壳聚糖/氧化石墨烯复合材料吸附U(Ⅵ)的特性与机理

Characteristics and mechanism of uranium(Ⅵ) adsorption by chitosan/graphene oxide composite

采用溶液共混法制备了壳聚糖/氧化石墨烯(CS/GO)复合材料,探讨了GO含量、pH值、CS/GO投加量、时间以及U(Ⅵ)初始浓度等对CS/GO吸附U(Ⅵ)效果的影响.试验结果表明,GO质量分数为40%,pH值为5时吸附效果最好,吸附在5 h达到平衡.准二级动力学模型和Langmuir等温吸附方程可较好地拟合其吸附过程,30℃时饱和吸附量为227.3 mg·g-1.CS/GO对U(Ⅵ)的吸附是自发的吸热反应.SEM、FTIR和XRD分析结果表明,CS/GO表面凹凸不平,羟基和氨基是U(Ⅵ)的主要结合位点.解吸试验结果表明CS/GO具有良好的重复使用性能.

The chitosan/graphene oxide composite was prepared in mix-solution. The effects of graphene oxide concentration,pH value,adsorbent dosage,contact time and initial U（ Ⅵ） concentration on the adsorption behavior of chitosan/graphene oxide composite on uranium（ Ⅵ） were investigated.The results show that the maximum adsorption capacity was obtained at pH of 5 with 40 wt% of GO. The adsorption equilibrium was obtained at 5 h. The adsorption process were better fitted by pseudo-second-order kinetic model and Langmuir isotherm model,respectively. The maximum adsorption capacity for U（ Ⅵ） at 30 ℃ was 227.3 mg·g（-1）. Thermodynamic study revealed that the adsorption of U（ Ⅵ） on CS/GO was spontaneous and endothermic. SEM images illustrate that CS/GO had a rough surface and an uneven porous structure. FTIR spectra demonstrated that hydroxyl and amine groups were the main binding sites of U（ Ⅵ） in CS/GO. Desorption experiments results indicate that the adsorbent had a good property for reuse.