Kinetics, Isotherms and Thermodynamics of the Adsorption of Lead(II) Ions onto Porous Mono-Sized Microspheres Possessing Imidazole Functional Groups

Abstract

A modified two-step seeded polymerization was used for the preparation of porous mono-sized microspheres of poly(ethylene glycol dimethacrylate-co-1-vinylimidazole) [poly(EGDMA-co-VIM)] of 7 μm in size. The specific surface area and the EGDMA/VIM molar ratio of the microspheres were determined as 64.5 m2/g and 1.5:1.0 mol/mol, respectively. The adsorption of Pb(II) ions from aqueous solution onto the porous mono-sized poly(EGDMA-co-VIM) microspheres was examined. The maximum adsorption capacities of the microspheres towards Pb(II) ions were determined as 21.74, 30.52, 49.23 and 56.48 mg/g at 293 K, 303 K, 318 K and 338 K, respectively. The dynamic and equilibrium adsorption behaviours of the system were adequately described by the pseudo-second-order kinetic model and the Langmuir isotherm, respectively. The apparent activation energy was determined as 6.212 kJ/mol, which is characteristic of a chemically controlled reaction. The values of Efe obtained from the Dubinin-Radushkevich equation in the non-lin...