Kinetic, isotherm, and thermodynamic studies on diesel oil adsorption by biodegradable cellulose aerogel from rambutan peel waste

Oil spills pose a significant environmental threat, necessitating the development of efficient and eco-friendly sorbent materials. In this study, a biodegradable cellulose aerogel was successfully synthesized from rambutan peel (RP) waste and evaluated for its diesel oil adsorption performance. The aerogel exhibited ultra-low density (0.027 ± 0.002 g/cm3), high porosity (97.88% ± 0.19%), and excellent hydrophobicity (152.7°). Adsorption experiments demonstrated a maximum diesel oil uptake capacity of 58.8235 g/g under optimal conditions: pH 7, oil concentration of 25 g/L, contact time of 25 s, salinity range of 0‰–35‰, and temperature range of 25–35 ℃. Adsorption equilibrium data were best described by the Langmuir isotherm model (R2 = 0.9974), indicating monolayer adsorption with RL values ranging from 0.0409 to 0.2301 at 25 ℃. Kinetic studies revealed that the pseudo-second-order model provided the best fit (R2 = 0.9998), suggesting that adsorption occurred through both boundary layer diffusion and intraparticle diffusion mechanisms. Thermodynamic analysis confirmed the spontaneity and exothermic nature of the adsorption process. Furthermore, the adsorption mechanism was primarily governed by hydrophobic interactions, van der Waals forces, and hydrogen bonding. Overall, this study highlights the potential of cellulose aerogels derived from agricultural waste as sustainable and highly efficient sorbents for diesel oil removal, offering a promising solution for oil spill remediation in various aquatic environments.