Study On Superwettability Lignin Filter Membrane For Multiphase Liquid Separation

With the rapid development of economy,oil spill accidents at sea and the discharge of a large number of untreated oily sewage,oil pollution has become more and more serious,which has endangered ecosystem safety and human health.Traditional methods of treating oily wastewater include combustion,adsorption and biodegradation,and so on.In addition,due to the existence of various surfactants,the oil/water mixtures were easily emulsified into small droplets less than 20 μm in size.Compared with immiscible oil/water mixtures,surfactant stabilized emulsions was more difficulty be separated.In fact,the composition of industrial pollutants is very complex.It includes not only the oil/water mixture but also organic liquids(OLs)mixtures.However,just a simple oil/water separation system cannot satisfy the treatment requirements of complex liquid mixture in industry.In the literature currently reported on the separation of OLs,only when the surface free energy of the membranes lies between the surface tensions of two OLs,realizing the successful separation of the OLs mixture.However,the above separation method requires low surface energy substances,which are complex,high-cost and impractical for wide use.So it is necessary to find an efficient and low-cost separation method.The specific research content is as follows:(1)The corn cob powders coated mesh was prepared successfully by spraying coating method.The coated mesh possessed underwater superoleophobic and underoil superhydrophobic property,which can separate various oil/water mixtures on demand with high separation efficiency.In addition,the coated meshes can maintain its special wettability under corrosive conditions and separate successfully corrosive solution/oil mixtures with separation efficiency larger than 99.9 %,showing good stability of the coated mesh.(2)The wood slice with superhydrophobic/superoleophilic performance was prepared by vacuum filtration and redox reaction.Various of water-in-oil emulsions were successfully separated using the wood slice with superhydrophobic/superlipophilic property and the sieving effect.After 6 cycles,the separation efficiency of superhydrophobic wood slice to kerosene-in-water emulsions is still as high as 98.0 %,showing excellent cycle performance.Moreover,the possible separation mechanism of water-in-oil emulsions was theoretically analyzed,indicating that the emulsion separation is feasibility.(3)The coconut shell powder coated mesh was prepared by a facile spraying method.Utilizing underliquid superlyophobic concept,through the introduction of the high surface tension liquid inject into superamphiphilic membrane with rough structure,the as-prepared mesh shows under high surface tension liquid(super)lyophobicity for immiscible low surface tension liquid,achieving separation of OLs Mixtures.Finally,the feasibility of the coated mesh for the separation of immiscible OLs mixtures was further confirmed by the analysis of the infiltration model of coconut shell powder coated mesh.