Adsorption of Heavy Metal Ions [Cr(VI), Fe(III) And Zn(II)] on Chemically Activated Murraya Koenigii(Curry Leaf) Biosorbent

Abstract

The present study investigates the potential of chemically activated Murrayakoenigii biosorbent (CAMKB) for the efficient removal of Cr (VI), Fe (III), and Zn (II) ions from aqueous solutions. The biosorbent was prepared from waste curry leaves through phosphoric acid activation followed by thermal treatment. Batch adsorption experiments were performed to evaluate the effects of pH, adsorbent dose, contact time, temperature, and initial metal ion concentration on removal efficiency. Optimum pH values were found to be 2.0 for Cr(VI), 6.0 for Fe³⁺, and 8.0 for Zn²⁺, with removal efficiencies exceeding 90% under optimized conditions. Adsorption equilibrium data were best fitted to the Langmuir isotherm model, with maximum adsorption capacities (qm) of 25.1 mg/g for Cr(VI), 22.4 mg/g for Fe³⁺, and 20.3 mg/g for Zn²⁺. Thermodynamic analysis confirmed that the adsorption process was spontaneous and endothermic for all three metal ions. These results demonstrate that CAMKB is a low-cost, eco-friendly, and highly effective biosorbent, offering significant potential for sustainable wastewater treatment applications targeting multi-metal contamination.