Synthesis of chitosan/γ-Fe2O3/fly-ash-cenospheres composites for the fast removal of bisphenol A and 2,4,6-trichlorophenol from aqueous solutions

The chitosan/fly-ash-cenospheres/gamma-Fe2O3 (CTS/gamma-Fe2O3/FACs) magnetic composites were prepared by microemulsion process. The resulting composites were charcterized by XRD, FT-IR, SEM, TGA, DTG and VSM, and the results indicated that CTS/gamma-Fe2O3/FACs exhibited magnetic property (M-s = 6.553 emu g(-1)) and thermal stability, and composed of chitosan wrapping magnetic gamma-Fe2O3 and fly-ash-cenospheres (thickness of the cross-linked chitosan was about 5.2 mu m). Then the CTS/gamma-Fe2O3/FACs were employed as adsorbents for the fast removal of bisphenol A (BPA) and 2,4,6-trichlorophenol (TCP) from aqueous solutions. The adsorption performances of CTS/gamma-Fe2O3/FACs were investigated by batch mode experiments with respect to pH, temperature, initial concentration, contact time and binary solution system. The Langmuir isotherm model was fitted to the equilibrium data better than the Freundlich model, and the kinetic properties were well described by the pseudo-second-order equation. The effects of binary solution systems also demonstrated that BPA adsorption onto CTS/gamma-Fe2O3/FACs was more affected by the simultaneous presence of competitive phenolic compound than that of TCP. In addition, the resulting composite reusability without obviously deterioration in performance was demonstrated by at least three repeated cycles. (C) 2011 Elsevier B.V. All rights reserved.