原位制备磁性壳聚糖纳米粒子及其对Ag(I)的吸附性能

以壳聚糖、Fe2+/Fe3+盐为水相,环已烷/正已醇为油相,TritonX-100为乳化剂,通过在W/O微乳体系中加NaOH溶液沉淀剂,原位制备磁性壳聚糖纳米粒子(MCN),用于吸附Ag(I)。考察了pH值、Ag(I)浓度和温度对MCN吸附Ag(I)的影响。结果表明,MCN分散良好,粒径15～40nm,饱和磁化强度25.6emu·g-1,pH6.0时吸附最佳,Ag(I)吸附容量随温度升高而降低。吸附动力学符合拟二级方程,且为自发放热过程。吸附等温线分别用Langmuir,Freundich和D-R模型拟合,表明Langmuir模型拟合最好,为单分子层吸附,最大吸附容量2.06mmol/g。吸附活化能E为8.94～9.10kJ/mol,表明以化学吸附为主。

In-situ Preparation of Magnetic Chitosan Nanoparticles and Its Adsorption Properties for Ag (I)

The magnetic chitosan nanoparticles (MCN) are in-situ prepared by adding the NaOH solution precipitant into a W/O microemulsion system, which is composed of chitosan and Fe2+/ Fe3+ salts solution as water phase, cyclohexane/ n-hexyl alcohol as oil phase, and Triton X-100 as emulsifier. The influences of different parameters such as pH, initial Ag (I) concentration and temperature on Ag (I) adsorption by MCN are investigated. The results show that MCN are monodispersed and have a particle size of 15~40 nm and a saturation magnetization of 25.6 emu/g. The optimum pH value for Ag(I) adsorption is pH 6.0. The Ag(I) adsorption capacity decreased with increasing the temperature. The adsorption kinetic is fitted well with the second-order model and the adsorption process is spontaneous and exothermic. Langmuir, Freundlich and D–R models are used for fitting the equilibrium data, and the results show very good fits with the Langmuir isotherm equation for the monolayer adsorption process, and the maximum adsorption capacity is 2.06 mmol/g. The E values (E=8.94~9.10 kJ/mol) indicated that the adsorption is predominant on the chemisorption.