Thermal decomposition behavior of CCA-treated wood for safe disposal and the safe recovery of heavy metals through pyrolysis
Dong Won Son, Dong-heub Lee, Sun-hae Cheon, Myung Jae Lee
If we could estimate the chemical changes in heavy metals by temperature in chromated copper arsenate (CCA)-treated wood during pyrolysis, it is expected that we could solve the environmental problems of heavy metals, which may occur during pyrolysis, and therefore, the thermal decomposition behavior of effective elements of CCA-treated wood was examined to find a safe disposal method. First, CCA-treated wood was combusted at a temperature that prevents volatilization of arsenic compounds, and the arsenic compounds were extracted from carbonized wood. Then, it was considered how to recover heavy metals from chromium compounds and copper compounds. The Thermo Gravimetric Analysis (TGA) result of CCA-treated wood showed that arsenic (III) oxide was volatilized into the atmosphere at 300? and arsenic (V) oxide was volatilized at 800?. When heavy metals were recovered from the carbonized-treated wood after thermal decomposition of CCA-treated wood at 300?, which could suppress the volatilization of arsenic compounds, it was relatively easy to recover copper and arsenic while it was difficult to recover chromium from the carbonized-treated wood.
Keywords: CCA-treated wood during pyrolysis, thermal decomposition, Thermo Gravimetric Analysis, TGA, volatilization of arsenic compounds, carbonized-treated wood