Polymers Having Dicationic Structure in Dumbbell Shape for Forward Osmosis Process

국문 초록 (Abstract)

본 저자는 열 감응성 고분자인 poly(alkane-1,#-diylbis(tri-nbutylphosphonium) 4-vinylbenzenesulfonate) (PSSBP#) 시리즈를 정삼투 공정의 유도용질로서의 잠재적인 활용 가능성을 확인하기 위해 합성했다. 여기서, #은 쌍양이온성 phosphonium moiety의 중앙에 위치한 다리 구조의 탄소 원자 수이다. PSSBP# 시리즈는 하한임계용액온도 특성을 나타내며, 이는 순수한 물로부터 유도용질 회수 능력을 부여하는 필수 요소이다. 수용액 상에서의 PSSBP8, PSSBP6, PSSBP4의 하한임계용액온도는 20 wt% 농도에서 각각 30, 38, 26 ℃로 확인되었으며, 이는 유도용질을 회수하는데 필요한 에너지 관점에서 유리하다. PSSBP4 유도용액의 농도가 20 wt% 일 때, 유입수를 증류수로 설정하고 active layer facing draw solution (AL-DS) 방식을 적용했을 때의 투수량과 역확산도는 약 1.61 LMH 및 0.91 gMH로 확인되었다.
열 감응성 유도용질인 PSSBP#은 적절한 삼투 성능과 효과적인 회수 에너지로 인하여 차세대 유도용질 후보가 될 수 있다. 따라서 이 연구는 고분자 구조 변형에 대한 새로운 아이디어와 유도용질로서의 적용 가능성에 대한 영감을 보여준다.

다국어 초록 (Multilingual Abstract)

I synthesized thermal-responsive polymers, poly(alkane-1,#-diylbis(tri-n-butylphosphonium) 4-vinylbenzenesulfonate) (PSSBP#, # = 8, 6, and 4) series, where # is number of carbon atoms in centered bridge structure of dicationic phosphonium moiety, to confirm potential application as draw solute in forward osmosis (FO) process. The polymers show lower critical solution temperature (LCST) characteristic in aqueous solution, which is an essential element that gives function of recovering draw solute from pure water. The LCST of aqueous solutions of PSSBP8, PSSBP6, and PSSBP4 were confirmed to be about 30, 38, and 26 oC at 20 wt% aqueous solution concentration, respectively, which is advantageous in terms of energy requirement for recovering draw solute. When concentration of PSSBP4 draw solution was 20 wt%, water flux and reverse solute flux were determined to be 1.61 LMH and 0.91 gMH approximately in active layer facing draw solution (AL-DS) system in setting feed solution to distilled water. PSSBP#, thermal-responsive draw solute, can be a nominee for next generation of draw solute due to its proper osmotic performance and effective recovery energy. Therefore, this study shows inspiration for novel ideas in structural transformation of polymer and applicability as draw solute.

목차 (Table of Contents)

• Ⅰ. Introduction 1
• 1. Background 1
• 1.1. Global water scarcity and its breakthrough 1
• 1.2. Forward osmosis (FO) 2
• 2. External-stimulus-responsive draw solutes 3
• 2.1. Chemical-stimulus-responsive draw solute 3
• 2.2. Physical-stimulus-responsive draw solute 5
• Ⅱ. Theory 8
• 1. Menshutkin reaction 8
• 2. Solution polymerization 10
• 3. Forward osmosis performance 11
• Ⅲ. Experimental 12
• 1. Reagents and instrumentations 12
• 2. Material preparation 14
• 2.1. Preparation of BP#Br2 14
• 2.2. Preparation of SSBP# and SSMP 16
• 3. Polymer synthesis 18
• 3.1. Synthesis of PSSBP# and PSSMP 18
• 4. FO performance 20
• Ⅳ. Results and discussion 22
• 1. Synthesis and characterization for PSSBP# 22
• 2. Solution property 34
• 2.1. Viscosity 34
• 2.2. Conductivity 37
• 2.3. Osmotic pressure 40
• 3. FO performance 44
• 3.1. Recovery property 44
• 3.2. Water flux and reverse solute flux 48
• Ⅴ. Conclusions 51
• References 53
• Abstract 59