Synergistic effects of silica derived granite dust and MoS2 on oil-water separation performances of mixed matrix PES membrane

Abstract

Membrane separation technology has been widely examined for the treatment of oily wastewater owing to its numerous advantages, including high efficiency, energy saving, compact structure, and ease of operation. However, the overall performance of membrane separation highly depends on the membrane properties such as hydrophilicity and morphology structure. Nanoparticles (NPs) have been widely used to increase membrane hydrophilicity and fouling resistance. In this work, silica derived from granite dust (GD) via the sol–gel method was hydrothermally treated with molybdenum disulfide (MoS2) and used for the fabrication of MoS2-silica-PES mixed matrix membranes (MMMs). The synthesis of MoS2-silica composite was first confirmed via XRD analysis. Then, 1.0 wt% of MoS2-silica was blended into the PES casting solution, and the flat sheet membrane was cast by controlling the thickness of about 100 μm. The MoS2-silica-PES MMMs were then subjected to chemical, hydrophilicity and surface morphology studies. It was found that the addition of silica into MoS2 leads to a notable improvement in hydrophilicity and water flux as compared to bare PES and MoS2-PES membranes. The performance of MoS2-silica-PES membrane was then evaluated for oil–water separation using 1000 ppm oil concentrations at 1 bar and room temperature. The membrane was first compacted for 2 h at 2 bar before the oil–water separation test to maintain a stable flux. It was found that there was a substantial increase in the oil–water flux of the composite membranes (from 3.25 LMH to 41.68 LMH) when silica was added. This was due to the enhancement in membrane properties and morphology structure. Generally, the oil rejection of the MoS2-silica-PES MMMs fabricated in this work was maintained above 95 %. This study indicates that the fabricated MoS2-silica-PES MMMs have excellent potential for commercial applications. Using silica-derived granite dust offers an opportunity to lower the cost of the membrane.