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. [ABSTRACT FROM AUTHOR]