Remediation of CCA-C treated wood using chelating agents

Abstract

This study evaluates the effects of the common chelating agents, ethylenediaminetetracetic acid (EDTA), nitrilotriacetic acid (NTA), and oxalic acid (OA) on the removal of copper, chromium, and arsenic from CCA-C treated wood. In the study, the removal of the metal oxides from treated chips and sawdust by EDTA and NTA in conjunction with OA in dual extraction processes was investigated using batch-leaching experiments. Exposing CCA-C treated chips and sawdust to chelat extraction enhanced the removal of CCA-C components compared to extraction by deionized water. Grinding CCA-C treated wood chips into 40-mesh sawdust provided greater access to and removal of CCA-C components. Extraction with EDTA/OA and NTA/OA in dual extraction processes removed about 100% copper and arsenic and 90% chromium from CCA-C treated sawdust. However dual extraction of CCA-C treated chips resulted in about 80% copper and arsenic, and 70% chromium removal. In single extraction processes, EDTA and NTA removed significant amounts of copper from CCA-C treated chips and sawdust compared to other components.