Facile fabrication of silane modified melamine sponge for highly efficient oil absorption properties

Separating waste oil spills is a global challenge in environmental governance. Adsorption separation technology, with its simplicity of operation, broad separation range, small footprint, and high efficiency, has attracted increasing attention. Silane coupling agents are commonly employed as hydrophobic modification materials in adsorption separation. However, the effects of silane chain length on performance remain unclear. This study aimed to elucidate the effects of different silane chain lengths on oil-water separation performance. A silane-modified melamine sponge was developed for oil-water separation. The adsorption performance was evaluated using four oil solvents: dichloromethane, n-hexane, heptane, and petroleum ether. The effects of silane chain length on adsorption capacity were investigated, followed by the optimization of parameters for achieving a superhydrophobic sponge with high adsorption capacity. The results indicated that short-chain silane-modified sponges exhibited notable hydrophobicity and high performance. Besides, the contact angle of oil and water on pristine sponge surfaces was nearly 0°, it reached 0° and 149.8°, respectively, on short-chain trimethoxysilane-modified sponges. The adsorption capacities of these modified sponges achieved 120.68 g·g−1, 93.5 g·g−1, 59.0 g·g−1, and 34.3 g·g−1 for heptane, dichloromethane, n-hexane, and petroleum ether, respectively. Adsorption kinetic results confirmed that the adsorption capacity of trimethoxysilane-modified sponges aligned well with both pseudo-first-order and pseudo-second-order kinetics models, indicating a rapid adsorption rate. Furthermore, the sponge demonstrated consistent separation performance under acidic and alkaline conditions.