Rapid microwave-assisted acid extraction of southern pine waste wood to remove metals from chromated copper arsenate (CCA) treatment

Abstract Recovery of metals from chromated copper arsenate (CCA)-treated southern pine wood particles was investigated by extraction in a microwave reactor with binary combinations of acetic acid (AA), oxalic acid (OxA), and phosphoric acid (PhA). Use of OxA was not successful, as insoluble copper oxalate complexes impeded copper removal. The combination of OxA and AA also had adverse effects on copper extraction. In contrast, the combination of AA and PhA enhanced the chromium recovery rate. The highest recovery rate of metals could be achieved with a mixture of 2.75% PhA and 0.5% AA at 130°C for 10 min in the microwave oven. The total recovery rate approached 100% for arsenic, 96.7% for chromium, and 98.6% for copper in a one-step process.