疏水改性多孔陶瓷管在膜蒸馏中的应用及传质分析

Application and mass transfer analysis of hydrophobically modified porous ceramic tubes in membrane distillation

采用引发式化学气相沉积技术,将反应物单体1H、1H、2H、2H-全氟癸基丙烯酸酯(PFDA)和引发剂过氧化二叔丁基聚合于多孔陶瓷膜表面,获得疏水性Al_2O_3陶瓷管。扫描电镜结果显示,疏水改性前后多孔陶瓷管表面形貌和结构没有发生明显变化;水接触角实验结果显示,改性多孔陶瓷管表面呈现超疏水特性,水接触角为154°。改性后的陶瓷管应用于气隙式膜蒸馏(AGMD)实验,结果表明,渗透通量随料液温度的升高呈指数型增长,在料液温度80℃、料液流速1.2 L/min时,渗透通量为3.5 kg/(m^2·h)。在20 h的稳定性运行实验中,渗透通量基本稳定,脱盐率大于99.9%。水分子在疏水多孔陶瓷中的传质系数实验值与理论值相符。

The porous ceramics were rendered hydrophobic via initiative chemical vapor deposition (iCVD),applied by a conformal coating of poly (1H,1H,2H,2H-Perfluorodecyl acrylate) (PFDA).The scanning electron microscope (SEM)confirmed that the morphology and structure were kept the same when comparing the images of the modified porous ceramics with those of the corresponding original ceramics.The water contact angle values of the modified porous ceramics were 154°,which showed superhydrophobic character.The results of the air gap membrane distillation (AGMD) tests showed that the hydrophobic porous ceramics can b'e applied in membrane distillation. With the increase of the feed temperature,the permeate flux increased exponentially.The higher permeate flux (3.5kg/(m^2·h)) was achieved at the feed temperature of 80℃,the flow rate 1.2L/min.The permeate flux remains nearly constant and salt rejection rate larger than 99.9% within 20h operation process of the system.The experimental value of the mass transfer coefficient of water molecules in the pores of the ceramic membrane agreed with the theoretical value.