Adsorption property of alizarin red S by NiFe2O4/polyaniline magnetic composite

NiFe2O4/polyaniline (PANI) magnetic composite was prepared by in situ chemical oxidative polymerization of aniline in the presence of NiFe2O4 particles, where the NiFe(2)O(4)particles were synthesized by a facile hydro thermal method. The magnetic composite was characterized by X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, Brunauer-Emmett-Teller (BET) surface area method and vibrating sample magnetometer (VSM) techniques. The adsorption characteristics of the NiFe(2)O(4/)PANI composite were assessed by using alizarin red S (ARS) as an adsorbate. The adsorption process was investigated as the function of ionic strength, temperature, solution pH, adsorbent dosage, contact time and initial ARS concentration. The equilibrium adsorption data fitted well to the Langmuir model and the maximum adsorption capacity was found to be 186 mg g(-1) at 303 K. The remarkable adsorption capacity of ARS onto NiFe2O4/PANI was attributed to stronger pi-pi interaction and weak electrostatic attraction between ARS and NiFe2O4/PANI. Kinetic studies indicated that ARS adsorption followed the pseudo-second-order kinetic model. The whole adsorption process was jointly controlled by external mass transfer and intraparticle diffusion. Thermodynamic parameters (Delta G degrees, Delta H degrees and Delta S degrees) revealed that the adsorption of ARS on the NiFe2O4/PANI composite was a spontaneous and endothermic process. Magnetic NiFe2O4/PANI with adsorbed ARS could be regenerated using basic ethanol solution and was separable from liquid media using a magnetic field.