The use of supercritical fluid was tested for the purpose of developing an environmentally benign technique for metal extraction from CCA-treated waste wood. The effects of a chelating agent and extraction conditions on metal recovery were examined experimentally. The recovery for copper and chromium was relatively high but that for arsenic was very low. Metal recovery by pure supercritical carbon dioxide was very low because the affinity between carbon dioxide and metal seemed to be weak. However, it was significantly improved by adding acetylacetone as a chelating agent. The metals in wood were found to be extracted uniformly in all regions of a piece. It was also found that continuous addition of acetylacetone increased metal recovery compared with the one-time addition at the beginning.

View full abstract

The service life of Sugi (Cryptomeria japonica) heartwood treated with wood-vinegar and wood-tar was estimated by a field stake test. The test site was located in Tsukuba, Ibaraki, Japan. Results after 15 years exposure in a outdoor condition indicated that service life of wood-tar treated-heartwood was 6, 15, 15, and 15 years in the uptake of 61kg/m³, 146kg/m³, 149kg/m³ and 227kg/m³, and that of wood-vinegar treated-heartwood was 5, 6, 7 and 5 years in the uptake of 99kg/m³, 260kg/m³, 480kg/m³ and 639kg/m³ and that of untreated-heartwood was 4 years respectively.

View full abstract