Synthesis, characterization, photoluminescent properties of carbon quantum dots and its applications in wastewater treatment

Abstract

Carbon-based nanomaterials are currently gaining attention in wastewater treatment. They have gained a prime position in membrane filtration to degrade pollutants. One of the most recent additions to the field of carbon-based nanomaterials is quantum dots (QDs). Due to their exceptional qualities, QDs are among the most promising carbon-based nanomaterials at the forefront of the wastewater treatment research field. Nonetheless, most quantum dots were not sustainably fabricated. Therefore, this study aims to evaluate the carbon-based carbon quantum dots derived from biomass wastes (rubber seed shells) where the properties, behaviour and photoluminescence characteristics were evaluated through several characterization analyses. The QDs were characterized using Fourier-transform infrared spectroscopy (FTIR), x-ray diffraction (XRD), field emission scanning electron microscope (FESEM) equipped with energy-dispersive X-ray spectroscopy (EDX), photoluminescence spectroscopy, zeta potential analyser and Raman spectroscopy. The morphological analysis revealed multi-layered planes with highly porous and uneven surfaces, consisting of a large number of oxygen-functional groups (hydroxyl, carboxyl, carbonyl). The mapping results showed a large uniform distribution of carbon and oxygen elements on the surface of QDs with a more signified composition of wt% carbon (72.4%) compared to oxygen elements, with 23.6%. The spectroscopic and photoluminescence studies confirmed the fabrication of high-quality carbon quantum dots with blue-greenish fluorescence emissions. These results have shown promising biomass-based QDs that can be applied in wastewater treatment based on their unique characteristics. Thus, the derived biomass-based QDs can be viewed as a promising and cost-effective adsorbent for wastewater and water treatment.