The lack of control over the pollution in waters has provoked an imminent global water crisis, which restrains access to potable water for billions of people worldwide. The design and development of functionalized advanced polymeric composites that can remove pollutants and purify waters have been presented as a promising solution to this problem. A powerful strategy is the surface modification of highly porous substrates to increase their affinity toward certain classes of pollutants and enhance their adsorptive removal. The commercially available melamine foam (MF) presents a highly porous 3D framework structure (0.994) and nitrogen-rich chemical structure (66 %), which endow a large surface area and inherent encapsulating properties. These characteristics have boosted its use as a substrate to prepare functional materials for water purification. For instance, MF doped with silver nanoparticles (AgNPs) obtained through a straightforward process developed in our previous work showed excellent antibacterial performance in contaminated water [1].

Along the same line, this work evaluates the calcination of AgMF foams as a novel strategy for further enhancement of the water-cleaning properties of these advanced materials. The XPS and infrared analysis of the calcined foams confirmed the obtention of highly valuable active N-doped products with catalytic properties during the calcination [2], [3], [4]. Interestingly, anchored AgNPs promoted the formation of these active substances in foams. As a result of these chemical changes, the removal capability of calcined foams against the hazardous methylene blue dye dissolved in an aqueous solution was highlighted. Calcined foams eliminated up to 80 % more of the pollutant in comparison with the non-calcined foams regardless of the environmental light, ensuring a stable and reliable catalytical response. Moreover, this work also addresses a thorough study regarding the morphological transformations that occurred during calcination, which proved to be decisive for defining the final materials’ properties.