Selective recovery of pure copper nanopowder from indium-tin-oxide etching wastewater by various wet chemical reduction process: Understanding their chemistry and comparisons of sustainable valorization processes

Basudev Swain, Chinmayee Mishra, Hyun Seon Hong, Sung-Soo Cho
  • Environmental Research, May 2016, Elsevier
  • DOI: 10.1016/j.envres.2016.01.032

What is it about?

Sustainable valorization processes for selective recovery of pure copper nanopowder from Indium-Tin-Oxide (ITO) etching wastewater by various wet chemical reduction processes, their chemistry has been investigated and compared. After the indium recovery by solvent extraction from ITO etching wastewater, the same is also an environmental challenge, needs to be treated before disposal. After the indium recovery, ITO etching wastewater contains 6.11 kg/m3 of copper and 1.35 kg/m3 of aluminum, pH of the solution is very low converging to 0 and contain a significant amount of chlorine in the media. In this study, pure copper nanopowder was recovered using various reducing reagents by wet chemical reduction and characterized. Different reducing agents like a metallic, an inorganic acid and an organic acid were used to understand reduction behavior of copper in the presence of aluminum in a strong chloride medium of the ITO etching wastewater. The effect of a polymer surfactant Polyvinylpyrrolidone (PVP), which was included to prevent aggregation, to provide give dispersion stability and control the size of copper nanopowder was investigated and compared. The developed copper nanopowder recovery techniques are techno-economical feasible processes for commercial production of copper nanopowder in the range of 100-500 nm size from the reported facilities through a one-pot synthesis. By all the process reported pure copper nanopowder can be recovered with > 99 % efficiency. After the copper recovery, copper concentration in the wastewater reduced to acceptable limit recommended by WHO for wastewater disposal. The process is not only beneficial for recycling of copper, but also helps to address environment challenged posed by ITO etching wastewater. From a complex wastewater, synthesis of pure copper nanopowder using various wet chemical reduction route and their comparison is the novelty of this recovery process.

Why is it important?

 From the Indium-Tin-Oxide etching wastewater, copper nanopowder was synthesized.  Solution chemistry of ITO etching wastewater is addressed.  A techno-economical feasible, environment friendly and occupational safe process.  Brings back the material to production stream and address the circular economy.  A cradle to cradle technology management, which lowers the futuristic carbon economy


Dr Basudev Swain (Author)
Institute for Advanced Engineering (IAE)

Three different valorization processes for selective and efficient recovery of pure copper micro and nanopowder from ITO etching wastewater from various wet chemical reduction process investigated and compared. The fundamental chemistry involved in the process is explored and discussed, which can add value for flexible and versatile application of the process other than particular wastewater system. The same process can even be used for different compositions of copper bearing wastewater. Unlikely most of the copper nanopowder preparation reported literature, instead of the pure chemical precursor, from a complex and impure industrial wastewater the value added copper nanopowder was synthesized, which are novel, economical and environment friendly process. Using PVP the shape and size can be controlled through wet chemical reduction of copper in various acidity, which is a very important information for total recycling of ITO etching waste, an industrial waste stream. More importantly, the process can be applied in industrial production and recycling resources. The developed copper nanopowder recovery processes are techno economical feasible process for commercial production of copper nanopowder in the range of 100-500 nm size from the reported facilities through a one-pot synthesis. The combination of processes offers versatility and flexibility for mass production capability up to kilogram scale. As reported processes are simple process do not require any special industrial facilities, through which electronics manufacturing industry can address various issues like; (i) waste disposal as well as value added copper recovery, (ii) brings back the material to production stream and address the circular economy, and (iii) can be part of cradle to cradle technology management and lower the futuristic carbon economy, simultaneously.

The following have contributed to this page: Dr Basudev Swain