The facile removal of cyanide anions from cyanide-containing water was achieved using CO 2 in conjunction with aldehydes which can be recycled from the process. The conversion of the cyanide ion into an insoluble cyanohydrin in water allowed the removal of cyanide and could be used as a method for treating cyanide contaminated wastewater and for recovering cyanide or cyanohydrins for further applications.Water purification is a prerequisite component for sustainable development of human society. [1] Most of modern water purification processes involve a process to physically reject and separate contaminants (ions, organic molecules, and heavier particles) from water. Physical separation is an energy-intensive process, often requiring high pressures (membrane separation) and temperatures (distillation). Therefore energy-efficient, or energy-neutral water purification processes would be ideal for sustainable water supply.Among many water contaminants, cyanide is known as being notoriously toxic as an inhibitor of cytochrome C oxidase by binding tightly to the iron center. 1-2 mg/kg of cyanide can be fatal for grown adult man, therefore, maximum contaminant level has been restricted to a low level (0.2 mg/L) in drinking water. [2] However, cyanide is a valuable chemical, used on industrial scale; around 1.1 million tons of HCN is produced annually worldwide where approximately 6 % of HCN is used to produce metal cyanide (NaCN and KCN) for gold and silver processing and electroplating. [3] The wastewater produced by gold extraction and electroplating still contains excess amounts of cyanides and poses a significant environmental challenge. [4] Releasing untreated cyanide waste into waterways has devastating effects on the environment. [5] In pharmaceutical manufacturing, cyanide control is critical to maintain safety while ensuring the process and waste streams compatible to regulations. [6] Hence cyanide waste, being detrimental to all lifeforms, is hazardous to handle and therefore expensive to dispose of. Sustainable methods for the re-isolation of cyanide[a] Dr. A