a kinetic study on adsorption of congo red from aqueous solution by zno-znfe2o4-polypyrrole magnetic nanocomposite

in this work, magnetically separable zno-znfe2o4-ppy nanocomposite as an efficient adsorbent was synthesized by two steps. at first, zinc oxide (zno) and znfe2o4 nanoparticles were synthesized using simple and facile precipitation method. then, zno-znfe2o4 mixed oxide was modified by polypyrrole (ppy). the adsorbent was characterized by x-ray diffraction (xrd), fourier transform infrared (ft-ir), uv-vis and scanning electron microscopy (sem). the synthesized nanocomposite were used as adsorbent to remove congo red dye from aqueous solution and were compared with pure zno and zno-ppy adsorbents. the zno-znfe2o4-ppy nanocomposite adsorbent showed a superior congo red removal efficiency than zno and zno-ppy adsorbents. this efficiency is attributed to the charge of surface obtained in nanocomposite adsorbent. furthermore, the adsorption kinetics of congo red onto the nanocomposite followed by the pseudo-second-order kinetic model.