Novel chitosan-based phase-selective organogelator for efficient separation of oil/water mixtures

Phase-selective organogelators (PSOGs) can selectively gel the oil phase in oil/water biphasic systems, demonstrating significant research value in organic solvent leakage and oil spill emergency response. In this study, N-cinnamoyl-6-dodecanoyl chitosan (L_1.75C₁CS) oil gelling agent was successfully prepared using natural biopolymer chitosan as the backbone through a two-step grafting modification process. The gelling mechanism of L_1.75C₁CS to form gels in solvents was investigated via UV-vis, FT-IR, and XRD. The experimental results showed that the formation of gel mainly depended on the synergistic effect of intermolecular hydrogen bonding, π-π stacking, and van der Waals force. At room temperature, L_1.75C₁CS exhibited critical gel concentrations ranging from 0.09 to 0.18 g/g in various oils and rapidly solidified high-viscosity crude oil within 2 min. It also exhibited excellent gelling performance at low temperatures, achieving over 80% of its optimal value. Meanwhile, the gel exhibited a maximum strain of 8.09%, which enabled it to effectively withstand a certain degree of environmental disturbance and created favorable conditions for the physical recovery of oil spills. To sum up, the powdered oil gelling agent preparation process developed in this work was energy-efficient, simple, and low-cost. The material has excellent phase selectivity and wide substrate applicability, demonstrating significant application potential in the field of marine oil spill emergency response.