Hydrophobic carbon dots modified porous thermoplastic polyurethane for effective and durable oil/water separation

Abstract

Porous thermoplastic polyurethane (PTPU) materials have shown potential for oil/water separation due to their high porosity, good elasticity and repeatability. It is urgent to find an appreciated method that modifies the surface properties of PTPU so as to improve the separation efficiency by effectively enhancing the interaction between the surface and organic pollutant. In this paper, hydrophobic carbon dots (CDs) were applied to modify PTPU (PTPU/CDs) to improve the oil/water separation performance. As a result of optimization of the preparation of PTPU and the addition of CDs, the hydrophobicity (from 120° to 138.1°), compressive strength (from 186 to 233 kPa) and saturated absorption capacity (from 2.4–23 to 4–39 g−1) were improved significantly compared with pure PTPU. In addition, in this process, the PTPU/CDs composites were endowed with bright yellow fluorescence due to the CDs, making it possible to track the oil absorption progress under ultraviolet irradiation. Furthermore, the PTPU/CDs composites demonstrated exceptional durability and environmental adaptability in the process of treating oily-water. Additionally, the absorption kinetics demonstrated that the PTPU/CDs material showed an approximately 1.5-fold increase in absorption rate compared with PTPU. When used as filter membrane, the PTPU/CDs composites could effectively separate surfactant-stabilized toluene-in-water emulsion with up to 99% efficiency, demonstrating an effective way for treatment of various oily wastewater.

Keywords

• Oil/water separation
• Porous materials
• Thermoplastic polyurethane
• Carbon dots