Efficient glycolysis of polyurethane (PU) foam using biobased crude glycerol for oil–water separation sponge and rigid PU foam preparation: Optimization and techno-economic evaluation

Abstract

Tremendous efforts have been dedicated to recycling waste polyurethane foam (WPUF) and developing an efficient and eco-friendly method for separating oil–water mixtures. However, the research on the application of high-value WPUF was insufficient. Herein, we proposed using biobased crude glycerol (CG) for split-phase glycolysis of WPUF. The upper polyol (Pol A) was used to prepare a porous sponge for the field of oil–water separation, and the lower-phase product (LPP) was converted into rigid polyurethane (PU) foam with thermal insulation properties. The research investigated the effects of various reaction conditions on the glycolysis of PU foam and optimized the formulations of the porous hydrophobic sponge and rigid PU foam. The porous sponge demonstrated a high degree of porosity and a remarkably low density of 31.9 kg/m³, along with a notably efficient affinity for absorbing oils and organic solvents. It could absorb oil and organic solvents up to 27–94 times its weight, achieve rapid absorption within 5 s, and demonstrate superior reusability for 100 cycles. The prepared rigid PU foam showed compressive strengths exceeding 150 kPa and met the standards for thermal insulation materials. Besides, a techno-economic evaluation of the glycolysis process demonstrates the project’s profitability and viability. These results showed that CG could achieve efficient glycolysis and high-value application of WPUF. This study provides a new method for producing porous sponges for oil–water separation and rigid PU foam with thermal insulation properties.