Hydrophobic Microfibrillated Cellulose Aerogels via Dual-Silane Modification for Sustainable Oil Spill Recovery

Abstract Oil spills in marine waters threaten sensitive ecosystems. This highlights the need for effective cleanup methods. While cellulose-based aerogels absorb oil effectively, improving their water resistance without compromising their eco-friendliness remains essential. This study aims to produce hydrophobic aerogels by combining methyltrimethoxysilane (MTMS) and octadecyltrimethoxysilane (OTMS) to create a hierarchical surface with low surface energy and high hydrophobicity. The goal is to modify them and compare their performance with bleached and brown microfibrillated cellulose (MFC). The resulting aerogels have water contact angles of 133.68° ± 1.16° and show excellent selective oil absorption. The bleached MFC aerogel has absorption capacities of 20.2 g g–1 for cooking oil, 15.6 g g–1 for diesel, and 13.3 g g–1 for petroleum, with low water absorption of 5.2 g g–1. In comparison, the brown MFC aerogel performs similarly, absorbing 17.1 g g–1 for cooking oil, 14.9 g g–1 for diesel, and 12.4 g g–1 for petroleum, with even lower water absorption (0.5 g g–1). These renewable MFC aerogels selectively take up oil from oil–water systems and provide a laboratory-scale basis for further evaluation in remediation settings such as Guanabara Bay.