辛胺萃取银的热力学研究

Thermodynamic Study on the Extraction of Silver with Octylamine

研究了以磺化煤油为稀释剂,辛胺为萃取剂萃取银的反应过程和热力学性质。在293.15~318.15 K的温度范围内和0.2~2.0 mol/kg的离子强度下萃取银,使用pH计测定水相的pH值,原子吸收分光光度法测定水相中的银含量,计算了萃取反应的萃取率,确定了最佳萃取条件。利用多项式拟合得到不同温度下的标准平衡常数K■,并研究了K■、熵、焓、吉布斯自由能与温度的关系。实验结果表明,低温和低离子强度更加有利于辛胺对银的萃取。热力学计算表明,萃取反应的吉布斯自由能、焓、熵均随着温度的降低而增加,均与温度负相关。

The reaction process and thermodynamic properties of silver extraction with sulfonated kerosene as diluent and octylamine as extractant were studied.Silver was extracted in temperature range of 293.15~318.15K and ionic strength of 0.2~2.0mol/kg.The pH value of aqueous phase was determined by pH meter,and the silver content in aqueous phase was determined by atomic absorption spectrophotometry.The extraction rate of the extraction reaction was calculated and the optimum extraction conditions were determined.The standard equilibrium constant K■ at different temperatures wow obtained by polynomial fitting,and the relations between K■,entropy or enthalpy,Gibbs free energy and temperature were stu-died.The experimental results show that low temperature and low ionic strength are more conducive to the extraction of silver by octylamine.Thermodynamic calculation shows that the Gibbs free energy,enthalpy and entropy of extraction reaction increase with the decrease of temperature,which are negatively correlated with temperature.