Comment on 'Mechanochemically Enhanced Degradation of Pyrene and Phenanthrene Loaded on Magnetite'

摘要

I read this paper with great interest and would like to raise a few scientific and practical questions on the interpretation of the experimental data and the proposed pathway of PAH degradation in "magnetite" and "soil" systems, and I hope that helps toward a better understanding of the main mechanisms. First, the authors found that grinding with the low particle sized samples (called magnetite b and magnetite c) resulted in little degradation, whereas that of "magnetite a" (size ≤500 μm) resulted in high degradation of PAH. The authors thought that this experiment corroborated their hypothesis, that is, large particles are cleaved into small fragments leading to the formation of chemically active sites, with the ultimate conclusion that the smaller the particle size, the lower the PAH degradation rate. I will explain in the following lines why this experiment cannot support the authors' conclusive statement.