Cellulose membranes for organic solvent nanofiltration

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Tezin Türü: Yüksek Lisans

Tezin Yürütüldüğü Kurum: Orta Doğu Teknik Üniversitesi, Mühendislik Fakültesi, Kimya Mühendisliği Bölümü, Türkiye

Tezin Onay Tarihi: 2016

Öğrenci: FAQIH MUHAMMAD SUKMA

Danışman: PINAR ZEYNEP ÇULFAZ EMECEN

Özet:

Cellulose is an alternative polymer that can be used in Organic Solvent Nanofiltration (OSN) where lack of chemically-stable membranes is a major problem. Cellulose, due to strong inter and intramolecular hydrogen bonding, is difficult to dissolve in many solvents, which is an advantage for OSN applications. Common solvent systems like Sodium Hydroxide/Carbon Disulfide (NaOH/CS2) or N-Methylmorpholine-N-oxide (NMMO) for cellulose solubilization are either toxic or unstable. Recent studies have shown that there is an alternative way of dissolving cellulose using ionic liquids. The aim of this study is to fabricate cellulose membranes for OSN via phase inversion using ionic liquids as solvents. 1-ethyl-3-methylimidazolium acetate ([EMIM]OAc) was used as the ionic liquid to dissolve cellulose, while acetone was used as cosolvent and water as nonsolvent. Solutions of probe molecules in both ethanol and water were used to study the separation performance of membranes. It was observed that increased cellulose concentration in the membrane precursor solution, decreased membrane permeance and increased rejection of Bromothymol Blue (BTB) and Cresol Red (CR) in ethanol. Solute-solvent-membrane interactions have an important role in determining the rejection performance as a higher molar volume dye, Brilliant Blue R (BBR), was retained less than CR, BTB, and Crystal Violet (CV) when dissolved in ethanol. Change of solvent also affected the rejection as was shown by a higher value of BBR rejection in water and the absence of rejection of CV as opposed to the behavior in ethanol. Drying the membranes increased the rejection but decreased the permeances by at least an order of magnitude. Compared to OSN membranes reported in literature, the membranes fabricated in our study have comparable performance.