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

Abstract

• The Green method developed a low-cost adsorbent from Punica granatum peel to remove RhB. • SEM, FTIR, XRD, TGA, DSC, and pH PZC analyses were conducted for adsorbent characterization. • Adsorption highly depends on pH, with maximum uptake occurring at neutral pH. • Statistical metrics support the adequacy of the Langmuir and PSO kinetic models. • Effectiveness, cost analysis, and potential reusability of the adsorbent were investigated. 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.