Recent experimental studies demonstrate the need to take into account weak interactions in the understanding of solvent extraction processes. This well-established industrial technology now beneficiates of a supramolecular approach, complementary to the traditional analysis based on coordination chemistry. In this article, we focus on the integration of a colloidal approach in the analysis of solvent extraction systems: organic phases employed are complex fluids, in which extracting molecules self-assemble into reverse aggregates. We detail the available analytical tools employed towards characterization of these organic phases, and emphasize the recent results in aggregation driven extraction. All experimental data is discussed in light of theoretical approaches which propose adequate thermodynamic models and shed light on the importance of entropy on the phenomena. Diluent effects or synergism have been successfully rationalized, efficient new formulations based on a physico-chemical analysis have been proposed, and the door is now open for further development at industrial scale.