Enhanced adsorption capability of Congo red dye onto novel Polypyrrole/ZnO/ZnCr2O4 composite

Abstract In this study, the polypyrrole/ZnO/ZnCr₂O₄composite as an efficient adsorbent was synthesized by two steps. At first, zinc oxide/zinc chromite (ZnO/ZnCr₂O₄) composite was synthesized using simple and facile co-precipitation method. Then, ZnO/ZnCr₂O₄composite was modified by polypyrrole (PPy). The adsorbent was characterized by X-ray diffraction (XRD), Fourier transform infrared (FT-IR), scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDXA). The PPy/ZnO/ZnCr₂O₄ compositeshowed excellent adsorption properties towards Congo red (CR) than ZnO and ZnO/ZnCr₂O₄ adsorbents. The adsorption studies have been carried out for contact time, different pH values, different temperatures, and adsorbent doses. The investigation of removal kinetics of CR indicates that the removal process obeys the rate of second-order kinetic equation. The results indicate that the Langmuir adsorption isotherm fitted the data better than the Freundlich.

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