An adsorption surface was constructed using a three-dimensional model to predict the adsorption behavior of copper and cadmium ions by extracellular polymers(EPS)in activated sludge and the mechanism of ion-competitive adsorp-tion was discussed.The adsorption of Cu ions(534.72 mg/g)by EPS in the single metal system was higher than that of Cd ions(504.71 mg/g),and the adsorption process was more applicable to the Langmuir isotherm,where the adsorbate and adsorption sites corresponded one to one.The combination of infrared spectroscopy,three-dimensional fluorescence spectros-copy and SEM-EDX analysis showed that the morphology of EPS changed significantly before and after the adsorption,and the reason for this phenomenon may be that the adsorption of metal ions is through the carboxyl,hydroxyl,amide,and other reactive functional groups and metal ions bonding and complexation.At the same time,the ion exchange is also an important mechanism for the adsorption of metal ions on EPS.The study provides theoretical basis and technical support for further exploration and utilization of extracellular polymers and subsequent applications.
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