Cyanide is the most widely used leaching reagent for gold extraction. Its environmental behaviour and fate is of significant environmental concern. β-cyanoalanine synthase(CAS) was found to be able to catalyse the conversion of cyanide to the ammino acid asparagine. This paper presents an investigation on the potential use of plant tissues to degrade cyanide. Excised plant tissues (1.0g fresh weight) from 3 woody plant speices out of the Salicaceae family were kept in a glass vessel with 100 mL spiked aqueous solution (oxygen-saturated deionized water) at room temperature of 20~23℃ for 28h. Samples were taken directly from the solution and determined photometrically at a wavelength of 638 nm. The cyanide removal rate was determined experimentally between 22.13% and 67.04% over a 28 h exposure period and varied with plant tissues and species. The maximum metabolic velocity, vmax, was 0.4934~1.9449 mg CN·kg-1 (fresh weight)·h-1. The highest removal velocity was 1.9449 mg CN·kg-1(fresh weight)·h-1 with the leaves from Poplar trees (Populus deltoides), followed by 1.7259 mg CN·kg-1 (fresh weight)·h-1 with the leaves of hybrid willow trees (Salix matssudana Koidz×Salix alba L). The lowest removal velocity was 0.4934 mg CN·kg-1 (fresh weight)·h-1 with the new stem from hybrid willow trees. Results of this investigation indicated that the plant tissues were able to metabolize cyanide. The maximum removal capacity was found in plant leaves of the three groups tested. In conclusion, using excised plant tissues seems to be a feasible option for the characterization of the degradation pathways of cyanide.
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