Reutilization of melamine‐formaldehyde foam wastes: Removing Sn²⁺ in simulated tin‐containing wastewater to transform a fire hazard suppressant of flexible poly(vinyl chloride)

Abstract

Melamine‐formaldehyde (MF) foam has wide applications due to good flame retardancy, excellent sound absorption, and high thermal stability. However, the recycling of MF foam wastes remains a challenge due to its thermosetting nature. Here, we demonstrate a new strategy for discarded foams as solid adsorbents for removing tin ions in simulated tin‐containing wastewater. Results showed that the removal rate of tin in simulated wastewater is as high as 99.996%. Moreover, after simple calcination, as‐obtained products can be used as high‐efficiency flame retardants for flexible poly(vinyl chloride) (PVC), reducing the peak of heat release rate and total smoke production of PVC by 51.8% and 45.8%, respectively, under the condition of 2.5 wt.% addition. In short, this strategy successfully converted MF foam and tin wastewater to valuable flame retardants, opening the way for the environmentally friendly recycling of MF waste and the simultaneous treatment of tin‐containing wastewater.

Roll-to-Roll Processing of Hybrid MOF and Nylon Membranes for High Efficiency Removal of Toxic Gases, Heavy Metals, and Dyes

“…On account of rapid industrialization over the past decades, one of the biggest challenges facing the world is environmental pollution due to contaminated wastewater and smoke from factories, power plants, automobile exhausts, and waste disposal. , Many people suffer symptoms from toxic gases, such as hydrogen sulfide (H 2 S), ammonia (NH 3 ), NO x , and SO x . This problem has attracted the attention of scientists worldwide to prevent harmful and toxic chemicals from being released into the environment.…”

Multifunctional Melamine Formaldehyde Composite Foam for High-Temperature Insulation, Flame Retardancy, and Oil–Water Separation

“…Melamine formaldehyde (MF) foams are common flame-retardant materials with three-dimensional (3D) macroporous structure, , low density, and low thermal conductivity . MF foams have good flame retardancy (limiting oxygen index (LOI): 33%) and are widely applied in construction as flame retardants and thermal insulation materials. , However, the hydrophilicity and poor compression properties of pure melamine foam affect its practical application in thermal insulation and flame retardancy. , In addition, MF collapses, decomposes rapidly, and releases smoke in case of fire, thereby resulting in safety hazards. Most fire deaths in buildings result from smoke inhalation rather than burns. , Therefore, the development of flame-retardant foam with less smoke emission and high-temperature thermal stability is essential for reducing/preventing the occurrence of such deaths.…”

“…4 MF foams have good flame retardancy (limiting oxygen index (LOI): 33%) and are widely applied in construction as flame retardants and thermal insulation materials. 5,6 However, the hydrophilicity and poor compression properties of pure melamine foam affect its practical application in thermal insulation and flame retardancy. 7,8 In addition, MF collapses, decomposes rapidly, and releases smoke in case of fire, thereby resulting in safety hazards.…”