Valorisation of ceramic materials from circular economy sources for high-value applications

Given the increasingly urgent need to implement the principles of the circular economy in industrial processes, this thesis aims to reuse by-products from the fishing industry as a source of natural raw materials. Notably, fish bones represent a by-product rich in valuable materials such as hydroxyapatite (HA) and collagen (Col), substances that are widely used in fields such as cosmetics, medicine, agri-food and many others. Usually synthesised in laboratories or derived from non-renewable raw materials, HA and Col can be obtained in a more environmentally and economically sustainable way. However, current extraction methods do not allow these two materials to be obtained simultaneously, as the extraction processes of one completely destroys the other. The aim of this work was therefore to develop extraction methods that would allow for the simultaneous extraction of HA and Col from salmon bones, and to test HA uses in oral care, sun care and wastewater treatment. In particular, HA has been studied as a remineralising agent for dental enamel, as a preventive agent for tooth sensitivity, and as a sun protection factor booster in sunscreen formulations. For wastewater treatment, HA has been studied as an adsorbent phase for dyes used in the textile industry.