The Preparation Of Super-hydrophobic And Super-lipophilic Three-dimensional Sponge And Its Oil-water Separation Performance

A variety of materials with superwetting property are fabricated for separation of immiscible oils/organic solvents and water mixture.However,the complex fabrication process,requirement of sophisticated equipment,and associated toxicity strongly limit the development of the superwetting materials.In this paper,a simple two-step dip coating strategy is demonstrated to prepare polydopamine-octadecane thiol(PDA-ODT)modified 3D porous sponge with superhydrophobic and superoleophilic properties(a water contact angle of 156.8±2.50° and an oil contact angle of nearly 0°)through the combination of enhanced surface roughness and low surface energy coating for separation of oil/water mixture.The as-prepared superhy drop hob ic sponges possess high porosity(greater than 99.2%),low density(below 10 mg/cm3),and 3D porous network structure,which meet well with the needs for adsorption the actual oil pollutions.More importantly,in situ continuous removal of oil from oil/water mixture is successfully accomplished via a vacuum assisted system,even in the corrosive environments including turbulent situation,heat,acidic,alkaline,seawater,and glacial water.The continuous oil collection system could avoid the limit in adsorp tion saturatio n e ffectively.We believe that the superhydrophobic sponge with the characteristics of easy large-scale production,economical,and environmentally friendly can be a superior candidate for the treatment of oily wastewater and practical oil-spill accidents.In addition,oil/water mixtures are easily converted into microemulsions(diameter below 20 ?m)with high stability and complex structures under the action of surfactant,causing great difficulties for effective separation.In order to satisfy the requirement of pore sizes in emulsion separation,a novel and controllable approach has been explored to control the pore sizes and 3D porous structure of the resultant sponge by the mechanical compression strategy.Notably,when the emulsified oil/water mixtures were poured into the modified sponge with 90%compression degree of its original volume,the demulsification occurred immediately and then the oil phase passed through the sponge quickly,while water droplets were interrupted in the tortuous pore channels.Combined with the special wettability and the novel pore sizes tuning strategy,the resulting sponges can effectively separate a wide range of surfactant-stabilized water-in-oil emulsions with fast permeation flux of 24500±2000 L m-2 h-1 bar-1 under the action of gravity and extremely high oil purity(>99.97%').It is expected that the superhydrophobic sponge with the novel compression approach can provide a general strategy for 3D porous materials used for e ffective separation of emulsified oil/water emulsions.