The electrode reactions of the Ce 3+ /Ce couple in molten LiCl–KCl eutectic in the temperature range 723–823 K on solid Mo electrodes were investigated by electrochemical techniques . The mechanism of deposition of metallic cerium has been established. It was found that the cathode reaction is irreversible and proceeds in one stage. The apparent standard Gibbs energy of CeCl 3 formation from the elements was calculated. The values of enthalpy and entropy were equal: ΔH* = − 1000.2 kJ/mol, ΔS* = 166.0 J/mol·K. The conditions of high-purity cerium production have been studied. The chemical structure of cathode deposits as well as the surfaces of the crucible were investigated by XRD , ICP and SEM-EDS methods. It was established that the best results for purification of the cathode product from impurities were achieved in the range 40–60 mA/cm 2 using a two-stage electrolysis. The amounts of the main impurities in the final product were 0.005 wt% Al, 0.0021 wt% Fe, and 0.003 wt% Si. The total purity of metallic cerium after cleaning was increased up to 99.971 wt% if a vitreous carbon crucible was used.
Xi Zhang,Huaimeng Li,Mengxiang Ye,Haimin Zhang,Guozhong Wang,Yunxia Zhang
To solve metal resource shortage and alleviate environmental issues, it is in urgent need to explore cost-effective and environment-friendly adsorbents for sustainable recovery of valuable gold from e-waste. Herein, bacterial cellulose (BC) hybrid membrane grafted with adipic dihydrazide (ADH) has been fabricated via a facile schiff base reaction strategy for efficient and selective recovery of gold from complex aqueous media. The resulting [email protected] hybrid membrane features high ratio of hydrazide groups (67% of ADH by mass content) and hierarchical porous structure, ensuring high adsorption capacity (1149 mg/g) and fast adsorption equilibrium time (20 min) toward gold. Meanwhile, the remarkable recovery selectivity of gold is achieved in the simulated e-waste leachate containing a large amount of interfering metal ions. Notably, the captured Au(III) species on [email protected] hybrid membrane can be directly converted by redox-active hydrazide groups into Au(0) with no need of any external reductant. Furthermore, the developed [email protected] membrane possesses superior recycling and reusability performance, as reflected by no obvious decrease in gold extraction capability after six cycles. More importantly, the [email protected] hybrid membrane is capable of extracting almost 100% of gold from actual waste central processing unit (CPU) leachate, yielding high-purity gold (23.7 K) after pyrolysis.
危险品化学品经营许可证（带存储）