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영어

In this presentation, we suggest two methods for the recovery of gold from gold-cyanide solutions. The biomass of Corynebacterium glutamicum generated from fermentation industry was used as a biosorbent. The capacity of the biosorbent for the binding of Au(I) ions from for cyanide solutions was examined through batch experiments, such as pH edge, isotherms and kinetics. For the pH edge experiment, the solution pH strongly influenced the sorption capacity. With the increase in the pH value, the uptake of Au(I) decreased, except at pH under 3. The Langmuir and Freundlich models were used to fit the experimental data. Between them, the Langmuir model described the experimental data very well with high correlation coefficient (R2=0.9946). According to Langmuir isotherm the maximum uptake of Au(I) at pH 2.5 were estimated to be 35.149 mg/g. The equilibrium of sorption process could be attained after 15 min. Gold ion (Au+) was able to be successfully eluted from the Auloaded biosorbent with D.I. water at pH 7, where the desorption efficiency was 91%. However, aqua regia was not a good eluent (41% of desorption efficient). From the results, it can be noted that the combined process of biosorption and desorption would be effective for the recovery of gold as the form of gold ion (Au+). We tried a different approach to recover zero-valent gold by incinerating the Auloaded biosorbents. Incineration resulted in the removal organic impurities and at the same time, reduction of the gold ions during oxidation of organics. As a result, the zero-valent gold content in ash was as high as 60 – 70%. It was also found that the purity of gold in ash could be enhanced by increasing the the uptake of gold by the biosorbent. Therefore, we may suggest that the combined method of biosorption and incineration can be useful for the recovery of zero-valent gold from goldcyanide solutions