Sources of Active Ingredients for Sustainable Corrosion Inhibitors

Metal corrosion is a grave problem, having deleterious effects on human health, the economy, the environment, and many engineering schemes, for example, automobiles, aircraft, naval vessels, and pipelines. For the confirmation of enduring reliability and stability of alloys and metals, corrosion-protective surfaces are of the greatest significance, for example, ions and water, through restraining their interactions with corrosive species. Though, their applied submissions are frequently bounded whichever through deprived mechanical robustness or else through the incapability to resist low surface tension liquids, for example, alcohols and oil. In this chapter, we have focused on diverse materials as sustainable corrosion inhibitors such as organic corrosion inhibitors, green corrosion inhibitors, and polymer-based corrosion inhibitors to protect materials from being corroded. Amongst them, we especially focus on green corrosion inhibitors as a consequence of simple manufacturing, easy availability, cost-effectiveness, and biodegradable nature.

Case-Studies on Green Corrosion Inhibitors

Corrosion in metals and its alloys is an inevitable phenomenon but can be controlled by suitable classical methods like process control, cathode protection, surface treating methods, impurity reduction in metals and addition of metals to form alloys. Nevertheless, the employment of corrosion inhibitors is still a noteworthy and simplest of all the above processes in protecting the metals and alloys especially in acidic media. Protection of metals against corrosion not only prevents corrosion but also is beneficial in terms of money loss as far as industrial equipment, surfaces and vessels are concerned. Since the use of organic and inorganic inhibitors are highly discouraged due to their high cost and toxicity, necessity has adequately aroused the development of corrosion inhibitors which are natural and green. Trends, nowadays, focussed in controlling corrosion in various metals and alloys through green corrosion inhibitors consisting of natural elements alone. In contrast to the inorganic inhibitors, green corrosion inhibitors are characterized by biodegradability, low cost and meagre toxicity. Several researchers are now turning themselves towards the research of green inhibitors which are of no threat to humans and the ecosystem. The current discussion is focussed on the fundamentals of corrosion, corrosion inhibition, materials used for it and case studies of green inhibitors used for corrosion control in various conventional and monolithic metals.

Sustainable Corrosion Inhibitors for Copper and its Alloys

The good properties of copper, as well as its alloys, make them a often used metallic materials in various industries. Regardless of their excellent corrosive resistance, the corrosion process of copper materials can occur under some specific conditions, hence, the need for corrosion inhibitors. Recently, due to many environmental agencies, the “green” aspect was introduced in many fields, including inhibition of corrosion. Keeping in mind economic and eco-friendly aspects, a wide range of compounds were employed as ecological inhibitors for copper materials. For this purpose, the current chapter aims to explore the application of numerous compounds as sustainable inhibitors to control the corrosion of copper materials in various media.

Green Corrosion Inhibitors from Biomass and Natural Sources

Considering the fact that corrosion of metals and alloys presents a significant problem all over the world, the one of most recently utilized approaches to combat this problem necessitates the researches for employment of new materials, which satisfied the green chemistry idea. In this connection, the development of sustainable corrosion inhibitors is highly demanded due to the increasing of awareness of green chemistry principles not only in corrosion discipline, but also in all branches of science and technology. Due to natural and biological origin as well as their eco-friendly extraction, the plant materials and biomass derived from various waste sources could be applied as beneficial substances for metals and alloys protection in different corrosion environment. Therefore, this work reports the main findings regarding their employments as green anticorrosion substances.

Green Organic Inhibitors for Corrosion Protection

Plants are a rich source of different varied organic compounds. Due to the important applications of naturally occurring chemicals their derivatives are also pursued for modifying and potentiating the activities of natural products. Metallic corrosion is a natural process resulting in heavy losses in various fields. Non hazardous and non toxic corrosion inhibitors gained significance due to the environmental regularities and guidelines issued in the course of saving the pristine nature of environment and to maintain the sustainability of our earth. Green corrosion inhibitors play a potential role for the above said cause. Recent research contributions on green corrosion inhibitors from the active researchers in the concerned expertise are presented briefly here to give an idea about the current research activity across the world.

Polysaccharide as Green Corrosion Inhibitor

The carbohydrates associated with polysaccharide glycosidic bonds are tightly chained, usually linear and highly branched complex molecules. Their structure mainly consists of hydroxyl groups in the form of functional groups, in which an oxygen heterogeneous atom is present. Some polysaccharides have hetero atoms. Nitrogen and Sulfur in addition to oxygen, which have unshared electron pairs. Hetero atoms easily share their electron pair to the vacant d orbitals of the metal ion and prevent the metal from corrosion. Polysaccharides are biodegradable, renewable, inexpensive and environment friendly due to which they are easily used as corrosion inhibitors. The present study mentions some major research work in which polysaccharides are used as corrosion inhibitors. Their mixed type nature has been reported in most research papers, and in the case of steel metal, they mainly follow the Langmuir adsorption isotherm. Chemical (gravimetric analysis) and electrochemical (EIS & PDP) studies are frequently used for the corrosion inhibition study. Some of the current research papers have also used computational or theoretical studies such as quantum chemical study and MD simulation. At the end of this book chapter, a discussion is also given regarding further research and direction related to the topic.

Current Status, Opportunities and Challenges of Green Corrosion Inhibitors

The term ‘Corrosion’ is associated with the deterioration of materials. To get rid of this problem corrosion inhibitors are commonly used. Though many conventional corrosion inhibitors can efficiently reduce corrosion, their disposal often adversely affects the environment. However, there are many natural products that have the potential of reducing corrosion and they are referred to as green corrosion inhibitors. They are much safer to use and most importantly cost-effective. This chapter deals with the current development of the use of green corrosion inhibitors, their opportunities and challenges.

Sustainable Corrosion Inhibitors for Concrete

Green chemistry and sustainability encourages the significance of preserving the nature and individual’s wellbeing in cost effective way that intends to avoid toxicity and reduction of wastes. Therefore, the implication of green corrosion inhibitors in the field of concrete protection has also received immense attention these days. Indeed, the usage of such inhibitors is a well-known strategy for producing high performance concrete. In view of this, the present chapter discusses the research in the area of sustainable corrosion inhibitors for concrete assurance used commercially in various industries. It also highlights the concrete corrosion mechanisms and its protective measures, recent advances in this field.

Green Corrosion Inhibitors for Coatings

Corrosion is emerging as a potential hazard which abolishes metals and their structures and hence become an imperative menace. It is an omnipotent and omnipresent process which is present in every environment, i.e., air, soil, water. Green chemistry is one of the notable branches of chemistry that focuses on the protection of environment and human well–being in an economically viable approach allowing dodging of toxins and reducing hazards due to corrosion. Green chemistry exploited well–known strategy namely green inhibitors to prevent, control or impede the growth of corrosion. Green inhibitors are eco–friendly, cost–effective, renewable natural products which are favourable over toxic synthetic corrosion inhibitors. Extracts of natural products contain natural products containing alkaloids, carboxylic acids, nicotine, polyphenols, quinine, terpenes, and other functional groups possessing elements like C, N, O, S, etc., prompting adsorption via forming a thin layer (coating) on the metallic surface to shield the surface and encumber corrosion. In the field of economical loop, this approach develops various potential applications in manufacturing areas other than ‘Trash to treasure’. Even though a bunch of experiments have been performed and several research articles have been in print, however, the area of green inhibitors is still demanding more investigation on this open issue. More and more interest in the area extended the research, consequentially to a large variety of tried molecules. Nevertheless, the most accepted protocols are classical and, therefore, are incompetent to completely portray the probable worth of inhibitors. Hence all above stated features should be the objective of the contemporary research so that productive analysis to emphasize the weak areas of the green inhibitors field and tackle the prospect research in the field that still requires validation.