An intelligent dual mode filtration device for separation of immiscible oil/water mixtures and emulsions

Abstract Herein, we report an intelligent mesh for dual mode reversible separation of immiscible heavy/light oil water mixture and both oil-in-water as well as water-in-oil emulsions. ZnO nanowires coated stainless steel mesh with pore size 50 μm and 10 μm were fabricated successfully. The wettability of mesh can be reversibly switched between “oil-blocking” and “water-blocking” modes by alternatively annealing the smart mesh at about 210 °C for about 20 min in presence of poly (dimethyl siloxane) vapors and at 300 °C for 25 min in air, respectively. The “oil-blocking” mode was suited for the efficient separation of light oil/water mixture and oil-in-water emulsion, while “water-blocking” mode was found to be suitable for the separation of heavy oil/water mixture and water-in-oil emulsion. This work provides a simple, cost effective, eco-friendly and time saving approach applicable for separation of both form of oil/water mixture, free as well as surfactant stabilized emulsions, irrespective of the types of oil involved. The separation efficiency of the mesh was found to be more than 99% for free as well as emulsified mixtures. Even after cyclic usage in both modes alternatively, the separation efficiency of the mesh remained relatively unchanged, showing antifouling property and excellent recyclability of the mesh.