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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。
The adsorption isotherms of Pt4 + and Pd2 + at different temperatures were obtained by using thiourea-modified chitosan microspheres (TCS) to adsorb Pt4 + and Pd2 + in aqueous solution. The adsorption thermodynamics of Pt4 + and Pd2 + by TCS, the adsorption thermodynamics of Pt4 + and Pd2 + Desorption and reusability of TCS. The experimental results show that with the increase of adsorption temperature, the saturated adsorption capacity of Pt4 + and Pd2 + decreases with the increase of adsorption temperature. The adsorption isotherms conform to the Langmuir model. The adsorption of Pt4 + and Pd2 + by TCS is dominated by chemical adsorption. The enthalpy changes of Pt4 + and Pd2 + adsorbed by TCS were -55.25 and -54.77kJ / mol respectively, indicating that the adsorption process was exothermic. The Gibbs free energies of Pt4 + and Pd2 + adsorbed by TCS were -27.52 ~ -24.73kJ / mol and -28.18 ~ -25.50kJ / mol, indicating that the adsorption process can spontaneously proceed. The desorption of Pt4 + and Pd2 + with 1.0mol / L thiourea solution and 0.5mol / L H2SO4 solution showed better effect, and the desorption rates of Pt4 + and Pd2 + were as high as 97.16% and 99.38% respectively. TCS has good reusability and separation and enrichment of Pt4 + and Pd2 +.