A Case Study of the Effectiveness of Plant Extracts Leaves to Inhibit rate of Corrosion in Metals Alloys

Abstract

newlineMetal corrosion is a common problem affecting both the economy and the newlineenvironment. Corrosion of mild and carbon steels in aggressive environments is intensive. newlineInhibitors must be used in processes such as pickling, pickling and metal pickling newlinewhere the metal is in contact with an acid solution. Organic compounds are widely used as newlinecorrosion inhibitors for metals and alloys. newlineThe use of plant extracts as natural corrosion inhibitors is becoming increasingly popular newlinebecause they contain various organic compounds adsorbed on metal surfaces. Most synthetic newlineinhibitors are expensive synthetic chemicals that are harmful to living organisms and the newlineenvironment. These toxic and expensive chemical inhibitors must be replaced with newlineenvironmentally friendly, biodegradable and economical inhibitors of natural origin.The newlineabundantly available Rhoeo discolor leaves, commonly known as boat lilly, was selected and its newlineethanolic extract used as natural inhibitor to mild and carbon steel in HCl media. Rhoeo discolor newlineextracts contain a mixture of natural organic compounds and are used as corrosion inhibitors for newlinemild and carbon steel in 0.1M to 0.5M HCl. This plant is selected based on its easy availability, newlinebiodegradability and less or nontoxic. The effectiveness of the selected plant materials is studied newlineusing the weight loss method at room temperature, different concentrations of acid and inhibitor, newlineand various immersion periods. The study is carried out instrumentally by linear polarization and newlineelectrochemical impedance spectroscopic methods. The Rhoeo discolor leaves extract was newlineeffective under the studied conditions. Corrosion inhibition efficiency for mild steel in 0.1M HCl newlineand 0.5 g/L of inhibitor is found to be maximum at 94.60% estimated by the weight loss method. newlineThe potentiodynamic polarization method indicates 85.28% and it is 88.36% by the impedance newlinemethod. The inhibitor efficiency for carbon steel by weight loss method, polarization, and newlineimpedance method is 75.31%, 66.66% and 86.60% respectively. The extrac