Influence of Tannin Concentration from Banana Peel as Iron

Inhibition in Hydrochloric Acid Solution

R. Tambun

, Y. F. Pakpahan

, E. Christamore

and B. Haryanto

Department of Chemical Engineering, Universitas Sumatera Utara, Padang Bulan, Medan 20155, Indonesia

Keywords: Banana Peel, Tannin, Corrosion Rate, Inhibition Efficiency.

Abstract: Banana peel contains tannin that could be used as corrosion protection of iron. This study aims to determine

the effect of tannin from banana peel on corrosion inhibition of iron plate in 3% hydrochloric acid solution.

The banana peel used in this study is unripe Awak Banana peel. The variables observed are soaking method,

inhibitor concentration and immersion time, and the parameters studied are corrosion rate of iron and

corrosion inhibition efficiency. In this experiment, the lowest corrosion rate and highest inhibition efficiency

are obtained on immersion of iron for 12 days in hydrochloric acid solution and addition of 9 g of tannin

inhibitor. In this condition the corrosion rate is 7.2578 mpy and the corrosion inhibition efficiency is 97.79%.

The results showed that tannin from Awak banana peel could be used as corrosion inhibition of iron in

hydrochloric acid solution.

1 INTRODUCTION

Corrosion is the most common problem found on a

daily life, both in the household and in industry.

Corrosion is the degradation of the destruction of the

quality of metallic properties through a natural

electrochemical reaction and it happens because of

chemical phenomena with the environment.

Corrosion can’t be stopped but can be controlled, so

various attempts are done to inhibit corrosion

(Darmokoesoemo et al., 2018). Organic inhibitors or

commonly referred to as green inhibitors are a safe

type of inhibitor because they have an eco-friendly or

biodegradable, economical, and widely available in

nature. The plants that can be used as organic

inhibitors are plants that have antioxidant properties,

such as containing flavonoid compounds, tannins,

ascorbic acid, phenolic, and others (Chancay and

Poosaran, 2009).

In this study, the corrosion inhibitor used is unripe

Awak banana peel (Musa paradisiacal var. Awak).

Unripe banana peels have a tannin content about

6.48%, almost mature banana peels about 4.97 % and

ripe banana peel about 4.69% (Tartrakoon et al.,

1999). Tannins protect the iron from corrosion in

hydrochloric acid (HCl) solution due to the

adsorption of tannins onto the iron surface (Agi et al.,

2018; Madhu et al., 2018). Tannin inhibits the

oxidation of Fe

2 +

ions to iron oxides and avoid

corrosion inhibition (Al-Amiery et al., 2014). Banana

peel is very potential to be used as a corrosion

inhibitor because it has high antioxidant (Gopal et al.,

2015). Wang, et al. vary the addition of a corrosion

inhibitor concentration and the results obtained that

the efficiency of the inhibitor is higher with

increasing inhibitor concentration (Wang et al.,

2016). Al-Moubaraki, et al. vary the time of

immersion metal plates in the media and the results

obtained that the longer the immersion time, the

corrosion rate of metal will be higher (Al-moubaraki

et al., 2015). Based on the above study, this study is

aimed to develop banana peel tannin as iron corrosion

inhibitor in HCl medium. In this experiment, the

influence of tannin concentration from Awak banana

peel and duration of immersion of iron in HCl

solution will be investigated experimentally.

2 METHODS

2.1 Qualitative Analysis of Tannins on

Extracts

Materials used in this study are iron specimen (Fe)

with the size 1 cm x 2 cm x 0.2 cm, 3% HCl solution

of 50 ml as medium, Awak banana peel (Musa

Tambun, R., Pakpahan, Y., Christamore, E. and Haryanto, B.

Inﬂuence of Tannin Concentration from Banana Peel as Iron Inhibition in Hydrochloric Acid Solution.

DOI: 10.5220/0010087502970301

In Proceedings of the International Conference of Science, Technology, Engineering, Environmental and Ramiﬁcation Researches (ICOSTEERR 2018) - Research in Industry 4.0, pages

297-301

ISBN: 978-989-758-449-7

297

paradisiacal var. Awak) from Pringgan Market

Medan, distilled water, methanol, FeCl

, ethyl

acetate, and the equipment used in this research

include beaker glass, rotary vacuum evaporator,

Whatman no 41 filter paper, oven, blender, and

analytical balance. In this experiment, the smooth

iron surface is washed with detergent and distilled

water, then dried in an oven at 110 ° C for 2 hours so

that the iron does not contain water.

In this study, the unripe Awak banana peel is dried

in the air to remove the water content then the banana

peel is cut into small pieces about 1 cm, then dried in

the sun for 3 days. Banana peel is put in an oven at 80

C. Banana peel is blended to be powder and sieved

by using sieve tray of 50 mesh. The powder is

macerated with methanol at a ratio of 7:1 for 24 hours

then filtered by using filter paper of Whatman no

41. The filtrate is removed with a rotary vacuum

evaporator at a temperature of 65

C into a paste

form. The crude extract is analyzed qualitatively. The

crude extract of banana peel is dissolved with ethyl

acetate, stirred until dissolved, then settled to form

precipitate. The precipitate is filtered and then

washed again with ethyl acetate until the filtrate is

clear. The insoluble precipitate in ethyl acetate is

tannin. Iron is then immersed in a 3% HCl of 50 ml

without the presence of tannin and with additions of

1 gram, 3 gram, 5 gram, 7 gram, and 9 gram of tannin.

The immersion durations are 3 days, 6 days, 9 days,

and 12 days. Then the rate of corrosion reaction and

the corrosion inhibition efficiency are calculated.

The corrosion rate, CR (mils/year or mpy) is

determined by equation (1) (Ali and Hamedh, 2016):

CR=

DAt

(1)

where K is constant (3.45 x 10

), W is mass loss (g),

D is density (g/cm

), A is surface area (cm

), and t is

immersion time (hours).

The corrosion inhibition efficiency is determined by

equation (2) (Ali and Hamedh, 2016):

Inhibition Efficiency (%) =

-C

x 100 % (2)

where C

R௜

is corrosion rate with inhibitor (mils/year)

and C

R଴

is corrosion rate without inhibitor

(mils/year).

Corrosion rate determination is carried out by

following the steps:

1. After the corrosion process is carried out within

a certain time, the pH of the medium is

measured with a pH meter and set as the final

2. Corrosion products are removed from corrosion

media, and dried in an oven at 110

C for 2

hours, then weighed as final mass

2.2 Tannins Content Analysis with

UV-Vis Spectrophotometer

Determination of tannin levels in Awak banana peel

is carried out using UV-Vis Spectrophotometer, and

absorbance is observed in wave numbers 765 nm.

2.3 Immersion of Iron Plate in HCl

Solution without Inhibitors

Immersion of iron plate in HCl solution without

inhibitor is carried out in accordance with the

following steps:

1. The mass of the iron plate is weighed as the

initial mass

2. The iron plate is soaked in 50 mL of 3% HCl

solution

3. The pH of the medium is measured with a pH

meter and set as the initial pH

4. The iron plate that has been soaked is stored for

3 days, 6 days, 9 days, and 12 days, then the

corrosion rate and inhibition efficiency are

determined by equation 1 and equation 2.

2.4 Immersion of Iron Plate in HCl

Solution with Addition of Inhibitors

Immersion of iron plate in HCl solution with inhibitor

is carried out in accordance with the following steps:

1. The mass of the iron plate is weighed as the

initial mass

2. The iron plate is soaked in 50 mL of 3% HCl

solution

3. Awak banana peel tannins are added 1 g, 3 g, 5

g, 7 g, and 9 g, respectively

4. The pH of the medium is measured with a pH

meter and set as the initial pH

5. The iron plate that has been soaked is stored for

3 days, 6 days, 9 days, and 12 days, then the

corrosion rate and inhibition efficiency are

determined by equation 1 and equation 2.

ICOSTEERR 2018 - International Conference of Science, Technology, Engineering, Environmental and Ramiﬁcation Researches

298

3 RESULTS AND DISCUSSION

3.1 Fourier Transform-Infrared

(FTIR) Analysis of Awak Banana

Peel

In this study, FTIR is used to analyze chemical

compounds of Awak banana peel compound. Based

on the analysis, the banana peel compound could be

seen in Figure 1. This figure shows us the presence

of hydroxyl group (OH) in the area of 3398.5 cm

-1

This FTIR result analysis is similar to the results

obtained by Zhao, et al., 2017 (Zhao et al., 2018).

Hence, this FTIR result analysis indicates that Awak

banana peel contains tannins.

Figure 1: FTIR Analysis of Awak banana peel.

3.2 Tannins Content Analysis Awak

Banana Peel with UV-Vis

Spectrophotometer

Analysis using UV-Vis spectrophotometer is a

qualitative analysis to determine the levels of tannins

contained in the Awak banana peel. The

spectrophotometer is operated at a wave number of

765 nm for its absorbance. Tannins on banana peels

are identified by observing the maximum wave

number absorbed by the Awak banana peel extract.

The results of UV-Vis spectrophotometer analysis on

the Awak banana peel extract are seen in Figure 2.

Figure 2: Standard Curve of UV-Vis Spectrophotometry

Analysis.

3.3 Effect of Tannin Concentration of

Banana Peel on Corrosion Rate of

Iron

The effect of tannin concentration of banana peel on

corrosion rate of iron could be seen in Figure 3. The

presence of tannin is very influential to reduce the

corrosion rate of iron in HCl solution. This result is

consistent with the theory that the absorption at the

metal surface increases with increasing inhibitor

concentration (Umoren et al., 2015). The presence of

electrons in the oxygen atoms of the hydroxyl group

of inhibitors increase the interaction of the inhibitors

formed on the iron surface. The presence of a

hydroxyl group in the inhibitor molecule could

decrease the corrosion rate (Hassan and Zaafarany,

2013). The lowest corrosion rate is obtained on

immersion of iron for 12 days in HCl solution and

addition of 9 g of tannin inhibitor. In this condition,

the corrosion rate is 7.2578 mpy. Hence, the tannin

from Awak banana peel could be used as corrosion

inhibition of iron in HCl solution.

y = 0,005x + 0,242

R² = 0,996

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

0 50 100 150

Absorbance

Gallic acid concentration (ppm)

Tannin

Inﬂuence of Tannin Concentration from Banana Peel as Iron Inhibition in Hydrochloric Acid Solution

299

Figure 3: Effect of Tannin Concentration of Banana Peel on

Corrosion Rate of Iron.

3.4 Effect of Tannin Concentration of

Banana Peel on Inhibition

Efficiency of Iron

Figure 4 describes the effect of tannin concentration

of banana peel on inhibition efficiency of iron. This

figure shows us that the highest inhibition efficiency

is achieved in addition tannin of 9 g and the lowest in

addition tannin of 1 g. In this condition the corrosion

inhibition efficiency is 97.79%. The inhibition

efficiency of iron increases with the increase of tannin

content. This result in accordance with the theory that

the inhibition efficiency depends on the concentration

of tannin and the duration of contact between metal

with corrosive medium (Khadom et al., 2018 and

Rondang et al., 2015.

Figure 4: Effect of Tannin Concentration of Banana Peel

on Inhibition Efficiency of Iron.

4 CONCLUSION

The corrosion rate of iron plate decreases with the

addition of tannin inhibitor from Awak banana peel

in a corrosive media of 3% HCl solution. The

corrosion rate decrease with the increase of tannin

content and the inhibition efficiency of iron increases

with the increase of tannin content. The lowest

corrosion rate about 7.2578 mpy and the highest

inhibition efficiency about 97.79 % are achieved on

the addition of tannin inhibitor of 9 g and immersion

duration of 12 days.

ACKNOWLEDGEMENT

This study is supported by Universitas Sumatera

Utara under TALENTA Fundamental Research

Scheme 2018, No: 2590/UN5.1.R/PPM/2017, dated

March 16, 2018.

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