Adsorptive removal of a reactive azo dye using polyaniline-intercalated bentonite

For this study we conducted a series of adsorption experiments to study the adsorption performance of reactive red 2 (RR-2), a typical anionic dye, on polyaniline-intercalated bentonite (Pani-Bent). The adsorbent was characterized by XRD, FTIR, SEM, TEM, and BET. We investigated the influences of several parameters, including pH, reaction time, temperature, inorganic salts, and initial concentrations. The results indicate that the adsorption of RR-2 is better in an acidic solution. Both NaCl and Na₂SO₄ can improve RR-2 uptake. The adsorption process follows the pseudo second-order kinetic model. The non-linear regression method was adopted to analyze the obtained equilibrium data in terms of the Langmuir, Freundlich, Temkin, Dubinin-Radushkevich (D-R), and Flory-Huggins models. The Langmuir isotherm fits the equilibrium data best among the five models, and the adsorption capacity increases from 202.0 to 257.7 mg/g as the temperature increases from 5ºC to 33ºC Pani-Bent can be an efficient adsorbent for adsorption removal of RR-2 from its aqueous solutions.