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ICAMME 2017 IOP Publishing
IOP Conf. Series: Materials Science and Engineering 290 (2018) 012087 doi:10.1088/1757-899X/290/1/012087
1234567890‘’“”
Ginger extract as green corrosion inhibitor of mild steel in
hydrochloric acid solution
A Fidrusli, Suryanto and M Mahmood
Department of Manufacturing and Materials Engineering, International Islamic
University Malaysia (IIUM), Jalan Gombak, 53100 Kuala Lumpur, Malaysia
Email: surya@iium.edu.my
Abstract. Ginger extract as corrosion inhibitor from natural resources was studied to prevent
corrosion of mild steel in acid media. Ginger rhizome was extracted to produce green corrosion
inhibitor (G-1) while ginger powder bought at supermarket was also extract to form green
corrosion inhibitor (G-2). Effectiveness of inhibitor in preventing corrosion process of mild
steel was studied in 1.0 M of hydrochloric acid. The experiment of weight loss method and
polarization technique were conducted to measure corrosion rate and inhibition efficiency of
mild steel in solution containing 1.0 M of hydrochloric acid with various concentration of
inhibitor at room temperature. The results showed that, the rate of corrosion dropped from 8.09
mmpy in solution containing no inhibitor to 0.72 mmpy in solution containing 150g/l inhibitor
while inhibition efficiency up to 91% was obtained. The polarization curve in polarization
experiments shows that the inhibition efficiency is 86% with high concentration of inhibitor.
The adsorption of ginger extract on the surface of mild steel was observed by using optical
microscope and the characterization analysis was done by using pH measurement method.
When high concentration of green inhibitor in the acid solution is used, the pH at the surface of
steel is increasing.
1. Introduction
Corrosion is a deterioration of a metal alloy under the influence of its environment [1]. Corrosion is a
destructive result of chemical reaction between a metal and its environment. The environment such as
humid air, steam, seawater, alkaline and acids are positive towards the corrosion process. Corrosion
happens because metal wants to achieve a stable state since metals are unstable after extracted from
their ores.
Green corrosion inhibitor had been studying to relate to this “greenish” theme and reduce the
corrosion process as well. The plants such as rosemary leaves, garlic, tamarind, tea leaves,
pomegranate juice and peels, aloe leaves, mango or orange peels, and banana peels are very useful for
green inhibitor application.
Organic compound that contains oxygen, sulphide and nitrogen which is basically the active center
for the absorption process on the metal surface to reduce the corrosion attack on several steel has been
studied recently. Corrosion prevention is very important because many industrial companies have
suffered from this activity process. Environment with pollutant will cause damage to the systems and
reduce machines lifetime especially equipment that uses acid solution.
In this paper, the effect of ginger extract as a green corrosion inhibitor of mild steel in 1.0M of
hydrochloric acid has been studied.
Content from this work may be used under the terms of the Creative Commons Attribution 3.0 licence. Any further distribution
of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.
Published under licence by IOP Publishing Ltd 1
ICAMME 2017 IOP Publishing
IOP Conf. Series: Materials Science and Engineering 290 (2018) 012087 doi:10.1088/1757-899X/290/1/012087
1234567890‘’“”
2. Experimental procedures
2.1 Preparation of Ginger extract
The ginger was washed, cut, dried and ground into a fine powder. The powder is then used to soak in
distilled water with the ratio of 1g of powder with 8 ml of distilled water for 20 hours at room
temperature. The extract was filtered and evaporated in the oven with the temperature 40oC for about
24 hours to produce ginger extract (G-1). Another ginger extract (G-2) was prepared from ginger
powder bought at supermarket. It was macerated in the distilled water and filtered. The concentration
of 50g/l, 100g/l, and 150g/l of aqueous extract ginger were prepared.
2.2 Preparation of specimens
Mild steel was cut into 6.2 x 2.1 x 0.1 cm3. The steels were ground with emery paper of 180 to 1200
grits. Then, they were washed using distilled water and degreased with acetone.
2.3 Weight loss experiment
The weight of sample was measured using electronic balance before and after soaking in 100 ml of 1
M HCl. The samples were immersed in HCL solution for 22 hours at room temperature with the
absence and presence of different concentrations of ginger extract (G-1) and also (G-2). To get the
best result, the experiment was conducted twice. The weight loss of the test specimens were calculated
by using equation (1).
𝑊𝑒𝑖𝑔ℎ𝑡 𝑙𝑜𝑠𝑠 (∆w) = 𝑊𝑖 − 𝑊𝑓 𝐸𝑞 (1)
Where Wi is the initial weight and Wf is the final weight of mild steel specimens. Corrosion rate and
inhibitor efficiency can be calculated by using the equation shows in equation (2) and equation (3),
respectively.
86.7𝑥 ∆w
𝑅= 𝐸𝑞 (2)
𝐴𝑥𝑇𝑥ρ
𝑅0 − 𝑅𝑖
𝐼𝐸 = 𝑋 100 𝐸𝑞 (3)
𝑅0
Where 𝑅 = Corrosion rate (mmpy), ∆𝑤 = Weight loss (mg), A = Area of metal exposed to corrosive
media (cm2), 𝜌 = Density of mild steel (𝑔/𝑐𝑚3) = 7.86𝑔/𝑐𝑚3, T = Time of immersion (h), Ro =
Corrosion rate without inhibitor and Ri = Corrosion rate with inhibitor.
2.4 Polarization test
Polarization test uses three types of electrodes which are working electrode, counter electrode and the
reference electrode with the mild steel, graphite, and the silver/silver chloride electrode respectively.
These three electrodes were connected to the Autolab potentiostat. The scan rate of 0.5mV/s was set
up on the setting option. The curve was set to start at -800mV until -200mV at room temperature. The
inhibition efficiency can be calculated and known based on the formula:
𝑜
𝐼𝑐𝑜𝑟𝑟 − 𝐼𝑐𝑜𝑟𝑟
𝐼𝐸 = 𝑜 𝑋 100 𝐸𝑞 (4)
𝐼𝑐𝑜𝑟𝑟
2.5 Surface analysis
The surface of the mild steel was analysed by using Nikon Model Epiphot 200 optical microscope.
The analysis was conducted after the experiment of weight loss was done. The samples after
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ICAMME 2017 IOP Publishing
IOP Conf. Series: Materials Science and Engineering 290 (2018) 012087 doi:10.1088/1757-899X/290/1/012087
1234567890‘’“”
immersing in 1M HCl with different concentration of ginger extract were collected to be observed
using the optical microscope.
3. Results and Discussion
3.1 Weight loss measurement
Experiment was conducted to study the corrosion rates and the percentage of inhibition efficiency
from four samples of mild steels in the absent and presence of different concentration of ginger extract
inhibitor. The concentration of 50g/l, 100g/l and 150g/l of inhibitors at room temperature were used in
this experiment as shown in table 1.
Table 1. Effect of ginger extract (G-1) concentration on corrosion rate of mild steel.
Inhibitor
Corrosion rate Inhibition
Concentration
(mmpy) Efficiency (%)
(g/l)
0 8.09 -
50 1.04 87
100 0.96 88
150 0.72 91
The weight loss experiment also has been conducted on ginger extract that produced from the
source of ginger powder product (G-2). The result is shown on the table 2.
Table 2. Effect of ginger extract (G2) concentration on the corrosion rate of mild steel.
Inhibitor
Corrosion rate Inhibition
Concentration
(mmpy) Efficiency (%)
(g/l)
0 6.91 -
50 0.94 86
100 0.85 88
150 0.66 90
10.0
8.0
Corrosion Rate
Rate (G-1)
6.0 Rate (G-2)
(mmpy)
4.0
2.0
0.0
0 50 100 150
Concentration (g/l)
Figure 1. Corrosion Rate of mild steel in various inhibitor concentrations.
From the graph shown in this experiment, the line is increasing where the higher concentration of
inhibitor used, the higher the inhibition efficiency. The inhibitor was absorbed in the steel and forming
the layer on the surface of the steel. The layer which is like the coating, prevents the contact of the
acid to the surface of the steel. The corrosion process will not happen when there is thick protection
layer on the surface.
3
ICAMME 2017 IOP Publishing
IOP Conf. Series: Materials Science and Engineering 290 (2018) 012087 doi:10.1088/1757-899X/290/1/012087
1234567890‘’“”
Inhibitor Efficiency
0.8
0.6
(%)
0.4
0.2 E (G-1)
0
E (G-2)
50 100 150
Concentration (g/l)
Figure 2. Inhibitor Efficiency in various inhibitor concentrations
The graph in figure 2 clearly shows the trend of the inhibition efficiency. The efficiency of
inhibition of is 91% at concentration of inhibitor of 150g/l. Inhibition efficiency of 50g/l and 100g/l
inhibitor is 87% and 88% respectively which showed slightly increasing in inhibition efficiency.
From the results, when comparing between G-1 and G-2, it shows that G-1 produced higher
percentage in inhibition efficiency of the inhibitor that can prevent corrosion process of mild steel in
1M HCl better than G-2. But the trend from both aqueous ginger extract show same pattern which is
the inhibition efficiency is increasing when the higher concentration of the extract was used.
3.2 Polarization test
The polarization curve is presented in figure 3. The data of the test used which is 1M HCl without
inhibitor and 1M HCl with different concentration are summarized in the table 3. The corrosion
potential (Ecorr), corrosion current density (Icorr) and corrosion rate were obtained from the curve.
The inhibition efficiency was calculated using equation 4.
Table 3: Data from polarization experiment for mild steel in Ginger extract
Concentration Ecorr Icorr Rate I.E
(g/l) (V) (mA/cm2) (mmpy) (%)
- -0.411 0.394 1.412 -
50 -0.424 0.135 0.495 65
100 -0.411 0.109 0.401 72
150 -0.409 0.054 0.195 86
0.6 Blank HCl 1M
0.35 50g/l AGE
100g/l AGE
Ecorr (V)
0.1
150g/l AGE
-0.15
-0.4
-0.65
-0.9
-6 -5 -4 -3 -2 -1 0
log I (A/cm2)
Figure 3: Polarization curve of mild steel in 1M HCl with different inhibitor concentration
From the graph in below, the colour lines are called observed polarization curve. In this curve,
there is partial current for forward reaction, known as the anodic reaction and the partial current for
reverse reaction known as the cathodic reaction. The both partial currents are precisely equal and
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ICAMME 2017 IOP Publishing
IOP Conf. Series: Materials Science and Engineering 290 (2018) 012087 doi:10.1088/1757-899X/290/1/012087
1234567890‘’“”
opposite. Since there is no net current flow, the potential shift from their equilibrium value with the
help from the external current is called polarization. In this experiment, the value started from -0.8V
and the curve shifted at the point about -0.4V until the reaction is fully utilized. Anodic reaction
occurred at the curve after the observed polarization curve was shifting to the positive values. The
Tafel slopes can be sketch by putting the tangent line to the both anodic and cathodic polarization
curves. The data can be shown that the values for Tafel slopes decrease when the higher concentration
of aqueous ginger extract was used in 1M HCl at room temperature. As the corrosion potential is
increase towards positive, corrosion current density, Icorr decrease with higher concentration of
aqueous ginger extract in 100ml of 1M HCL solution.
3.3 Surface analysis
The microstructure of sample was observed to identify the reaction of the inhibitor with mild steel in
1M of HCl. The microstructure of the mild steel experiences the corrosion process in the solution
containing only 1 M HCl is presented in figure 4(a). The corrosion formed darker appearance than the
original mild steel. When the 50g/l concentration of the inhibitor was mixed in the acid solution, the
microstructure of the layer of the mild steel changed as shown in figure 4(b). It can be observed when
comparing the mild steel microstructure in HCl solution with the microstructure of mild steel mixed
with the 50g/l concentration of inhibitor where the corrosion process retard in certain places because
the inhibitor prevents the corrosion. In figure 4(c) and (d), the brighter in color indicates the inhibitor
on the surface of the mild steel where there is no corrosion process happens. Figure 4(c) and (d) show
the effect of inhibitor concentration to the microstructure of the mild steel in 1M HCl. It can be said
that the inhibitor was absorbed into the mild steel to produce a protective layer to prevent the
corrosion process on the surface.
(a) (b) (c) (d)
Figure 4. (a) Mild steel in 1M HCl, (b) Mild steel in 1M HCl +50 g/l Inhibitor, (c) Mild steel in 1M
HCl +100 g/l Inhibitor, (d) Mild steel in 1M HCl +150 g/l Inhibitor.
4. Conclusion
Ginger extract can be used as corrosion inhibitor for mild steel in hydrochloric acid solution. The
higher concentration of inhibitor is the lower corrosion rate and the higher corrosion inhibition
efficiency. Weight loss experiment shows that maximum inhibition efficiency of the high
concentration of inhibitor is 91%. The surface analysis has carried out to observe the microstructure of
mild steel in the absence and presence of inhibitor. Polarization experiment also shows similar results
to that of weight loss experiment. It showed that the ginger extract from rhizome (G-1) and the ginger
extract from powder (G-2) have same effectiveness in preventing corrosion of mild steel in
hydrochloric acid solution. The efficiency both of them is about 90%.
Acknowledgements
The authors would like to acknowledge the financial support given from FRGS-14-117-0358 grant of
International Islamic University Malaysia.
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ICAMME 2017 IOP Publishing
IOP Conf. Series: Materials Science and Engineering 290 (2018) 012087 doi:10.1088/1757-899X/290/1/012087
1234567890‘’“”
References
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Officinal Roscoe Extract Using as Green Corrosion inhibitor for Mild Steel.
[2] Gentil V 2003 Corrosão. 4ed. Rio de janeiro: Editora LTC.
[3] Hong J, Kai Z, and Li Y 2008 Corrosion Science 50 865-871
[4] Ramanathan L 2014 Corrosão e seu controle
[5] Yaro A, Khadom A, and Wael R 2013 Alexandria Engineering Journal 52 129-135
