Adsorptive Sequestration of Chromium (VI) from Aqueous Solution by ZnCl2 Activated Carbon from an Agrowaste – Punica granatum – Optimized using Box-Behnken Design Model

IJEP 46(6): 499-511 : Vol. 46 Issue 6 (June 2026)

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S. J. Pradeeba1*, B. Jeyagowri1, T. Mohanraj2, L. Vidhya1 and V. Nirmala Devi1

1. Hindusthan College of Engineering and Technology, Department of Chemistry, Coimbatore – 641 032, Tamil Nadu, India
2. Amrita Vishwa Vidyapeetham, Amrita School of Engineering, Department of Mechanical Engineering, Coimbatore – 641 112, Tamil Nadu, India

Abstract

In this study, an agro-waste-derived Punica granatum peel carbon (PPC) was chemically activated with ZnCl2 and evaluated as a sustainable adsorbent for removing Cr(VI) from aqueous solutions. Thermogravimetric analysis (TGA), energy-dispersive x-ray spectroscopy (EDX), scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) were used to comprehensively characterize the improved adsorbent’s physico-chemical properties. Using response surface methodology (RSM) based on the box–Behnken design (BBD), the adsorption process was systematically optimized. The RSM model predicted optimal operating parameters of an initial Methylene Blue (MB) concentration of 0.04 mg/L, an adsorbent dose of 0.0089 mg and a solution pH of 3.11. Under these conditions, a maximum Cr(VI) removal efficiency of 92% was achieved. These findings demonstrate the potential of ZnCl2-activated PPC as an economical and eco-friendly bio-adsorbent for environmental remediation and validate its practicality for wastewater treatment.

Keywords

Punica granatum peel carbon, Chromium (VI), Response surface methodology, Wastewater treatment, Sustainable bio-adsorbent

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