Yes they can. Hydroxyl radicals are very reactive species, which react with almost every organic compound, at nearly diffusion- controlled reaction rates (kHO = 107 - 109 l/mol.s for most organics). Because acetic acid is actually a very simple compound, not so much different by-products are likely to be formed.

From the attached article, it appears that a few short-chain carboxylic acids (formic acid and oxalic acid in particular), are the major by-products, originating from acetic acid decomposition during peroxone (O3/H2O2) treatment.

Considering the similarities between the Fenton reaction, and the peroxone process (both will primary generate HO radicals) the same reaction intermediates might be formed after treatment with the Fenton process.

Article High-efficiency mixing process in secondary rotating stream

It depends on how you define "Fenton's reagent."

" hydroxyl radicals ('OH), produced by the reaction of Fe2+ and H2O2 in water. "

The hydroxyl radical might not be the reactive species produced by the reaction of Fe2+ and H2O2 in water. It depends on conditions.

"I want to understand the mechanism." There are numerous papers on the reaction of hydroxyl radicals with acetic acid, see e.g.

Article Chemical insights, explicit chemistry, and yields of seconda...

Please have a look at the following link

https://books.google.cz/books?id=icxjDwAAQBAJ&pg=PA360&lpg=PA360&dq=Oxidation+of+acetic+acid+by+fenton%C2%B4s+oxidation&source=bl&ots=s7iWIxIYd8&sig=_Oy4EtYbijCiiK_b9Ef9xGSx6XE&hl=cs&sa=X&ved=2ahUKEwiU4arauMXdAhVGXiwKHU2BD5Y4HhDoATADegQIBhAB#v=onepage&q=Oxidation%20of%20acetic%20acid%20by%20fenton%C2%B4s%20oxidation&f=false

You can find answer to your questions there.

Best regards

Vit

Niels Wardenier

Thank you for your reply. Actually, I have read in some places that acetic acid is very resistant to heterogenous Fenton oxidation (using Fe and H2O2) and that the oxidation can be enhanced only by using a combination of the heterogeneous Fenton-like oxidation process with other treatment processes like ultrasound, UV, ozone etc.

Please check the following links-

https://pdfs.semanticscholar.org/7bd7/ef4493102357d6bdaa5b438f4d0a297bc19f.pdf

Article Influence of ultrasound on the heterogeneous Fenton-like oxi...

Dr Yurii V Geletii

Thank you for your reply. I think that the OH radicals, generated when ferrous ions and H2O2 are mixed in water, are the reactive (oxidizing) species in any Fenton oxidation reaction, while iron acts as a catalyst. But as I have replied to Dr. Wardenier above, I find some references which mention that acetic acid is resistant to Fenton oxidation!

I will surely go through the reference provided by you to understand more about the reaction.

Regards.

Dr. Vit Mateju

Thank you. But looks like I cannot open/access the online book at my place. Can you provide the answers in any other way?

Regards.

Dr. B. Chandrashekhar :

Thank you for your response. The link is to page 360 in the folloving publication:

Advanced Oxidation Processes (AOPs) in Water and Wastewater Treatment

upravili: Aziz, Hamidi Abdul, Abu Amr, Salem S. p. 360, published by IGI Global, 1978.

I do not know why link doesn´t work. I could open it without problem.

Best regards

Vit

It could be that acetic acid is quite resistant to degradation by AOPs, but then acetic acid degradation efficiency should also be rather limited for any other AOPs, as these mostly differ in the mechanisms that eventually lead to HO generation.

One reason for the poor efficiencies, reported in some publications could be related to the fact that rather inefficient parameters (pH, oxidant concentrations, …) have been used. Like any other AOP, the efficiency of the Fenton process is determined by a number of factors. As Yurii Geleti's answer above already suggested, simply adding Fe2+ ions and H2O2 into your solution will not work to generate HO radicals in an efficient way. Usually, the Fenton process is the most effective while working at acidic pH. Ideally, the pH should be kept around pH = 2.00, while above pH = 4.00 the Fenton process becomes quite efficient due to hydrolysis of Fe2+, yielding Fe3+ ions. As a results, Fe2+ could not be used again for the generation of HO. Besides the influence of pH, the ratios Fe2+ / H2O2 and Fe2+ /acetic acid are also important from the viewpoint of degradation efficiency. The optimal ratios of these reagent has to be deduced from experiments.

Concerning your question about the enhanced removal which has been observed when a homogeneous process is used; it needs to be noted here that this is generally valid for any AOP. Some experimental works and reviews have reported that the combination of several oxidants, or the addition of a catalyst can be beneficial for pollutant degradation. For instance, if the efficiency of single ozonation (O3) is compared with the peroxone process (O3/H2O2) and UV/O3/H2O2, than the best results are almost always obtained with the UV/O3/H2O2 process ,followed by O3/H2O2 and O3 treatment.

Hopefully this helps,

Niels

Depending on conditions the reactive product of Fenton reaction is hydroxyl radical or ferryl.

Google for ferryl in Fenton reaction

Dr. Yurii V Geletii

Thank you so much. I will check it out.

Dr. Niels Wardenier

Thank you for the detailed response. I will try to do some experiments based on your inputs in my lab!

Regards.

Dr. Vit Mateju

Thank you. I can now open the link here. Again, here too it is mentioned that Fenton's reagent is not supposed to oxidize acetic acid with ease, so it is proposed by some researchers to be used in combination with electricity and UV. But as Dr. Niels and Dr. Yurii said, the mechanism depends on the conditions.