A Green and Novel Technology for Recovering Copper and Wood from Treated Wood Waste – Part II: Optimization, copper metal recovery, and process design

IRG/WP 17-50326

S Chen, R Patel

The US consumes 70 million pounds of copper and produces 580 million cubic feet treated wood annually. The EPA disallows burning and reusing treated wood waste due to health/environmental concerns. Vast quantities of copper and wood are landfilled. Two safe and low cost extraction systems, citric acid and ammonium citrate, were identified in Part I of this study. In Part II of the study, effects of extraction conditions such as time, temperature, and equilibrium copper concentration were determined. More than 95% of copper was removed either at ambient temperature for 8 hours or at 40oC for 4 hours. The resulting solution was used in consecutive extractions with new batches of wood until copper reached its rate limiting concentration. The study demonstrated that copper in the extraction solutions could be electroplated onto various metal surfaces, thus efficiently recovered. This process regenerated aqueous solutions to be reused for future extraction. A chemical/engineering process was developed with this study for extracting copper from treated wood wastes, recovering copper from extraction solutions by electroplating, and cyclic use of regenerated aqueous solution. This green and novel technology can keep copper and wood from the landfill and bring tremendous environmental, economic, and social benefits.

Keywords: treated wood waste, copper recovery, electroplating, citric acid, ammonium citrate, chemical engineering process

Conference: 17-06-04/08 Ghent, Belgium

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