Hydrophobically Modified and Reusable Graphene Structures for High Diesel Sorption Capacity

Diesel contamination in aquatic environments presents a significant ecological risk, necessitating the use of efficient and sustainable cleanup systems. In this study, a hydrophobically modified melamine composite, coated with SiO₂‑functionalised graphene oxide (GSMF) was developed for enhanced diesel adsorption performance. The GSMF composite was fabricated by incorporating SiO₂‑functionalised GO onto a three-dimensional melamine scaffold to improve functionality, hydrophobicity and mechanical stability. Characterisation analyses confirmed the effective integration of GO and SiO ₂, accompanied by improved diesel adsorption. Response surface methodology (RSM) with applied to optimise major parameters for both GSMF synthesis and diesel adsorption conditions. Under optimum conditions (GSMF dosage = 35 mg, salinity = 0.2 M, contact time = 9 min and shaking speed = 250 rpm), the composite achieved a maximum diesel adsorption capacity of 61.02 g/g, with < 6.3 % deviation from model predictions. Adsorption kinetics followed pseudo‑second‑order model (R² = 0.9981, RMSE = 0.5368), indicating chemisorption as the dominant mechanism. Regeneration tests showed > 90 % retention of adsorption capacity over five cycles, demonstrating promising reusability with simple mechanical compression. These results support GSMF as a robust, high‑performance adsorbent with strong potential for scalable diesel spill remediation.