VALORISATION DES RESIDUS ISSUS DE L’EXTRACTION SUPERCRITIQUE EN PRODUITS INNOVANTS À APPLICATION VERTE DANS L’ENVIRONNEMENT

Abstract

The valorization of agri-food waste is a promising way to meet current environmental and economic challenges. This dissertation focused on onion seed residue (TGO), residues from supercritical CO₂ extraction, as a resource for sustainable applications. Three main approaches were investigated: the use of TGO as biochar for soil amendment, the extraction and optimization of cellulose for eco-responsible uses, as well as their use as a natural biocoagulant in the treatment of water loaded with copper ions. The results obtained show that biochar derived from TGO improves the physico-chemical properties of soils. Furthermore, the alkaline and bleaching treatments applied enabled cellulose to be extracted with optimized yields of 51.5% for an extraction time of 1.5h and a NaOH concentration of 2M. Finally, coagulation-flocculation tests confirmed the effectiveness of TGOs in removing copper heavy metals in aqueous solution, with a yield of 90.15% at a mass of 1.7g and a pH of 7-8, reaching a residual concentration of 0.0067mg/L. These results highlight the multifunctional potential of TGOs, from a circular economy and sustainable development perspective, while offering alternative solutions to conventional chemicals used in agriculture, industry and water treatment.