Abstract
We researched the influence of the characteristics of fly ash in supercritical carbon dioxide extraction of dioxins from fly ash.
Supercritical carbon dioxide extraction was applied to the analysis of dioxins from fly ash. We extracted dioxins from various fly ash samples with supercritical carbon dioxide under the condition of temperature of 190°C and the pressure of 40 MPa, and we obtained wide range extration efficiency of dioxins in this analysis. Many reports for extraction of dioxins from fly ash with supercritical fluid have been reported, but a little reports described for the influence of fly ash components for the extraction of dioxins. Thus we tried to clear the correlations between the characteristics of fly ash and the extraction efficiency.
We measured up the carbon content and surface area of fly ash samples, and searched the correlation between these parameters and extraction efficiency. These experiments revealed that extraction efficiencies of both PCDD/DFs and non-ortho-Co-PCBs decreased with increasing carbon content and surface area of fly ash, and the number of chlorine atom of their chemical molecule. In particular, we found a significant negative correlation between surface area and extraction efficiency of PCDD/DFs or non-ortho-Co-PCBs, and it became clear that surface area greatly affected to the extraction efficiency.
