Magnetite particles covered by amino-functionalized poly(dimethylsiloxane) network for copper(II) adsorption from aqueous solution

An amino-functionalized poly(dimethylsiloxane) (PDMS) were obtained over magnetite particles. The materials obtained were characterized by Fourier transform infrared spectroscopy (ATR-FTIR), X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), and thermogravimetric analysis (TGA). ATR-FTIR spectra showed adsorption bands attributed to the amino-functionalized polymeric network and the Fe–O bonds of magnetite, while XRD patterns indicated that magnetite was covered with an amorphous material, the PDMS polymeric network. Thermal analysis showed that the obtained materials were thermally stable up to 300 °C. SEM micrographs revealed that the polymer network coated the magnetite particles, since the surface roughness decrease. Adsorption of Cu(II) was conducted in aqueous medium at different pH values, contact times, and metal ion concentrations. The adsorption capacities obtained were of 0.56, 0.44, and 0.41 mmol L −1 for the materials with a decreasing content of amino group, respectively. Nonlinear kinetic model equations were applied, showing that the materials with lower and higher content of APTMS was described by chemisorption model, while that the intermediary content by a pseudo-second-order fit. The experimental data of adsorption isotherm were studied by various models and Sips model exhibited the best fit for all materials.