title: Factors affecting chelating extraction of Cr, Cu, and As from CCA-treated wood.
abstract: The disposal of chromated copper arsenate (CCA)-treated waste wood is becoming a serious problem in many countries due to potential leaching of hazardous elements from in-service use in the environment or disposal of solutions after remediation; therefore, it is necessary to develop proper remediation techniques. The effects of concentration, extraction period, temperature, and sequential extraction on the extraction of Cr, Cu, and As from CCA-treated wood using [S,S]-ethylenediaminedisuccinic acid (EDDS), ethylenediaminetetraacetic acid (EDTA), and nitrilotriacetic acid (NTA) were studied. Mobility of metal in the samples was evaluated by using a sequential extraction scheme that could give the information needed to explain different extraction efficiencies for different metals. Results of long-term leaching tests of CCA-treated wood before and after EDDS extraction were used to evaluate Cr, Cu, and As leachability. Kinetic experiments showed that 6 h was the optimum extraction time for all metals and CCA-treated wood. Experimental results showed that EDDS is a very effective chelating agent for the extraction of Cr, Cu, and As from CCA-treated wood. Increased temperature significantly enhanced the extraction efficiency of CCA metals, especially Cr and As. The much better extractability of Cu compared to Cr and As by chelating agents can be attributed to the presence of larger weakly bound fractions. The CCA-treated woods after EDDS extraction have met the EPA's TCLP regulatory limit and could be classified as a non-hazardous waste according to identification standard of hazardous wastes.
authors.affiliation: Department of Environmental Engineering, National Cheng Kung University, Tainan City 701, Taiwan, ROC. hfcchang@gmail.com
authors.forename: Fang-Chih
authors.initials: FC
authors.lastname: Chang
authors.forename: Ya-Nang
authors.initials: YN
authors.lastname: Wang
authors.forename: Pin-Jui
authors.initials: PJ
authors.lastname: Chen
authors.forename: Chun-Han
authors.initials: CH
authors.lastname: Ko
mesh_terms: D001149:Arsenates / Q000737:chemistry*; D002614:Chelating Agents / Q000737:chemistry*; D004492:Edetic Acid / Q000737:chemistry; D005029:Ethylenediamines / Q000737:chemistry; D009571:Nitrilotriacetic Acid / Q000737:chemistry; D012037:Refuse Disposal / Q000379:methods; D013386:Succinates / Q000737:chemistry; D014934:Wood / Q000737:chemistry*
chemical_list: D001149:Arsenates; D002614:Chelating Agents; D005029:Ethylenediamines; D013386:Succinates; C041447:N,N'-ethylenediamine disuccinic acid; C040890:chromated copper arsenate; D004492:Edetic Acid; D009571:Nitrilotriacetic Acid