Dechlorination/hydrogenation and destruction reactions of PCDDs in OCDD-added fly ash heated under vacuum.

Octachlorodibenzo-p-dioxin (OCDD)-added, pretreated fly ash was heated under vacuum at sample temperatures ranging from T(s)=450 to 650 K. The fly ash and liquid nitrogen-cooled trap samples were analyzed for DD/DF through OCDD/DF. The total amounts of DD through OCDD decrease with increasing T(s), which indicates that dechlorination/hydrogenation (DCH) reactions are not the only reaction channels.

Removal of PCDDs/DFs and dl-PCBs in MWI fly ash by heating under vacuum.

Temperature dependence of PCDD/DF and dioxin-like polychlorinated biphenyl (dl-PCB) concentrations in fly ash from a municipal waste incinerator (MWI) heated under vacuum has been investigated as a function of sample temperature ranging from T(s)=425 to 800 K to find out if PCDDs/DFs in fly ash evaporate and are trapped in a liquid nitrogen-cooled trap. The results show that more than 99.98% of PCDDs/DFs in TEQ is removed from fly ash by vacuum heat treatment at T(s)>650 K for 4 h.