Formation of dioxin during smoldering of cca treated wood char

Production of dioxin during the smoldering of wood char containing chromated copper arsenate (CCA) was investigated. Preliminary results are presented for the smoldering of treated wood char at 300 and 400°C, as a function of char loading, smoldering time and inlet oxygen concentrations. PCDF (mainly Cl4DF) were the preferred products of smoldering, and the results indicate the dependence of PCDD/F yields on competing formation/dechlorination reactions. Early periods of mass conversion favored PCDD/F formation, but with increasing mass loss, dechlorination and decomposition began to dominate. While the amounts detected were not particularly high (maximum yield of 95 ng TEQ/kg char oxidized), PCDD/F formation in wood fires may drastically increase with CCA combined with inorganic and organic chlorine contaminants.