Abstract

With growing global awareness and concern for environmental protection through the use of less hazardous and environmentally-friendly extracts of plant origin, there has been a plethora of green corrosion inhibitors research with far reaching contributions to the science of corrosion prevention and control. Attention has increasingly turned towards green corrosion inhibitors, compounds of natural origin with anti-oxidant activity towards metals and their alloys. Green inhibitors have been investigated for their corrosion and adsorption properties with good results. The findings from these research works provide evidence of the adsorption behavior of green inhibitors which was confirmed by the adsorption isotherms that were proposed. Adsorption is the first step of any surface reaction and since corrosion is a surface phenomenon the effectiveness of green corrosion inhibitors is related to their ability to adsorb on metal surfaces. This review proposes the potential of plant dna as an emerging and promising novel inhibitor for mild steel. It begins with a list of plants that have been used in studies to determine corrosion inhibition properties and moves on to establish the adsorption behavior of bio macromolecules; protein, polysaccharides (chitosan) and dna. It reviews studies and investigation of dna interaction and adsorption on inorganic surfaces before focusing on the use of salmon (fish) sperm dna and calf thymus gland dna as green corrosion inhibitors for mild steel. It concludes that plant dna is a promising candidate for green corrosion inhibitor given the similarity between the plant and animal dna structure and function, and the fact that the use of plant is more environmentally sustainable than animal-based product.

Highlights

  • Introduction The AmericanSociety for testing and Materials defines corrosion as the chemical or electrochemical reaction between metals and their environment which results in the ruination of metals and their characteristics [1, 2]

  • With growing global awareness and concern for environmental protection through the use of less hazardous and environmentally-friendly extracts of plant origin, there has been a plethora of green corrosion inhibitors research with far reaching contributions to the science of corrosion prevention and control

  • Adsorption is the first step of any surface reaction and since corrosion is a surface phenomenon the effectiveness of green corrosion inhibitors is related to their ability to adsorb on metal surfaces

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Summary

Published under licence by IOP Publishing Ltd

The corrosion process requires four factors to occur. First is the anode, where metal dissolution takes place. Metal ions and electrons are released by oxidation and the electrons travel through an external conductor, a metallic path, to a cathode in close proximity to the anode, where they are consumed by positively charged ions in a reduction process. The metal ions from the anode travels through an ionic current path to the cathode. In addition to these four; anode, cathode, metallic external conductor and ionic current path, are associated fluid dynamics i.e. high water velocities which exposes fresh metal surface to water by sweeping away protective films, low pH (high concentration of free H+ ion), this increases the release of electrons, high water temperatures, concentration of dissolved oxygen, and the presence of dissolved salts, which brings about the increased water conductivity [3]. Corrosion can be classified into different types on the basis of mechanism and media or environment of occurrence.

Corrosion type Description
Findings
Types of corrosive Description environment
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