The preparation of PCL/MSO/SiO2 hierarchical superhydrophobic mats for oil-water separation by one-step method

Abstract

Hydrophobic polycaprolactone (PCL) membranes with hierarchical structure were fabricated via one-step electrospinning technique. Meanwhile, the addition of the liquid methyl silicone oil (MSO) and hydrophobic silica (SiO2) nanoparticles in the PCL membrane were expected to improve the hydrophobicity of PCL membranes. FE-SEM images showed the microsphere-fiber interlinked hierarchical morphology of PCL/MSO/SiO2 composite fiber. FT-IR confirmed the formation of PCL/MSO/SiO2 composite fibers. XPS approved its hierarchical structure of the composition. By comparing with pure PCL membrane which the water contact angle (WCA) was 132.2 ± 1.2°, the WCAs of PCL/MSO and PCL/SiO2 membrane increased to 143.3 ± 1.2° and 141.7 ± 1.9°, respectively. It was worth noting the WCA of PCL/MSO/SiO2 composite mat could reach 151.6 ± 1.7° and the sliding angle was 7.4 ± 1.2°. The excellent surface roughness and air-pocket capacity on the hierarchical membranes were believed to contribute to the superhydrophobicity of PCL/MSO/SiO2 membrane. The unique microsphere-fiber interlinked hierarchical structure and superhydrophobicity of membrane could provide adequate support for oil adsorption and oil-water separation. The maximum n-hexane adsorption capacity of PCL/MSO/SiO2 membrane was 41.37 g g−1. Separation efficiency for n-hexane-water mixture of PCL/MSO/SiO2 membrane was as high as 99.92%. The PCL/MSO/SiO2 hierarchical superhydrophobic mats indicate the potential applications of environmental-friendly biopolymers as separator.