Preparation and characterization of hexadecyl functionalized magnetic silica nanoparticles and its application in Rhodamine 6G removal

► C 16/Si–OH–Fe 3O 4 NPs were prepared by simultaneous hydrolysis of TEOS and HTMOS. ► Hydrophobic and electrostatic interaction both took effect, which favored adsorption. ► Facile synthetic conditions and magnetic separation enhanced operating efficiency. ► Bi-functional magnetic adsorbent have potential use in dyes removal. In this paper, a new adsorbent, hexadecyl functionalized magnetic silica nanoparticles (C 16/SiO 2–Fe 3O 4 NPs), was prepared by a facile method. The final product was characterized by X-ray diffractometer, transmission electron microscope, Fourier transform infrared spectrometer and vibration sample magnetometer. The preparation and adsorption conditions of the adsorbent were optimized. The adsorbent prepared maintaining volume ratio of tetraethylorthosilicate to hexadecyltrimethoxysilane at 1:0.5 and their total volume at 1100 μL exhibited high adsorption capacity. The optimum pH value for the adsorption experiments was 11.00. The adsorption behavior of Rhodamine 6G onto C 16/SiO 2–Fe 3O 4 NPs obeyed pseudo-second-order kinetic model and Langmuir isotherm. Thermodynamic data indicated that the adsorption process was spontaneous and exothermic. The adsorption capacity of the adsorbent could reach to 35.6 mg g −1, owing to the hydrophobic attraction and the enhanced electrostatic attraction. The saturation magnetization of the magnetic adsorbent was 35 emu g −1, which ensured the magnetic separation after adsorption.