Evaluation of Inhibition Efficiency of Oak Galls Extract as a Green Corrosion Inhibitor of Archaeological Iron Artifacts in the Atmospheric Environment

Salem, Yussri

doi:10.1590/1980-5373-MR-2020-0354

Yussri Salem ^**e-mail: Yousry.ali@arch.svu.edu.eg

South Valley University, Conservation Department, Faculty of Archaeology, Qena 83523, Egypt

https://orcid.org/0000-0001-5098-8772

*e-mail: Yousry.ali@arch.svu.edu.eg

Thumbnail

Figure 1
The elemental analysis by ED-XRF of the experimental studies coupons

Thumbnail

Figure 2
The preparation stages of oak galls extract powder, (a and b) oak galls with natural gummy core, (c) the soaked oak galls in absolute methanol on shaker, (d) during the extraction of the powder from methanol solution by rotary evaporator, (e) OGE powder, (f) the methanolic extract solution.

Thumbnail

Figure 3
SEM and PM show the morphology of OGE on the surface of high carbon steel coupons; the investigation reveals homogeneous thickness and high coverage rate.

Thumbnail

Figure 4
The appearance of the studied coupons, (a) an artificial corroded coupon and (b) a clean coupon, the area above the arrow in the two coupons is treated with OGE while the down is untreated.

Thumbnail

Figure 5
Treated and untreated coupons with OGE in the presence (left) and absence (right) of corrosion patina after the humidity chamber test. All corroded coupons were affected by moisture, and the corrosion patina became wet and more powdery while the treated clean coupons revealed high inhibition efficiency compared with untreated coupons.

Thumbnail

Figure 6
PM of the coupons before and after humidity chamber test: (a) and (b) before the test, (c) and (d) 6% con., (e) 4% con., (f) 2% con. and (g) and (h) untreated. The inhibitor on the surface appeared under the microscope in a light color while the original surface showed a dark color. The reddish-brown color indicates the occurrence of the corrosion process.

Thumbnail

Figure 5
Treated and untreated coupons with OGE in the presence (left) and absence (right) of corrosion patina after the humidity chamber test. All corroded coupons were affected by moisture, and the corrosion patina became wet and more powdery while the treated clean coupons revealed high inhibition efficiency compared with untreated coupons.

Thumbnail

Figure 7
Polarization curves of the coupons in the absence and presence of varying concentrations of OGE.

Thumbnail

Figure 8
Nyquist plots for the coupons without and with various concentrations of OGE: Untreated, 2%, 4% and 6% concentration.

Thumbnail

Figure 9
bar diagram shows inhibition efficiency comparison of OGE concentrations at the three tests.

Thumbnail

Figure 10
Skeletal representation of adsorption of the main active components of OGE on the HCS surface: (a) Gallic acid C₇H₆O₅, (b) ellagic acid C₁₄H₆O₈ and (c) tannic acid C₇₆H₅₂O₄₆.

Thumbnail

Table 1
Values of the color change of treated coupons with OGE.

Thumbnail

Table 2
Shows the results of humidity chamber test of the coupons with and without OGE.

Thumbnail

Table 3
Electrochemical polarization parameters obtained from Tafel plots in the absence and presence of OGE with the three studied concentrations.

Thumbnail

Table 4
Shows electrochemical parameters calculated from EIS measurements.

(1)

(2)

(3)

(4)

(7)

(8)

Con.	Un-corroded coupons			Color change of un-corroded				Corroded coupons			Color change of Corroded coupons
Con.	L	a	b	ΔL	Δa	Δb	ΔE	L	a	b	ΔL	Δa	Δb	ΔE
Untra.	35	-1	11	---	---	---	---	20	14	13	---	---	---	---
2%	33	17	20	2	18	9	20.2	28	8	4	8	-6	5	11.1
4%	30	12	15	5	13	4	14.5	28	7	4	8	-7	5	11.7
6%	33	17	20	2	18	9	20.2	26	5	5	6	-9	8	13.5

Conc.	corroded coupons				clean coupons
Conc.	Weight loss (g)	IE %	Rcorr mg cm^-2 h^-1	θ	Weight loss (g)	IE %	Rcorr mg cm^-2 h^-1	θ
Untre.	2.65	---	.0089	---	1.21	---	0.0040	---
2%	1.02	61.5	.0034	0.616	0.12	90	0.0004	0.90
4%	1.34	49.4	.0045	0.49.4	0.06	95	0.0002	0.95
6%	0.96	63.7	.0032	0.63	0.05	95	0.0002	0.95

Con.	I_corr. µA/cm^-2	-E_corr/V	β_a/V dec^-1	β_c/V dec^-1	C Rate mm/y	E_Tafel/%
Untrea.	.3901	-0.1184	.096	.097	0.3302	---
2%	.0494	-0.1838	0.143	0.129	0.0373	87.6%
4%	.0437	-0.190	.133	.112	.0405	88.7%
6%	.0391	-0.222	.094	.074	.0444	90%

Con.	R_s (X cm²)	R_p=R_ct (Ω cm²)	Chi-square	IE_%
Untre.	31.255	283.6	3.5E+00	---
2%	40.14	768.2	6.7E+00	63
4%	15.30	676.9	2.4E+00	58
6%	29.73	973.6	7.4E+00	70

[1] *e-mail: Yousry.ali@arch.svu.edu.eg

Brasil

Brasil

Evaluation of Inhibition Efficiency of Oak Galls Extract as a Green Corrosion Inhibitor of Archaeological Iron Artifacts in the Atmospheric Environment

Abstract