硫脲改性壳聚糖微球对Pt^(4+)和Pd^(2+)的吸附特性 Ⅱ.吸附热力学和脱附  

Adsorption Performance of Thiourea-Modified Chitosan Microspheres to Pt^(4+) and Pd^(2+) Ⅱ.Adsorption Thermodynamics and Desorption

作　　者：刘成佐[1] 周利民[1,2] 黄群武[2] 刘峙嵘[1] 

机构地区：[1]东华理工大学核资源与环境教育部重点实验室,江西抚州344000 [2]天津大学化工学院,天津300072

出　　处：《石油化工》2009年第6期635-639,共5页Petrochemical Technology

基　　金：江西省教育厅科技项目(GJJ08302);东华理工大学核资源与环境开放基金项目(070710)

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。Thiourea-modified chitosan microspheres （TCS） were used in adsorption of Pt^4＋ and Pd^2＋ in aqueous solution. Adsorption isotherms of Pt^4＋ and Pd^2＋ at different temperatures obtained batchwisely were investigated. Desorption of Pt^4＋ and Pd^2＋ and potential regeneration of TCS were also studied. Saturated adsorption amounts of both Pt^4＋ and Pd^2＋ decreased with raising of adsorption temperature. Adsorption isotherm were well described by Langmuir model. Main mechanism for Pt^4＋ and Pd^2＋ 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 Pt^4＋ and - 54.77 kJ/mol for Pd^2＋ , 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 Pd^2＋ , which indicates that adsorption reaction is spontaneous. Mixture of 1.0 mol/L thiourea solution and 0. 5 mol/L H2SO4 solution could desorb Pt^4＋ and Pd^2＋ effectively with desorption efficiency of 97. 16% and 99. 38% respectively. TCS showed excellent performance for separation and concentration of Pt^4＋ and Pd^2＋ , and can be reused several times.

关 键 词：硫脲改性壳聚糖 铂离子 钯离子 脱附 吸附 

分 类 号：TQ425.23[化学工程]