Study of degradation mechanism of dechlorane plus by mechanochemical reaction with aluminum and quartz sand

• Mechanochemical destruction of DP was prompted by Al and quartz sand.
• Main solid products include carbon, AlCl3·6H2O, silicon etc.
• Main gaseous products include H2, CH4, C2H6, C2H4 etc.
• Thermite-type reaction and dechlorination followed by carbonization are mechanism.

Mechanical force, which directly induced specific chemical reaction by the collision between balls or ball and vial, have recently attracted much attention on efficient and rapid destruction of organic pollutants. To exploit this mechanochemical destruction (MCD) technology, it is essential to develop a fundamental understanding of the mechanism of degradation contaminant. Here we report a detailed study on the MCD of the additive flame retardant of dechlorane plus (DP), using Al and quartz sand (SiO2) as additives. Degradation data and quantum chemical calculations based on density functional theory (DFT) confirmed that the different mechanism of MCD for treatment of different mass ratio of DP in the mixture of Al + SiO2. The intermediate products of DPs′ (C18H13Cl11) and DPs″ (C18H14Cl10) were observed in the low mass ratio. Sequential dechlorination followed by the destruction of hydrocarbon skeleton should be the main degradation pathway of low mass ratio of DP. Moreover, mechanically induced thermite-type reaction is responsible for the more efficient destruction of high mass ratio of DP. The potential fate of C and Cl present in DP was in the form of amorphous and graphite carbon, AlCl3⋅6H2O, and certain polymerized with SiCl bonds, respectively. The H present in DP was mainly contained in the final gas products H2, CH4, C2H6, C2H4 etc. This study paves the way toward the efficient and rapid destruction of toxic chlorinated organic pollutants like DP using MCD.