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

Abstract

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

POLİLAKTİK ASİT TEMELLİ MEMBRANIN MORFOLOJİSİNİN DESALİNASYON PERFORMANSINA ETKİSİ

Abstract

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.

Keywords

• Desalinasyon
• pervaporasyon
• PLA membran

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