اثر پلاريزاسيون غلظتي در فرآيند شيرين سازي آب به روش اسمز مستقيم (مروري)

The Effect of Concentration Polarization in the Process of Water Desalination by Forward Osmosis Method (Review)

زﻣﯿﻨﻪ و ﻫﺪف: اﻧﺮژي و آب دو ﻋﺎﻣﻞ از ﻣﻬﻢ ﺗﺮﯾﻦ ﻋﻮاﻣﻞ ﭼﺎﻟﺶ ﺑﺮاﻧﮕﯿﺰ ﻫﺴﺘﻨﺪ ﮐﻪ ﺑﺸﺮ در ﻫﺰاره ﺳﻮم ﺑﺎ آن ﻫﺎ ﻣﻮاﺟﻪ اﺳﺖ. در اﯾﻦ ﻣﯿﺎن روش ﻫﺎي ﻣﺨﺘﻠﻔﯽ ﺑﺮاي ﻧﻤﮏ زداﯾﯽ آب ﺑﻪ ﮐﺎرﺑﺮده ﺷﺪه ﮐﻪ ﺿﻤﺎﻧﺖ اﺟﺮاﯾﯽ و ﺻﻨﻌﺘﯽ ﺷﺪن اﯾﻦ روش ﻫﺎ، ﺑﻬﯿﻨﻪ ﺑﻮدن آن ﻫﺎ ازﻟﺤﺎظ ﻣﺼﺮف اﻧﺮژي و داﺷﺘﻦ ﺑﺎزده ﻣﻨﺎﺳﺐ اﺳﺖ. ﯾﮑﯽ از اﯾﻦ روش ﻫﺎ، اﺳﺘﻔﺎده از ﻓﺮآﯾﻨﺪ اﺳﻤﺰي اﺳﺖ ﮐﻪ ﺧﻮد ﺑﻪ دو ﺑﺨﺶ اﺳﻤﺰ ﻣﻌﮑﻮس و اﺳﻤﺰ ﻣﺴﺘﻘﯿﻢ ﺗﻘﺴﯿﻢ ﻣﯽ ﺷﻮد. در ﺣﺎل ﺣﺎﺿﺮ، ﻓﺮآﯾﻨﺪ اﺳﻤﺰ ﻣﻌﮑﻮس ﺑﻪﺻﻮرت وﺳﯿﻊ در ﻣﻘﯿﺎس ﺻﻨﻌﺘﯽ ﺑﻪ ﮐﺎرﺑﺮده ﻣﯽﺷﻮد. ﻓﺮآﯾﻨﺪ اﺳﻤﺰ ﻣﺴﺘﻘﯿﻢ ﻃﯽ دﻫﻪ اﺧﯿﺮ ﻣﻮردﺗﻮﺟﻪ ﻗﺮارﮔﺮﻓﺘﻪ و در راه ﺗﺠﺎري ﺷﺪن ﺑﺎ ﭼﺎﻟﺶ ﻫﺎي ﺟﺪي ﻣﻮاﺟﻪ اﺳﺖ. ازﺟﻤﻠﻪ ﻋﻮاﻣﻞ ﺗﺄﺛﯿﺮﮔﺬار در ﻓﺮآﯾﻨﺪ اﺳﻤﺰ ﻣﺴﺘﻘﯿﻢ ﻣﯽ ﺗﻮان ﺑﻪ: ﺧﻮاص ﻣﺤﻠﻮل ﺧﻮراك و ﻣﺤﻠﻮل ﮐِﺸﻨﺪه )اﺳﻤﺰي(، ﭘﻼرﯾﺰاﺳﯿﻮن ﻏﻠﻈﺘﯽ، ﺟﻬﺖ ﻏﺸﺎ، ﮔﺰﯾﻨﺶ ﭘﺬﯾﺮي و ﺗﻮاﻧﺎﯾﯽ ﻏﺸﺎ در ﻋﺪم ﻋﺒﻮر ﺣﻞ ﺷﻮﻧﺪه ﻫﺎي ﻣﻮﺟﻮد در ﻣﺤﻠﻮل ﻫﺎي دو ﻃﺮف ﻏﺸﺎ، اﯾﺠﺎد اﺧﺘﻼف ﻓﺸﺎر اﺳﻤﺰي ﺑﺎﻻ و ﻗﺎﺑﻠﯿﺖ ﺑﺎزﯾﺎﺑﯽ آﺳﺎن ﻣﺤﻠﻮل ﮐﺸﻨﺪه، اﺷﺎره ﮐﺮد. روش ﺑﺮرﺳﯽ: در اﯾﻦ ﻣﻘﺎﻟﻪ ﭘﺪﯾﺪه ﭘﻼرﯾﺰاﺳﯿﻮن ﻏﻠﻈﺘﯽ، ﻣﺪلﻫﺎي رﯾﺎﺿﯽ ﺣﺎﮐﻢ ﺑﺮ آن و روش ﻫﺎي ﮐﺎﻫﺶ آن ﺑﻪ ﺻﻮرت ﻣﺮوري ﻣﻮرد ﻣﻄﺎﻟﻌﻪ ﻗﺮارﮔﺮﻓﺘﻪ اﺳﺖ. ﯾﺎﻓﺘﻪ ﻫﺎ: راﻫﮑﺎرﻫﺎي ﻣﻬﻤﯽ ﺑﺮاي ﮐﺎﻫﺶ ﭘﻼرﯾﺰاﺳﯿﻮن ﻏﻠﻈﺘﯽ، ﺗﻐﯿﯿﺮ ﺳﺎﺧﺘﺎر ﻏﺸﺎء و ﺑﻬﯿﻨﻪﺳﺎزي ﺷﺮاﯾﻂ ﻓﺮاﯾﻨﺪي و ﻣﺤﻠﻮل ﮐﺸﻨﺪه ﺗﻮﺳﻂ ﭘﮋوﻫﺶ ﮔﺮان ﻣﻮردﺑﺮرﺳﯽ ﻗﺮارﮔﺮﻓﺘﻪ اﻧﺪ. ﻧﺘﯿﺠﻪ ﮔﯿﺮي: ﺑﺎ اﯾﻦ ﮐﻪ ﭘﻼرﯾﺰاﺳﯿﻮن ﻏﻠﻈﺘﯽ ﺗﺄﺛﯿﺮ ﻣﻬﻤﯽ ﺑﺮ ﮐﺎﻫﺶ ﺷﺎر آب ﻋﺒﻮري از ﻏﺸﺎ دارد، ﺑﻪ ﻃﻮري ﮐﻪ ﭘﻼرﯾﺰاﺳﯿﻮن ﻏﻠﻈﺘﯽ داﺧﻠﯽ ﻣﯽ ﺗﻮاﻧﺪ ﺷﺎر آب را ﺗﺎ ﺣﺪود 80% ﺷﺎر آب ﻋﺒﻮري اوﻟﯿﻪ ﮐﺎﻫﺶ دﻫﺪ، وﻟﯽ ﻣﯽ ﺗﻮان ﺑﺎ اﺗﺨﺎذ ﺷﺮاﯾﻂ ﻋﻤﻠﯿﺎﺗﯽ ﻣﻨﺎﺳﺐ و ﺑﻬﯿﻨﻪ ﺳﺎزي ﺳﺎﺧﺘﺎر ﻏﺸﺎ آﺛﺎر ﻣﻨﻔﯽ آن را ﮐﺎﻫﺶ داد.

Background and Objective: Energy and water are two of the most important challenging factors which human faces in the third millennium. Various methods of water desalination were employed that the applicability and industrialization of these methods are dependent on the optimization of the energy consumption and the appropriate efficiency. One of these methods is osmosis process that is divided into two sections: reverse osmosis and forward osmosis. Now, the reverse osmosis process is extensively used on industrial scale. The reverse osmosis process has more industrial applications than the forward osmosis. Currently, the forward osmosis process in commercialization path faces serious challenges. The factors that effect on the forward osmosis process include: properties of feed and draw solutions, concentration polarization, membrane orientation, selectivity and membrane ability to the rejection of solute on both sides of the membrane, creating a high osmotic pressure difference and easy regeneration capability of draw solution. Method: In this article an overview of concentration polarization, its mathematical models and its reduction methods are studied. Findings: The most important strategies proposed by researchers for reducing concentration polarization is changing the membrane structure and optimizing process conditions and draw solution. Discussion and Conclusion: Although the concentration polarization has a significant influence on the control and reduction of the water flux to pass through the membrane, it can reduce the water flux up to 80% of the initial water flux but with using appropriate operating conditions and optimizing membrane structure, the neglect results of it can reduce.