Study On Surface Superhydrophilic Modification And Oil/Water Separation Performance Of Polypropylene Membranes

With the increase in demand and use of oil products,oil pollutants will inevitably enter the water body,causing serious impact on environment.Membrane separation technology is a simple and efficient method to purify oily wastewater.Inspired by natural organisms such as lotus leaves,researchers have introduced special wettability into membrane separation technology and obtained special wettability conditions suitable for oil/water separation by designing the chemical characteristics and roughness of the membrane material surface.Among them,superhydrophilic/underwater superoleophobic membrane materials have attracted extensive attention because of their excellent antifouling performance.Meanwhile,polypropylene（PP）melt-blown nonwoven was regarded as an ideal substrate for oil/water separation membrane attributing to its low cost,light weight and corrosion resistance.However,inherent hydrophobicity makes it easily contaminated by oil pollution.Thus,the hydrophilic modification of PP membranes is of vital importance.Based on above background,this paper aims to develop efficient,stable,and reusable PP-based superhydrophilic/underwater superoleophobic membrane materials.The detail works are as follows:（1）A novel MnO_x particles mineralized oxidized-polypropylene（MnO_x-OPP）membrane was fabricated through a simple one-step immersion process,which could be used for efficient oil/water separation.In acidic KMnO₄ solution,PP membrane was oxidized,and resulting MnO_x particles deposited on the surface of membrane fiber.The hydrophilicity of the modified membrane was greatly improved.The chemical composition and surface structure of the membrane were analyzed by various characterization methods.The results of contact angle measurement showed that the prepared membrane successfully obtained superhydrophilicity/underwater superoleophobicity,the water contact angle was 0°,and the underwater oil contact angle was above150°,showing high repulsion to various oils.The membrane showed excellent performance in oil/water separation tests,with high separation efficiencies of over 99%and the maximum permeable flux was up to6.12×10⁴ L·m^-2·h^-1.Even after 30 separation cycles,there was no significant loss of separation efficiency,showing excellent separation stability.In addition,the MnO_x-OPP membrane also possessed superior chemical stability and long effectiveness,which had broad application prospects in the practical treatment of oily wastewater.（2）Based on the reaction between tea polyphenols（TP）andγ-aminopropyltriethoxysilane（APTES）,this experiment proposed a facile co-deposition strategy.Hierarchical nanoparticles were successfully constructed on PP membrane surface via a mild preparation process,which endowed it with superhydrophilicity and underwater superoleophobicity.Water droplets could completely spread out on the membrane surface within 1.8 s,the water contact angle was 0°,and the underwater oil contact angle was no less than 152°.The as-prepared membrane could realize the efficient separation of oil/water mixtures,whether for vegetable oil/water mixtures or mineral oil/water mixtures.All separation efficiencies were above 99.1%and the optimal permeation flux was as high as 1.13×10⁵ L·m^-2·h^-1.The“30+clean+30”cyclic experiments further proved the reusability and recoverability of the membrane.Additionally,the modified membrane also exhibited superior underwater oil resistance,low oil adhesion,self-cleaning capacity,mechanical stability,and remained stable underwater superoleophobicity though after ultrasonic treatment for 60 min.Therefore,the PP-TP/APTES membrane with high efficiency,energy saving,environmental protection,and anti-pollution is a potential material for oil/water separation.