Are extracts really green substitutes for traditional toxic corrosion inhibitors? Challenges beyond origin and availability

The use of plant extracts in sustainable corrosion protection has gained substantial courtesy due to their natural origin and huge availability. The sustainability of corrosion protection using extracts is questioned in the current study, and some additional factors beyond the origin and accessibility of plant materials are suggested for determining the sustainability and cost. It takes a lot of time and money for the collection, cleaning, processing of plant materials and extraction preparation. The extraction process sometimes uses highly toxic and expensive organic solvents and instruments that can hurt sustainability and cost. More so, the use of extracts for any specific purpose can not be a green approach unless their sustainability is measured. Sustainability can be discussed in terms of toxicity, bio-accumulation and bio-degradability. Guidelines for a substance to be non-toxic, environmentally friendly, and non-bioaccumulative are provided by the Oslo and Paris Commission (OSPAR) and Registration, Evaluation, Authorisation and Restriction of Chemicals (REACH). Unfortunately, these sustainability parameters are very scarily reported in previous studies. More so, the use of extracts in sustainable corrosion protection has also many challenges including their low efficiency (43-75%) at very high concentrations (2000-4000 ppm) and the use of toxic organic solvents for extraction. This article also proposes many challenges and outlooks that investigators need to think seriously beyond origin and availability before claiming any plant extract as a green and cost-effective alternative.

Automated summary

The use of plant extracts for sustainable corrosion protection has gained attention due to their natural origin and availability. However, the sustainability and cost of using extracts is questioned, as factors beyond origin and accessibility need to be considered. The collection and processing of plant materials, as well as the extraction process using toxic solvents, can impact sustainability. Guidelines for measuring sustainability are lacking, and challenges such as low efficiency and the use of toxic solvents need to be addressed before claiming plant extracts as a green and cost-effective alternative.