自然水体生物膜和表层沉积物对Hg2+的吸附、解吸研究

选择卫河流域河南段(鹤壁段)为研究站位,在水环境中直接采集生物膜和沉积物样品,进行了Hg2+吸附实验。研究结果表明水体生物膜、沉积物/生物膜复合对Hg2+的吸附动力过程符合Lagergren准二级动力学方程(R20.98),Freundlich和Langmuir等温曲线均可描述Hg2+在表层沉积物和生物膜样品上的热力学吸附过程,显著性水平达到P=0.005(n=7),pH对Hg2+在沉积物、水体生物膜、及二者复合体系的吸附均产生显著的影响,最佳吸附pH介于5~7之间,通过Langmuir等温曲线计算了三类材料对Hg2+的最大吸附容量:水体生物膜沉积物/水体生物膜沉积物。三种吸附材料上Hg2+的NaNO3解吸率从大到小依次为:沉积物沉积物/生物膜生物膜。

Adsorption-desorption Kinetic Characteristics of Hg2+ in Surface Sediments and Natural Biofilm from the Watershed

Natural biofilm represents a kind of stable ecological system by a variety of microbial cells, playing an immeasurable role in the migration of Hg in the watershed.The present study is based on sediments and biofilm from the Weihe River at the Henan section to study the characteristics of static adsorption thermodynamics in the course of Hg adsorption into those materials.The results indicated that the adsorption of Hg by sediment and biofilm belongs to a non-linear one and the adsorption progress fits well to the Freundlich and Langmuir isotherms at a significance level of P=0.005(n=7). The adsorption dynamic processes of Hg²⁺ on the biofilm or biofilm mixed sediments could be fitted by the Lagergren kinetic model (R²>0.98). The pH is an important factor affecting the adsorption of Hg on sediment and biofilm, and the peak adsorption pH is within the range of 5~7. The maximum adsorption rate and capacity of Hg for three materials follow the order of biofilm > biofilm mixed sediments > sediment. While the desorption rates of the three materials by NaNO₃ follow the order of sediment > biofilm mixed sediments > biofilm.