[Thermal desorption behavior of PCDD/Fs on the fly ash].

The article studied the thermal desorption behavior of PCDD/Fs on the fly ash under anoxic conditions. From the analysis of the PCDD/Fs concentrations in the gas phrase and solid residual, the several kinds of potential chemical reaction and physical changes of dioxin that occur at the different temperature are concluded. At the same time, desorption ratios of 17 toxic dioxin congers and the better desorption conditions are studied. At 200 degrees C and 300 degrees C, the average desorption ratio of PCDD/Fs are 96.2% and 95.5% respectively. At 400 degrees C, the average desorption ratio of PCDD/Fs is 99.7%. The experiment results show that the PCDD/Fs is dechlorinated at 300 degrees C. At 400 degrees C, a lot of precursor reactions happen in the fly ash, which enhance the content of PCDD/Fs.