An Efficient Removal of Toxic Cr(VI) from Aqueous Solution by MnO2 Coated Polyaniline Nanofibers: Kinetic and Thermodynamic Study

摘要

The present study explored the removal of toxic Cr(VI) ions by MnO2 coated polyaniline nanofibers (MPNF) adsorbent by batch mode technique. The MnO2 coated polyaniline nanofibers were synthesized by in-situ oxidative polymerization of polyaniline by rapid mixing technique and were employed for the removal of Cr(VI) ions from aqueous solution. The synthesized adsorbent was characterized by various techniques to elucidate the structure, composition, and morphology. The effects of pH, initial Cr(VI) concentration, adsorbent dose, temperature and operating time on adsorption were investigated. The maximum adsorption removal efficiency was observed at low pH i.e., 1.0. Spectrophotometric method was used to examine the Cr(VI) concentration in the filtrate after batch adsorption studies. The equilibrium adsorption capacity and adsorption kinetics followed Freundlich isotherm and pseudo-second-order respectively, with a capacity of 39.3 mg/g. The thermodynamic study parameters like: ΔH°, ΔS° and ΔG° revealed that the adsorption process is spontaneous and endothermic at high temperature.