Design and manufacturing of cost-effective tannin-based polyurethane foam as an efficient and reusable absorbent for oil and solvents

Developing low-cost, efficient, and renewable polyurethane as an efficient absorbent for oil spill clean-ups is still a challenge. Herein, tannin-based polyether polyol (MTEBP) was synthesized using tannin extract as feedstocks through graft-liquefaction, and then to produce tannin extract-based foams (MTPFs). Benefiting from the better hydrophobicity, and porosity of MTPFs, the adsorption capacities of modified foam with 100 wt%MTEBP (MTPF100) to soybean oil, xylene, dichloromethane, n-hexane and cyclohexane increased by 53.5%, 57.9%, 115.1%, 83.5%, and 97.2%, respectively, and could be recycled stably for 6 times, compared with the unmodified foam (RPUF). In addition, the mechanical properties of MTPFs including compressive and flexural strength are comparable or superior to that of RPUF, which could be ascribed to the good crosslink density and flexible long-polypropylene oxide chain in the structure of MTEBP. Thermal analysis showed that partial or complete substitution of polyols (SA-380) by MTEBP delayed the first onset of degradation of the polyurethane foams, providing better thermal stability. Particularly, the initial degradation temperature of MTPF100 was immensely increased (209.5 °C), compared to that of the reference RPUF (121.4 °C). This work affords a feasible and sustainable strategy to fabricate the biobased, eco-friendly, high adsorption capacities tannin-based materials for oil spill clean-ups.