What is it about?
A laboratory scale sustainable commercial green process for treatment of indium-tin-oxide (ITO) etching wastewater and total recovery of In, Mo, Sn and Cu by combination liquid-liquid extraction and wet chemical reduction has been developed. The ITO etching wastewater is a threat to the ecosystem and human health, containing significant amounts of valuable metals like In and Cu. In metal and 100nm Cu nanopowder with 5N purity has been recovered. The developed process concurrently treats the ITO etching wastewater and recovers pure metals. By the process, Mo and Sn are recovered by liquid-liquid extraction, In is recovered through liquid-liquid extraction followed by wet chemical reduction. Value added semiconductor industry grade Cu nanopowder is recovered through wet chemical reduction using ascorbic acid. After a series of treatment, the wastewater is free of pollutant, worthy to use in the same industry or disposed. The process is a sustainable, green, versatile and flexible process.
Why is it important?
(i) This paper addresses the gap between research on metal value recovery and wastewater treatment process, commercially applicable process development and fundamental research. (ii) Most of the recovery processes reported in the open literature is about a gram to sub-gram metal recovery process, but the developed process offers versatile and flexible approach for mass production capability up to kilogram scale. (iii) The developed proposed flow sheet is a clean, green and a techno-economical feasible process for commercial treatment of several tons (m3) etching wastewater per day. (iv) The proposed process could completely recover the In with 99.999 % (5N) purity, quantitatively recover Mo and Sn with at least 99 % purity and value added Cu nanopowder with 99.999 % (5N) purity. (v) Wastewater after treatment is heavy metal free and can be disposed or reused in the same ITO etching process. (vi) Regeneration and reuse of all the organic extractant, use of non-hazardous inexpensive chemical in the process, and recovery of industrially valuable metals eventually, make the process an economical clean and green process.
The following have contributed to this page: Dr Basudev Swain
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