Abstract
A novel magnetic composite bioadsorbent composed of chitosan wrapping magnetic nanosized γ-Fe
2O
3 and multi-walled carbon nanotubes (m-CS/γ-Fe
2O
3/MWCNTs) was prepared under relative mild conditions and was characterized. Adsorption of methyl orange (MO) onto m-CS/γ-Fe
2O
3/MWCNTs was investigated with respect to pH, initial MO concentration, coexisting anions and temperature. Results of characterizations indicated that magnetic nanosized γ-Fe
2O
3 and MWCNTs have been wrapped by crosslinked chitosan. Introduction of MWCNTs could obviously increase the adsorption capacity (
q
e
) of MO onto bioadsorbent by 2.2 times. Kinetics data and adsorption isotherm were better fitted by pseudo-second-order kinetic model and by Langmuir isotherm, respectively. Values of activation parameters such as free energy (△
G°), enthalpy (△
H°) and entropy (Δ
S°) were determined as 3.15–3.78
kJ
mol
−1, −9.94
kJ
mol
−1 and −20.65
J
mol
−1
k
−1, respectively, indicating that the adsorption was feasible, spontaneous and exothermic process in nature. After adsorption, m-CS/γ-Fe
2O
3/MWCNTs could be effectively and fleetly separated by applying a magnetic field.