Towards an efficient and durable superhydrophobic mesh coated by PDMS/TiO2 nanocomposites for oil/water separation

Abstract

Oil spill accidents and industrial oily wastewater are threatening all living species in the ecological system. Development of materials with special wettability for oil/water separation has been the subject of many researches. Herein, superhydrophobic and superoelophilic nanocomposite coatings, based on titanium dioxide (TiO2) nanoparticles and polydimethylsiloxane (PDMS), were applied on metal meshes with different pore sizes (25 and 100 μm). Morphological analysis revealed that adding PDMS, as a binder, significantly changes the surface structure of the coatings. For 100 μm-sized meshes, PDMS causes a two-tier roughness whereas a uniform and finely packed single-scale nanostructure was formed for 25 μm-sized meshes upon PDMS addition. Exceedingly high content of nanoparticles was found to impose a detrimental influence on uniformity of morphology. All the samples exhibited superhydrophobicity; however, their mechanical durability results were significantly diverse. PDMS introduction was found to impose a substantial improvement in abrasion resistance. Oil/water separation experiments revealed that the mesh with smaller pore size exhibited a more efficient separation while a much shorter separation time and higher flux could be achieved by the mesh with larger pore size. In addition, the mesh with smaller pore size exhibited a more abrasion resistant coating which could be more beneficial in real-life applications.