博碩士論文 105324603 詳細資訊




以作者查詢圖書館館藏 以作者查詢臺灣博碩士 以作者查詢全國書目 勘誤回報 、線上人數:9 、訪客IP:3.226.245.48
姓名 陶方(Phuong-Thao Nguyen)  查詢紙本館藏   畢業系所 化學工程與材料工程學系
論文名稱 水包油之乳液和凝膠及其分離
(The Oil in Water Emulsions and Gels and Their Separation)
相關論文
★ 單一高分子在接枝表面的吸附現象-分子模擬★ 化學機械研磨的微觀機制探討
★ 界面活性劑與微脂粒的作用★ 家禽傳染性華氏囊病病毒與VP2次病毒顆粒對固定化鎳離子之異相吸附
★ 液滴潤濕與接觸角遲滯★ 親溶劑奈米粒子於高分子溶液中的自組裝現象
★ 具界面活性溶質之蒸發殘留圖形研究★ 奈米自泳動粒子之擴散行為
★ 抗氧化奈米銅粒子的製備及分析★ 柱狀自泳動粒子之擴散行為與沉降平衡
★ 過氧化氫的界面性質與穩定性★ 液橋分離與液面爬升物體之研究
★ 電潤濕動態行為探討★ 表面粗糙度對接觸角遲滯影響之效應
★ 以耗散粒子動力學法研究奈米自泳動粒子輸送現象★ 低溫還原氧化石墨烯薄膜
檔案 [Endnote RIS 格式]    [Bibtex 格式]    [相關文章]   [文章引用]   [完整記錄]   [館藏目錄]   至系統瀏覽論文 (全文檔遺失)
請聯絡國立中央大學圖書館資訊系統組 TEL:(03)422-7151轉57422,或E-mail聯絡
摘要(中) Part I
水包油凝膠(O/W gel)根據成膠時是否添加膠凝劑,可分為凝膠誘導型與無凝膠型兩種。在此研究中,成功製造出水性界面活性劑添加量低至1wt%的無凝膠型水包油凝膠。本實驗方法分為兩種,第一種方法是藉由凝膠核的生長所誘發,機制類似於晶體生長;第二種則是通過凝膠仍在乳液狀時,逐次添加少量油來稀釋,最終達成乳液到凝膠的轉化。兩種方法皆經歷過渡相轉換,且透過連續攪拌而達成。此外,我們的膠經由流變學的分析,膠呈現類似固體的性質,具有 彈性模數和降伏強度,且發現透過降低水含量可增強機械性質。
Part II
以界面活性劑穩定超過五個月之水包油乳液和乳液凝膠已透過簡易以重力為驅動力的攪拌裝置分離成功。此裝置包含了旋轉攪拌磁石和具有超疏水性/超親油性質的柔軟銅網,並摺疊而成所需尺寸的三維形狀。乳液的製備為混合不同比例的烷烴和水(1 % to 99 %)並透過水溶性界面活性劑的穩定而成。當乳液中水的分率較低時,界面活性劑的含量較高,因此得到類固體的乳液型態。研究結果發現,以應力為驅動力的方式能夠有效分離穩定的乳液,其效率高達98%,而分離乳液凝膠的效率也達到96%。以應力為驅動力將油從穩定的乳液中回收的機制,主要是基於銅網水層(超疏水性)的瞬間破裂和增加與油網的接觸所導致油的滲透行為(超親油性)。對於乳液凝膠而言,應力的施加功用主要為誘導乳液短暫的由固體型態轉換為液體型態。該方法可用於有效分離通常由工業過程產生的高度穩定的水包油乳液和乳液凝膠。
摘要(英) Part I - The Oil-in-Water Gels with Scanty-Water
The oil-in-water (O/W) gel can be classified into two types, gelator-induced and gelator-free, based on the requirement of gelator addition. In this work, the O/W gel with scanty-water belonging to the gelator-free type was successfully produced even when the content of aqueous surfactant solution was as low as 1 wt%. In an attempt to develop this scanty-water O/W gel, two purposely designed approaches with continuous mechanical agitation were proposed. The first approach of gel formation was induced by the growth of gel nuclei, which is similar to the mechanism of crystal growth. Distinct from the first approach, the water content in the emulsion was diluted by oil addition, leading to the transformation from emulsion to gel eventually. Both approaches undergo a phase change associated with the jamming transition. According to rheological measurements, our gels possess solid-like behaviors such as elastic modulus and yield stress. Moreover, the O/W gels with scanty-water can be strengthened by reducing the water content. 
Part II - Stress-Driven Separation of Surfactant Stabilized Emulsions and Emulsion Gels by Superhydrophobic/Superoleophilic Meshes
Oil-in-water emulsions and emulsion gels which are stabilized by surfactants for more than five months have been successfully separated by a simple gravity-driven agitation-assisted device. The device contains a rotating magnetic stir-bar and a flexible superhydrophobic/superoleophilic Cu mesh which has been folded into the desired three-dimensional shape. The emulsions were prepared by mixing various fractions of alkane and water (1 % to 99 %) stabilized by a water-soluble surfactant. For low water fractions which contained higher concentrations of surfactant, solid-like emulsion gels were obtained. The stress-driven process was found to effectively separate stable emulsions with a separation efficiency  98 % and emulsion gels with separation efficiency as high as 96 %. The mechanism for oil recovery from stable emulsions by the stress-driven device is based on momentary breakage of the water barrier layer (superhydrophobicity) and enhancement of the oil-mesh contact leading to oil permeation (superoleophilicity). For emulsion gels, the additional function of the stress is to induce a temporary transformation from the solid-like gel into a liquid-like stage. This methodology can be employed for efficient separation of highly stable oil-in-water emulsions and emulsion gels that are often produced by industrial processes.
關鍵字(中) ★ 油包水
★ 乳液
★ 銅網
關鍵字(英) ★ Scanty water
★ Oil-in-water
★ Emulsion
★ Copper mesh
論文目次 Abstract ..................................................................................................................................... I
Acknowledgements ................................................................................................................. III
Contents .................................................................................................................................. IV
List of Figures......................................................................................................................... VI
Chapter 1 The Oil-in-Water Gels with Scanty-Water .............................................................1
1-1 Introduction ................................................................................................................................. 1
1-2 Materials and experimental methods .......................................................................................... 4
1-2-1 Materials ........................................................................................................................... 4
1-2-2 Preparation of emulsions and emulsion gels .................................................................... 4
1-2-2-1 Oil-in-water emulsion ................................................................................................... 4
1-2-2-2 Gelator-induced gel ...................................................................................................... 4
1-2-2-3 Gelator-free gel ............................................................................................................. 5
1-2-3 Mechanical and rheological characterizations................................................................. 6
1-2-4 Optical microscope ........................................................................................................... 6
1-3 Results and discussion ................................................................................................................. 7
1-3-1 Gelator-induced emulsion gels ......................................................................................... 7
1-3-2 Scanty water gelator-free emulsion gels ......................................................................... 10
1-3-3 Gelation mechanism ....................................................................................................... 12
1-3-4 Mechanical and rheological characterizations............................................................... 15
1-4 Conclusions ................................................................................................................................ 21
1-5 References .................................................................................................................................. 23
Chapter 2 Stress-Driven Separation of Surfactant Stabilized Emulsions and Emulsion Gels
by Superhydrophobic/Superoleophilic Meshes ...................................................................... 28
2-1 Introduction ............................................................................................................................... 28
2-2 Materials and experimental methods ........................................................................................ 32
2-2-1 Materials ............................................................................................................................. 32
2-2-2 Fabrication of superhydrophobic/superoleophilic Cu meshes .......................................... 33
2-2-3 Emulsion preparation ......................................................................................................... 34
2-2-4 Emulsion separation ........................................................................................................... 35
2-2-5 Wetting property measurement ......................................................................................... 35
2-2-6 Optical microscope ............................................................................................................. 37
2-3 Results and discussion ............................................................................................................... 38
2-3-1 Characterization of the emulsion type ............................................................................... 38
2-3-2 Ineffective separation of stable emulsions in the absence of agitation .............................. 42
2-3-3 Agitation-assisted separation of stable O/W emulsions ..................................................... 47
2-3-4 Agitation-assisted separation of stable emulsion gels ........................................................ 52
2-3-5 Mechanism of agitation-assisted separation ...................................................................... 56
2-4 Conclusions ................................................................................................................................ 60
2-5 References ........................................................................................................................... 62
參考文獻 [1] Peng, Y.; Guo, Z. Recent advances in biomimetic thin membranes applied in emulsified oil/water separation. J. Mater. Chem. A 2016, 4, 15749-15770.
[2] Jian, C., Liu, Q., Zeng, H., Tang, T. Effect of model polycyclic aromatic compounds on the coalescence of water-in-oil emulsion droplets. J. Phys. Chem. C 2017, 121, 10382−10391.
[3] Myers, D. Surfaces, Interfaces, and Colloids: Principles and Applications. John Wiley & Sons, Inc., NYC, USA, 1999.
[4] Ma, C.; Bi, X.; Ngai, T.; Zhang, G. Polyurethane-based nanoparticles as stabilizers for oil-in-water or water-in-oil Pickering emulsions. J. Mater. Chem. A 2013, 1, 5353–5360.
[5] Si, Y.; Fu, Q.; Wang, X.; Zhu, J.; Yu, J.; Sun, G.; Ding, B. Superelastic and superhydrophobic nanofiber-assembled cellular aerogels for effective separation of oil/water emulsions. ACS Nano 2015, 9, 3791–3799.
[6] Al-Sabagh, A. M.; Kandile, N. G.; El-Din, M. R. N. Functions of demulsifiers in the petroleum industry. Sep. Sci. Techn. 2011, 46, 1144–1163.
[7] Gao, S. J.; Shi, Z.; Zhang, W. B.; Zhang, F.; Jin, J. Photoinduced superwetting single-walled carbon nanotube/TiO2 ultrathin network films for ultrafast separation of oil-in-water emulsions. ACS Nano 2014, 8, 6344–6352.
[8] Deng, W.; Long, M.; Zhou, Q.; Wen, N.; Deng, W. One-step preparation of superhydrophobic acrylonitrile-butadiene-styrene copolymer coating for ultrafast separation of water-in-oil emulsions. J. Coll. Interf. Sci. 2018, 511, 21–26.
[9] Gupta, R. K.; Dunderdale, G. J.; England, M. W.; Hozumi, A. Oil/water separation techniques: a review of recent progresses and future directions. J. Mater. Chem. A 2017, 5, 16025–16058.
[10] V. Singh, Y.-J. Sheng, and H.-K. Tsao, Facile fabrication of superhydrophobic copper mesh for oil/water separation and theoretical principle for separation design. J. Taiwan Inst. Chem. Eng. 2018, 87, 150–157.
[11] Aleem, W.; Mellon, N. Model for the prediction of separation profile of oil-in-water emulsion. J. Disper. Sci. Technol. 2018, 39, 8-17.
[12] Gillies, R. G.; Sun, R.; Shook, C. A. Laboratory investigation of inversion of heavy oil emulsions. Can. J. Chem. Eng. 2000, 78, 757-763.
[13] Krebs, T.; Schroen, C. G. P. H.; Boom, R. M.; Separation kinetics of an oil-in-water emulsion under enhanced gravity. Chem. Eng. Sci. 2012, 71, 118-125.
[14] Mason, S. L.; May, K.; Hartlan, S. Drop size and concentration profile determination in petroleum emulsion separation. Colloids Surf. A: Physicochem. Eng. Asp. 1995, 96, 85-92.
[15] Zolfaghari, R.; Fakhru’l-Razi, A.; Abdullah, L. C.; Elnashaie, S. S. E. H.; Pendashteh, A. Demulsification techniques of water-in-oil and oil-in-water emulsions in petroleum industry. Sep. Purif. Technol. 2016, 170, 377–407.
[16] Hao, L.; Jiang, B.; Zhang, L.; Yang, H.; Sun, Y.; Wang, B.; Yang, N. Efficient demulsification of diesel-in-water emulsions by different structural dendrimer-based demulsifiers. Ind. Eng. Chem. Res. 2016, 55, 1748−1759.
[17] Nii, S.; Kikumoto, S.; Tokuyama, H. Quantitative approach to ultrasonic emulsion separation. Ultrason. Sonochem. 2009, 16, 145–149.
[18] Wang, Z.; Jiang, X.; Cheng, X.; Lau, C. H.; Shao, L. Mussel-inspired hybrid coatings that transform membrane hydrophobicity into high hydrophilicity and underwater superoleophobicity for oil-in-water emulsion separation. ACS Appl. Mater. Interfaces 2015, 7, 9534−9545.
[19] Xue, Z.; Wang, S.; Lin, L.; Chen, L.; Liu, M; Feng, L.; Jiang, L. A novel superhydrophilic and underwater superoleophobic hydrogel‐coated mesh for oil/water separation. Adv. Mater. 2011, 23, 4270−4273.
[20] Lee, M. W.; An, S.; Latthe, S. S.; Lee, C.; Hong, S.; Yoon, S. S. Electrospun polystyrene nanofiber membrane with superhydrophobicity and superoleophilicity for selective separation of water and low viscous oil. ACS Appl. Mater. Interfaces 2013, 5, 10597−10604.
[21] Kagawa, Y.; Ishigami, T.; Hayashi, K.; Fuse, H.; Mino, Y.; Matsuyama, H. Permeation of concentrated oil-in-water emulsions through a membrane pore: numerical simulation using a coupled level set and the volume-of-fluid method. Soft Matter 2014, 10, 7985–7992.
[22] Cheng, Z.; Li, C.; Lai, H.; Du, Y.; Liu, H.; Liu, M.; Sun, K.; Jin, L.; Zhang, N.; Jiang, L. Recycled superwetting nanostructured copper mesh film: toward bidirectional separation of emulsified oil/water mixtures. Adv. Mater. Interfaces 2016, 1600370.
[23] Shi, Z.; Zhang, W.; Zhang, F.; Liu, X.; Wang, D.; Jin, J.; Jiang, L. Ultrafast separation of emulsified oil/water mixtures by ultrathin free‐standing single‐walled carbon nanotube network films. Adv. Mater. 2013, 25, 2422-2427.
[24] Zhang, R.; Liu, Y.; He, M.; Su, Y.; Zhao, X.; Elimelech, M.; Jiang, Z. Antifouling membranes for sustainable water purification: strategies and mechanisms. Chem. Soc. Rev. 2016, 45, 5888-5924.
[25] Matsubayashi, T.; Tenjimbayashi, M.; Komine, M.; Manabe, K.; Shiratori, S. Bioinspired hydrogel-coated mesh with superhydrophilicity and underwater superoleophobicity for efficient and ultrafast oil/water separation in harsh environments. Ind. Eng. Chem. Res. 2017, 56, 7080−7085.
[26] Wang, F.; Lei, S.; Li, C.; Ou, J.; Xue, M.; Li, W. Superhydrophobic Cu mesh combined with a superoleophilic polyurethane sponge for oil spill adsorption and collection. Ind. Eng. Chem. Res. 2014, 53, 7141−7148.
[27] Chen, Y.; Wang, N.; Guo, F.; Hou, L.; Liu, J.; Liu, J.; Xu, Y.; Zhao Y.; Jiang, L. A Co3O4 nano-needle mesh for highly efficient, high-flux emulsion separation. J. Mater. Chem. A, 2016, 4, 12014–12019.
[28] Li, X.; Hu, D.; Cao, L.; Yang, C. Sensitivity of coalescence separation of oil–water emulsions using stainless steel felt enabled by LBL self-assembly and CVD. RSC Adv. 2015, 5, 71345–71354.
[29] Feng, L.; Zhang, Z.; Mai, Z.; Ma, Y.; Liu, B.; Jiang, L.; Zhu, D. A super-hydrophobic and super-oleophilic coating mesh film for the separation of oil and water. Angew. Chem. Int. Ed. 2004, 43, 2012-2014.
[30] Zeng, X.; Qian, L.; Yuan, X.; Zhou, C.; Li, Z.; Cheng, J.; Xu, S.; Wang, S.; Pi, P.; Wen, X. Inspired by stenocara beetles: From water collection to high-efficiency water-in-oil emulsion separation. ACS Nano 2017, 11, 760−769.
[31] Lin, X.; Lu, F.; Chen, Y.; Liu, N.; Cao, Y.; Xu, L.; Wei, Y.; Feng, L. One-step breaking and separating emulsion by tungsten oxide coated mesh. ACS Appl. Mater. Interfaces 2015, 7, 8108−8113.
[32] Yang, H.-C.; Pi, J.-K.; Liao, K.-J.; Huang, H.; Wu, Q.-Y.; Huang, X.-J.; Xu, Z.-K. Silica-decorated polypropylene microfiltration membranes with a mussel-inspired intermediate layer for oil-in-water emulsion separation. ACS Appl. Mater. Interfaces 2014, 6, 12566−12572.
[33] Liu, X.; Zhou, J.; Xue, Z.; Gao, J.; Meng, J.; Wang, S.; Jiang, L. Clam′s shell inspired high‐energy inorganic coatings with underwater low adhesive superoleophobicity. Adv. Mater. 2012, 24, 3401−3405.
[34] Zhang, F.; Zhang, W. B. Z. Shi, D. Wang, J. Jin, Jiang, L. Nanowire‐haired inorganic membranes with superhydrophilicity and underwater ultralow adhesive superoleophobicity for high‐efficiency oil/water separation. Adv. Mater. 2013, 25, 4192–4198.
[35] Luo, Z.-Y.; Lyu, S.-S.; Wang, Y.-Q.; Mo, D.-C. Fluorine-induced superhydrophilic Ti foam with surface nanocavities for effective oil-in-water emulsion separation. Ind. Eng. Chem. Res. 2017, 56, 699−707.
[36] Cai, Y.; Lu, Q.; Guo, X.; Wang, S.; Qiao, J.; Jiang, L. Salt‐tolerant superoleophobicity on alginate gel surfaces inspired by seaweed (Saccharina japonica). Adv. Mater. 2015, 27, 4162−4168.
[37] Luo, Z.-Y.; Chen, K.-X.; Wang, J.-H.; Mo, D.-C.; Lyu, S.-S. Hierarchical nanoparticle-induced superhydrophilic and under-water superoleophobic Cu foam with ultrahigh water permeability for effective oil/water separation. J. Mater. Chem. A 2016, 4, 10566−10574.
[38] Wan, F.; Yang, D.-Q.; Sacher. E. Repelling hot water from superhydrophobic surfaces based on carbon nanotubes. J. Mater. Chem. A 2015, 3, 16953–16960.
[39] Liu, Y.; Chen, X.; Xin, J. H. Can superhydrophobic surfaces repel hot water? J. Mater. Chem. 2009, 19, 5602–5611.
[40] Zhang, L; Zhong, Y.; Cha, D.; Wang, P. A self-cleaning underwater superoleophobic mesh for oil-water separation. Sci. Rep. 2013, 3, 2326.
[41] Xu, L.; Liu, N.; Cao, Y.; Lu, F.; Chen, Y.; Zhang, X.; Feng, L.; Wei, Y. Mercury ion responsive wettability and oil/water separation. ACS Appl. Mater. Interfaces 2014, 6, 13324−13329.
[42] Cheng, Z.; Wang, J.; Lai, H.; Du, Y.; Hou, R.; Li, C.; Zhang, N.; Sun, K. Underwater oil droplet splitting on a patterned template. Langmuir 2015, 31, 1393−1399.
[43] Zhang, L.; Gu, J.; Song, L.; Chen, L.; Huang, Y.; Zhang, J.; Chen, T. Underwater superoleophobic carbon nanotubes/core–shell polystyrene@Au nanoparticles composite membrane for flow-through catalytic decomposition and oil/water separation. J. Mater. Chem. A 2016, 4, 10810–10815.
[44] Li, L.; Yan, L.; Li, H.; Li, W.; Zha, F.; Lei, Z. Underwater superoleophobic palygorskite coated mesh for the efficient oil/water separation. J. Mat. Chem. A 2015, 3, 14696-14702.
[45] Yang, J.; Zhang, Z.; Xu, X.; Zhu, X.; Men, X.; Zhou, X. Superhydrophilic–superoleophobic coatings. J. Mat. Chem. 2012, 22, 2834-2837.
[46] Li, F.; Wang, Z.; Huang, S.; Pan, Y.; Zhao, X. Flexible, durable, and unconditioned superoleophobic/superhydrophilic surfaces for controllable transport and oil–water separation. Adv. Funct. Mater. 2018, 1706867.
[47] P. S. Brown, B. Bhushan, Bioinspired, roughness-induced, water and oil super-philic and super-phobic coatings prepared by adaptable layer-by-layer technique. Sci. Rep. 2015, 5, 14030.
[48] Pan, Y.; Huang, S.; Li, F.; Zhao, X.; Wang, W. Coexistence of superhydrophilicity and superoleophobicity: theory, experiments and applications in oil/water separation. J. Mater. Chem. A, 2018, 6, 15057-15063.
[49] Wana, Z.; Lia, D.; Jiao, Y.; Ouyang, X.; Chang, L.; Wang, X. Bifunctional MoS2 coated melamine-formaldehyde sponges for efficient oil–water separation and water-soluble dye removal. App. Mat. Today 2017, 9, 551–559.
[50] Gao, X.; Wang, X.; Ouyang, X.; Wen, C. Flexible superhydrophobic and superoleophilic MoS2 sponge for highly efficient oil-water separation. Sci. Rep. 2016, 6, 27207.
[51] Lin, X.; Heo, J.; Jeong, H.; Choi, M.; Chang, M.; Hong, J. Robust superhydrophobic carbon nanofiber network inlay-gated mesh for water-in-oil emulsion separation with high flux. J. Mater. Chem. A 2016, 4, 17970–17980.
[52] Al-Anzi, B. S.; Siang, O. C. Recent developments of carbon based nanomaterials and membranes for oily wastewater treatment. RSC Adv. 2017, 7, 20981–20994.
[53] Tua, S.-H.; Wu, H.-C.; Wu, C.-J.; Cheng, S.-L.; Sheng, Y.-J.; Tsao, H.-K. Growing hydrophobicity on a smooth copper oxide thin film at room temperature and reversible wettability transition. App. Surf. Sci. 2014, 316, 88–92.
[54] Cai, Y.; Chen, D.; Li, N.; Xu, Q.; Li, H.; He, J. Lu, J. A facile method to fabricate a double-layer stainless steel mesh for effective separation of water-in-oil emulsions with high flux. J. Mater. Chem. A 2016, 4, 18815–18821.
[55] Lu, G. W.; Gao, P. Handbook of Non-Invasive Drug Delivery Systems. William Andrew Publishing, Boston, 2010, Ch. 3, 59–94.
[56] Mohamed, A. I. A.; Sultan, A. S.; Hussein, I. A.; Al-Muntasheri, G. A. Influence of surfactant structure on the stability of water-in-oil emulsions under high-temperature high-salinity conditions. J. Chem. 2017, 1-11.
[57] Ruckenstein, E. Microemulsions, Macroemulsions, and the Bancroft Rule. Langmuir 1996, 12, 6351-6353.
[58] Ono, F.; Shinkai, S.; Watanabe, H. High internal phase water/oil and oil/water gel emulsions formed using a glucose-based low-molecular-weight gelator. New J. Chem. 2018, 42, 6601-6603.
[59] Roy, A.; Roy, S.; Pradhan, A.; Choudhury, S. M.; Nayak, R. R. Gel-emulsion properties of nontoxic nicotinic acid-derived glucose sensor. Ind. Eng. Chem. Res. 2018, 57, 2847−2855.
[60] Singh, V.; Huang, C.-J.; Sheng, Y.-J.; Tsao, H.-K. Smart zwitterionic sulfobetaine silane surfaces with switchable wettability for aqueous/nonaqueous drops. J. Mater. Chem. A 2018, 6, 2279–2288.
[61] Panatdasirisuk, W.; Liao, Z.; Vongsetskul, T.; Yang, S. Separation of oil-in-water emulsions using hydrophilic electrospun membranes with anisotropic pores. Langmuir 2017, 33, 5872−5878.
[62] Kang, H. S.; Cho, H.; Panatdasirisuk, W.; Yang, S. Hierarchical membranes with size-controlled nanopores from photofluidization of electrospun azobenzene polymer fibers. J. Mater. Chem. A 2017, 5, 18762–18769.
[63] Schatzberg, P. Solubilities of water in several normal alkanes from C7 to C161. J. Phys. Chem. 1963, 67, 776–779.
指導教授 曹恆光(Heng-Kwong Tsao) 審核日期 2019-8-7
推文 facebook   plurk   twitter   funp   google   live   udn   HD   myshare   reddit   netvibes   friend   youpush   delicious   baidu   
網路書籤 Google bookmarks   del.icio.us   hemidemi   myshare   

若有論文相關問題,請聯絡國立中央大學圖書館推廣服務組 TEL:(03)422-7151轉57407,或E-mail聯絡  - 隱私權政策聲明