Sustainable hydrophobic bio-based adsorbent from modified sphagnum moss for efficient oil-water separation

Oil spills pose a major environmental challenge, highlighting the urgent need for effective materials capable of achieving efficient oil-water separation to mitigate their detrimental impacts. While various bio-based and synthetic adsorbents have been explored for this purpose, existing materials often suffer from low adsorption capacity, poor reusability, limited hydrophobicity, or environmental concerns. In particular, natural bio-based materials frequently exhibit inherent hydrophilicity, limiting their effectiveness in selective oil adsorption. To address this gap, we developed a novel bio-based oil adsorbent derived from sphagnum moss, modified via sequential pretreatment with hydrogen peroxide and sodium hydroxide, followed by chemical functionalization with silane. This modification enhanced hydrophobicity and structural stability, overcoming the limitations of unmodified bio-based adsorbents. Characterization using SEM, XPS, FTIR, and TGA confirmed the successful grafting of hydrophobic functional groups and the formation of a uniformly rough surface, leading to a water contact angle of 157°. Comparative analysis demonstrated that the modified sphagnum moss exhibited a significantly enhanced adsorption capacity of 22.756 g/g for motor oil, outperforming conventional bio-based adsorbents, including currently prevalent biological adsorbents (1.69-12.8 g/g) and biochar (8.1-18.2 g/g). Furthermore, the adsorption kinetics conformed to a pseudo-second-order model, indicating chemisorption as the dominant mechanism. This suggests strong interactions between oil molecules and the functionalized surface, contributing to enhanced efficiency and selectivity. These findings highlight the novelty, superior performance, and environmental compatibility of modified sphagnum moss as an effective and sustainable solution for oil spill remediation. Its high adsorption capacity, selective oil affinity, and reusability make it a promising alternative to existing bio-based adsorbents, providing an eco-friendly approach to oil spill management and environmental restoration.