Process And Mechanism Study Of Mechanochemical Destruction Of POPs Wastes Using Fe-SiO₂

Persistent organic Pollutants （POPs） have three kinds of characteristics which willlead to cancer, teratogenic and the mutation. They will damage human lives andenvironment. The Stockholm convention requests non-hazardous administration anddisposal of POPs wastes since2001. China now has plenty of POPs wastes to be treated,such as DDT, benzex, chlordane and mirex. The traditional high temperatureincineration will generate the much more toxic compounds such as dioxins and furans,so the non-combustion technologies became more and more attractive internationally.According to the problems of slower reaction and lower dechlorination in the CaOreagents applied in mechanochemical destruction, our thesis will try to develop a moreeffective dechlorniation reagent, and to investigate the kinetics and mechanisms of theprocess, the possibility of reutilization of non-hazardous products.The mechanochmeical degradations of four model pollutants （HCB, Mirex, DPand PCNB） under different reagents proved that Fe-SiO₂（containg iron powder andquartz sand） is the highest and best reagents. To analyze the technological parametersof mirex destruction by using Fe-SiO₂process, the second derivatives of reaction rateconstants to charge ratio and rotation speed were the same numerical value,⁰.00038.This value was the internal relations between rotation speed, charge ratio and reactionrate constants. The response-area-equation was deduced and its feasibility waspredicted.After solid powder’s characterization by degradation, dechlorination,intermediates from GC/MS, FTIR spectrum, Raman spectrum and ESR spectrum, thefinal products contains graphite, amorphous carbon and inorganic chlorine. Thedechlorination-polymerization-carbonization pathways in MCD process wereconcluded respectively by Fe and by SiO2. The SiO2has the dechlorination reactionwith chlorinated organic compounds in the mechanochemical system. The mechanicradicals produced by smash of quartz sand were the main factor for this dechlorinationreaction. It is concluded that the iron powder was in favor of triboplasma areaproduction and SiO2was in favor of formation of mechanic-radicals. They bothpromoted and complemented each other. Based on the principle of micro-electrolysis by Fe/C, it is found that the non-hazardousproducts of MCD PCNB by Fe-SiO₂can reduce and dechlorinate4-Chlorophenol（4-CP）. The carbon materials formed after MCD treatment fercilitated thedechlorination of4-CP.