Nickel Ferrite/Polyaniline Nanocomposite doped with 2-Naphthalene sulfonic acid as aqueous chromium adsorbent

Abstract

Chromium is one of the most toxic heavy metals found in many industrial effluents due to its ability to easily enter the human body and cause serious health problems. In this study, the ability of a nanocomposite of nickel ferrite and polyaniline doped with 2-naphthalene sulfonic acid (PANINSA/NiFe2O4) to remove chromium (Cr (VI)) from synthetic wastewater was studied. The doping of the material with 2-NSA leads to the formation of tubular-shaped rods which increases the surface area of the material. Adsorption parameters such as solution pH, dosage of adsorbent, time of agitation, and initial concentration of pollutant were studied and optimized. The adsorption was highly dependent on solution pH with a maximum adsorption observed at pH 2. The results revealed a maximum removal of 99.9% from 50 mg/L Cr (VI) solution for a catalyst loading of 1 g/L. Freundlich, Langmuir and Two-Surface Langmuir non-linear isotherm models were fitted to the data. Kinetics studies revealed a fast adsorption process in the first 30 minutes followed by slower adsorption with maximum Cr (VI) removal achieved within 24 hours. The Two-Surface Langmuir model best described the isotherm data from the experiment. The effect of the temperature study revealed that the adsorption capacity for the Cr (VI) increased with an increase in temperature with the maximum adsorption capacity (420 mg/g) observed at 45 °C. The calculated thermodynamic parameters revealed endothermic and spontaneous adsorption process. The Cr (VI) removal mechanism was by electrostatic attraction, reduction, and surface complexation. The reusability studies showed that PANI-NSA/NiF𝑒��2O4 could be used for 5 cycles with a 99 % Cr (VI)removal from 50 mL solution containing 50 mg/L Cr (VI)in the first 2 cycles This study demonstrated that PANI-NSA/NiFe2O4 has a potential in the industrial application for removal of Cr (VI).