Tailoring Carbon Dot Properties Through Phenolic-Enriched Agro-Waste

The valorization of agro-waste through controlled carbonization presents a sustainable route to engineer functional carbon dots (CDs) with tailorable properties. In this study, the CDs were derived from biomass waste such as olive mill wastewater (OMW), olive leaves, hibiscus calyxes, and chokeberry pomace through hydrothermal method. Comprehensive characterization revealed size-dependent properties, with most CDs ranging between 4.2-7.6 nm (except OMW-derived CDs at 32.7 nm), and distinct surface chemistries correlated to their biomass precursors. Notably, CDs derived from olive leaves (OLCDs) and hibiscus calyxes (HCDs) exhibited higher carbonyl and carboxyl group densities, correlating with the elevated phenolic content of their biomass precursors. All CDs demonstrated exceptional antioxidant activity (>88% DPPH radical scavenging), attributable to the abundance and diversity of bioactive compounds in the source materials. These findings highlight the dual potential of agro-waste-derived CDs as sustainable nanomaterials and potent antioxidants, offering scalable solutions for both environmental waste management and food preservation technologies—particularly as active packaging components or edible coatings to extend shelf life.