Adsorption of metanil yellow from aqueous solution using polyaniline-bentonite composite

The polyaniline-bentonite composite (Bent−APTES−PANI), as a novel adsorbent for anionic dyes, was successfully synthesized by the oxidative polymerization method using ammonium persulfate as an oxidant. The prepared samples were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), zeta potential, scanning electron microscopy (SEM), and thermal gravimetric analysis (TGA). Our results indicated that the polyaniline was successfully grafted on the surface of bentonite. The positive charge on the surface of the adsorbent was generated by using amino-activated bentonite (Bent−APTES) grafted with the polyaniline doped with citric acid. The adsorbent was applied to remove metanil yellow (MY) from aqueous solution. The adsorption process is hardly influenced by pH, because there are many amino groups (−NR 3 + ) on the surface of the adsorbent. And the maximum adsorption capacity of Bent−APTES−PANI is 444.44 mg g −1 , which is better than other materials. Furthermore, the adsorption kinetics study of MY onto Bent−APTES−PANI obeyed pseudo-second-order model and the adsorption isotherm data were fitted well by Langmuir isotherm. The results of this study suggest Bent−APTES−PANI is a promising material for anionic dye removal.