Preparation Of Fine Copper Powder And Stable Form Of Copper Ions By Electrolysis In Choline Chloride-urea Eutectic Solvent

Ultrafine copper powder is widely used in many areas due to its many characteristics.But the traditional aqueous electrolysis method and atomization oxidation-reduction method have some disadvantages,such as high energy consumption,big waste water emissions,high requirements for equipment,unstable quality of copper powder and so on.Deep eutectic solvents have non-combustion,high ion conductivity and electrochemical stability,wide electrochemical window,and a good solvent resistance and other characteristics.Therefore,with the development of metallurgical technology and new materials preparation technology,the electrodeposition of metals in deep eutectic solvents are attracting widespread attention.Ultrafine copper powder was prepared by electrolysis in choline chloride-urea deep eutectic solvent in this paper.The concentration of Cu(?)and Cu(?)in the electrolyte under various experimental conditions were determined by Uv-vis spectrophotometry.The effect of the various experimental conditions on the concentration of Cu(?)and Cu(?)in the electrolyte,particle size and morphology of copper powder,current efficiency and the direct current consumption were investigated.The ligand structure of Cu(?)ions in the electrolyte was studied by electro spray mass spectrometry and infrared absorption spectrometry.The major research results are drawn as follows:(1)During the preparation of fine copper powder in choline chloride-urea deep eutectic solvent,the copper ions mainly exists in the form of monovalent copper species and the monovalent copper species can not easy to be oxidized into bivalent copper,so the energy consumption is lower.(2)The raising of cathodic current density leads to the reducing in current efficiency and the increasing dc power consumption.The raising of electrolyzing temperature leads to the increasing in current efficiency and the reducing of power consumption.When the oxalic acid concentration is 0.1 mol· L-1,the current efficiency is highest and the power consumption is lowest.Adding a certain amount of CuCl2 and CuCl can improve the current efficiency and reduces the power consumption.(3)With the raising of cathodic current density,the particle size of copper powder increases firstly and then decreases.The particle size of copper powder is smallest and particle size distribution is the most narrow at 50 ?.Concentrations of oxalate in the context of 0.2 mol·L-1 has little effect on the particle size of copper powder.Compared with the experimental without CuCl,the adding of CuCl had no effect on the particle size and distribution of copper powder,but the particle size of copper powder with CuCl2,decreases.(4)There are dendritic copper powders in various experimental conditions,but other morphologies are also observed,such as:big block obtained at low temperatures,large "leaves" obtained at high concentration of oxalic acid,and spherical copper powder obtained under high current density.Adding a certain amount of CuCl and CuCl2 have effect on the morphology of copper powder.(5)[Cu1(Cl-)2]-ligand is formed from monovalent copper and chloride ion in electrolyte.