超积累植物李氏禾叶细胞干粉对Cr(VI)的吸附特性研究

Character of Cr(VI) Biosorption by the Leaf Cell Biomass of Hyperaccumulative Plant Leersia hexandra Swartz

借助拟合吸附动力学和等温热力学方程,研究了湿生超积累植物李氏禾叶细胞干粉对Cr(VI)的吸附性能.考察了pH值、吸附时间等多种因素对吸附性能的影响;利用扫描电镜(SEM),X射线能谱(EDS)对李氏禾干粉表面形貌及元素分布进行了表征.结果表明,该吸附是单分子吸附的伪二级动力学过程,吸附过程包含两个步骤:Cr(VI)离子通过静电作用富集在干粉材料表面,随后干粉表面存在的功能配位官能团会与Cr(VI)发生化学作用.结合红外光谱图发现对铬起吸附作用的主要是含O,N功能原子的配位官能团,并且不同功能原子与Cr(VI)的作用方式不同.

Adsorption of Cr（VI） by the hygrophyte with chromium hyper-accumulative plant Leersia Hexandra Swart was studied, with the effect of physico-chemical parameters pH and contact time focused. The test results of sorption kinetics conformed to the pseudo-second order kinetics equation. Meanwhile, the correlation coefficient values indicated that the data of sorption thermodynamic fit better the Langmuir model. The adsorption process was found to be first controlled by the electrostatic interaction due to the formation of H^＋/H3O^＋ barrier, and then the function groups could coordinate the Cr（VI）. The morphology and elemental distribution in the leaf cell biomass were evaluated by scanning electron microscopy （SEM） and energy dispersive spectrometry （EDS）. IR analysis of Leersia Hexandra Swart biomass revealed the presence of carboxyl, amide, hydroxyl and carbonyl groups, which are responsible for biosorption of the metal ion. The functional atoms bind Cr（VI） with different interaction on the surface of cell wall, which indicates the selectivity of adsorption.