Carrageenan-assisted liquid-phase exfoliation of MoS₂ for sustainable hybrid films enabling dye removal and SERS detection in water

This work presents, for the first time, a sustainable strategy for the production of few-layer molybdenum disulfide (MoS₂) nanosheets using carrageenan as a green exfoliating and stabilizing agent via liquid-phase exfoliation (LPE). The process was systematically optimized using response surface methodology (RSM) with a Box–Behnken design, thereby identifying key parameters that influence exfoliation efficiency. Under optimized conditions, MoS2 nanosheets with a low number of layers (4.3 using κ-carrageenan and 6.6 using -carrageenan) were successfully obtained, as confirmed by optical spectroscopy, electron microscopy, and Raman analysis. The resulting MoS2/Carrageenan (MoS2/Carr) hybrid materials were used to fabricate thin films via vacuum filtration on polyamide supports. As a proof-of-concept, the hybrid films were evaluated for the removal and detection of methylene blue (MB) in aqueous media. MoS2/Carr films exhibited high dye removal efficiencies (up to ~89%), driven by a combination of electrostatic interactions, hydrogen bonding, and π–π interactions. Furthermore, the films demonstrated surface-enhanced Raman scattering (SERS) sensitivity to detect MB without the need for noble metal nanoparticles. The best-performing hybrid film (MoS2/κ-carr_0.4) showed a good balance between adsorption capacity, SERS sensitivity, and satisfactory signal reproducibility (RSD ~16%). Overall, this study highlights carrageenan-assisted exfoliation as a green and effective route to produce functional MoS2-biopolymer hybrid films. The combination of process optimization via response surface methodology and film fabrication by vacuum filtration highlights the potential for translation to industrially relevant systems. The resulting hybrid materials exhibit dual functionality for pollutant removal and sensing, making them attractive candidates for integrated separation–detection platforms in advanced water treatment.