LI Qing-Zhao, LUO Xu

（Institute of Resources and Environment, Zhengzhou Institute of Aeronautical Industry Management, Zhengzhou 450015, China） 

Abstract: 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.

Key words: Hg; natural biofilm; surface sediment; non-linear adsorption