Eco-friendly adsorption of Rhodamine B dye using Punica granatum peel from an aqueous medium

Abstract

This study investigates the development of a low-cost, eco-friendly adsorbent from Punica granatum peel for removing Rhodamine B (RhB) dye from an aqueous medium. The hypothesis was that agricultural waste could be repurposed as an effective adsorbent while minimizing environmental impact. The material was characterized using SEM, FTIR, XRD, TGA , DSC , and pH PZC analysis. Its adsorption performance was evaluated under varying pH, temperature, and ionic strength conditions. The adsorbent achieved a maximum capacity of 44.28 mg/g at neutral pH within 120 min. Adsorption followed the Langmuir isotherm and pseudo-second-order kinetic models , with thermodynamic studies confirming an endothermic and spontaneous process. Regeneration tests identified 1 M citric acid as the most effective eluent, achieving 52.35 % desorption efficiency. The adsorbent preparation cost was $0.00338 /g, reflecting the method's scalability and alignment with green chemistry principles through agricultural waste valorization, minimal energy use, and reduced environmental impact.