Castor Bean ( Ricinus communis L.) for Phytoremediation: Strategy to Improve and Integrate the Circular Economy

Phytoremediation is increasingly recognized as a sustainable and low-impact approach for the remediation of contaminated and marginal soils, particularly when combined with the cultivation of resilient non-food crops. Castor bean ( Ricinus communis L.) is a multipurpose industrial oilseed crop characterized by high biomass production, strong tolerance to abiotic stresses, and a remarkable ability to accumulate and tolerate potentially toxic elements. This review provides a comprehensive overview of the role of castor bean in phytoremediation systems, integrating agronomic management, physiological traits, traditional and industrial uses, and sustainability perspectives. Particular attention is given to agronomic practices that enhance plant establishment and remediation efficiency on contaminated lands. Beyond its environmental role, this review highlights the long-standing traditional uses of castor oil and the growing importance of castor bean as an energy and industrial crop, supplying renewable feedstocks for biofuels, bio-based chemicals, and materials within a circular economy framework. While genetic improvement and molecular tools offer future opportunities to optimize specific traits, the current potential of castor bean relies largely on its agronomic adaptability and multifunctionality. Overall, R. communis emerges as a strategic species for integrated phytoremediation systems that couple soil restoration with renewable resource production and sustainable land management.