FIXATION AND LEACHING CHARACTERISTICS OF CCA-TREATED MALAYSIAN HARDWOOD

Abstract

Effects of chromated copper arsenate (CCA) on fixation and leaching characteristics of eight Malaysian commercial hardwood, namely, acacia (Acacia mangium), bintangor (Calophyllum sp.), geronggang (Cratoxylum arborescens), medang (Litsea sp.), meranti rambai daun (Shorea acuminata), putat (Planchonia sp.), ramin (Gonystylus sp.) and simpuh (Dillenia sp.) were studied. CCA-fixation rate in wood was evaluated by monitoring the reduction of hexavalent to trivalent chromium in expressates. The amounts of copper, chromium and arsenic remaining in the unfixed state after 14 days were also determined. Acacia was the most suitable species for treatment with CCA. In comparison with radiata pine, leaching of CCA components from treated timbers was high and varied between species owing to their chemical composition especially lignin content. An additional study was conducted with geronggang and ramin to determine the effect of pre-extraction on fixation. Results indicated that differences in fixation and leaching characteristics of CCA-treated timbers (especially geronggang and ramin) were influenced by the extractive content of the wood.