Micro-Engineered Capsules: A Powerful Tool in Green Chemistry

To meet the requirements of a responsible and sustainable use of nanotechnology, and to expand the design possibilities for advanced multicomponent materials, we employed two spray-based methods (spray drying and spray freeze drying) with the aim of producing dry powders that preserve both the nanostructure and the compositional gradient of the original colloidal formulations. Two case studies, developed within separate European projects, are presented with a focus on the advantages these techniques offer in terms of reducing emission and release potential during manufacturing operations. In the first case, silver nanoparticles coated with hydroxyethyl cellulose were processed via spray drying and spray freeze drying to obtain dry powders intended for use in more complex cosmetic formulations. As part of the SSbD assessment framework, we focused on the results of an emission monitoring campaign carried out during lab-scale processing and showed that no significant emissions occur when operations are conducted under a chemical hood. In the second case, we investigated spray-dried (SD) and spray-freeze-dried (SFD) modified MWCNTs as reinforcing fillers for polypropylene plastics produced via laboratory-scale extrusion. We compared the dustiness levels of pristine and modified CNTs. The modified samples exhibited a significantly lower dust release, by approximately two orders of magnitude, highlighting their potential to reduce worker exposure during manufacturing processes. This approach not only enhances safety by containing and controlling nanoscale materials but also promotes sustainability by preserving material efficiency and reducing environmental risks, a crucial step toward responsible nanotechnology development.