Résumé
AbstractThe development of appropriate disposal options for copper-based treated wood waste has been encouraged owing to stringent regulations regarding solid-waste landfilling or burning. Previous studies identified an efficient chemical process for removing metals from wood treated with chromated copper arsenate (CCA), alkaline copper quaternary (ACQ), copper azole (CA), and micronized copper quaternary (MCQ). The objective of this research was to identify optimal leaching parameters for removing copper from ACQ-, CA-, and MCQ-treated wood in terms of efficiency and operating costs. A 24 Box-Behnken design was used for determining influential parameters (sulfuric acid concentration, temperature, retention time, and number of leaching steps) on the copper removal and for identifying optimal leaching conditions. The results obtained showed that sulfuric acid concentration and number of leaching steps were the main influential parameters on copper solubilization from alternatively treated wood. The values of R2>0.91 for the mathematical models indicate a high correlation between observed and predicted values. The leaching conditions were optimized using response surface methodology, in which copper removal from ACQ-, CA-, and MCQ-treated wood wastes were to be maximized and operational costs were to be minimized. The optimum copper solubilization conditions were satisfied after three leaching steps of 2 h and 40 min each at room temperature and with an acid concentration fixed at 0.13 N followed by three rinsing steps. These optimal conditions led to 90, 90, and 93% of copper recovery from ACQ-, CA-, and MCQ-treated wood for a total cost of about US$180 per ton of treated wood. According to these results, chemical remediation from copper-treated wood appears to be an interesting solution to wood waste disposal problems.