Economical electrostatic assembly of halogen-free coatings imparting hydrophobic, flame-retardant, and fuel-recycling properties to wood pulp paper

Fuel spills frequently result in extensive ecological damage and substantial property losses, necessitating the use of oil-water separation devices for swift recovery. These devices, however, often rely on significant quantities of organic solvents or halogenated substances during manufacturing and encounter challenges related to cost and efficiency. In this work, a simplified layer-by-layer self-assembly technique was employed to design the coating, constructing a single-layer halogen-free intumescent flame retardant coating on the surface of wood pulp paper (WPP) through the interaction between phytic acid (PA, negative charge) and polyacrylamide (PAM, positive charge). Subsequently, a fluorine-free and environmentally friendly hydrophobic encapsulation layer was built over the flame retardant coating using a Polydimethylsiloxane-tetraethoxysilane (PDMS-TEOS) system. Notably, the modified samples exhibit multi-element synergistic flame retardant properties, with a limiting oxygen index (LOI) reaching 35.1 %, and reductions in peak heat release rate (pHRR) and total heat release (THR) by 66.4 % and 48.1 %, respectively, thereby ensuring fire safety during fuel recovery. Additionally, inspired by tree root penetration, a novel fuel recovery package was developed using waste cotton wool and modified paper, significantly enhancing the recycling efficiency of the modified paper. Overall, the hydrophobic, flame-retardant wood pulp paper constructed through this coating design demonstrates high flame safety and fuel recovery efficiency, offering promising prospects for marine environmental protection and sustainable development.