咪唑基氰酸盐离子液体溶金性能及其对电子废弃物中贵金属溶出的应用研究

Study on Gold Solubilization Properties of Imidazolium Cyanate Ionic Liquids and Its Application in the Leaching of Precious Metals from Electronic Waste

在实验室条件下合成1-乙基-3-甲基咪唑氰酸盐([C_(2)MIM][OCN]),对其结构及性质进行了表征。研究了Au在([C_(2)MIM][OCN])中的溶解特性,分析了不同条件对([C_(2)MIM][OCN])溶金效果的影响,并对([C_(2)MIM][OCN])的溶金选择性进行初步研究。以电子废弃物针脚为浸出对象,通过扫描电镜能谱(SEM-EDS),X射线荧光光谱分析仪(XRF)及电感耦合等离子发射光谱(ICP-OES)等方法对针脚在([C_(2)MIM][OCN])中反应前后的形貌与成分进行分析,探究了([C_(2)MIM][OCN])对针脚中Au的浸出效果。并利用核磁共振波谱(NMR)及电喷雾质谱(ESI-MS)对溶金产物进行分析。结果表明,在乙腈等非质子溶剂中,([C_(2)MIM][OCN])的溶金效果更好。增加反应温度、药剂浓度及搅拌强度均可提高Au在([C_(2)MIM][OCN])中的溶出量。不同金属在([C_(2)MIM][OCN])中的浸出试验及电化学分析结果表明,Cu的溶解性最好,反应24 h后Cu的溶出量为171.6 mg/cm^(2),Ag的溶出量为19.7 mg/cm^(2),而Au为10 mg/cm^(2)且Ni不发生溶解。针脚中Au含量为2.58%且主要以镀层形式富集于针脚表面。([C_(2)MIM][OCN])可有效溶解针脚上的Au,但针脚中Cu的存在对Au的浸出效果存在影响。结合核磁共振波谱及电喷雾质谱分析,认为([C_(2)MIM][OCN])的溶金反应过程为Au失去电子形成金离子,咪唑阳离子发生去质子化形成N杂环卡宾并与金配位,形成氮杂环卡宾金配合物。

1-ethyl-3-methylimidazolium cyanate([C_(2)MIM][OCN])was synthesized under laboratory conditions and its structure and properties were char acterized.The dissolution characteristics of Au in([C_(2)MIM][OCN])were studied,the effects of different conditions on the gold dissolution of Au in([C_(2)MIM][OCN])were analyzed,and the gold dissolution selectivity of([C_(2)MIM][OCN])was preliminarily studied.Taking the pins as the leaching object,the reaction of the pins in([C_(2)MIM][OCN])was detected by scanning electron microscopy energy spectroscopy(SEM-EDS),X-ray fluorescence spectroscopy(XRF)and inductively coupled plasma emission spectroscopy(ICP-OES).The gold-dissolved products were analyzed by nucl ear magnetic resonance spectroscopy(NMR)and electrospray mass spectrometry(ESI-MS).The results show that the dissolution of Au in([C_(2)MIM]COCN])is better in aprotic solvents such as acetonitrile.The dissolution of Au in([C_(2)MIM][OCN])can be improved by increasing the reaction temperature,the concentration of the agent and the stirring intensity.The leaching test and elect rochemical analysis of different metals in([C_(2)MIM][OCN])showed that the dissolution of Cu in([C_(2)MIM][OCN])was the best,and the dissolution amount was 171.6 mg/cm^(2)after 24 h of reaction.The dissolution of Ag is second,its dissolution amount is 19.7 mg/cm^(2),while that of Au is 10 mg/cm^(2)and Ni does not dissolve in([C_(2)MIM][OCN]).The Au content in the pins is 2.58%and is mainly concentrated on the surface in the form of plating.([C_(2)MIM][OCN])can effectively dissolve Au on the pins,but the presence of Cu in the pins has an impact on the dissolution of Au.Combined with the analysis of NMR and ESI-MS,it is believed that the gold dissolution reaction process of([C_(2)MIM][OCN])is that Au loses electrons to form gold ions,and imidazolium cations deprotonate to form N-heterocyclic carbene and coordinate with gold ions to form nitrogen-heterocyclic car bene gold complex.