Copper ferrite nano-particles (CuFe2O4) were synthesized, characterized, modified with polyaniline to form CuFe2O4/PANI nano-composite. They were used as new adsorbents for the removal of the hazardous mercuric ions from aqueous solutions. High resolution transmission electron microscope (HR-TEM), X-ray diffraction (XRD), Fourier-transform infrared (FT-IR) and Brunauer-Emmett-Teller (BET) were used for the characterization of the synthesized CuFe2O4 nano-particles (NPs) in presence and absence of PANI nano-composite. The synthesized CuFe2O4NPs were of spherical shape with an average size of 10.8 nm. XRD analysis displayed crystal peaks for CuFe2O4NPs and amorphous peaks CuFe2O4/PANI nano-composite due to the existence of polyaniline layer. Contact time, adsorbent dose, solution pH, adsorption kinetics, adsorption isotherm and recyclability were studied. The method at the optimum conditions exhibited high performance with high mercury removal percentage of up to 99% with a maximum adsorption capacity 12.5 and 157.1 mg/g for CuFe2O4 and CuFe2O4/PANI, respectively. The adsorption processes were fitted to Langmuir isotherms. The adsorption behavior of CuFe2O4@PANI composite towards Hg2+ ions is attributed to the soft acid-soft base strong interaction between PANI and Hg(II) ions. High stability and enhanced re-usability are offered using CuFe2O4@PANI composite due to its enhanced removal efficiency. No significant removal decrease was noticed after five adsorption-desorption cycles. In addition, it possesses an easy removal from aqueous solutions by external magnetic field after adsorption experiments. These indicated the enhancement of polyaniline to the surface of CuFe2O4 toward the adsorption of mercury from aqueous solutions.
Keywords: CuFe2O4 nano-particles; CuFe2O4/PANI composite; adsorption; mercury (II) removal.