奈米過濾程序中，濾膜的電性是影響其分離效能的重要因素ㄧ，而在一般文獻中常藉由鹽類阻擋之實驗數據配合數值解的方式反推估膜整體之淨電荷密度。本研究則藉由流線電位法量測薄膜之界達電位以及利用交流電阻法量測膜孔內溶液之電導度，配合理論模式來決定膜整體之靜電荷密度，並分析離子種類、pH值以及離子濃度對膜淨電荷密度的影響。在恆壓過濾實驗中，本研究選用Desal DK以及NF-270兩型號之商業奈米膜材進行過濾，實驗結果也與膜淨電荷密度配合Linearized Transport模式所預估之鹽類阻檔結果相比較。
由於奈米濾膜選擇層多由高分子所組成，因此溶液的性質對膜面界達電位之影響甚大，在DK以及NF-270之中，膜面界達電位與道南電位皆隨著溶液pH值的提高而增加，而隨著離子濃度的增加而下降，薄膜整體淨電荷密度之負電荷則隨著離子濃度與pH值的增加而增加。
在NF-270與DK於NaCl溶液進行過濾時，離子阻擋率隨著濃度的增加而下降，而DK於CaCl2溶液時，Ca2+離子阻擋率會隨著濃度的增加而上升，但在NF-270於CaCl2時，結果則相反。
最後本研究將膜整體之淨電荷密度值配合Linearized Transport模式預估離子阻擋率，在定性上與實驗所作之結果有相同之趨勢，而於定量上誤差皆在30%以內，然而估算結果與實驗結果的誤差原因為，由於奈米濾膜分離效能多由選擇層所主導，但是基於實驗上之限制，只能量測膜整體之淨電荷密度，導致誤差的存在，但整體而言，於定性上在奈米過濾分離效能上之結果能有效的預估。

Membrane charge density is one of the main factors which influence separation efficiency in nanofiltration, however very few pay attention to how to measure the charge density in membrane. In this study, a method combining the hydraulic permeation test and streaming potential measurement was developed to determine the membrane charge density. Two commercial nanofiltration membranes, DK and NF-270 were used to investigate the effect of pH and electrolyte concentration on the charge density and salt rejection. In addition, the salt rejection was also predicted using a theoretical relationship based on Linearized Transport model and compared with the experimental values.
Experimental results indicated that in the pH range from 5 to 6.5 used in the study the zeta potentials of DK and NF-270 membranes are negative and decrease with electrolytic concentration. However, charge densities of both membranes increase with the increase of the pH and ionic concentration.
Donnan potential between solution and membrane was evaluated using the measured bulk charge density of membrane. Results showed that the two membranes used have higher Donnan potential in NaCl solution than in CaCl2 solution. Results from DK membrane showed that Ca2+ rejection increases with the CaCl2 solution concentration, while NF-270 gives opposite tendency.
Based on the membrane charge density, the salt rejection was predicted and compared with the measured values. The differences between both are about 5-10 % and 10-30% for filtering NaCl and CaCl2 solution, respectively. This discrepancy may be due to that commercial membranes used are composites in which the charge density in the skin layer is quite different from that in the supported layer. The method developed in the study can only provide the global charge density of membrane, how to determine the charge density in the skin layer remains a challenge.

目錄
摘要 I
Abstract III
誌謝 V
目錄 VI
圖目錄 X
表目錄 XV
第一章 緒論 1
第二章 文獻回顧 5
2.1 奈米過濾之應用 5
2.2 奈米濾膜的材質與特性 8
2.2.1 奈米濾膜的材質 8
2.2.2 奈米濾膜的特性 12
2.2.3 奈米濾膜的特徵參數 13
2.3 奈米過濾之分離機制 17
2.3.1 溶解擴散效應 18
2.3.2 篩析效應 18
2.3.3 道南效應 19
2.4 影響濾膜性能之操作因素 20
2.4.1 操作壓力 20
2.4.2 進料溶液離子濃度與離子強度 21
2.4.3 進料溶液pH值 22
2.5 電場奈米過濾 23
第三章 理論背景 24
3.1 空間位阻孔道(steric hindrance pore, SHP)模式 24
3.2 奈米膜之淨電荷密度 26
3.3 膜孔內溶液之電導度 30
3.4 道南平衡 (Donnan equilibrium) 33
3.5 DSPM-DE (Donnan Steric Pore Model and Dielectric Exclusion) 37
3.6 Linearized Transport 模式 40
3.6.1 單一鹽類阻擋率 41
3.6.2 中性溶質阻擋率 43
第四章 實驗方法與材料 45
4.1 實驗材料 45
4.2 實驗裝置 51
4.2.1 奈米恆壓過濾系統 51
4.2.2 膜孔流線電位量測系統 55
4.2.3 膜面流線電位量測系統 55
4.2.4 膜內部電導度量測系統 58
4.3 分析儀器 60
4.4 實驗步驟 61
4.4.1 恆壓過濾實驗 61
4.4.2 膜孔流線電位實驗 62
4.4.3 膜面流線電位實驗 62
4.4.4 膜內部電導度實驗 63
4.5 實驗分析方法 64
4.5.1 離子分析實驗 64
第五章 結果討論 65
5.1 奈米濾膜之特性參數 65
5.1.1 奈米濾膜之純水透過率 66
5.1.2 濾膜厚度 67
5.1.3 濾膜孔徑大小 69
5.1.4 奈米濾膜之界達電位 74
5.1.5 濾膜之淨電荷密度 77
5.2 分離機制 90
5.2.1 篩析作用之影響 90
5.2.2 道南效應之影響 92
鹽類之分離效能 94
5.2.3 鹽類濃度及pH值對阻擋率之影響 98
5.3 鹽阻擋率理論預估與實驗值之比較 102
5.3.1 NaCl溶液 102
5.3.2 CaCl2溶液 102
第六章 結論 111
符號說明 113
參考文獻 116
附錄 120



圖目錄
第三章
Fig. 3- 1 Schematic diagram of fluid flow imposed with hydraulic pressure and electric field through porous membrane. 29
Fig. 3- 2 Schematic diagram of cell for measuring electrical resistance inside membrane pores. 32
Fig. 3- 3 Schematic drawing for interface of electrolyte/membrane with Na+ and Cl- ions and a fixed negatively membrane charge . 36
第四章
Fig. 4- 1 Schematic diagram of the electro-nanofiltration system. 52
Fig. 4- 2 Schematic diagram of the electro-nanofiltration cell. 53
Fig. 4- 3 Details of the electro-nanofiltration chamber. 54
Fig. 4- 4 Schematic diagram of the system for measuring streaming potential through membrane pores. 56
Fig. 4- 5 Schematic diagram of the system for streaming potential at membrane surfaces. 57
Fig. 4- 6 Schematic diagram of the measuring electrical resistance inside membrane pore. 59
第五章
Fig. 5- 1 Pure water permeate flux of NF-270 and Desal DK membranes. 66
Fig. 5- 2 The membrane thickness by SEM (a) NF-270 Top layer (b) NF-270 Downside layer (c) DK Top layer (d) DK Downside layer (e) DK Skin layer. 68
Fig. 5- 3 Rejection of the saccharides by DK and NF-270 membranes versus the respective molecular weight cutoff. 70
Fig. 5- 4 Saccharides rejection measured using DK membrane and fit with DSPM-DE measured. 72
Fig. 5- 5 Saccharides rejection measured using NF-270 membrane and fit with DSPM-DE measured. 73
Fig. 5- 6 Zeta potential of DK membrane in 1 mole/m3 NaCl and CaCl2 solution 75
Fig. 5- 7 Zeta potential of NF-270 membrane in 1 mole/m3 NaCl and CaCl2 75
Fig. 5- 8 Zeta potential of DK membrane as a function of electrolyte concentration at pH = 5.8 . 76
Fig. 5- 9 Zeta potential of NF-270 membrane as a function of electrolyte 76
Fig. 5- 10 The values of εkm measured of DK membrane in NaCl solution. 80
Fig. 5- 11 The values of εkm measured of NF-270 membrane in NaCl solution 80
Fig. 5- 12 The values of εkm measured of DK membrane in CaCl2 solution. 81
Fig. 5- 13 The values of εkm measured of NF-270 membrane in CaCl2 solution. 81
Fig. 5- 14 Net charge density of the DK membrane as a function of NaCl solution concentration. 82
Fig. 5- 15 Net charge density of the DK membrane as a function of CaCl2 solution concentration. 82
Fig. 5- 16 Net charge density of the NF-270 membrane as a function of NaCl solution concentration. 83
Fig. 5- 17 Net charge density of the NF-270 membrane as a function of CaCl2 solution concentration. 83
Fig. 5- 18 The values of εkm measured of DK membrane in NaCl solution. 86
Fig. 5- 19 The values of εkm measured of DK membrane in CaCl2 solution. 86
Fig. 5- 20 The values of εkm measured of NF-270 membrane in NaCl solution. 87
Fig. 5- 21 The values of εkm measured of NF-270 membrane in CaCl2 solution. 87
Fig. 5- 22 Net charge density of the DK membrane as a function of NaCl solution pH. 88
Fig. 5- 23 Net charge density of the DK membrane as a function of CaCl2 solution pH. 88
Fig. 5- 24 Net charge density of the NF-270 membrane as a function of NaCl solution pH. 89
Fig. 5- 25 Net charge density of the NF-270 membrane as a function of CaCl2 solution pH. 89
Fig. 5- 26 Radius of hydrated ion and ionic radius with no hydration. 91
Fig. 5- 27 Na+ and Cl- ion rejection by the DK and NF-270 membranes. 95
Fig. 5- 28 Ca2+and Cl- ion rejection by the DK and NF-270 membranes. 97
Fig. 5- 29 Compare predicted and experimental NaCl rejection for NF-270 membrane with different NaCl concentrations at pH=5 105
Fig. 5- 30 Compare predicted and experimental NaCl rejection for NF-270 membrane with different NaCl concentrations at pH=5.8 105
Fig. 5- 31 Compare predicted and experimental NaCl rejection for NF-270 membrane with different NaCl concentrations at pH=6.5. 106
Fig. 5- 32 Compare predicted and experimental NaCl rejection for DK membrane with different NaCl concentrations at pH=5. 106
Fig. 5- 33 Compare predicted and experimental NaCl rejection for DK membrane with different NaCl concentrations at pH=5.8 107
Fig. 5- 34 Compare predicted and experimental NaCl rejection for DK membrane with different NaCl concentrations at pH=6.5. 107
Fig. 5- 35 Compare predicted and experimental CaCl2 rejection for NF-270 membrane with different CaCl2 concentration ats pH=5.. 108
Fig. 5- 36 Compare predicted and experimental CaCl2 rejection for NF-270 membrane with different CaCl2 concentrations at pH=5.8. 108
Fig. 5- 37 Compare predicted and experimental CaCl2 rejection for NF-270 membrane with different CaCl2 concentrations at pH=6.5. 109
Fig. 5- 38 Compare predicted and experimental CaCl2 rejection for DK membrane with different CaCl2 concentrations at pH=5. 109
Fig. 5- 39 Compare predicted and experimental CaCl2 rejection for DK membrane with different CaCl2 concentrations at pH=5.8. 110
Fig. 5- 40 Compare predicted and experimental CaCl2 rejection for DK membrane with different CaCl2 concentrations at pH=6.5 110


表目錄
第一章
Table 1- 1 Membrane categories and characteristics 4
第二章
Table 2- 1 Comparison of the features of commonly used membranes 11
第五章
Table 5- 1 Pure water permeability of membranes. 66
Table 5- 2 Molecular weight (MW), diffusivity (Ds) and Stokes radius (rs) of the saccharides used to characterize the membrane pore size. 70
Table 5- 3 Molecular weight cutoff (MWCO), reflection coefficient (σ) and pore size (rp) . 71
Table 5- 4 Reflection coeffilient(σ) for ions in nanofiltration membrane. 91
Table 5- 5 Donnan potential ΔEDon (mV) data of DK and NF-270 in NaCl solution. 93
Table 5- 6 Donnan potential ΔEDon (mV) data of DK and NF-270 in CaCl2 solution. 93
Table 5- 7 Rejection of salt by DK nanofiltration membrane at various feed concentration and pH.(ΔP=5 bar) 100
Table 5- 8 Rejection of salt by NF-270 nanofiltration membrane at various feed concentration and pH.(ΔP=5 bar) 101

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