A complex, magnetic iron – zinc compound was lab tested to adsorb copper ions then tested as an FR coating for PU foam. An iron – zinc – ammonium compound (FeO-ZIF8) was synthetised from magnetic Fe3O4 nanoparticles, zinc nitrate and 2-methylimidazole. This compound showed to be effective in adsorbing copper from (pure) solution, and it is suggested it could therefore be used for water treatment (interference of other ions in wastewaters was not tested). The copper loaded FeO-ZIF8 was then coated onto polyurethane foam using silicone rubber adhesive then fire performance tested. The silicone adhesive coating alone reduced heat release rate by 25% whereas coating with FeO-ZIF68 led to a 69% reduction. Release of toxic carbon monoxide is also reduced. This paper provides a demonstration of concept, but further work would be needed to verify the effectiveness of copper removal in real wastewater, the durability of the foam coating and the possible implications for PU recycling of the copper or other elements from wastewater.
“Magnetic Fe3O4 Nanoparticle/ZIF‑8 Composites for Contaminant Removal from Water and Enhanced Flame Retardancy of Flexible Polyurethane Foams”, Z. Xi et al., ACS Appl. Nano Mater. 2022, 5, 3491−3501 https://doi.org/10.1021/acsanm.1c04115