Underwater superoleophobic PVDF membrane with robust stability for highly efficient oil-in-water emulsion separation

Abstract

Membrane technology greatly boost the quick collection process of clean-water from oily wastewater. Although a great mount of researches have been devoted to fabricating super wetting membranes to efficiently separate...

Intelligent Devices Harnessing Underwater Superoleophobic and Underoil Superhydrophobic Quartz Sands for the Separation of Diverse Stratified and Emulsified Water–Oil Mixtures

“…Hydrophilic materials with OCAs of >90°in water are considered underwater oleophobic materials, where OCAs of >150°are called underwater superoleophobic materials. 24 In contrast, oleophilic materials with WCAs of >90°in oil are considered underoil hydrophobic, whereas WCAs of >150°are called underoil superhydrophobic. 23 As shown in Figure 2a, the WCAs of HS-1−HS-4 were 134.2°, 142.0°, 148.5°, and 157.1°, respectively, and the OCAs of S-1−S-4 were 131.0°, 137.8°, 147.1°, and 152.7°, respectively, with DCM in water.…”

“…HS was employed as a filter medium in high-density oil and water mixtures such as dichloromethane and bromoethane because of the tendency of the high-density oil to settle beneath the water, necessitating the utilization of an oil-wet filter for effective oil–water separation. The calculation method for separation efficiency is shown in eq E = V 2 / V 1 where V 1 is the volume of the liquid collected (milliliters) and V 2 is the volume of the collected wetting phase liquid (milliliters).…”

“…As we all know, superwetting material is an advanced oil–water separation material. − By changing the surface free energy and roughness of the materials, the researchers constructed superhydrophobic materials, , underoil superhydrophobic materials, and underwater superoleophobic materials. , These materials are widely used in the field of oil–water separation by regulating the flow of fluid through capillary forces. Among them, the underoil superhydrophobic material is applied in the separation of water-in-oil emulsions and high-density oil and water mixtures.…”

“…Superhydrophobic quartz sand and underoil superhydrophobic quartz sand can efficiently separate immiscible oil–water mixtures and water-in-oil emulsions. ,, However, materials with a single wettability can achieve only either water or oil separation and cannot handle actual separation environments with large density differences. Underwater superoleophobic materials cannot separate high-density oil and water systems and water-in-oil emulsions, and underoil superhydrophobic materials cannot separate low-density oil and water systems and oil-in-water emulsions. − Additionally, the nonwetting phase is still retained in the filtration equipment, which requires a secondary purification and collection process, increasing the difficulty of the overall process. Surprisingly, multifunctional filtering materials can separate diverse oil–water mixtures.…”

“Two birds with one stone” strategy for oil/water separation based on Ni foams assembled using metal–organic frameworks

“…4,5 Membrane separation is undoubtedly a very promising and economical method to tackle energy and environmental challenges. [6][7][8][9] Inspired by their magical and almighty nature, biomimetic superantiwetting/superwetting mesh materials have attracted wide attention as a solution. 10,11 At present, oil-water separation is mainly acquired by membrane materials with superhydrophobicity-superoleophilicity (SHB&SOL).…”