A solid waste with special surface wettability under-liquid used for surfactant-stabilized emulsion separation

Inspired by the strong adsorption of oil and moisture for the ashes of mosquito-repellent incense (MRI) in daily life, their potential application for the highly efficient separation of water-in-oil (W/O) and oil-in-water (O/W) emulsions was developed. Scanning electron microscopy (SEM) and energy spectrometer (EDS) were used to determine the micromorphology and composition of the MRI ashes. The packed ashes were both superhydrophilicity/superoleophilicity in the air, and underwater superoleophobicity/under-oil superhydrophobicity. Based on the special dual wettability of the ash layer, the resultant packed column was used for the efficient separation of O/W emulsions and the corresponding W/O emulsions, respectively. The separation flux of different types of O/W and W/O emulsions was over 2×10⁴ L/m²h and their separation efficiencies were maintained at over 95%. The waste MRI ashes without any physical and chemical treatment provided a new idea for the selection of efficient separation materials.