【摘要】 利用硫脲改性的壳聚糖微球(TCS)吸附水溶液中的Pt4+和Pd2+,得到了不同温度下Pt4+和Pd2+的吸附等温线,研究了TCS对Pt4+和Pd2+的吸附热力学、Pt4+和Pd2+的脱附以及TCS的重复使用性。实验结果表明,随吸附温度的升高,TCS对Pt4+和Pd2+的饱和吸附容量降低;吸附等温线符合Langmuir模型,TCS对Pt4+和Pd2+的吸附均以化学吸附为主。吸附温度为25~55℃时,TCS吸附Pt4+和Pd2+的焓变分别为-55.25,-54.77kJ/mol,表明吸附过程为放热过程;TCS吸附Pt4+和Pd2+的Gibbs自由能分别为-27.52~-24.73kJ/mol和-28.18~-25.50kJ/mol,表明吸附过程可自发进行。用1.0mol/L硫脲溶液和0.5mol/L H2SO4溶液的混合液脱附Pt4+和Pd2+时效果较好,对Pt4+和Pd2+的脱附率分别高达97.16%和99.38%。TCS有良好的重复使用性以及对Pt4+和Pd2+的分离富集性能。更多还原

【Abstract】 Thiourea-modified chitosan microspheres(TCS) were used in adsorption of Pt4+ and Pd2+ in aqueous solution.Adsorption isotherms of Pt4+ and Pd2+ at different temperatures obtained batchwisely were investigated.Desorption of Pt4+ and Pd2+and potential regeneration of TCS were also studied.Saturated adsorption amounts of both Pt4+ and Pd2+ decreased with raising of adsorption temperature.Adsorption isotherm were well described by Langmuir model.Main mechanism for Pt4+ and Pd2+ adsorption by TCS is complexing reaction so chemisorption is dominant.Enthalpy change at adsorption temperatures in range of 25-55 ℃ is-55.25 kJ/mol for Pt4+ and-54.77 kJ/mol for Pd2+,which suggests that adsorption process is exothermic.Gibbs free energy is from-27.52 kJ/mol to-24.73 kJ/mol for Pt4+ and from-28.18 kJ/mol to-25.50 kJ/mol for Pd2+,which indicates that adsorption reaction is spontaneous.Mixture of 1.0 mol/L thiourea solution and 0.5 mol/L H2SO4 solution could desorb Pt4+ and Pd2+ effectively with desorption efficiency of 97.16% and 99.38% respectively.TCS showed excellent performance for separation and concentration of Pt4+ and Pd2+,and can be reused several times.更多还原