Sustainable removal of methylene blue dye from textile effluents by magnetized Tea waste and Peanut shells

Methylene blue finds numerous applications across various industries but its prolonged exposure to living organisms can result in significant health risks. In this study, the adsorption of magnetized Peanut shells and Tea waste for methylene blue dye removal has been reported. The biosorbents were synthesized by co-precipitation method and their suitability for methylene blue adsorption was confirmed through characterization techniques including Scanning Electron Microscope, Fourier Transfer Infrared Spectroscopy and X-Ray Diffraction analysis. After optimizing for pH (8.0), temperature (312 k), biosorbents dosage 25 mg/L with contact periods (35 min for Tea waste@Fe₃O₄ and 40 min for Peanut shells@Fe₃O₄), and initial methylene blue concentrations (5 ppm), the removal percentages of 95.88 % for Tea waste@Fe₃O₄ and 84.11 % for Peanut shells@Fe₃O₄ were achieved effectively. The equilibrium data for MB dye adsorption fitted well with the Langmuir model (R² = 0.99) for Tea waste@Fe₃O₄ which indicated the formation of monolayer formation of adsorbate at the surface of adsorbent and the Freundlich model (R² = 0.98) for Peanut shells@Fe₃O₄ confirmed the multilayers formation of MB dye at the material surface. Kinetic studies specified that both Tea waste@Fe₃O₄ (R² = 0.99) and Peanut shells@Fe₃O₄ (R² = 0.99) followed the pseudo-second order. Thermodynamic analysis showed that the adsorption process on Tea waste@Fe₃O₄ and Peanut shells@Fe₃O₄ was spontaneous (−ΔG) and endothermic. Tea waste@Fe₃O₄ exhibited ΔH (27.97 kJ/mol) and entropy ΔS (93.69 kJ/mol) while ΔH = 208.9 kJ/mol and ΔS 62 kJ/mol were found for Peanut shells@Fe₃O₄. The performance of the proposed biosorbent in industrial effluent demonstrated their effectiveness, highlighting their potential as a cost effective and sustainable solution for wastewater treatment.