Green synthesis of jarosite nanoparticles for photocatalytic degradation of Rhodamine B under simulated sunlight radiation

Abstract

Green synthesis of efficient photocatalysts using agricultural waste is a promising approach toward sustainable wastewater treatment. In this work, magnetite (Fe₃O₄) and jarosite (KFe₃(SO₄)₂(OH)₆) nanoparticles were synthesized using banana peel extract as a natural reducing/stabilizing agent and potassium source under microwave-assisted conditions. The structural, optical, and magnetic properties of the nanoparticles were systematically characterized. Photocatalytic performance was evaluated for Rhodamine B (RhB) degradation under simulated sunlight irradiation, and reaction kinetics were analyzed using pseudo-first-order models. Jarosite exhibited a rate constant (k) of 0.0198 min⁻¹, approximately double that of magnetite (k = 0.0098 min⁻¹), achieving >99% RhB removal within 30 minutes. Mechanistic studies, including scavenger tests and photoluminescence analysis, confirmed the dominant role of ˙OH radicals and efficient charge separation in jarosite. The catalyst retained >94% activity over five cycles, and total organic carbon (TOC) removal reached 92%, indicating effective mineralization. This study demonstrates a low-cost, scalable, and environmentally friendly route for synthesizing iron-based photocatalysts, aligning with the UN Sustainable Development Goals (SDGs) for clean water and responsible consumption.