Sustainable rPET/sepiolite-based adsorbents for methylene blue dye removal in wastewater treatment

Water pollution by organic dyes such as methylene blue (MB) poses significant environmental and health risks due to their toxicity and persistence in water bodies. This study addresses the urgent need for effective and sustainable adsorbents by developing a novel adsorbent using recycled poly (ethylene terephthalate) (rPET) and sepiolite, a natural clay mineral, to remove MB dye from aqueous solutions. The rPET/sepiolite adsorbent was synthesized through solution blending, optimizing parameters such as rPET concentration (1, 5, 10, 15 and 20 wt%), blending time (10, 30, 60, 120 and 180 minutes), and sepiolite loading (0, 0.1, 0.25, 0.7, and 0.8 g). The resulting adsorbent was characterized using scanning electron microscopy (SEM), mapping, Brunauer-Emmett-Teller (BET) surface area analysis, thermogravimetric analysis (TGA), Fourier-transform infrared spectroscopy (FTIR), and zeta potential to evaluate its morphological, thermal, and functional properties. The best condition of ad-sorbent, composed of 10 wt% rPET and 0.25 g sepiolite blended for 1 hour, exhibited a hierarchical porous structure, combining micro-, meso-, and macropores, enhancing MB adsorption capacity to 96.7%. The TGA results indicated improved thermal stability, while FTIR confirmed the successful integration of sepiolite into the rPET matrix. These findings demonstrate that the rPET/sepiolite nanocomposite offers a promising, sustainable solution for dye removal in wastewater, contributing to environmental pollution control and plastic waste management. The study highlights the potential of utilizing recycled materials to develop efficient adsorbents, offering a more affordable and sustainable option than traditional techniques.