Removal of Pb2+ in aqueous solutions using Na-type zeolite synthesized from coal gasification slag in a fluidized bed：Hydrodynamic and adsorption

Abstract

As the heavy metal ion in aqueous solutions, Pb2+ has certain harm to the surrounding natural and ecological environment. To eliminate the pollution of Pb2+ in aqueous solution, Na-type zeolite was prepared from the coal gasification slag by alkaline activation technology, and then the hydrodynamic of fluidized bed with Na-type zeolite granules was studied to achieve fluidization stability. Finally, the adsorption process and mechanism of Pb2+ in aqueous solutions using Na-type zeolite were studied by multiple adsorption experiments in stable fluidized bed. The results showed that: The removal process of Pb2+ using Na-type zeolite is a single-layer adsorption dominated by chemical adsorption, companying with surface electrostatic interaction and ionic exchange processes in the interlayer. Fluidized adsorption process of Pb2+ by Na-type zeolite is mainly affected by rising-water velocity, original concentration of Pb2+, and bed material quantity in fluidized bed. The order of influence significance was as below: Original concentration (co) > Bed material quantity (mo) > Rising-water velocity (vt). Under optimal operating conditions (co=200 mg/L, vt=0.053 m/s, mo =72 g), the fluidized bed have higher adsorption saturation (qs=0.649 g/g) than that of fixed bed (qs=0.501 g/g), promoting the adsorption process of Pb2+ by Na-type zeolite. This research provided a new method for the efficient removal of Pb2+ from aqueous solution.