A comparative study on Cu, Cr and As removal from CCA-treated wood waste by dialytic and electrodialytic processes

In this study, electrodialytic and dialytic techniques were used for Cu, Cr and As removal from 20-years out-of-service CCA-treated Pinus pinaster Ait. pole. The effect of applying direct current, as "cleaning agent", of up to 120 mA was investigated. Focus was given to a parallel comparison with the performance of a pure dialytic experiment (without an external power supply) in order to reveal transport of charged particles induced solely by internal electrochemical potential differences in the system. Oxalic acid proved to be a more suitable pre-treatment solution than deionised water for wood chips incubation. Evaluation of the IARs of Cu, Cr and As showed that the rates of their appearance in the electrolytes were not linearly related to the current (except for Cr in the catholyte), mainly because of membrane retention. The maximum removal efficiencies obtained in a batch electrodialytic cell operated for 14 days were as follows: Cu, 84%; Cr, 87%; and As, 95%.