Xi Chen,Xincun Tang,Zhihao Rong,Liping Wu,Pin Deng,Yang Wang,Xing Li,Liuchun Huang,Wei Dang
This paper presents an eco-friendly method for recovery of cadmium by solvent extraction and stabilization of arsenic through one-pool treatment on arsenic-rich flue dust. The morphology-controlled scorodite can be realized by adjusting reaction temperature. It is worth emphasizing that the arsenic-immobilized scorodite precipitates have superior crystallinity which exhibit excellent safety for long-term storage. In addition, the advantage brought about by taking hydrogen peroxide as leaching agent is that leachate is weakly acidic, which removes the need to add a large amount of neutralizing agent and facilitates the synthesis of scorodite. The results show that 97.3% of arsenic was leached from arsenic-rich flue dust and then 92.8% of the leached arsenic was transferred into scorodite with the recovery of 81.5% of cadmium under the optimal conditions. We hope that this work will provide a facile and environmentally friendly protocol for those interested in developing a new strategy for simultaneously recovering and stabilizing toxic heavy metal ions from industrial dust.
Cadmium-based semiconductors have a wide range of applications in light-emitting, energy conversion, photodetection and artificial photosynthesis. With the concern about the potential toxicity of Cd, it is necessary to recycle the element from the Cd based semiconductors. Commonly, the precipitation of Cd cations with S 2− is deemed as the end point of recycling. However, actually, CdS is easy to be oxidized and released into the environment and accumulate in the food chain. It still remains challenges on how to refine the Cd element and convert it to the raw material. Herein, we demonstrate a facile room temperature method for recycling Cd from CdS. Cd can be produced from CdS within 3 h with the help of the lithium-ethylenediamine solution. DFT calculations further confirm that the high surface energy of (100) and (101) planes are selectively attacked by the solvated electrons in the solution, which is in good accordance with the XRD, STEM-HAADF and XPS characterizations. With a total recovery efficiency of 88%, Cd is successfully recovered from the CdS powder. This method provides a new perspective on the treatment of Cd-based semiconductor waste, which is of great significance for the recycling of cadmium metal.
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