Abstract
ABSTRACT
The hypochlorite method of cyanide removal from electroplating wastewaters (both real and simulated) is compared to that of air stripping for cyanide removal, and recovery as sodium cyanide. The cyanide, as HCN, is purged with air at about 80 C, and then absorbed in a 1.5% sodium hydroxide solution. Although sodium cyanide is not a precious commodity the process can be cost effective for concentrated electroplating baths. Removal of cyanide was generally better by air stripping than by standard hypochlorite destruction. Additionally, 97.3 to 100% of the cyanide was recovered by a sodium hydroxide bath, and the removal of metals (Cd, Cu, Fe, Na and Zn) by sulfide precipitation was equivalent or better than the removal following hypochlorite destruction.
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