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Degradation of free cyanide by
photocatalytic oxidation Gold
is normally recovered from its ores by cyanidation process, which is a well-known
technique used worldwide. The merits of cyanide heap leaching technology of gold are well
known, but environmental problems arise occasionally due to high toxicity of cyanide.
Photocatalytic decomposition of cyanide was achieved using TiO2-SiO2
aerogel, V2O5-SiO2 xerogel or ozone. The cyanide removal
efficiencies were increased from 87 to 98.74% and from 85 to 99% by increasing loading wt.
% from 0.083 to 0.666 and from 0.083 to 0.166 for TiO2-SiO2 aerogel
and V2O5-SiO2 xerogel respectively. Also, the rates
constant were increased from 0.020 to 0.044 min-1 and from 0.022 to 0.045 min-1
for TiO2-SiO2 aerogel and V2O5-SiO2
xerogel respectively and the reaction kinetics were found to be first order. On the other
hand the optimum conditions of Photocatalytic degradation of cyanide using ozone were
found to be 2.5 wt. % ozone concentration, 1.14 m3/h airflow as well as 36 Watt
(W) UV light power . At these conditions, the cyanide removal efficiency was 99%, the rate
constant was found to be 0.0075 min-1 and the reaction kinetic was found to be
first order. |
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