Synthesis and Modification of Polyurethane Foam Doped with Multi-walled Carbon Nanotubes for Cleaning up Spilled Oil from Water

Abstract

Marine oil spills have raised widespread environmental concerns. Adsorbents with high oil absorption efficiency and reusability are highly desirable. This paper demonstrates a technical route for the manufacture of polyurethane-based adsorbents, aiming at developing robust and efficient materials for treating oil-contaminated water or remedying emergency oil spill accidents. The investigation includes the synthesis of polyurethanes modified with multi-walled carbon nanotubes, the characterizations of their properties, and the analysis of the capacity and feasibility of their applications in oil–water separation. The compositions of the products were characterized by FTIR, XPS, and Raman spectroscopy; the morphologies were analyzed by SEM; the hydrophobicities were tested by the water contact angle, and the thermal properties by TGA; the mechanical properties were depicted by Young’s modulus and the tensile-strain response performance; and the measurements of the absorption capacities and their performance in applications for oils-water separation were conducted in a self-designed apparatus and determined by gravimetric analysis. The results indicate that the developed adsorbents are superhydrophobic and highly robust with a water contact angle of 159°, tensile strain 27% higher and compressive strain 35% lower than regular polyurethanes, absorption capacity up to 60 g g⁻¹, and reusability of 900 absorption–desorption cycles. The high oil absorption efficiency, capacity, and reusability of the adsorbents were confirmed by various oil/organics-water systems, such as engine oil-, silicone oil-, chloroform-, hexane-, toluene-, and kerosene-water system. It is concluded that the adsorbents are efficient not only for floating oils/organics-water but also for well dispersed or mixed oils/organics-water systems; and they can be operated in not only a batch mode for high absorption–desorption cycles but also in a continuous mode for a long operational period, which exhibits great potential and is of particular interest for the adsorbents to be used in large scale oil/organics spill cleanups.

Graphic Abstract