The treatment of cyanide from gold mine effluent by a novel five-compartment electrodialysis

• The five-compartment ED could be used for the recovery / removal of cyanide.
• The CN− extraction percent of 87.14% was achieved at 30 V applied voltage.
• The removal rate of cyanide reached up to 97.90% at 38 V applied voltage.
• The recovery of alkaline solution was achieved in the five-compartment ED process.
• This research provides a new insight into the resource recycling of cyanide.

In this paper, a novel approach of five-compartment electrodialysis was proposed for the treatment of cyanide from gold mine effluent. Two different processing modes were introduced. In mode 1, the cyanide was removed with homogeneous ion exchange membranes and heterogeneous ion exchange membranes respectively. In mode 2, the recovery of cyanide was achieved with homogeneous monovalent anion exchange membranes (1-AEMs) and cation exchange membranes (CEMs). The applied voltage was optimized to improve the removal and recovery efficiency. In addition, pH variation (the recovery of alkaline solution) was investigated. The results showed that the CN− extraction percent of 87.14% was achieved at 30 V applied voltage with the energy consumption of 8.33 kWhm−3 in mode 2. Meanwhile, the removal rate reached up to 97.90% with homogeneous ion exchange membranes at 38 V applied voltage in mode 1, which was much higher than the case of heterogeneous ion exchange membranes (74.02%). Finally, the recovery of alkaline solution was achieved as above and the recovered alkaline solution could be reused for pH adjustment in ED process. This research provides a new insight into the resource recycling of cyanide from gold mine effluent in industrial application.

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