Effect of Silica on Pyrene-Contaminated Soil Subjected to Mechanochemical Remediation

Soil contaminated by polycyclic aromatic hydrocarbons (PAHs) is a common problem in the world. Mechanochemical treatment is a promising technology for remediation of PAH-contaminated soil. This study investigated the feasibility of pyrene degradation with silica by mechanochemical remediation. The effects of ball milling time and rotation speed on the removal efficiency of pyrene in soil were also studied. When the milling time was 3 h and the rotation speed was 500 rpm, the removal efficiency of pyrene in soil was over 98%. The intermediate products detected by gas chromatography–mass spectrometry proved that the hydrogenation reaction and the destruction of benzene rings occurred in the milling process. Both graphite and amorphous carbon were detected by Raman spectra. The main degradation pathway and mechanism of pyrene by mechanochemical treatment should be the destruction of benzene rings caused by free radicals and further carbonization.