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Leachability of Spent Chromated Copper Arsenate (CCA)-Treated Wood Encapsulated in Geopolymer Cement
Chromated copper arsenate (CCA) is one of the most commonly used waterborne preservatives to protect wood from environmental damage in various outdoor applications. However, the leaching of arsenic and chromium into the environment has been confirmed in recent years. As a result, CCA-treated woods are classified as hazardous waste and must be disposed of in sanitary landfills. In this study, a sustainable reuse option for the spent CCA-treated wood, with a focus on the environmental and economic benefits of the process, is investigated. The pilot-scale decontamination of CCA-treated wood chips is performed with 0.05 M oxalic acid at 45 °C for 4 hours with a solid: liquid ratio of 50 g/L. To increase copper removal, the pH of the leachate is increased by adding sodium hydroxide towards the end of the reaction. Under the optimum operational condition, over 60% of arsenic, 55% of chromium, and 40% of copper ions are removed from the wood chips. These results compared well with the laboratory-scale experiments under the same operating conditions. The decontaminated wood chips were used to make geopolymer cement (GPC) wood composites. Similar blocks were made with CCA-treated wood chips that were not decontamination. To ensure that the GPC-wood blocks are environmentally safe, three basic tests, namely the synthetic precipitation leaching procedure (SPLP), the toxicity characteristics leaching procedure (TCLP), and the accelerated evaluation of preservative leaching (AEPL) test, were performed on both types of blocks. In all tests, the CCA leached from decontaminated GPC-wood blocks was less than 5 mg/L. However, arsenic leached from the contaminated blocks exceeded the environmental limit of 5 mg/L. These results confirmed the environmental safety of GPC-wood blocks made with decontaminated CCA wood, which can be an economical and safe solution for the disposal of CCA waste wood.
Leachability of Spent Chromated Copper Arsenate (CCA)-Treated Wood Encapsulated in Geopolymer Cement
Chromated copper arsenate (CCA) is one of the most commonly used waterborne preservatives to protect wood from environmental damage in various outdoor applications. However, the leaching of arsenic and chromium into the environment has been confirmed in recent years. As a result, CCA-treated woods are classified as hazardous waste and must be disposed of in sanitary landfills. In this study, a sustainable reuse option for the spent CCA-treated wood, with a focus on the environmental and economic benefits of the process, is investigated. The pilot-scale decontamination of CCA-treated wood chips is performed with 0.05 M oxalic acid at 45 °C for 4 hours with a solid: liquid ratio of 50 g/L. To increase copper removal, the pH of the leachate is increased by adding sodium hydroxide towards the end of the reaction. Under the optimum operational condition, over 60% of arsenic, 55% of chromium, and 40% of copper ions are removed from the wood chips. These results compared well with the laboratory-scale experiments under the same operating conditions. The decontaminated wood chips were used to make geopolymer cement (GPC) wood composites. Similar blocks were made with CCA-treated wood chips that were not decontamination. To ensure that the GPC-wood blocks are environmentally safe, three basic tests, namely the synthetic precipitation leaching procedure (SPLP), the toxicity characteristics leaching procedure (TCLP), and the accelerated evaluation of preservative leaching (AEPL) test, were performed on both types of blocks. In all tests, the CCA leached from decontaminated GPC-wood blocks was less than 5 mg/L. However, arsenic leached from the contaminated blocks exceeded the environmental limit of 5 mg/L. These results confirmed the environmental safety of GPC-wood blocks made with decontaminated CCA wood, which can be an economical and safe solution for the disposal of CCA waste wood.
Leachability of Spent Chromated Copper Arsenate (CCA)-Treated Wood Encapsulated in Geopolymer Cement
Innovative Renewable Energy
Sayigh, Ali (editor) / Katoozi, Elmira (author) / Liow, Jong-Leng (author) / Khennane, Amar (author) / Pignatta, Gloria (author)
2023-09-08
10 pages
Article/Chapter (Book)
Electronic Resource
English
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