Rapid green synthesis of carbon dots from Cleome viscosa seeds for the catalytic reduction of methylene blue and rhodamine B dyes

This study presents a rapid and eco-friendly method for synthesizing carbon dots (CDs) using Cleome viscosa (CV) seeds powder via microwave carbonization. The synthesized CDs exhibit bright blue fluorescence under UV light, with a relative fluorescence quantum yield of 9.3%. Transmission electron microscopy (TEM) analysis revealed that the CDs possess an average diameter of 4.9 ± 1.2 nm and a spherical morphology and X-ray diffraction (XRD) patterns indicating their amorphous nature. Moreover, the CDs demonstrate robust fluorescence emission stability under diverse conditions including exposure to salt, continuous UV irradiation, pH variations, and prolonged storage. Furthermore, catalytic studies employing NaBH₄-assisted reduction showcased the remarkable catalytic activity of the CDs towards the degradation of methylene blue (MB) and rhodamine B (RhB) dyes. The kinetics of the catalytic process followed pseudo first-order kinetics, yielding rate constants of 0.118 ± 0.002 min⁻¹ and 0.161 ± 0.007 min⁻¹ for MB and RhB, respectively. These findings underscore the potential of CV seed-derived CDs as efficient and versatile catalysts for wastewater treatment applications.