An overview on plant extracts as environmental sustainable and green corrosion inhibitors for metals and alloys in aggressive corrosive media

A critical review on the recent studies on plant biomaterials as corrosion inhibitors for industrial metals

Over the past decade, green chemistry has been emphasizing the importance of protecting the environment and human health in an economically beneficial manner aiming at avoiding toxins and reducing wastes. The field of metallic materials degradation, generally faced by using toxic compounds, found a fertile research field in green chemistry. In fact, the use of inhibitors is a well-known strategy when metal corrosion needs to be prevented, controlled, or retarded. Green inhibitors are biodegradable, ecologically acceptable and renewable. Their valorization expands possible applications in industrial fields other than ‘waste to energy’ in the perspective of circular economy. Although lot of experimental work has been done and many research papers have been published, the topic of green inhibitors is still an open issue. The great interest in the field expanded the research, resulting in high numbers of tested molecules. However, the most frequently adopted approaches are conventional and, hence, not suitable to fully characterize the potential efficacy of inhibitors. All the mentioned aspects are the object of the present review and are meant as a constructive criticism to highlight the weak points of the green inhibitors field as to re-evaluate the literature and address the future research in the field that still lacks rationalization.

/pdf/green-corrosion-inhibitors-from-natural-sources-and-biomass-9jfjn1pmrj.pdf

Green Corrosion Inhibitors from Natural Sources and Biomass Wastes

This review summarises the research work published in the last two decades on the use of natural compounds as corrosion inhibitors for aluminium and aluminium alloys in different solutions. Herein, plant extracts, gums, drugs, and oils have been considered as green corrosion inhibitors. The advantages and disadvantages of the methods used to obtain green corrosion inhibitors are presented. Additionally, the inhibition effectiveness of these corrosion inhibitors, including the techniques used to evaluate them and the respective inhibition mechanisms, are discussed. Finally, a critical evaluation is presented together with the outlook as regards possible future improvements.

/pdf/green-corrosion-inhibitors-for-aluminium-and-its-alloys-a-1hl92rs06y.pdf

Green corrosion inhibitors for aluminium and its alloys: a review

Corrosion behaviour of 6063 aluminium alloy in acidic and in alkaline media

The inhibition of corrosion of aluminum in hydrochloric acid solutions by the ethanolic extract of the leaves of Ananas sativum was studied using weight loss and hydrogen evolution methods. It was found that the plant extract retarded the acid induced corrosion of aluminum. Inhibition efficiency increased with increasing concentration of the extract and temperature. Adsorption studies revealed that Langmuir adsorption isotherm is the best adsorption model applicable to the adsorption of A. sativum on aluminum surface. Activation parameters such as activation energies (E a), activation enthalpy (ΔH o), and activation entropy (ΔS o) were evaluated from the effect of temperature on the corrosion and inhibition processes.

E.I. Ating

Papers

Leaves extract of Ananas sativum as green corrosion inhibitor for aluminium in hydrochloric acid solutions