Toxicity characteristic leaching procedure (TCLP) is an extraction method to simulate a soil or sediment leaching. The method employed two extraction fluids - one is a buffered solution of acetic acid and sodium hydroxide while the another one is an unbuffered acetic acid solution. [1] Although this protocol is widely used by many government instances, I still can not find any meaningful justification on whether first solution should and should not be able to thoroughly leach a sodiment or soil. I also can not find any theoretical, computational, or spectroscopic basis that can explain the mechanism behind the dissolution of such soils by unbuffered and buffered solutions, let it be a common ferrihydrite or goethite soil. Could there be any evidence that it might transform into an unstable hydroxide-hydrate-acetate ferrihydrite species?
Any insight from research article is appreciated and please do not put simple textbook explanations. Thank you very much.
[1] https://www.epa.gov/sites/default/files/2015-12/documents/1311.pdf
