Evaluation and Testing of Analytical Methods for Cyanide Species in Municipal and Industrial Contaminated Waters

Abstract

Total cyanide analysis by distillation is used most commonly to assess cyanide content of water samples. This manual method is robust but slow and provides no information about cyanide speciation, a significant limitation in that cyanide species have substantially different toxicity characteristics. Seven alternative methods for the analysis of cyanide species or groups of species were evaluated in reagent water and five different contaminated water matrices, including five species-specific methods--weak acid dissociable (WAD) cyanide, free cyanide by microdiffusion, available cyanide, automated WAD cyanide by thin film distillation, metal cyanides by ion chromatography--and two automated techniques for total cyanide--total cyanide bythin film distillation and total cyanide by low-power UV digestion. The species-specific cyanide analytical techniques achieved low, ppb-level detection limits and exhibited satisfactory accuracy and precision for most contaminated waters. Analysis of low concentrations of cyanide species in raw wastewater was problematical for the available cyanide and ion chromatography methods, which experienced significant interference problems and/or low recoveries. There was recovery of significant diffusible cyanide in microdiffusion tests with nickel-cyanide-spiked samples, reflecting dissociation of this weak metal-cyanide complex during the test and demonstrating that the test can recover some fraction of WAD cyanide in addition to free cyanide. The automated total cyanide methods, which involve UV digestion, achieved low detection limits for most waters but exhibited low recoveries for some waters.

Review of the Impact on Water Quality and Treatment Options of Cyanide Used in Gold Ore Processing

“…The use of microorganisms in the degradation of cyanide in tailing ponds has often been found to be potentially inexpensive and environmentally friendly compared to conventional chemical and physical processes [23,71,72]. Enzymatic activities associated with certain species of bacteria, fungi and algae are known to oxidise cyanide to less toxic cyanate [20,73,74].…”

“…Compounds of cyanides present in water can be generally classified into total cyanide, complex cyanide and free cyanide [23][24][25]. These aqueous cyanide compounds exist as simple and complex cyanides, cyanates and nitriles.…”

Isolation of a strain of Aspergillus fumigatus able to grow in minimal medium added with an industrial cyanide waste

“…In general it is estimated that the release of cyanide from industries is [14 million kg/year (Ebbs 2004). Cyanide may be present in the environment in various forms including hydrogen cyanide, salts such NaCN and KCN, metal cyanide complexes and nitriles (Dubey and Holmes 1995;Young and Jordan 1995;Aksu et al 1999;Patil and Paknikar 2000;Botz 2001;Akcil 2003;Zheng et al 2003;Ebbs 2004). The metal cyanide complexes form by reaction of cyanide with metal ions such as copper, nickel, zinc and iron and have varying stability and toxicity (Patterson 1985;Silva-Avalos et al 1990;Desai and Ramakrishna 1998;Gonçalves et al 1998;Patil and Paknikar 2000).…”

Treatment of metal cyanide bearing wastewater by simultaneous adsorption and biodegradation (SAB)

“…The release of cyanide from these industries worldwide has been estimated to be more than 14 million kg/year [1]. Generally cyanide compounds present in environmental matrices and waste streams as simple and complex cyanides, cyanates and nitriles [1,7]. The stability of cyanide salts and complexes is pH dependent, and therefore, their potential environmental impacts and interactions (i.e.…”