交联淀粉微球对Co^2＋吸附行为的研究

Studies on Adsorption Behaviors of Cobalt Ions on the Crosslinked Starch Microspheres

研究了以可溶性淀粉为原料，N，N’-亚甲基双丙烯酰胺为交联剂，采用反相悬浮聚合得到的一种交联淀粉微球（CSM）对Co^2＋的静态吸附行为，测定了吸附等温线，分析了吸附热力学性质和动力学特征。用红外光谱仪和X射线衍射仪对CSM及其吸附产物的结构特征进行了对照分析，探讨了吸附机理。在实验条件下，CSM对Co^2＋的吸附模式同时符合Langmuir和Freundlich等温方程，表观吸附速率常数k308k为0．0686min-1。不同温度下，CSM吸附Co^2＋的吸附焓变△H、吸附熵变△S、吸附吉布斯函数变△G均为负值，表明吸附是自发放热过程，降低温度有利于吸附。CSM主要通过物理吸附和配位吸附等方式吸附Co^2＋，这些吸附作用进一步破坏了CSM的结晶结构。

The static adsorption behaviors of Co^2＋ on the cross - linked starch microspheres （CSM） ） synthesized from soluble starch by inverse suspension polymerization with N, N＇ -methylenebisacrylamide as cross- linking agent were investigated at different temperatures. The property of adsorption kinetics was studied, and the thermodynamics parameters in adsorption process were calculated according to adsorption isotherm. The CSM and its adsorption product were comparatively characterized by Fourier Transform Infrared Spectroscopy （FTIR） and X -ray diffraction （XRD）, and the adsorption mechanism was also discussed. The results show that the adsorpti Co^2＋ on CSM is adapted to isothermal equation of Longmuir as well as Freundlich in the experimental on mode of conditions. The adsorption rate is mainly controlled by liquid film diffusion, and the constant of adsorption rate is 0.0686min^-1 at 308K. The adsorption thermodynamic parameters of Co^2＋ on CSM including enthalpy change ΔH, Gibbs function change ΔG and entropy change ΔS are negative in the temperature ranging from 308 K to 328K, which indicates the adsorption is a spontaneous and exothermic process, and the decrease of temperature should benefit the adsorption of Co^2＋ on CSM. The Co^2＋ was absorbed by means of physical adsorption and weakly complexation, and the sorption took from the crystallinity of CSM much more.