Preparation of hydrophobic and fire-retarding poly(lactic acid)/graphene oxide foams for oil/organic solvents absorption

Petroleum leakage, oil spill and toxic organic solvent emissions have become a global water contamination issue. To solve this problem, it is a promising solution to develop a simple and green strategy to prepare environmentally friendly and high absorption capacity absorbents from biodegradable polymers. Herein, in this work, PLA was used as the matrix to prepare the foam absorbent. Firstly, the flame retardant methoxy-phosphonitrilic trimer (HEPCP, FR) was synthesized. Then PLA composite foams were produced by melting PLA with FR, and mixing with GO through a freezing-dry method. The results showed that FR-PLA/5GO foam self-extinguished immediately when removing the ignition source, due to the fact that the incorporation of GO further improve the fire retardancy of FR-PLA foam. The porosity and the water contact angle of FR-PLA/5GO were gradually increased up to 94.0% and 127.4°, showing a lightweight, highly hydrophobic and homogeneous pore structure. Then the FR-PLA/5GO foam was used as the oil/organic solvent absorbent, which reached the saturated adsorption capacity within 10 s due to the high hydrophobicity and porosity. Meanwhile, the absorbent showed good recyclability, and the FR-PLA/5GO foam still maintained > 75.0% of its original capacity after 10 cycles of the evaporation−adsorption procedure. This work provides a method for developing a biodegradable absorbent for the oil/organic contaminant.