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

The rattle-type gamma-Fe2O3/mesoporous silica spheres (gamma-Fe2O3/mSiO(2) 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 gamma-Fe2O3/mSiO(2) spheres exhibited magnetic property (M-s = 14.43 emu g(-1)) and composed of mesoporous silica (mean diameter, thickness and pore size was 660 nm, 60 nm, and 2.29 nm, respectively). Then the gamma-Fe2O3/mSiO(2) spheres were employed as sorbents to remove tetracycline (TC) and sulfamethazine (SMZ) in both single and binary aqueous solutions. The adsorption kinetics of gamma-Fe2O3/mSiO(2) 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 gamma-Fe2O3/mSiO(2) spheres for TC and SMZ were 0.0791 mmol g(-1) and 0.0342 mmol g(-1) at 298K, respectively. In binary systems, SMZ adsorption onto gamma-Fe2O3/mSiO(2) 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In addition, the reusability of the material without obviously deterioration in performance was observed at least four repealed cycles. (C) 2011 Elsevier B.V. All rights reserved.