【作者】 王涛；

【导师】 贠延滨；

【作者基本信息】 北京林业大学 ， 环境科学与工程， 2020， 硕士

【摘要】 在真空膜蒸馏分离过程中以膜两侧的压力不同而产生的压差为推动力,使热料液在膜表面产生的水蒸气穿过膜孔,进入真空侧后被冷凝从而达到分离效果。由于膜蒸馏具有高效的分离效果和较低的能耗而被广泛的应用,但也存在膜材料易污染、润湿的问题。为了解决膜材料的耐受性和膜污染问题,通过ZnO纳米棒和氟硅烷涂层在中空纤维陶瓷膜表面制备了具有低表面能的微/纳分层结构,使之具有超疏水和自清洁特性。在本文中对原始陶瓷膜的疏水改性过程可分成以下几步:首先,ZnO种晶层通过热解-粘合法在350℃下种植在氧化铝陶瓷中空纤维膜上。在此基础上,采用水热法制备了具有微米级/纳米级分级结构的新型ZnO纳米棒改性陶瓷中空纤维膜。最后,通过涂覆1H,1H,2H,2H-全氟癸基三乙氧基硅烷（PDTS）得到了一种新型的超疏水陶瓷膜,并将其应用于真空膜蒸馏。由疏水改性后陶瓷膜的表面形态、接触角及化学组成等参数进行表征,可知在疏水改性后的陶瓷膜表面存在大量具有理想特性的ZnO纳米棒如:超疏水性、出色的热稳定性和机械稳定性以及接触角为160.12°。同时也保留了基本的膜孔结构。将这种新型膜用于真空膜蒸馏系统处理模拟氯碱厂再生废水和燃煤电厂产生的脱硫废水。在真空膜蒸馏（VMD）系统处理高盐废水中疏水改性陶瓷膜表现出了出色的自清洁性能和抗污染能力。也保持了较高的渗透通量27.34-23.66 kg m^-2h^-1和较低的电导率5.13-14.32μS cm^-1。探究和模拟了料液温度、流速和真空度对疏水改性陶瓷膜渗透通量的影响;同时在脱硫废水的处理过程中获得了疏水改性陶瓷膜的最佳运行条件为:料液温度:65℃,料液流速:0.032 m s^-1,真空度:0.080 MPa,连续运行周期:40 min。更多还原

【Abstract】 In the process of vacuum membrane distillation separation,to achieve the separation effect,the pressure difference between the two sides of the membrane is used as the driving force to make the water vapor produced by the hot material liquid on the membrane surface pass through the membrane hole and be condensed after entering the vacuum side.Membrane distillation is widely used because of its high separation effect and low energy consumption.However,it also has the problems of easy fouling and wetting.To solve the problems of membrane material tolerance and membrane fouling,a micro/nano hierarchial structure with low surface energy was constructed on the ceramic hollow fiber membrane surface by using ZnO nanorod arrays and fluorosilane coatings,which make it superhydrophobic and self-cleaning.In this thesis,the hydrophobic modification process of the original ceramic membrane can be divided into the following steps:First,the ZnO seeds layer was planted on alumina ceramic hollow fiber membrane at 350℃ by the pyrolysis-adhesion method.On this basis,new ZnO nanorods modified ceramic hollow fiber membrane with micro/nanoscale hierarchical structured was fabricated by the hydrothermal method.Finally,a novel superhydrophobic membrane structure was created by coating1H,1H,2H,2H-perfluorodecyltriethoxysilane（PDTS）and applied to the vacuum membrane desalination.The surface morphology,contact angle and chemical composition of the hydrophobic modified ceramic membrane were characterized.It can be seen that there are a large amount of ZnO nanorods with ideal properties on the surface of the hydrophobic modified ceramic film,such as super hydrophobicity,excellent thermal and mechanical stability,and the contact angle is 160.12°.At the same time,the basic membrane pore structure is also retained.In this thesis,the novel membrane is used in the vacuum membrane distillation（VMD）system to treat the regenerated wastewater from the simulated chlor alkali plant and the desulfurization wastewater from the coal-fired power plant.The hydrophobicity modified ceramic membrane shows excellent self-cleaning performance and good antifouling ability in the utilization of VMD system for high-salinity water desalination.It also maintains a high permeate flux of 27.34-23.66 kg m^-2h^-1and a low conductivity of 5.13-14.32μS cm^-1.The effects of temperature,velocity and vacuum pressure of the permeation flux of hydrophobic modified ceramic membrane were investigated and simulated.Meanwhile,the optimal operation conditions of hydrophobic modified ceramic membrane were obtained during the treatment of desulfurization wastewater:feed temperature:65℃,feed velocity:0.032 m s^-1,vacuum degree:0.080 MPa,continuous operation cycle:40 min.更多还原