Performance of rattle-type magnetic mesoporous silica spheres in the adsorption of single and binary antibiotics

The rattle-type γ-Fe₂O₃/mesoporous silica spheres (γ-Fe₂O₃/mSiO₂ spheres) were synthesized with a facial and selectively etching strategy. The prepared particles were characterized by FT-IR, XRD, TEM, SEM, VSM, Raman spectroscopy and nitrogen adsorption-desorption analysis, and the results indicated that γ-Fe₂O₃/mSiO₂ spheres exhibited magnetic property (M_s=14.43emug^-1) and composed of mesoporous silica (mean diameter, thickness and pore size was 660nm, 60nm, and 2.29nm, respectively). Then the γ-Fe₂O₃/mSiO₂ spheres were employed as sorbents to remove tetracycline (TC) and sulfamethazine (SMZ) in both single and binary aqueous solutions. The adsorption kinetics of γ-Fe₂O₃/mSiO₂ spheres were well-described by the pseudo-second-order equation, initial adsorption rate, and half-adsorption time. The Langmuir isotherm model was fitted to the equilibrium data better than that for Freundlich model, and the monolayer adsorption capacity of γ-Fe₂O₃/mSiO₂ spheres for TC and SMZ were 0.0791mmolg^-1 and 0.0342mmolg^-1 at 298K, respectively. In binary systems, SMZ adsorption onto γ-Fe₂O₃/mSiO₂ spheres was more affected by the simultaneous presence of competitive antibiotics than that for TC. In addition, the reusability of the material without obviously deterioration in performance was observed at least four repealed cycles.