STUDY OF NATURAL PLANT-BASED CORROSION INHIBITORS

** STUDY OF NATURAL CORROSION-BASED CORROSION INHIBITORS **

** Effectiveness study of hydrochloric acid. The study was conducted on various concentrations of grapefruit peel extract and soaking time. Corrosion testing was performed by gravimetric method with measurement of carbon steel weight loss during exposure time and concentration of guava leaf and papaya leaf extract. The measurement results will show the concentration of guava leaf extract and papaya leaf against the corrosion rate of the metal. And The result of the measurement affects the temperature, then the value of the corrosion rate will be known. The corrosion rate at concentration of guava leaves and papaya leaf extract was 4 ml in 250 ml of 0.5 M HCl solution and 5 days exposure time. obtained on the condition of guava leaves extract and papaya leaf 4 mL and soaking time 5 days. The mechanism of formation of the protective passive membrane follows the Langmuir adsorption process. **

Corrosion is a process of destruction of metals or non-metals due to interaction with the environment. The occurrence of corrosion has a major impact on life, both economically and environmentally. From an economic point of view, it can lead to high maintenance costs, fuel and energy costs due to steam leakage and production losses in an industry due to stalled work at the time of repair of corrosion-resistant materials (Iqbal, 2008; Raharjo, 2010).
One way to control the corrosion rate is to use a corrosion inhibitor. The corrosion inhibitor is defined as a substance which, when added in small amounts into the corrosive environment, can decrease the corrosion of the environment against the metal. The study of extracts of various herbs and fruits is believed to act as a corrosion inhibitor because it contains long-chain organic molecules capable of precipitating the metal surface thus inhibiting the interaction of metals with their environment. Inhibitors of natural material extracts are a safer and more appropriate solution because they are easy to obtain, biodegradable, low cost, and environmentally friendly (Hermawan, 2007). Extracts of natural materials in particular compounds containing N, O, P, S, and atoms having free electron pairs. Elements containing these free electron pairs can later function as ligands that will form complex compounds with metals (Haryono et al., 2010).
In this study, the study was conducted to see the effect of papaya leaf extract and guava leaf extract, soaking time, and temperature to the corrosive rate of carbon steel in a solution of corrosive HCl 0.5 M. Guava leaves contained tannins ranging from 12 to 18% , so it can serve as a corrosion inhibitor (Irianty, 2013). While papaya leaf extract is an organic material used as a corrosion inhibitor because it contains N-acetyl-glucosamide compounds and amino acids that serve as a protective of corrosion reactions. The use of papaya leaf extract as corrosion inhibitor in sulfuric acid environment showed decreasing corrosion rate with addition of papaya leaf extract as corrosion inhibitor (Rendi Ramadhana, 2012).

The purpose of writing this article to know the process of corrosion on steel plate by using inhibitors of natural materials are guava leaves and papaya leaf as one way to prevent the occurrence of corrosion on steel plate.

---

![image]()

---

The raw materials used are guava leaf and papaya leaf, because the tannin and N-acetyl glucosamide compounds will function as various compounds that will react with carbon steel so as to protect the steel surface from further corrosion events. First extracts were taken on papaya and papaya leaf samples and the extract was used for the analysis of tannin content and N-acetyl glucosamide was used as inhibitory in determining corrosion rate on carbon steel. The process of extracting is done by boiling by using distilled water until boiling. The carbon steel used is a steel plate with a length of 4cm, 2cm wide and 1cm thick and then perforated at the top to place the hanging wire before testing. The first steel plate is sanded by abrasive paper from 400 up to 1200 grams and then dipped into aqueous hydrochloric acid and then analyzed to see the chemical content by SEM (Scanning electron microscopy) testing.

item Corrosion Rate Determination
This corrosion rate test is based on the weight loss that occurs in the material when immersed in corrosive media. In addition of the inhibitor solution in 0.5 M HCl solution as corrosion medium, it was carried out with various concentrations of 0, 1, 2, 3, 4, and 5% volume. After the specimens were immersed, the retrieval was performed 5 times each on the 1st, 2nd, 3rd, 4th, and 5th days.

Item Inhibition Efficiency
Efficiency inhibition of guava leaf and papaya leaf extract on steel corrosion is expressed in percent of inhibition efficiency (% E). The addition of an inhibitor to a medium can reduce the rate of corrosion rate, thereby increasing the value of its inhibitory efficiency. The magnitude or value of this inhibition efficiency also depends on the immersion time.
The immersion time may affect the protective layer of the guava extract inhibitor and the papaya leaf on the carbon steel surface because the coating begins to thicken, resulting in a higher corrosion rate value resulting in a decrease in the efficiency value.

Item The Absorption Mechanism
The surface of the solid can adsorb the solute from the solution. This is due to the collection of molecules of a substance on the surface of another substance as a result of the imbalance of forces on the surface.

Item SEM Analysis (Scanning electron microscopy)
SEM is an electron microscope designed to investigate the surface of a solid object directly from the surface, texture (hardness, reflective properties, etc.) and can also be seen from the shape and size of steel.
Morphological Analysis Steel surface to see the morphology of steel surface is used optical microscope with magnification 100 times. The morphological process can be seen from the surface of the steel before it is immersed and after soaking using a 0.5M HCL solution.

Item FTIR Testing
FTIR is a fairly reliable method of identifying a bond type, in particular the functional group of organic compounds. Since plant extracts used as inhibitors generally contain organic compounds which will be adsorbed on the surface of the metal (carbon steel) which can protect from corrosion reactions, it is necessary to test FTIR to support the explanatory fact that corrosive inhibition of specimens (carbon steel) in corrosive solution HCL 0.5 M is associated with the inhibitor adsorption mechanism of the guava leaf and papaya leaf on the specimen surface.

Conclusion
The carbon steel coated extract inhibitor may decrease the corrosion rate of the iron plate by the addition of tomato tanin inhibitors and papaya leaf amino acids, the concentrated extracts of these two inhibitors are mixed in HCL 0.5M corrosive media solution. The lowest corrosion rate was achieved each time the addition of 25 ml of HCL inhibitor and the duration of immersion for 5 days. The highest inhibitory efficiency was achieved when the addition of 200 g of inhibitor and duration of immersion time for 5 days. The use of concentrated extract inhibitors from papaya leaves and papaya leaves in iron plate inhibition in HCL medium is more effective than the use of NaCL.