| 摘要: | 本研究主要探討聚偏二氟乙烯 poly vinylidene fluoride(PVDF)管膜之製備、膜表面特性分析及其在薄膜蒸餾技術方面的運用。首先配製PVDF/NMP 鑄膜液，變因為PVDF 濃度、EG、PEG、PVA、界面活性劑、LiCl 及LiClO4 等之添加量。玻璃纖維為襯材以濕式含浸塗佈(dip coating)紡絲法製備PVDF管膜，非溶劑為水；藉由改變玻璃纖維管徑、紡絲頭尺寸、鑄膜液成分、抽絲速度與沉澱槽之組成等， 製作出一系列不同孔隙結構及膜厚之管膜。並以SEM、DSC、XRD、Contact Angle 等檢測分析各種製備條件下之膜表面性質，再利用空氣間隙薄膜蒸餾法(air-gap membrane distillation, AGMD)、真空薄膜蒸餾法(vacuum membrane distillation, VMD)及薄膜蒸餾結晶技術(MD-C)針對模擬鹽水及高濃度含鹽廢水作淡化及再結晶試驗，測試各種管膜膜組之通量與鹽阻率。操作變數包括：冷熱端溫度變化、熱端流速變化及微溫差對透過率與鹽阻率之影響。預期獲得最佳PVDF 管膜製備技術，並能有效應用於海水淡化及含鹽廢水回收技術，達到節省能源的目標並得到可再利用之滲透水質。
This research investigate the preparation and characterization of porous poly(vinylidene fluoride) (PVDF) tubular membrane. PVDF tubular membranes with different porous structures are prepared by dip coating glass fiber with immersion-precipitation of a casting solution in coagulation baths composed of NMP and water (nonsolvent). The optimal condition will be confirmed by investigating the concentration of PVDF, EG, PEG, PVA, surfactant, LiCl, and LiClO4 on membrane preparation. The effects of the glass fiber’s diameter, immersion time, polymer solution concentration, nonsolvent content, and casting solution temperature will investigate. SEM, DSC, XRD, and Contact Angle analyzer were used to characterize the tubular membranes. To enhance MD flux, PVDF tubular membranes will used for the AGMD (air-gap membrane distillation), VMD(vacuum membrane distillation) and MD-C(membrane distillation-crystallizer) experiments, which tested flux and salt reduction rate through the membrane. This research discussed the effect of little temperature difference, feed flow rate of MD system. Also, the effects of temperature and pressure gradient on the MD membrane performance for purifying drinking water were investigated. The preparation conditions of the membrane will be optimized in this project. PVDF tubular membrane can be applied to the seawater desalination and salt wastewater treatment effectively. |
