 1 of 6
200g of fresh green chili fruit was washed and ground using a mixer grinder till a paste of even consistency was obtained. The paste was squeezed and filtered through a double layered muslin cloth to obtain the liquid part. This liquid extract was used as the inhibitor solution.
ip t
Preparation of the metal samples Mild steel coupons (0.035% S, 0.05% P, 0.60 Mn, 0.15% C and the rest iron) of dimensions
cr
20mm x 40mm x 3mm were polished with Ajax emery paper grade 120 and washed with distilled water. Samples for the analysis were prepared by immersing these coupons in solutions
us
of 30ml 2N HCl, 10ml inhibitor solution with 10ml of distilled water or 10 ml of 95% ethanol for the weight loss, SEM and EDS studies and only distilled water for FTIR and contact angle
an
studies. The coupons were subsequently removed from the solution washed with distilled water and dried.
M
Weight-loss method
The polished coupons were initially weighed using a Shimadzu electronic balance-BL220H and
d
immersed in solutions as described above. The reference coupons were immersed in the acid without the inhibitor solution. The treated and dried coupons were then weighed after the
efficiency
(IE)
were
Ac ce p
Inhibition
te
stipulated time.
calculated
using
the
following
equations,
W1 – Weight loss in the absence of the inhibitor solution (reference) (mg) W2 – Weight loss in the presence of the inhibitor solution (test) (mg)
For the anti-corrosive coating tests the metal pieces were immersed in the inhibitor solution on a plate and placed in a hot air oven for 24hr till all the liquid was evaporated leaving behind a coat on the metal coupons. The coupons were then weighed and immersed in a solution containing 30ml of 2N HCl. Polished coupons were immersed in the acid as reference. The weight loss was determined for 1, 4 and 7 days of incubation. Contact angle measurements
Page 2 of 6
Sessile drop contact angle measurements were used to confirm the formation of the organic film [3]. The contact angle was measured by placing 100µl of distilled water on metal pieces immersed in acid with and without the inhibition solutions for 24 hours.
ip t
Analysis of the protective film The surface morphology and atomic compositions (from EDS) of the samples were analyzed
cr
using a Zeiss Ultra 55 FE-SEM machine. FTIR study was done to analyze the nature of the protective film formed on the mild steel surface [9]. FTIR spectrum of the inhibition solution,
us
inhibition solution mixed with ferrous sulphate and the film formed on the metal surface was obtained in their original state using ATR-FTIR by the Perkin Elmer Frontier FTIR Spectrum 10
an
instrument. Results and discussion
Time
1A
1E
2A
85.24
84.15
72.88
2E
d
(Days)
89.08
3A
3E
4A
4E
78.3
88.97
94.17
94.7
te
IE
M
Weight-loss experiment results
Table 1: Time of immersion versus IE. A- CFP added with distilled water, E- with
Ac ce p
95% ethanol.
Time
1
4
7
96.48
94.79
91.96
(Days)
IE
Table 2: Time of immersion versus IE for the coated sample
The inhibition efficiency of both the aqueous and ethanolic solutions of the inhibitor solution increased with the immersion period and reached a maximum of 94% on the 4th day. The increase suggests that the protective film on the metal surface either increases with the incubation time or remains largely unaltered. The coated samples showed considerably high IE in acid even after 7 days of incubation suggesting the formation of a very stable protective film.
Page 3 of 6
cr
ip t
Contact angle measurements
Figure 1: Sessile drop contact angle of (c) polished coupon, (b) coupon immersed in 2N HCl and
us
(a) aqueous inhibitor solution for 24 hours.
The figure shows the contact angle of the water drop with the steel surface under various
an
conditions. The contact angle of the reference coupon is seen at 51º which decreases to 31º when incubated in the acid. The contact angle of the coupon immersed along with the inhibitor solution increases to 59º. This decreased wettability and increased hydrophobic nature suggests the
M
formation of an organic film over the steel surface by the active compounds in CFP [3].
Ac ce p
te
d
Surface analysis
Figure 2: SEM images of the (d1, d2) reference coupon, coupon immersed in (a1, a2) 2N HCl and inhibitor solution with (b1, b2) distilled water with (c1, c2) ethanol at 500x and 2000x magnifications.
The morphology of the steel surfaces before and after incubation in 2N HCl with and without inhibitor solutions is shown in the figure. The metal immersed in the acid without the inhibitor solution shows intense corrosion with a highly rough surface. Corrosion pits formation is clearly observed. The metals immersed in the solution containing the inhibitor solution showed no surface roughness suggesting minimal corrosion. A smooth surface is observed, very similar to
Page 4 of 6
the reference coupon, with the marks observed being left only from the polishing. Complete coverage of the metal surface by the protective film without any cracks or gaps can be observed in the images.
ip t
The surface atomic composition of carbon and oxygen of the metal coupon immersed in the aqueous (22.45% C, 18.48% O, and rest iron) and ethanolic (19.85% C, 14.72% O, and rest iron) solution of the inhibitor solution was much higher than that of the reference (12.73% C, 9.25%
cr
O, and rest iron). This result confirms the presence of an organic film over the metal surface.
us
Analysis of the FTIR spectra
In the FTIR spectrum of the CFP is it was observed that the major polar functional groups
an
present are hydroxyl group and the amide carbonyl group. The OH stretching frequency and the amide carbonyl group stretching shifts from 3306cm-1 to 3285cm-1 and 1634cm-1 to 1635cm-1 respectively, when CFP is complexed with Fe2+. The OH and carbonyl stretching frequency of
M
the film formed on the metal coupons shifts from 3306cm-1 to 3182cm-1 and 1634cm-1 to 1622cm-1 respectively. The presence and shift of the stretching frequencies of the functional
te
Conclusion
d
groups confirms the formation of active compound- Fe2+ complex on the metal surface [10].
Ac ce p
The corrosion inhibition efficiency of CFP on mild steel immersed in 2N HCl increases with increasing incubation time. The dried CFP coat gives IE in excess of 90% even after 7 days of incubation in acid. The contact angle and EDS measurements verify the formation of a protective organic film over the mild steel surface when incubated in the inhibitor solution. The surface micrographs showed a corrosion-free morphology with continuous coverage of the protective film. The FTIR studies on the film showed peak maximums in the regions of hydroxyl (3182cm1
) and carbonyl (1622cm-1) functional groups. Formation of the active compound-Fe2+ complex
was confirmed from the peak shifts. Capsicum annuum (chili pepper) fruit can thus be concluded as a promising candidate for the development of eco-friendly corrosion inhibitors. References 1. Rani, B. E., and Bharathi Bai J. Basu. "Green inhibitors for corrosion protection of metals and alloys: An overview." International Journal of Corrosion 2012 (2011).
Page 5 of 6
2. Selvi, J. Arockia, Susai Rajendran, V. Ganga Sri, A. John Amalraj, and B. Narayanasamy. "Corrosion inhibition by beet root extract." Portugaliae Electrochimica Acta 27, no. 1 (2009): 1-11. 3. Souza, Fernando S. de, Reinaldo S. Gonçalves, and Almir Spinelli. "Assessment of adsorption
onto
mild
steel
surface
as
an
eco-friendly
corrosion
ip t
caffeine
inhibitor." Journal of the Brazilian Chemical Society 25, no. 1 (2014): 81-90.
cr
4. Africa, Southern. "Adsorption and inhibitive properties of ethanol extracts of Musa sapientum peels as a green corrosion inhibitor for mild steel in H2SO4." African Journal
us
of Pure and Applied Chemistry 2, no. 6 (2008): 046-054.
5. Fouda, A. S., Safaa H. Etaiw, and W. Elnggar. "Punica plant extract as green corrosion
an
inhibitor for C-steel in hydrochloric acid solutions." Int. J. Electrochem. Sci 9 (2014): 4866-4883.
M
6. Saratha, R., and V. G. Vasudha. "Emblica Officinalis (Indian Gooseberry) leaves extract as corrosion inhibitor for mild steel in 1N HCL medium."Journal of chemistry 7, no. 3
d
(2010): 677-684.
te
7. Wesolowska, Aneta, Dorota Jadczak, and Monika Grzeszczuk. "Chemical composition of the pepper fruit extracts of hot cultivars Capsicum annuum L."Acta Sci Pol Hortorum
Ac ce p
Cultus 10, no. 1 (2011): 171-184.
8. Marín, Alicia, Federico Ferreres, Francisco A. Tomás-Barberán, and María I. Gil. "Characterization and quantitation of antioxidant constituents of sweet pepper (Capsicum annuum L.)." Journal of Agricultural and Food Chemistry52, no. 12 (2004): 3861-3869. 9. Kalaivani, R., B. Narayanaswamy, J. Arockia Selvi, A. John Amalraj, J. Jeyasundari, and S. Rajendran. "Corrosion Inhibition by Prussian Blue."Portugaliae Electrochimica Acta 27, no. 2 (2009): 177-187. 10. Rajendran, Susai, B. V. Apparao, N. Palaniswamy, V. Periasamy, and G. Karthikeyan. "Corrosion inhibition by strainless complexes." Corrosion science 43, no. 7 (2001): 13451354.
Page 6 of 6
S2213-0209(16)30172-0 http://dx.doi.org/doi:10.1016/j.pisc.2016.06.033 PISC 318
To appear in: Received date: Revised date: Accepted date:
20-2-2016 12-6-2016 13-6-2016
Please cite this article as: Reddy, C.M., Sanketi, B.D., Narendra Kumar, S.,Corrosion inhibition of mild steel by Capsicum annuum fruit paste, Perspectives in Science (2016), http://dx.doi.org/10.1016/j.pisc.2016.06.033 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
Corrosion inhibition of mild steel by Capsicum annuum fruit paste Chandan M Reddy1, Bhargav D Sanketi1, Narendra Kumar S1 1
Department of Biotechnology, RV College of Engineering, RV Vidyanikethan Post, Mysore
+918904885909, [email protected] Abstract
ip t
Road, Bangalore-59
cr
The anti-corrosive property of Capsicum annuum fruit paste (CFP) on mild steel was investigated. Weight loss and SEM analysis showed that the aqueous and ethanolic solutions of
us
CFP exhibits excellent corrosion inhibition in 2M HCl. Contact angle, surface atomic composition and FTIR studies verified the presence of an organic film on the mild steel surface.
an
The FTIR spectra also indicated the formation of active compound- Fe complex. CFP thus shows potential as an inexpensive environment friendly corrosion inhibitor for mild steel.
M
Key words: Capsicum annuum fruit paste, Mild steel, Capsaicinoids, Anti-corrosive coating.
d
Introduction
Protection of steel from acid corrosion has become increasingly important in various industries.
te
The toxicity of most status quo corrosion inhibitors has increased the need for environment
Ac ce p
friendly ones [1]. Plant based polar organic compounds containing hetero-atoms and ring structures have been widely explored [2-6] and have proven to be effective. Capsicum annuum (chili pepper) fruit has a high concentration of alkaloids called capsaicinoids [7] and other polar molecules like ascorbic acid [8] hence making it a strong candidate in anticorrosion studies.
In this study, we explored the corrosion inhibitory properties of CFP as a solution and as dried coat in acid. Weight loss method and SEM were used to study the inhibition efficiency. Contact angle, EDS and FTIR studies were done to analyze the protective film. Materials and Methods Preparation of the corrosion inhibitor solution
Page 1 of 6
200g of fresh green chili fruit was washed and ground using a mixer grinder till a paste of even consistency was obtained. The paste was squeezed and filtered through a double layered muslin cloth to obtain the liquid part. This liquid extract was used as the inhibitor solution.
ip t
Preparation of the metal samples Mild steel coupons (0.035% S, 0.05% P, 0.60 Mn, 0.15% C and the rest iron) of dimensions
cr
20mm x 40mm x 3mm were polished with Ajax emery paper grade 120 and washed with distilled water. Samples for the analysis were prepared by immersing these coupons in solutions
us
of 30ml 2N HCl, 10ml inhibitor solution with 10ml of distilled water or 10 ml of 95% ethanol for the weight loss, SEM and EDS studies and only distilled water for FTIR and contact angle
an
studies. The coupons were subsequently removed from the solution washed with distilled water and dried.
M
Weight-loss method
The polished coupons were initially weighed using a Shimadzu electronic balance-BL220H and
d
immersed in solutions as described above. The reference coupons were immersed in the acid without the inhibitor solution. The treated and dried coupons were then weighed after the
efficiency
(IE)
were
Ac ce p
Inhibition
te
stipulated time.
calculated
using
the
following
equations,
W1 – Weight loss in the absence of the inhibitor solution (reference) (mg) W2 – Weight loss in the presence of the inhibitor solution (test) (mg)
For the anti-corrosive coating tests the metal pieces were immersed in the inhibitor solution on a plate and placed in a hot air oven for 24hr till all the liquid was evaporated leaving behind a coat on the metal coupons. The coupons were then weighed and immersed in a solution containing 30ml of 2N HCl. Polished coupons were immersed in the acid as reference. The weight loss was determined for 1, 4 and 7 days of incubation. Contact angle measurements
Page 2 of 6
Sessile drop contact angle measurements were used to confirm the formation of the organic film [3]. The contact angle was measured by placing 100µl of distilled water on metal pieces immersed in acid with and without the inhibition solutions for 24 hours.
ip t
Analysis of the protective film The surface morphology and atomic compositions (from EDS) of the samples were analyzed
cr
using a Zeiss Ultra 55 FE-SEM machine. FTIR study was done to analyze the nature of the protective film formed on the mild steel surface [9]. FTIR spectrum of the inhibition solution,
us
inhibition solution mixed with ferrous sulphate and the film formed on the metal surface was obtained in their original state using ATR-FTIR by the Perkin Elmer Frontier FTIR Spectrum 10
an
instrument. Results and discussion
Time
1A
1E
2A
85.24
84.15
72.88
2E
d
(Days)
89.08
3A
3E
4A
4E
78.3
88.97
94.17
94.7
te
IE
M
Weight-loss experiment results
Table 1: Time of immersion versus IE. A- CFP added with distilled water, E- with
Ac ce p
95% ethanol.
Time
1
4
7
96.48
94.79
91.96
(Days)
IE
Table 2: Time of immersion versus IE for the coated sample
The inhibition efficiency of both the aqueous and ethanolic solutions of the inhibitor solution increased with the immersion period and reached a maximum of 94% on the 4th day. The increase suggests that the protective film on the metal surface either increases with the incubation time or remains largely unaltered. The coated samples showed considerably high IE in acid even after 7 days of incubation suggesting the formation of a very stable protective film.
Page 3 of 6
cr
ip t
Contact angle measurements
Figure 1: Sessile drop contact angle of (c) polished coupon, (b) coupon immersed in 2N HCl and
us
(a) aqueous inhibitor solution for 24 hours.
The figure shows the contact angle of the water drop with the steel surface under various
an
conditions. The contact angle of the reference coupon is seen at 51º which decreases to 31º when incubated in the acid. The contact angle of the coupon immersed along with the inhibitor solution increases to 59º. This decreased wettability and increased hydrophobic nature suggests the
M
formation of an organic film over the steel surface by the active compounds in CFP [3].
Ac ce p
te
d
Surface analysis
Figure 2: SEM images of the (d1, d2) reference coupon, coupon immersed in (a1, a2) 2N HCl and inhibitor solution with (b1, b2) distilled water with (c1, c2) ethanol at 500x and 2000x magnifications.
The morphology of the steel surfaces before and after incubation in 2N HCl with and without inhibitor solutions is shown in the figure. The metal immersed in the acid without the inhibitor solution shows intense corrosion with a highly rough surface. Corrosion pits formation is clearly observed. The metals immersed in the solution containing the inhibitor solution showed no surface roughness suggesting minimal corrosion. A smooth surface is observed, very similar to
Page 4 of 6
the reference coupon, with the marks observed being left only from the polishing. Complete coverage of the metal surface by the protective film without any cracks or gaps can be observed in the images.
ip t
The surface atomic composition of carbon and oxygen of the metal coupon immersed in the aqueous (22.45% C, 18.48% O, and rest iron) and ethanolic (19.85% C, 14.72% O, and rest iron) solution of the inhibitor solution was much higher than that of the reference (12.73% C, 9.25%
cr
O, and rest iron). This result confirms the presence of an organic film over the metal surface.
us
Analysis of the FTIR spectra
In the FTIR spectrum of the CFP is it was observed that the major polar functional groups
an
present are hydroxyl group and the amide carbonyl group. The OH stretching frequency and the amide carbonyl group stretching shifts from 3306cm-1 to 3285cm-1 and 1634cm-1 to 1635cm-1 respectively, when CFP is complexed with Fe2+. The OH and carbonyl stretching frequency of
M
the film formed on the metal coupons shifts from 3306cm-1 to 3182cm-1 and 1634cm-1 to 1622cm-1 respectively. The presence and shift of the stretching frequencies of the functional
te
Conclusion
d
groups confirms the formation of active compound- Fe2+ complex on the metal surface [10].
Ac ce p
The corrosion inhibition efficiency of CFP on mild steel immersed in 2N HCl increases with increasing incubation time. The dried CFP coat gives IE in excess of 90% even after 7 days of incubation in acid. The contact angle and EDS measurements verify the formation of a protective organic film over the mild steel surface when incubated in the inhibitor solution. The surface micrographs showed a corrosion-free morphology with continuous coverage of the protective film. The FTIR studies on the film showed peak maximums in the regions of hydroxyl (3182cm1
) and carbonyl (1622cm-1) functional groups. Formation of the active compound-Fe2+ complex
was confirmed from the peak shifts. Capsicum annuum (chili pepper) fruit can thus be concluded as a promising candidate for the development of eco-friendly corrosion inhibitors. References 1. Rani, B. E., and Bharathi Bai J. Basu. "Green inhibitors for corrosion protection of metals and alloys: An overview." International Journal of Corrosion 2012 (2011).
Page 5 of 6
2. Selvi, J. Arockia, Susai Rajendran, V. Ganga Sri, A. John Amalraj, and B. Narayanasamy. "Corrosion inhibition by beet root extract." Portugaliae Electrochimica Acta 27, no. 1 (2009): 1-11. 3. Souza, Fernando S. de, Reinaldo S. Gonçalves, and Almir Spinelli. "Assessment of adsorption
onto
mild
steel
surface
as
an
eco-friendly
corrosion
ip t
caffeine
inhibitor." Journal of the Brazilian Chemical Society 25, no. 1 (2014): 81-90.
cr
4. Africa, Southern. "Adsorption and inhibitive properties of ethanol extracts of Musa sapientum peels as a green corrosion inhibitor for mild steel in H2SO4." African Journal
us
of Pure and Applied Chemistry 2, no. 6 (2008): 046-054.
5. Fouda, A. S., Safaa H. Etaiw, and W. Elnggar. "Punica plant extract as green corrosion
an
inhibitor for C-steel in hydrochloric acid solutions." Int. J. Electrochem. Sci 9 (2014): 4866-4883.
M
6. Saratha, R., and V. G. Vasudha. "Emblica Officinalis (Indian Gooseberry) leaves extract as corrosion inhibitor for mild steel in 1N HCL medium."Journal of chemistry 7, no. 3
d
(2010): 677-684.
te
7. Wesolowska, Aneta, Dorota Jadczak, and Monika Grzeszczuk. "Chemical composition of the pepper fruit extracts of hot cultivars Capsicum annuum L."Acta Sci Pol Hortorum
Ac ce p
Cultus 10, no. 1 (2011): 171-184.
8. Marín, Alicia, Federico Ferreres, Francisco A. Tomás-Barberán, and María I. Gil. "Characterization and quantitation of antioxidant constituents of sweet pepper (Capsicum annuum L.)." Journal of Agricultural and Food Chemistry52, no. 12 (2004): 3861-3869. 9. Kalaivani, R., B. Narayanaswamy, J. Arockia Selvi, A. John Amalraj, J. Jeyasundari, and S. Rajendran. "Corrosion Inhibition by Prussian Blue."Portugaliae Electrochimica Acta 27, no. 2 (2009): 177-187. 10. Rajendran, Susai, B. V. Apparao, N. Palaniswamy, V. Periasamy, and G. Karthikeyan. "Corrosion inhibition by strainless complexes." Corrosion science 43, no. 7 (2001): 13451354.
Page 6 of 6