【作者】 袁静；

【导师】 梁丽芸；

【作者基本信息】 华中科技大学 ， 高分子化学与物理， 2019， 硕士

【摘要】 传统的分离过程如精馏、闪蒸等,由于需要加热和降温过程,耗能过大,正逐渐被更节能的分离过程所代替。在常温、重力驱动下、操作简单的、低能耗的油水分离过程,在近几年来的含油废水处理中,得到了越来越多的重视。由于超亲水-超疏油型油水分离膜可通过在基底表面构筑微纳米多级结构,调控分离膜表面粗糙度及表面能,具有通用性好、分离效率高、抗油污染能力强等优势,成为油水分离领域的热门研究方向。本文以力学性能优异的不锈钢网为基底,制备并研究了“除水,water-removing”的低表面能聚合物复合膜与原位金属氧化物修饰膜,主要研究内容与结果如下:（1）构筑微纳米结构与低表面能相结合的复合膜。以阳离子聚二烯丙基二甲基氯化铵（PDADMAC）为粘结剂,掺杂不同比例的气相白炭黑（SiO₂）与氧化石墨烯（GO）混合纳米材料,再与全氟辛酸阴离子（PFO）在静电作用下络合,制得PDADMAC-PFO/GO&SiO₂复合材料,用浸涂法修饰到不同目数的不锈钢网上,对其表面形貌、化学组成、润湿性与油水分离性能进行表征。结果表明,PDADMAC-PFO/GO修饰600目网膜具有最快的水响应亲水性,植物油的接触角为126°,空气中抗油滴粘附能力也较强。PDADMAC-PFO/GO修饰600网膜的水通量最高,达1875 L·m^-2h^-1,分离效率为94.9%,具有较好的油水分离能力。虽然片状结构的GO未明显提高表面粗糙度,但是其高亲水性也提升了油水分离性能。（2）构筑多级微纳米结构与低表面能相结合的复合膜。为获得多级微纳米结构,自制毛刺状聚（苯乙烯-丙烯酸）-α-Fe₂O₃（PAF）纳米微球,与SiO₂以不同配比混合掺杂,得到PDADMAC-PFO/PAF&SiO₂复合材料,以浸涂法修饰到100、300、600目与FeCl₃刻蚀600目不锈钢网上,对其表面形貌、化学组成、润湿性与油水分离性能进行表征。结果表明,PDADMAC-PFO/PAF&SiO₂（1:1）修饰600目网膜具有较好的水响应亲水性和较高的疏油性,空气中植物油接触角为130.3°,修饰网膜具有最高的水通量为2585 L·m^-2h^-1,分离效率为96.5%。经过FeCl₃刻蚀的600目不锈钢修饰网膜的水响应亲水性与疏油性能稍提升,也具有更高的水通量,达到2724 L·m^-2h^-1,油水分离效率为96.5%,与SEM结果结合来看,经过刻蚀的不锈钢表面孔洞增多,表面粗糙度提升,PAF的掺杂提高了水响应亲水性与油水分离性能。（3）构筑原位金属氧化物微纳米复合膜。通过水热法与煅烧在不锈钢网表面原位生长具有多级粗糙结构的针叶状钴酸锌修饰层,得到超亲水-水下超疏油油水分离膜。探索最佳工艺,对网膜表面形貌、化学组成、润湿性、油水分离性能、机械稳定性与空气中稳定性进行了表征。结果表明,在六水合硝酸钴与六水合硝酸锌浓度分别为0.05 mol/L和0.025 mol/L时,在120℃下水热反应6 h,在400℃下煅烧3 h为最佳工艺,相对应的油水分离性能也是最佳的,其水通量达到了12485 L·m^-2h^-1,分离效率为98%,截油率为94%,循环使用5次后,水通量保持在8819 L·m^-2h^-1以上,分离效率也保持在96.6%以上。ZnCo₂O₄修饰网膜的水接触角为0°,对于各类油相,测得水下油滴接触角都在150°以上,显示出超亲水-水下超疏油性能。网膜还具有较好的耐碱、盐腐蚀性能、机械稳定性与空气中稳定性。比较以上三种方法,得出最终结论为:原位生长ZnCo₂O₄修饰网膜的水通量与分离效率均比前两种浸涂法修饰网膜的都高,虽然在空气中不能疏油,但是也具有优异的水下超疏油性与抗粘附性,综合来看性能更佳。更多还原

【Abstract】 Traditional separation processes,such as distillation and flash distillation,are gradually replaced by more energy efficient separation processes due to excessive energy consumption in heating and cooling processes.For example,membrane separation progress with room temperature,gravity-driven,simple operation and low energy consumption has been paid more and more attention.Superhydrophilic and superhydrophobic oil-water separation membranes have become a hot research direction in the oil-water separation field due to their advantages of good versatility,high separation efficiency and strong oil-pollution resistance,which can be achieved by establishing micro-nano hierarchical structures on the surface of different substrate to regulate the surface roughness and low surface energy.In this paper,"water removing"low-surface-energy polymer composite membrane and in-situ metal oxide coated mesh membrane were prepared and studied based on stainless steel mesh with excellent mechanical properties.The main research contents and results are as follows:（1）A low-surface-energy polymer composite membrane was constructed.With cationic polymer（PDADMAC）as binder,doping different ratios of aerosol silica（SiO₂）and graphene oxide（GO）mixed nanomaterials,and then positively charged PDADMAC alternately assembled with perfluorooctanoic acid anion（PFO）by the strong electrostatic interaction.The PDADMAC-PFO/GO&SiO₂ composites were prepared and modified on stainless steel mesh by dip coating,and their surface morphology,chemical composition,wettability and oil/water separation performance were characterized.Results show that film coated with PDADMAC-PFO/GO has the fastest water-response hydrophilicity,and the contact angle of vegetable oil reaches up to 126°,shows low oil adhesion.And film coated with PDADMAC-PFO/GO shows the highest flux of 1875 L·m^-2h^-1,separation efficiency of 94.9%,has good oil-water separation ability.Although the GO of the flake structure did not significantly improve the surface roughness,its hydrophilicity also improved the oil-water separation performance.（2）A low-surface-energy polymer composite membrane was constructed.For more hierarchical structure,rambutan-like poly（styrene-acrylic acid）-α-Fe₂O₃（PAF）mixed with SiO₂ in different ratio to prepare of PDADMAC-PFO/PAF&SiO₂ composites,then modified on stainless steel mesh by dip-coating method.The surface morphology,chemical composition,wettability and oil/water separation properties were characterized.Results show that PDADMAC-PFO/PAF&SiO₂（1:1）modified 600 mesh has good water-response hydrophilic and oleophobic properties for several kinds of oil.Contact angle of vegetable oil is 130.3°in the air.When ratio of PAF and SiO₂ were 1:1,the highest water flux of coated mesh is 2585 L·m^-2h^-1,and the separation efficiency is 96.5%.The hydrophilic and oleophobic properties of FeCl₃ etched 600 mesh membranes are slightly improved.It also has a higher water flux of 2724 L·m^-2h^-1,and the oil-water separation efficiency is 96.5%.Combined with the SEM results,the holes of mesh increase after etched,improving the surface roughness,and the doping of PAF improves the hydrophilicity and oil-water separation performance.（3）An in-situ metal oxide micro-nano composite membrane was constructed.Tussock-like micro/nano hierarchical structure of ZnCo₂O₄ was grown on stainless steel mesh by hydrothermal method and calcination.The surface morphology,chemical composition,wettability,oil/water separation property,mechanical stability and stability were studied.Results show that the concentration of Co（NO₃）₂·6H₂O and Zn（NO₃）₂·6H₂O are 0.05 mol/L and 0.025 mol/L,autoclave heated and maintained at 120℃for 6 h,annealing performed at 400℃for 3 h as the best technique.Flux of water of ZnCo₂O₄coated mesh can reach 12485 L·m^-2h^-1,separation efficiency is 98%.Flux and separation efficiency remain above 8819 L·m^-2h^-11 and 96.6%after 5 cycles.ZnCo₂O₄-coated mesh shows superhydropilicity and under water superoleophobicity for several kinds of oil.The ZnCo₂O₄-coated mesh has excellent alkali and salt corrosion resistance,mechanical stability and low under water oil-adhension.Comparing the three strategies,a general conclusion has been made that the flux of water and separation efficiency of ZnCo₂O₄-coated membrane are higher than those of the membrane modified by immersion coating.Although ZnCo₂O₄-coated membrane can not show oleophobic in air,it also has excellent underwater superoileophobic and anti-oilfouling properties,which shows better performance.更多还原