Superhydrophilic and superhydrophobic quartz sand hybrid filters for efficient on-demand oil/water separation

The development of an efficient and sustainable separation method for oily wastewater has become a major challenge for industrial development and environmental protection. In this work, the simple special wettability particle preparation method and the hybrid filters construction strategy was reported for enhanced oil/water separation efficiency. Two special wettability quartz sands mixed in a certain proportion could destroy the balance of dispersed droplets in the oil-water emulsion, induce the coalescence of dispersed droplets, and purify the oil-water emulsion by the tortuous channel in the filter. Based on the coupling effect of “size sieving” and “coalescence separation”, the special wettability particle hybrid filter with a mass ratio of 3:1 had good droplet coalescence ability, and the separation efficiency of various kinds of oil-water emulsions can reached more than 98%. The hybrid filters exhibited robust mechanical and chemical stability, excellent durability, which enable them to be competent for oil/water separation in multitasking and complex environment.