Facile method for the hydrophobic modification of filter paper for applications in water-oil separation

Abstract In this study, a facile method was applied to modify the hydrophobicity of filter paper, and the application of the filter paper in water-oil separation was investigated. The modification was accomplished by immersing the filter paper into the modifier solution containing poly(methylhydrosiloxane) (PMHS) for only 2 min at room temperature. PMHS was found to be covalently grafted onto the surface of filter paper. After PMHS modification, the hydrophobicity of filter paper was significantly improved, as indicated by the increase of the water contact angle from 19.0° to 131.8°. Because PMHS has very low surface energy, after modification, the wettability of filter paper was transformed from hydrophilic to very hydrophobic and subsequently to oleophilic; therefore, the modified filter paper presented excellent performance in water-oil separation. The separation efficiency of diesel and n-hexane from water was more than 94.3% and 80.0%, respectively. This method is simple and based on commercially available materials; moreover, it can be applied to the hydrophobic modification of not only filter paper but also any materials containing hydroxyl groups.