Evaluation of neem and papaya leaves extract as an eco-friendly corrosion inhibitor for carbon steel in 0.5 M HCl medium

Aja Mohammad Rizal Pahlepi, Aja Sofea Anissa (2022) Evaluation of neem and papaya leaves extract as an eco-friendly corrosion inhibitor for carbon steel in 0.5 M HCl medium. Project Report. Universiti Teknikal Malaysia Melaka, Melaka, Malaysia. (Submitted)

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Abstract

Carbon steel is made up of the fundamental elements of iron and carbon. Carbon steels are often used in different applications, including structural components such as steel frame buildings, automotive tubing, pipelines, and tanks. Corrosion is characterized as a indirectional electrochemical interaction between a material and it’s environment, which can result in the material corroding. Corrosion inhibitor is one of the method to corrosion protection. A corrosion inhibitor is a chemical compound that reduces the rate of metal corrosion when exposed to the environment. Green inhibitors are biodegradable corrosion inhibitors that are inexpensive and environmentally safe without heavy metals, chemicals, some hazardous substances and are capable of effectively retarding corrosion. This study aim is to evaluate neem and papaya leaves extract as an eco-friendly corrosion inhibitor for carbon steel in a 0.5 M HCl medium. The objectives of this study are to investigate the influence of the immersion period on the inhibition efficiency of the green inhibitors, to evaluate the inhibition efficiency of neem and papaya leaves as plant-based green inhibitors for low carbon steel in a 0.5 M HCl acidic medium, and also to compare the performances of the neem and papaya leaves in preventing corrosion in low carbon steel. In this research study, a mechanical testing had been done, which is to evaluate the analysis of the hardness and microstructure of the low carbon steel. The sample has been divided into three samples, which are HCl added with neem leaves extract, HCl added with papaya leaves extract, and HCl only. Each sample contains six low carbon steel specimens and has been observed for 7, 14, 21, 28 and 35 days. The specimen had been taken out according to the days that were required, and the result will be a visual inspection and calculation of weight loss measurement, corrosion rate and inhibitor efficiency. The mechanism of adsorption of inhibitors on the surface of low carbon steel materials had been studied by using Scanning Electron Microscopy (SEM) and Energy Dispersive X-Ray (EDX). The SEM study of the surface on low carbon steel was done to prove the effectiveness of the eco-friendly inhibitor as a corrosion preventative. The weight loss result such as on days 35 the total weight loss of 0.5 M HCl is 1.401 gram, papaya leaves solution is 0.846 gram and neem leaves solution is 0.692 gram has demonstrated that the involvement of an eco-friendly inhibitor, which is papaya and neem leaves, had reduce carbon steel’s corrosion rate with 0.0114 mm/year and 0.0093 mm/year respectively. SEM and EDX analysis proved that the specimen surface in 0.5 M HCl solution got a lot of pitting, which is corroded compared to specimen surfaces in the papaya and neem leaf medium. In other words, the green inhibitor has been used in close systems of the oil and gas industries, such as boilers, pipelines, pressure tanks, and pressure vessels. The inhibitor effectiveness of neem leaves is the best green inhibitor considering the maximum value of corrosion rate and the highest value of inhibitor efficiency.

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