超疏水性有機/無機奈米纖維薄膜及其於直接接觸式薄膜蒸餾之應用

Abstract

為了降低淡水的生產成本，本研究發展超疏水性有機/無機奈米纖維薄膜並藉由直接接觸式薄膜蒸餾(Direct contact membrane distillation, DCMD)法來進行海水淡化(Desalination)。超疏水性有機/無機奈米纖維薄膜主要是選用有機高分子之聚苯乙烯(Polystyrene, PS)與有機/無機高分子之聚二甲基矽氧烷(Polydimethylsiloxane, PDMS)作為材料，以靜電紡絲技術(Electrospinning)於聚對苯二甲酸乙二酯(PET)不織布上製備出具有超疏水性、高孔隙度之PDMS/PS奈米纖維薄膜，並將其薄膜作為高溫3.5 (wt%)鹽水進料端與低溫滲透端的接觸介面，以提供巨大的接觸面積供高溫3.5 (wt%)鹽水進料端的水蒸氣滲透至低溫滲透端。由本實驗結果證明，在溶劑組成比例四氫呋喃(Tetrahydrofuran, THF)/二甲基乙醯胺(Dimethylacetamide, DMAC)為1/2、PS溶液濃度為20 (wt%)、PDMS/(PS+PDMS)質量比值為0.4、紡絲溶液體積為8 (mL)、電壓強度為17.5 (kV)、工作距離為15 (cm)、進料流速為1.0 (mL/hr)及滾筒收集器轉速為600 (rpm)下所製備的PDMS/PS 奈米纖維薄膜，其在溫差60 (°C)、流速0.2 (LPM)及15.5(hr)的持續操作下，擁有42.8 (kg/m2hr)的高平均滲透通量及99.98 (%)的高脫鹽率。因此，PDMS/PS奈米纖維薄膜在海水淡化程序中具有實際應用的可行性。

In order to reduce the production cost of fresh water, this study developed a superhydrophobic organic/inorganic nanofibrous membrane and carried out desalination by the direct contact membrane distillation (DCMD). The superhydrophobic organic/inorganic nanofibrous membrane mainly selected the polystyrene (PS) of organic polymer and the polydimethylsiloxane (PDMS) of organic/inorganic polymer as material, and prepared the superhydrophobic and high porosity PDMS/PS nanofibrous membrane on the polyethylene terephthalate (PET) nonwoven by electrospinning. The PDMS/PS nanofibrous membrane was used as a contact interface between the high temperature feed side of 3.5(wt%) NaCl solution and the low temperature permeate side to provide a large contact area for the vapor of high temperature feed side to permeate to the low temperature permeate side. The results of this study proved that when the solvent ratio of tetrahydrofuran (THF)/dimethylacetamide (DMAC) was 1/2, the PS solution concentration was 20 (wt%), the PDMS/(PS+PDMS) mass ratio was 0.4, the spinning solution volume was 8 (mL), voltage was 17.5 (kV), working distance was 15 (cm), feed flow rate was 1.0 (mL/hr) and the rotating rate of drum collector was 600 (rpm), according to the above parameters which prepared the PDMS/PS nanofibrous membrane. It had the high average permeate flux rate of 42.8 (kg/m2hr) and the high salt rejection rate of 99.98 (%) under temperature difference of 60 (°C), flow rates of 0.2 (LPM) and continuous operation of 15.5 (hr). Therefore, the PDMS/PS nanofibrous membranes have the feasibility of practical application in desalination process.