Determination and Characterisation of Copper, Chromium and Arsenic in Chromated Copper Arsenate (CCA) Treated Wood and Its Pyrolysis Residues by Inductively Coupled Plasma Mass Spectrometry

Abstract

To dispose of chromated copper arsenate (CCA) treated wood waste, pyrolysis is a valuable method. In the context of a study aimed at optimising the pyrolysis of CCA treated wood, a method for the determination and characterisation of Cr, Cu and As in wood and its pyrolysis residues was developed. Leaching and dissolution procedures were applied and compared to determine the total amount of Cr, Cu and As in the dried wood and in the pyrolysis residue. A sequential extraction procedure was also applied to the pyrolysis residue and confirmed that As is bound to oxidised compounds, carbonates and the organic matrix. Copper showed a similar behaviour to As in the leaching environments considered, whereas Cr behaved in a totally different way. ICP-MS was used to determine Cu, Cr and As. Special attention was given to the analysis of the organic matrices resulting from the sequential extraction procedure. To determine the oxidation state of As in the different extraction steps, hydride generation coupled to ICP-MS was used. It could be seen clearly that AsIII is far more mobile than AsV and that the AsV compounds, originally present in the CCA solution and CCA treated wood, are partly reduced to AsIII compounds.