The chemistry of chromated copper arsenate II. Preservative-wood interactions

Abstract

 The reactions which cause chromated copper arsenate preservative  to fix strongly into wood are reviewed. A number of the mechanisms proposed in the literature appear chemically implausible. A new model is advanced in which the final fixation products are dominated by chromium (III) arsenate, chromium (III) hydroxide, and copper (II)- wood carboxylate complexes. Carboxylate groups should be generated in large numbers in the reduction of chromium (VI) by primary alcohol groups in lignin and carbohydrate fractions, or in the oxidative degradation of lignin. The model is supported by a recent X-ray absorption fine structure analysis.