A metal-free, dual catalyst for the removal of Rhodamine B using novel carbon quantum dots from muskmelon peel under sunlight and ultrasonication: A green way to clean the environment

Abstract

A green strategy for synthesizing fluorescent carbon quantum dots using muskmelon peel as a natural-based carbon precursor material was developed using a stirrer-assisted method for the application of catalytic degradation for Rhodamine B in the presence of sunlight and ultrasonication. For the first time, carbon source were made from the muskmelon peel, and it is used to produce ablue-fluorescent CQDs (carbon quantum dots), with a quantum yield (QY) of 39.51% and an excitation wavelength of 340 nm. The CQDs have a sphericalmorphology and a uniform distribution, with an estimated diameter of about 3 nm. Additionally, the CQDs exhibit excitation-dependent emission mainly due to a quantum confinement effect. Finally, we demonstrated that prepared CQDs could behave as an outstanding photocatalyst and a sonocatalyst to degrade the Rhodamine B (RhB) dye. The degradation efficiency of CQDs on RhB is99.11% under sunlight with a degradation rate constant of 0.06943 min−1 and 83.04% under ultrasonication. These findings suggest that the CQDs are an efficient catalyst for the breakdown of organic dyes in wastewater.