Mesoporous and Hydrophobic Carbon Dot Aggregates as Highly Efficient Sorbents for Emerging Environmental Contaminants

Sorption has been extensively studied and is considered a highly effective technique for mitigating the environmental hazards posed by emerging contaminants in both aqueous and gaseous phases. This study employs a simple solvothermal synthesis method to produce hydrophobic carbon dots (Cdots), whose mesoporous structure in the aggregated solid state is key in enhancing their sorption capacity for environmental contaminants such as radioactive iodine and crude oil. The strategic selection of 2,4-diamino-6-phenyl-1,3,5-triazine (DPT) as a precursor is essential to achieve this smart sorbent. Hydrophobic Cdots-coated polyurethane (Cdots@PUS) efficiently separates crude oil spills under diverse environmental conditions, showing ≈99.5% separation efficiency and 1085 wt% absorption capacity. In parallel, Cdots aggregates (Cdots-Agg), enriched with abundant adsorption sites, exhibit remarkable efficiency in radioactive iodine uptake from both aqueous media and the vapor phase. Cdots-Agg completely removed iodine from aqueous solutions and demonstrated an exceptional iodine vapor uptake of 1007 mg g^-1. The iodine capture efficiency remains excellent over five adsorption-desorption cycles, demonstrating potential practical applicability. This efficient iodine capture is primarily attributed to key adsorption sites on the aggregates, particularly nitrogen-containing functionalities and carbonyl groups. The above results highlight hydrophobic surfaces and mesostructures as key to sorption efficiency.