Preparation Of Two Magnetic Materials And The Adsorption Performance Of Dyes

The materials of Fe3O4/APTES and Fe3O4/NDCMC prepared by in-situ synthesis method and Schiff base reaction, respectively, were used as adsorbents for dye removal in this paper. The properties such as structure morphology, functional groups, crystal form, magnetic performance and particle size of prepared adsorbents were analyzed by SEM-EDS(scanning electron microscopy and energy dispersive spectrometer), FT-IR (fourier transform-infrared spectroscopy), XRD (X-ray diffraction), VSM (vibrating sample magnetometer), particle size analyzer and XPS (X-ray photoelectron spectroscopy), respectively. Batch experiments were conducted with varying adsorbent dose, initial concentration, contact time, temperature, initial pH and ionic strength. The isotherm models(Langmuir, Freundlich and Dubinin-Radushkevich), kinetic models(Pseudo-first-order model, Pseudo-second-order model, Boyd’s film-diffusion model) and thermodynamic parameters were also analyzed to describe the adsorptive behavior of the adsorbents. The results are as follows:(1) The magnetic material prepared in this work is superparamagnetic and has the cubic spinel phase. The saturation magnetization was found to be about65emu g-1, indicating that the adsorbents can be separated from aqueous solutions using a magnet. The modification by carboxymethyl ellulose (CMC) reduces a tendency to form aggregates.(2) The maximum adsorption capacities of Fe3O4/NDCMC for Remazol Turquoise Blue G-133dye (RTB G-133) and Congo Red (CR) were115.7and169.6mg g-1, respectively. The maximum adsorption capacities of Fe3O4/APTES for RTB G-133, Reactive red228(RR228) and CR were69.5,51.4and118.9mg g-1, respectively.(3) The adsorption corresponded well to D-R isotherm, the pseudo-second-order and Boyd’s film-diffusion models. The experimental data for removal of RTB G-133and RR228followed Langmuir isotherm model. The adsorption of CR dye can be described by Freundlich isotherm model. Thermodynamic parameters suggested that the adsorption was a spontaneous process. Furthermore, the process of RTB G-133, RR228and CR dye onto Fe3O4/APTES is exothermic. The process of CR dye onto Fe3O4/NDCMC is also exothermic. However, the process of RTB G-133dye onto Fe3O4/NDCMC is endothermic. The positive value of entropy change (ΔS0) implies some structural changes during the adsorption process, which leads to an increase in the randomness at the solid-solution system.(4) Fe3O4/APTES and Fe3O4/NDCMC can be potential magnetic adsorbents for dyes removal from aqueous solution.