Eliminating cyanide species from aqueous matrices: An overview on some physical-chemical and nano-based techniques

Treatment of polluted industrial waste waters attracts attention to protect environment and prevent hazards. Waste industrial waters containing metal cyanide are treated in various ways and several methods are explored in order to make the water free of highly poisonous cyanide. The present overview provides a study on the ways to reduce the toxicity of cyanide polluted water. The physical, chemical and biological methods employed to serve the purpose reveal that the treatment of cyanide containing water is best achieved by using biological methods by exploring the avenues of bio-sorption and biodegradation using micro-organisms. Results indicate that use of heterogeneous supports to immobilize living microbial cells under suitable reaction conditions improves efficiency of removal of cyanide. Several physical and chemical methods to remove cyanide from waste water are available and are employed; these methods often prove to be expensive and need costly chemicals or apparatus, require high pressure and temperature conditions to operate or may create byproducts or harmful waste that demands separate treatment. Environmentally benign solutions for treating waste water are of immense interest. Besides the use of conventional methods, the use of zeolites, clays, nano-materials and other materials such as resins for treatment of cyanide containing waste water are also reported.