Synthesis of ureido-functionalized Cr(Ⅵ) imprinted polymer: adsorption kinetics and thermodynamics studies

摘要

To achieve a fast adsorption and a high adsorption capacity, a new type of Cr(VI) surface ion imprinted polymer (Cr(VI)-IIP) using gamma-ureidopropyltrimethoxysilane as a functional monomer was prepared and characterized by scanning electron microscope (SEM) and fourier transform infrared spectroscopy (FTIR). The adsorption capacity of Cr(VI)-IIP was 1.96 times as high as NIP under the optimum conditions: the initial concentration of Cr(VI) ions was 100 mg/L, dosage of Cr(VI)-IIP was 0.01 g, pH value was 2, temperature was 303.15 K. The adsorption process of Cr(VI)-IIP followed pseudo-second-order kinetic model (R-2 0.99) and Langmuir adsorption isotherm model(R2 0.99). Results of intraparticle diffusion and external mass transfer models showed that the adsorption process was controlled by liquid film diffusion and intra-particle diffusion model. The adsorption process belonged to the endothermic reaction and could occur spontaneously. Cr(VI)-IIP showed good selectivity and the relative selectivity coefficients were 4.79, 3.44 and 4.50 for Cr(VI)/Cu(II), Cr(VI)/Cd(II) and Cr(VI)/Zn(II), respectively.