Stable hydrogen bonding interactions in supramolecular deep eutectic solvents based on carbon quantum dots: For extraction and oxidative desulfurization

Supramolecular deep eutectic solvent (SUPRADES) was a promising green solvent with physicochemical properties that was similar to those of conventional deep eutectic solvent (DES). The supramolecular deep eutectic solvent-based nanofluidic system (β-CD-CA/CQDs) was constructed by using β-cyclodextrin as the hydrogen bond acceptor and citric acid as the hydrogen bond donor with the addition of carbon quantum dots (CQDs). The addition of CQDs enhanced the desulfurization ability and hydrogen bonding stability of SUPRADES. By controlling the content of CQDs solution, the viscosity of β-CD-CA/CQDs can be easily changed without altering its eutectic nature. The effects of temperature, O/S, sulfur content, oil content and different sulfides on the sulfur removal of β-CD-CA/CQDs were investigated. The sulfur removal of β-CD-CA/CQDs was up to 99.32% at 50 °C. The cyclic voltammetric tests, recovery experiments, and characterization all showed that β-CD-CA/CQDs had excellent recoverability and stability in desulfurization.