Adsorption of Hexavalent Chromium on KOH Activated Carbon Derived from Water Hyacinth Leaf Coated with Polyaniline/Polypyrrole

Abstract

KOH-Activated carbon derived from Water Hyacinth (KOH-WHL-AC) was prepared and coated with Polyaniline-Polypyrrole (PANI/PPY) copolymer for the removal of hexavalent chromium (Cr(VI)) from wastewater. The prepared material was characterized by FT-IR and XRD. The effect of pH, contact time, dosage, and initial Cr(VI) concentrations were optimized using batch adsorption experiment. The adsorption kinetics was found to fit better to pseudo-second-order than the pseudo-first order model. Langmuir and Freundlich isotherm models were analyzed using linear fitting. It was found that the Langmuir adsorption model gives the best fit indicating that the monolayer adsorption of Cr(VI) on the KOH-WHL-AC. The highest adsorption capacity of 409.83 mg/g was achieved at pH 1.0, and equilibrium was achieved within 420 min. The reuse efficiency of the synthesized material was also found to be greater than 54% for five consecutive cycles. Thermodynamic studies have also been carried out and the adsorption was found to be spontaneous and endothermic