THE INFLUENCE OF ACCELERATED FIXATION ON THE STABILITY OF CHROMIUM(V) IN CCA-TREATED WOOD

Ponderosa pine match stick specimens were impregnated with chromated-copperarsenate preservative (CCA) and the treated wood subjected to, storing under ambient conditions, oven drying or steam treatment. The samples were analyzed by electron spin resonance spectrometry (ESR). Accelerated fixation of CCA by steam treatment initially produced a strong chromium(V) ESR signal, which quickly decreased. Complete reduction of Cr(VI) to Cr(III) was achieved in 2 hours by steaming. Samples stored under ambient conditions still exhibited a moderately strong chromium(V) signal after 44 days. Oven drying of the CCA-treated samples for four days, failed to convert all of the chromium(V) intermediate to the trivalent form. Leaching of CCA-treated samples, confirmed that fixation was best achieved with the steam treatment. Oven drying caused the samples to leach large amounts of copper and smaller amounts of chromium and arsenic.