Sorption of Cu( Ⅱ ) and Cd( Ⅱ ) by natural biofilms
自然水体生物膜对铜（Ⅱ）、镉（Ⅱ）的吸附研究

With high adsorption capability and adsorption surface area, biofilms are actively researched, especially in the area of adsorption of heavy metals. Heavy metal adsorption is greatly affected by the method of developing the biofilm. A biofilm was developed in Dongpu reservoir on the surface of a cotton thread. The characteristics and thermodynamics of Cu and Cd adsorption on the biofilm were studies. Statistical analysis of the adsorption data showed that the thermodynamic data for each metal fit the Freundlich(F) and Langmuir(L) isotherms. The capacity of adsorption of Cu was greater than that for Cd. The adsorption of both Cu and Cd reached equilibrium in less than one hour and fit a second-order kinetics equation. The adsorption of Cu and Cd increased with pH up to pH 7.