Removal of Mercury by an Aminated Fiber Prepared by Irradiation Grafting Copolymerization

A chelating fiber having amine functional group with high adsorption capacity for mercury ions was synthesized by grafting copolymerization of acrylic acid onto polypropylene fiber, consequently aminating with diethylenetriamine. The content of the amine groups of the chelating fiber and its adsorption capacity for mercury ion was evaluated. Isotherms were fitted by the Langmuir model, implying that the interaction between mercury and the adsorbent is mainly monolayer chelating adsorption. A comparison of the experimental adsorption capacity with the theoretical values of the chelating fibers indicated that the adsorption of the fiber for mercury ions in aqueous solution may involve ion exchange of carboxyl groups on the chelating fiber with mercury ions, besides the chelating adsorption of amine groups with mercury ions. The maximum adsorption capacity for mercury based on the Langmuir model is as high as 5.19 mmol/g. 99% removal efficiency would be achieved when feed concentration of mercury was 1 mg/L. The chelating fiber shows much higher adsorption capacity for mercury when pH value was higher than 3. The thermodynamic data indicated that the adsorption follows an endothermic and spontaneous process at solid/solution interface. Adsorption equilibrium was attained rapidly in 50 min. These results indicate that the chelating fiber is effective in practical treatment of mercury wastewater.