Green Transformation of Fish-Oil By-Products into Polysulfide-based Nanocomposite Adsorbents via Coupled Inverse Vulcanization and Exfoliation

Abstract

This study reports a sustainable route to sulfur-enriched foams (FO@S_X:Y) prepared via inverse vulcanization of elemental sulfur with fish oil (FO) byproducts. In contrast to vegetable oils, the high content of polyunsaturated fatty acid methyl esters in fish oil enables an extended cross-linking with sulfur, yielding highly branched, three-dimensional polysulfide foams with an open porous network, good elasticity and shape memory. Moreover, inverse vulcanization conducted in the presence of nanometric fillers (e.g., graphene oxide, montmorillonite) affords ternary nanocomposites with exfoliated sheets and expanded functionalities. The resulting materials denoted FO@S_X:Y-GO and FO@S_X:Y-MMT, integrate within their framework the hydrophobicity of fats, the reactivity of sulfur, and the regidity of the fillers. This ecodesign methodology provides access to cost-effective adsorbents for the removal of heavy metal ions and methylene blue dye from water, for reversible capture and release of iodine, and for efficient oil-water separation. Overall, the process described herein valorizes two abundant industrial byproducts and relies on solvent-free conditions, enabling access to sulfur-rich foams with high remediation efficiency, thereby offering a circular and eco-friendly platform for water purification and iodine management.