Effect of EDTA and CH2O on copper recovery from simulated electroless copper plating spent rinse water by unseeded fluidized-bed granulation process

Abstract

Copper-contaminated industrial wastewaters are usually treated by large-footprint conventional technologies that generate high-moisture sludge. These disadvantages led to the development of the unseeded fluidized-bed granulation process (UFBGP), an innovative green technology with potential to simultaneously remove copper from electroless copper plating spent rinse waters and recover them as high-quality granules. Electroless copper plating rinse water is a complex aqueous matrix containing copper ions and organic additives such as ethylenediaminetetraacetic acid (EDTA) and formaldehyde (CH2O) as complexing and reducing agents, respectively. Herein, we investigated copper removal and granulation from simulated electroless copper plating spent rinse waters containing EDTA and CH2O via the unseeded fluidized-bed granulation process. Results showed that copper removal and granulation from simulated spent rinse waters containing 186 mg L–1 EDTA reached 93% and 78%, respectively. On the other hand, copper removal and granulation from simulated spent rinse waters with 0.019 mg L–1 CH2O were 99% and 90%, respectively. However, simulated spent rinse waters containing both EDTA and CH2O had copper removal and granulation of 94% and 84%, respectively. Scanning electron microscope images of the recovered granules showed clusters of irregularly-shaped spherical solids while the X-ray diffractograms of the solids revealed crystalline properties identical to those of the mineral azurite. Overall, the study demonstrated the effectiveness of the UFBGP in recovering high-quality copper granules from simulated industrial wastewaters.