| Antimony and its compounds are widely used in flame retardants,ceramics,military products and other fields in national economic construction due to its unique physicochemical properties.As a member of metal powders,antimony powders have a wide application prospect in lubricating material,battery material,alloy manufacture and semiconductor research.The preparation of antimony powders by electrolysis is considered to be a method with strong controllability and easy to realize industrialization.However,most traditional electrolysis methods use aqueous solution or organic solvent system as electrolyte,which inevitably has the problems of low current efficiency and environmental pollution.Deep eutectic solvents?DESs?has the characteristics of simple synthesis,biodegradable,wide electrochemical window,cheap and easy to get,etc.In this paper,it is used as an electrolyte in the electrolytic preparation of antimony powders,aiming to solve the above problems existing in the traditional electrolytic method,and improve the production efficiency and quality of antimony powders.The major research results are drawn as follows:?1?Sb Cl3+choline chloride-ethylene glycol?Ch Cl-EG?DES is synthesized by dissolving Sb Cl3to the Ch Cl-EG DES.The effects of temperature and Sb Cl3concentration on viscosity and conductivity are measured.The results show that elevated temperature decreases the viscosity and increases the conductivity of Sb Cl3+Ch Cl-EG DES,while increasing the concentration of Sb Cl3increases the viscosity and decreases the conductivity.?2?A new process of preparing antimony powders by electrolysis in Sb Cl3+Ch Cl-EG DES is investigated and proposed.Taking Sb Cl3+Ch Cl-EG DES as electrolyte,titanium substrate as cathode and metallic antimony as anode,the effects of current density,reaction temperature and Sb Cl3concentration on current efficiency,specific energy consumption and antimony powders morphology are discussed by single factor variable experiment.The results demonstrate that the current efficiency increases with the increase of current density,reaction temperature and Sb Cl3concentration.However,the specific energy consumption decreases with the decrease of current density,the increase of reaction temperature and the increase of Sb Cl3concentration.In 100 m M Sb Cl3+Ch Cl-EG DES,electrolysis is conducted under the conditions of 353 K and constant current density of 40 m A·cm-2.The current efficiency and specific energy consumption are up to 97.44%and 912.696 k W·h·t-1,respectively.The particle size of the obtained antimony powders are in the micrometer range,and they become finer as the current density increases,the reaction temperature decreases,and the Sb Cl3concentration decreases.The initial nucleated antimony particles are embroidered spherical,and the morphology of antimony powders obtained under different process conditions are pine cone,wheat grain,dendritic,and fruit grain,etc.?3?The electrochemical behavior of the redox couple Sb?III?/Sb during electrolysis in Sb Cl3+Ch Cl-EG DES is analyzed by using electrochemical test technology.Cyclic voltammetry test results indicate that the reduction of Sb?III?to Sb on the titanium electrode is a quasi-reversible process via a one-step reaction and controlled by diffusion.The apparent activation energy is about 50.723 k J·mol-1.Both the increase of reaction temperature and the increase of Sb Cl3concentration are beneficial to the precipitation of Sb.The diffusion coefficient of Sb?III?in Sb Cl3+Ch Cl-EG DES increases with increasing reaction temperature and decreases with increasing Sb Cl3concentration.At 313 K,the diffusion coefficient obtained by the rotating disk electrode test is 7.266×10-8cm2·s-1,which is close to 6.301×10-8cm2·s-1measured by voltammetry.The linear sweep voltammetry tests illustrate that the anodic dissolution is accelerated with the increase of the reaction temperature and suppressed with the increase of Sb Cl3concentration.Cathodic processes are promoted under higher reaction temperature and higher Sb Cl3concentration.The chronoamperometry analysis reveals that the initial nucleation of antimony on titanium electrode is fit well with the three-dimensional progressive nucleation model at 10 m M Sb Cl3,while at50?100 m M does not strictly follow the three-dimensional nucleation model. |
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