Microplastics pollution is one of the main environmental challenges of our time, even though microplastics were observed for the first time almost 50 years ago. Microplastics—little plastic fragments smaller than 5 mm in size—are released from bigger plastic objects during their use, maintenance, or disposal. As their release is uncontrolled and mostly uncontrollable, microplastics end up in the environment and are easily transported across the world, polluting nearly every ecosystem, especially the aquatic ones. Hence, microplastics represent a huge menace for many living species: they are ingested unintentionally by smaller animals and transferred along the food chain up to human beings, even threatening our health. It is therefore vital to take action against microplastics and many technologies have been designed in recent years with this purpose in mind. This paper provides an overview of the main solutions developed thus far to reduce further microplastic emissions and to collect those already released.

An acid-free formulation based on water, glycerol, and polyvinyl alcohol (PVA) was studied to disperse and stabilize, via steric-like interaction, low surface area cerium oxide powders. A dispersion route that implies a milling process and a proper ratio among the components was experienced. PVA was used as viscosity modulator, to enhance viscosity and system stability. Newtonian fluids, suitable for foams dip-coating, were obtained in the application shear range. Foams with different porosities (20, 30, and 40 pore per inch density) were coated. It was found that withdrawal velocity did not affect deposition: a constancy in coating load was obtained once rheology was fixed, while multiple dipping was effective to enhance load. An optimal flash drying temperature (350°C) was identified to consolidate the coated layer and to decompose the organic additives. Good loads, homogeneous coverage, and no pore clogging were obtained after calcination at 900°C. Even though acceptable weight losses were obtained, further investigations need to be accomplished to understand data scattering after adhesion tests.

This work focuses on exploring a new configuration for the reduction of water hardness based on the surface modification of polyurethane (PU) open cell foams by the deposition of thin graphene oxide (GO) washcoat layers. GO was deposited by the dip–squeeze coating procedure and consolidated by thermal treatment. The final washcoat load was controlled by performing consecutive depositions, after three of which, a GO inventory up to 27 wt% was obtained onto PU foams of 60 pores per inch (PPI). The GO-coated PU foams were assembled into a filter, and the performance of the system was tested by continuously feeding water with hardness in the 190–270 mg_Ca2+,eq·L⁻¹ range. Remarkable results were demonstrated in terms of total adsorbing capacity, which was evaluated by measuring the outlet total hardness by titration and exhibited values up to 63 mg_Ca2+,eq·g_GO⁻¹ at a specific filtered water volume of 650 mL_H2O·g_GO⁻¹, outperforming the actual state-of-the-art adsorbing capacity of similar GO-based materials.

This study investigates the deposition of graphene oxide (GO) coatings on open-cell polyurethane foams through a soak-and-squeeze process for detergent removal. GO dispersions between 0.25 and 4 g/L were rheologically characterised to relate apparent viscosity to coating deposition. A first rationalisation of the squeeze-coating process was proposed by estimating the characteristic shear rates during squeezing, obtaining values of 12.2 s⁻¹ and 50.4 s⁻¹ for 20 and 60 PPI foams, respectively. Multiple deposition cycles were performed, achieving GO loads up to 12.7 wt% for both types of foam. The adsorption behaviour of GO powder toward a commercial detergent solution containing linear alkylbenzene sulphonate (LAS) was investigated at 25, 40 and 60 °C. UV-Vis spectroscopy was used to monitor concentration changes, while conductivity analyses investigated the temperature-dependent aggregation behaviour of the detergent system. The adsorption kinetics were well described by the Elovich model, suggesting adsorption on heterogeneous GO surfaces. Filtration tests using GO-coated foams showed a decrease in conductivity during flow-through experiments, whereas UV-Vis measurements indicated limited LAS removal under dynamic conditions, likely due to insufficient contact time between the detergent and the coated surface. Static contact tests performed for 1 h at 25 °C showed a reproducible detergent concentration decrease of approximately 16–18%. This value was further increased up to 65% under optimised conditions by modifying the GO-to-detergent ratio and foam configuration. The results demonstrate that the soak-and-squeeze approach is a simple and effective method for producing reproducible GO coatings on open-cell foams, while indicating that sufficient contact time is required to promote detergent removal.