Ball milling 2,4,6-trichlorophenol with calcium oxide: Dechlorination experiment and mechanism considerations

Mechanochemistry method is widely used for waste treatment and organic pollutant destruction. Previous research did not account for all phenomena in the mechanochemistry decomposition process. 2,4,6-trichlorophenol (2,4,6-TCP) with CaO and SiO2 as additives was grinded using a ball milling equipment in present work. Content of the residual 2,4,6-TCP was measured by Gas chromatography coupled electron capture detector (GC–ECD) and found that the degradation rate is 99.0% after 6 h milling. Cl− content detected by ion chromatography (IC) show inconformity with the degradation rate. Products of Ca(OH)2 and CaOHCl can be confirmed by crystal structure X-ray diffractometer (XRD). The residue samples were also examined using differential thermal analysis (DTA) and thermogravimetric analysis (TG and DTG) to see their thermal characterizations. Finally, a four-step pathway was proposed to describe the degradation process of 2,4,6-TCP during ball milling.

► 2,4,6-Trichlorophenol was ball milled with CaO and SiO2.
► Ball milling is found very effective for 2,4,6-TCP treatment.
► The dechloridation accounts for only part of the degradation.
► A four-step pathway mechanism for 2,4,6-TCP degradation is proposed.