An Efficient and Mild Recycling of Waste Melamine Formaldehyde Foams by Alkaline Hydrolysis

Melamine formaldehyde foam (MFF) generates many poisonous chemicals through the traditional recycling methods for organic resin wastes. Herein, a high MFF degradation ratio of ca. 97 wt.% was achieved under the mild conditions (160 °C) in a NaOH–H2O system with ammelide and ammeline as the main degradation products. The alkaline solvent had an obvious corrosion effect for MFF, as indicated by scanning electron microscopy (SEM). The reaction process and products distribution were studied by Fourier-transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and 13C nuclear magnetic resonance (NMR). Besides, the MFF degradation products that have the similar chemical structures and bonding performances to those of melamine can be directly used as the raw material for synthesis of melamine urea-formaldehyde resins (MUFs). Moreover, the degradation system demonstrated here showed the high degradation efficiency after reusing for 7 times. The degradation process generated few harmful pollutants and no pre- or post-treatments were required, which proves its feasibility in the safe removal or recovery of waste MFF.