Evaluation of piper sarmentosum leaves extract as an Eco-Friendly corrosion inhibitor for carbon steel in 5M HCl, lake water and 3.5 wt.% NaCl medium

Ahmad Kamarul Helmy, Ahmad Syamil (2024) Evaluation of piper sarmentosum leaves extract as an Eco-Friendly corrosion inhibitor for carbon steel in 5M HCl, lake water and 3.5 wt.% NaCl medium. Project Report. Universiti Teknikal Malaysia Melaka, Melaka, Malaysia. (Submitted)

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Abstract

Carbon steel is a type of steel that contains varying amounts of carbon, typically between 0.05% and 2.0% carbon content. It is one of the most used materials in manufacturing due to its strength, durability, and affordability but it has poor corrosion protection. Corrosion is a natural process that occurs when metals and alloys degrade due to chemical reactions with their environment. It is a complex electrochemical process that involves the transfer of electrons between a metal and an electrolyte solution. Corrosion inhibitors are chemical compounds that can be added to a corrosive environment to reduce or prevent corrosion of metals and alloys. Corrosion inhibitors work by interfering with the electrochemical reactions that cause corrosion, either by forming a protective layer on the metal surface or by modifying the chemistry of the environment. A green inhibitor, also known as an eco-friendly or environmentally friendly inhibitor, refers to a corrosion inhibitor that is derived from natural or renewable sources and exhibits minimal environmental impact. This study's aim is to evaluate the Piper sarmentosum leaves as an extract of an eco-friendly corrosion inhibitor for carbon steel in three different environments: 5M HCl, lake water, and 3.5 wt.% NaCl. Next, to investigate the influence of the immersion period on the inhibition efficiency of the green inhibitors, and to evaluate the effectiveness of green inhibitors derived from natural sources which is piper sarmentosum extract in preventing corrosion of metal surfaces in three different mediums, and also to compare the inhibition efficiency of piper sarmentosum leaves as plant-based green inhibitors of low carbon steel in three different mediums. The method that used in this study is by conducting mechanical testing which is to assess the microstructure and hardness study of low carbon steel. The substrate was divided into two group, the different of the two group is the presence of piper sarmentosum extraction. The carbon steel substrate was immerse in those three environment for observation within the number of days necessary to determine which extraction is the best inhibitor for low carbon steel. After the result was obtained the specimen will have visual inspection to calculate the weight loss, and corrosion rate. Scanning Electron Microscopy (SEM) and Energy Dispersive X-Ray Spectroscopy (EDX) were used to examine the mechanism of inhibitor adsorption on the surface of low carbon steel materials. To demonstrate the eco-friendly inhibitor's corrosion-preventative efficacy, a scanning electron microscopy (SEM) investigation was conducted on the surface of low carbon steel.The total weight loss on days 35 for solution with inhibitor was 2.318 gram for 5M HCl, 0.028 gram for 3.5 wt.% NaCl and 0.019 gram for lake water compared to solution without inhibitior which is 2.364 gram for 5M HCl, 0.086 gram for 3.5 wt% NaCl and 0.184 gram for lake water. The inhibitor extraction had reduce carbon’s steel corrosion rate from 0.314 mm/year, 0.0011 mm/year and 0.0007 mm/year to 0.0312 mm/year, 0.0004 mm/year and 0.0003 mm/year repectively. SEM and EDX analysis proved that the specimen with inhibitor surface has least pitting which is corroded compared to specimen without inhibitor surface. The inhibitor efficiency of 5M HCl is the highest which is 65.45% compared to the others. The inhibitor effectiveness in 5M HCl is the best by considering the value of corrosion rate and the value of inhibitor efficiencies. In general, the presence of inhibitor, be it chemical or green inhibitors, will significantly slow the rate of corrosion.

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