Dear Dr. Ayoub Najem ,

your experimentation makes logical sense in reference to the study of the inhibition efficiency of the compound you are considering but there is, in my opinion, an analytical and specific measurement system that is able to give you reliable data according to a well-in-depth methodology, naturally defined before the experiments. I do not know what indications you would like to obtain using the UV-Vis technique (generally used for colorimetric measurements).

You could, if you have an optical microscope, start with a view of the different sample surfaces, trying to evaluate the type and extent of any corrosive attack...

In general, you have 4 main different methods to study the corrosion behaviour of a specific material (protected or not by a coating or other surface treatments, as an inhibitor...) in the environment of possible use:

1 - Field tests (according to standard regulations and followed by appropriate characterizations / evaluations) in a corrosive environment very similar to the one of use that require an exposure time of at least one year (or more);

2 - Salt spray chamber tests (these, too, according to standard regulations), conducted in a series of corrosive environments simulating those of real application, with often rapid assessments of a photographic type. These tests require an exposure time of about 1-2 months and are considered "accelerated tests";

3 - Lab tests in free corrosion conditions, in a controlled environment, followed by analysis of weight loss (gravimetric test)and / or morphological and chemical analyzes of the surface of the samples by scientific instrumements, for example Optical Microscopy, SEM, et. (time required about 1 month);

4 - Electrochemical measurements (eg. Potentiodynamic Polarization Curves, EIS, etc.) carried out in an suitable aggressive solution which, once the experimental parameters are optimized, are able to provide a comparative or absolute evaluation, in a time of order of one hour every single measure.

Now all that remains is to choose. Personally I prefer to use at least two of the tests mentioned above ... it is always better to have two results in agreement with each other, if time allows us to do this...

Good luck and my best regards, Pierluigi Traverso.

https://www.researchgate.net/publication/264051065_Anticorrosive_Activity_of_Kigelia_pinnata_Leaves_Extract_on_Mild_Steel_in_Acidic_Media

Dear Alexander

One way to interpret the obtained results between different anticorrosion liquids and the UV-light bands is by correlating the measured corrosion rate ,i.e.,by DC or AC methods, of the mild steel samples in each test of the anticorrosion liquids with the recorded UV-light bands of the anticorrosion liquids.

This way ,one would observe a correlation between the measured corrosion rate of the mild steel samples and the corresponding UV-light bands of the anticorrosion liquids.