POLİLAKTİK ASİT TEMELLİ MEMBRANIN MORFOLOJİSİNİN DESALİNASYON PERFORMANSINA ETKİSİ

Nüfus artışı, küresel ısınma ve insanların sebep olduğu kirlilikler nedeni ile su kaynaklarımız azalmaktadır. Dünya üzerindeki sular doğrudan kullanılamayan tuzlu sulardan oluşmaktadır. Bu nedenle mevcut su kaynaklarının kullanımı için ayırma işlemlerinin kullanılması son yıllarda önem kazanmaktadır. Pervaporasyon tekniği, tuzlu sulardan saf su elde etmek için yeni gelişen bir tekniktir. Bu çalışmada, deniz suyunun saflaştırılması için Polilaktik asit (PLA) polimeri ile membranlar üretilmiş, membranın hidrofilitesini ve ayırma performansını iyileştirmek, aynı zamanda kararlılıklarını da korumak polietilen glikol (PEG) polimeri eklenmiştir. Çalışma kapsamında, gözeneksiz yoğun ve asimetrik olmak üzere iki farklı membran hazırlanmıştır ve morfolojik yapı farklılıklarının desalinasyon performansına etkileri incelenmiştir. Taramalı elektron mikroskobu (SEM) ve temas açısı testi ile membranlar karakterize edilmiş, ardından tuzlu su desalinasyon testleri yapılmıştır. Sonuç olarak membranın hidrofobitesi azaltılmış bu sayede akı değerleri artmıştır. Tüm membranlar %99 üzerinde tuz reddi elde edilmiştir. En iyi sonuçlar ise %5 PEG içeren PLA membran ile elde edilmiştir. Bu membranın akısı 1,57 kg/m2h, tuz reddi ise %99,98 olarak hesaplanmıştır. Üretilen membranın asimetrik yapıda olması akıyı arttırmış buna rağmen yüksek saflıkta su elde edilmesini sağlamıştır.

Anahtar Kelimeler:

Desalinasyon, pervaporasyon, PLA membran

THE EFFECT OF THE MORPHOLOGY OF A POLYLACTIC ACID BASED MEMBRANE ON DESALINATION PERFORMANCE

The water resources are decreasing due to population growth, global warming, and pollution. The water on Earth consists of salt water that cannot be used directly. For this reason, separation processes for the use of existing water resources, has gained importance in recent years. Pervaporation is a novel desalination technique for obtaining pure water from the saline water source. The most important part of the pervaporation method is the membrane. The difference of the pervaporation from other membrane-based techniques is the non-porous and selective membrane usage. It is possible to obtain high purity water due to the selective separation capability of pervaporation membranes. Therefore, most of the studies in the literature are related to innovative membrane production. Pervaporative desalination membranes should have high salt rejection and acceptable flux values. Moreover, the use of sustainable and environmentally friendly materials has also important to determine the membrane types. In this study, polylactic acid (PLA) based membranes prepared and used for the purification of sea water. Polyethylene glycol (PEG) polymer was added to improve the hydrophilicity and the separation performance of the membrane, while maintaining its stability. Within the scope of the study, two different membranes, nonporous dense and asymmetric, were prepared and the effects of morphological structure differences on the desalination performance were investigated. Scanning electron microscopy (SEM) and the contact angle tests were performed and the saltwater desalination tests were performed. As a result, the hydrophobicity of the membrane was decreased, and the flux was increased. The salt rejection results were obtained over 99%. The best results were obtained with % of PEG containing PLA membrane. The flux of this membrane was calculated as 1.57 kg/m2h, and the salt rejection was calculated as 99.98%. The asymmetrical structure of the produced membrane increased the flux, as well as providing high purity water.

Keywords:

Desalination, pervaporation, PLA membrane,

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1. An, W., Zhou, X., Liu, X., Chai, P. W., Kuznicki, T., & Kuznicki, S. M. (2014). Natural zeolite clinoptilolite-phosphate composite membranes for water desalination by pervaporation. Journal of membrane science, 470, 431-438.
2. Burn, S., Hoang, M., Zarzo, D., Olewniak, F., Campos, E., Bolto, B., & Barron, O. (2015). Desalination techniques—A review of the opportunities for desalination in agriculture. Desalination, 364, 2-16.
3. Drobek, M., Yacou, C., Motuzas, J., Julbe, A., Ding, L., & da Costa, J. C. D. (2012). Long term pervaporation desalination of tubular MFI zeolite membranes. Journal of Membrane Science, 415, 816-823.
4. Galiano, F., Ghanim, A. H., Rashid, K. T., Marino, T., Simone, S., Alsalhy, Q. F., & Figoli, A. (2019). Preparation and characterization of green polylactic acid (PLA) membranes for organic/organic separation by pervaporation. Clean Technologies and Environmental Policy, 21(1), 109-120.
5. Gude, V. G. (2017). Desalination and water reuse to address global water scarcity. Reviews in Environmental Science and Bio/Technology, 16(4), 591-609.
6. Huth, E., Muthu, S., Ruff, L., & Brant, J. A. (2014). Feasibility assessment of pervaporation for desalinating high-salinity brines. Journal of Water Reuse and Desalination, 4(2), 109-124.
7. Kaminski, W., Marszalek, J., & Tomczak, E. (2018). Water desalination by pervaporation–Comparison of energy consumption. Desalination, 433, 89-93.
8. Korin, E., Ladizhensky, I., & Korngold, E. (1996). Hydrophilic hollow fiber membranes for water desalination by the pervaporation method. Chemical Engineering and Processing: Process Intensification, 35(6), 451-457.
9. Khajavi, S., Jansen, J. C., & Kapteijn, F. (2010). Production of ultra pure water by desalination of seawater using a hydroxy sodalite membrane. Journal of Membrane Science, 356(1-2), 52-57.
10. Liang, B., Zhan, W., Qi, G., Lin, S., Nan, Q., Liu, Y., ... & Pan, K. (2015). High performance graphene oxide/polyacrylonitrile composite pervaporation membranes for desalination applications. Journal of Materials Chemistry A, 3(9), 5140-5147.
11. Liang, H. Q., Wu, Q. Y., Wan, L. S., Huang, X. J., & Xu, Z. K. (2014). Thermally induced phase separation followed by in situ sol–gel process: A novel method for PVDF/SiO2 hybrid membranes. Journal of membrane science, 465, 56-67.
12. Liu, X., Demir, N. K., Wu, Z., & Li, K. (2015). Highly water-stable zirconium metal–organic framework UiO-66 membranes supported on alumina hollow fibers for desalination. Journal of the American Chemical Society, 137(22), 6999-7002.
13. Qian, X., Li, N., Wang, Q., & Ji, S. (2018). Chitosan/graphene oxide mixed matrix membrane with enhanced water permeability for high-salinity water desalination by pervaporation. Desalination, 438, 83-96.
14. Quinones-Bolanos, E., Zhou, H., Soundararajan, R., & Otten, L. (2005). Water and solute transport in pervaporation hydrophilic membranes to reclaim contaminated water for micro-irrigation. Journal of Membrane Science, 252(1-2), 19-28.
15. Shen, P., Moriya, A., Rajabzadeh, S., Maruyama, T., & Matsuyama, H. (2013). Improvement of the antifouling properties of poly (lactic acid) hollow fiber membranes with poly (lactic acid)–polyethylene glycol–poly (lactic acid) copolymers. Desalination, 325, 37-39.
16. Wongchitphimon, S., Wang, R., Jiraratananon, R., Shi, L., & Loh, C. H. (2011). Effect of polyethylene glycol (PEG) as an additive on the fabrication of polyvinylidene fluoride-co-hexafluropropylene (PVDF-HFP) asymmetric microporous hollow fiber membranes. Journal of Membrane Science, 369(1-2), 329-338.
17. Wang, Q., Li, N., Bolto, B., Hoang, M., & Xie, Z. (2016). Desalination by pervaporation: A review. Desalination, 387, 46-60.
18. Xie, Z., Hoang, M., Duong, T., Ng, D., Dao, B., & Gray, S. (2011). Sol–gel derived poly (vinyl alcohol)/maleic acid/silica hybrid membrane for desalination by pervaporation. Journal of Membrane Science, 383(1-2), 96-103.
19. Zereshki, S., Figoli, A., Madaeni, S. S., Simone, S., Jansen, J. C., Esmailinezhad, M., & Drioli, E. (2010). Poly (lactic acid)/poly (vinyl pyrrolidone) blend membranes: Effect of membrane composition on pervaporation separation of ethanol/cyclohexane mixture. Journal of Membrane Science, 362(1-2), 105-112.
20. Zhang, Y., Feng, X., Yuan, S., Zhou, J., & Wang, B. (2016). Challenges and recent advances in MOF–polymer composite membranes for gas separation. Inorganic Chemistry Frontiers, 3(7), 896-909.
21. Zwijnenberg, H. J., Koops, G. H., & Wessling, M. (2005). Solar driven membrane pervaporation for desalination processes. Journal of Membrane Science, 250(1-2), 235-246.