Oil–Water Separation Using a Superhydrophilic Metallic Mesh in an Oscillatory Reactor

Efficient oil‒water (OW) separation is becoming increasingly important for mitigating the negative effects of the discharge of oily wastewater to the environment. Conventional treatment approaches such as precipitation, adsorption, coagulation and advanced oxidation as well as membrane separation are costly, involve the use of toxic chemicals and/or are limited by low flux due to fouling and loss of selectivity. In this study, a novel OW separation approach was applied to achieve high productivity and separation efficiency through the hybrid implementation of a high-porosity superhydrophilic metallic mesh (SHPM) with a near-zero contact angle in an oscillatory reactor augmented with turbulence promoters (TPs). The former allowed high-water flux while limiting the passage of the oil phase, whereas the latter provided a repelling effect of the oil droplet away from the mesh surface through the generated oscillatory shear and turbulence eddies. The SHPM was prepared via a spraying method using ZnO nanoparticles (NPs) and a stainless-steel mesh. In bench-scale gravity separation, the hierarchical mesh showed excellent superhydrophilic properties with near total oil rejection. In the reactor, increasing the oscillation intensity enhanced the separation performance, reaching a ~ 9.1 × 10³ LMH (Lm-²h^{− 1}) flux and ~ 99% separation efficiency. These results highlight the advantages of the combined effect of the superhydrophilic properties of the mesh and the oscillatory motion on enhancing OW separation.