RESUMO
In this work, a polyethyleneimine-modified chitosan/Ce-UIO-66 composite hydrogel (PEI-CS/Ce-UIO-66) was prepared using the ex-situ blend method. The synthesized composite hydrogel was characterized by SEM, EDS, XRD, FTIR, BET, XPS, and TG techniques, while the zeta potential was recorded for sample analysis. The adsorbent performance was studied by conducting adsorption experiments using methyl orange (MO), which showed that PEI-CS/Ce-UIO-66 exhibited excellent MO adsorption properties (900.5 ± 19.09 mg/g). The adsorption kinetics of PEI-CS/Ce-UIO-66 could be explained by the pseudo-second-order kinetic model, and its isothermal adsorption followed the Langmuir model. Thermodynamics showed that the adsorption was spontaneous and exothermic at low temperatures. MO could interact with PEI-CS/Ce-UIO-66 via electrostatic interaction, π-π stacking, and hydrogen bonding. The results indicated that the PEI-CS/Ce-UIO-66 composite hydrogel could potentially be used for the adsorption of anionic dyes.
RESUMO
As a biomass resource, corncob is a kind of agricultural by-product with wide sources and low cost. Because its composition contains a large number of functional polymers such as cellulose, chitosan, and semi chitosan, corncob can be chemically modified to prepare a variety of adsorption materials. In this study, a magnetic gel material (PEI-CC@Fe3O4) consisting of corncob modified by glutaraldehyde-crosslinked polyethyleneimine (PEI) was successfully prepared and applied to the adsorption of heavy metal ions in aqueous solutions. The structure, thermal stability, and adsorption of heavy metal ions of the magnetic gel material (PEI-CC@Fe3O4) were characterized by Fourier-transform infrared spectroscopy (FT-IR), X-ray diffraction phase analysis (XRD), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and X-ray photoelectron spectroscopy (XPS). The results showed that PEI was crosslinked to the corncob through Aldol reaction and Schiff-base reaction. The heavy metal ion adsorption experiment showed that the PEI-CC@Fe3O4 had better adsorption toward divalent copper ions and divalent lead ions at 303 K, and the maximum adsorption capacities reached 459.4 mg g-1 and 290.8 mg g-1, respectively. Moreover, the study of isothermal adsorption and adsorption kinetics shows that the adsorption process is pseudo-second-order kinetics model adsorption, which belongs to Langmuir isothermal adsorption. Such excellent adsorption performance will contribute to the application of corncob biomass materials in industrial polluted wastewater.
