Observation of scaling and wetting using the visualization system, and their retardations in membrane distillation(MD) : inhibition of scaling and wetting by adjusting major components in seawater membrane distillation (SWMD)

김혜원 Green School Graduate School of Energy and Environ 2020 국내박사

Scaling and wetting phenomena should be controlled for a commercialization of MD process. A visualization system was proposed to understand scaling and wetting by a real-time observation during the direct contact membrane distillation (DCMD) operation. The system was consisted of a MD module, a CCD camera and plate-type visible LED lights. To evaluate the applicability of the visualization system, visibility of the scales with the system and correlation between detected spots and wetting were verified during the MD process using a polyvinylidene fluoride (PVDF) 0.45 μm membrane. The white spots were observed in the images obtained by the visualization system and spread out with the increase in electrical conductivity (EC) indicating wetting. It was identified that the spots indicated the formation of CaSO4 scales inside the pores. Wetting potential of white spots were defined through the dye penetration test, which intended the occurrence wetting by a pressure applied. The visualization system was applied to the MD process under different permeate temperatures (20 and 55 ℃). The visualization system successfully detected the pore blocking related with different scale formation according to the temperatures at the membrane surface. In addition, the effects of potential scalants including Mg, Ca and Sr crystals on the scaling and wetting were investigated in the DCMD coupled with visualization system. Significant impacts of Mg(OH)2 and CaSO4, and low effects of CaCO3, SrCO3, SrSO4 on scaling and wetting were observed as single salt solution. And, co-precipitation of CaCO3 and CaSO4 were verified in synthetic seawater rather than Mg(OH)2. However, the deposition of Mg(OH)2 scales was concerned in the case of Ca removal from seawater. Therefore, both Mg and Ca ions needed to be removed for the control of scaling and wetting. NaOH/Na2CO3 softening was applied to normal seawater for the removal of Ca and Mg ions. In addition, the inhibition effects of Mg ions on Ca scales caused to use Na2CO3 softening and a new pretreatment method involving the Mg addition to increase the Mg/Ca ratio. Softening and Mg addition were effectively inhibited scaling and wetting in MD process using normal seawater. Nevertheless, softening was concerned to use as pretreatment of MD process due to the complicated process containing heating for reaction time and requirement of additional process for sludge. However, Mg addition showed the stability for wetting rather than the antiscalant made of organic matter with simple pretreatment process.

Development of Ion Mobility-Mass Spectrometry Methods for Membrane Proteins Incorporated into Nanodiscs

Parson, Kristine F ProQuest Dissertations & Theses University of Mich 2022 해외박사(DDOD)

소속기관이 구독 중이 아닌 경우 오후 4시부터 익일 오전 9시까지 원문보기가 가능합니다.

Membrane proteins (MPs) are vital therapeutic targets which play important roles in a multitude of cellular functions. MPs interact intimately with the cellular membranes in which they embed. Interactions between proteins and ligands such as membranous lipids and other small molecules can affect MP structure and function. Ion mobility-mass spectrometry (IM-MS) has recently emerged as a valuable tool for interrogating the interactions between proteins and ligands, offering direct measurements of protein-complex stoichiometry, ligand binding strengths, and stabilities. This dissertation seeks to extend IM-MS technologies to study the relationships between MPs and their lipid environment, probing directly long-standing questions surrounding the functional role of local lipid environments on MP structure and function. In chapter 2 we develop a workflow for studying different MP classes using various solubilization techniques and discuss the implications such membrane mimetics carry in the context of the embedded protein structures. We utilize four different MPs that vary in both the way that they span the membrane and in terms of their native oligomeric states. Specifically, we utilize a small multidrug resistance transporter (GDX), a transmembrane protein that has a unique antiparallel orientation, WT and the L16P disease-associated mutant form of peripheral myelin protein (PMP22), a transmembrane protein which occupies both a monomeric and dimeric state, and Cytochrome P450 (CYP), a monotopic membrane-bound enzyme. Each MP system was studied within at least two different mimetics, including: detergent-based micelles, lipid-bicelles, or lipid-nanodiscs (NDs). In general, we find evidence of differences in MP structure, oligomeric state, and ligand binding that appears to depend strongly on the membrane mimetic used. In chapters 3, 4 and 5 we focus on CYP and deploy IM-MS and collision induced unfolding (CIU) to study how this centrally important enzyme interacts with binding partners, ligand and its membrane environment in order to carry out essential functions. In chapter 3, we use NDs of carefully designed compositions to study the role of different lipid environments and ND scaffolding proteins on CYP structure. We find that CYP CIU, and by extension its structure, strongly depends on its local environment, and that more native membrane environments can result in more compact and more destabilized CYP forms. In chapter 4 we focus on CYP ligand binding and develop CIU classifiers capable of differentiating CYP binders based on their mode of attachment to the protein and their hydrophilicities. The ability of our CIU assays to differentiate CYP-ligand complexes to discern hydrophobic from hydrophilic binders relates directly to the proximity of the CYP active site to the biological membrane and supports the conclusion that lipids are significantly involved in structure of the CYP active site. In chapter 5 we study the interactions between full length CYP, cytochrome b5 (cytb5), and P450 oxioreductase (POR) within NDs. When we co-incubated these proteins with NDs we observed no direct evidence of stable complexes, but significant alterations in CYP CIU, suggesting changes in CYP structure when present within the same local membrane environment to cytb5 or POR. We observe evidence of additional lipid binding events within POR when reduced by NADPH, suggesting deeper membrane engagement when the protein is in its reduced state. We conclude in Chapter 6 by discussing the future of MP structural biology and how this dissertation works has emphasized the impact that a membrane environment has on the membrane protein structure.

Nonlinear Analysis and Design of Tensile Membrane Structures

Marta Gil P?rez 서울대학교 대학원 2015 국내석사

Membrane structures are one of spatial structures that allow for long span and light weight roofs. In many cases, the membrane roofs are supported with trusses or mats and prestressed together with cables to obtain a resistant shape for a given loading condition. For the design of membrane structures, nonlinear analysis is required. Besides, modeling of each membrane element and form-finding of the shape are of great importance in the design process. First, an equilibrium-finding analysis is conducted for the purpose of obtaining the optimal shape of the membrane structure, during which the initial stresses of the membrane and cables must be balanced. Next, the stress-deformation analysis is performed for the required loading condition. This analysis allows understanding the behavior of the structure and confirms that the design of the membrane satisfies the required safety factor for the construction. In this research, a broad definition and explanation about spatial structures and in particular membranes are given. Then, the detailed procedure for the design and analysis of those is introduced with a complete explanation of the modeling and conditions to be considered. For a better understanding, two case studies are introduced and described where each step for the modeling, design and analysis is illustrated. At the last part of this thesis, a parametric study on barrel vault shaped membranes is described. In this part, firstly regular membrane panels supported between arches are analyzed, leading to the development of a safe design aid for this type of membranes. Secondly, by adding one grade of irregularity, curved and inclined membrane barrel vault shaped panels are also studied, resulting on a similar safe design combination graph for each of this kind of panels. Finally, by the use of these design charts, simple design examples are illustrated to show the application of this study.

Membrane Filtration Processes for Energy Reduction, Brine Treatment, and In-Situ Ultrasonic Biofouling Mitigation

Anderson, William V The Ohio State University ProQuest Dissertations & 2021 해외박사(DDOD)

소속기관이 구독 중이 아닌 경우 오후 4시부터 익일 오전 9시까지 원문보기가 가능합니다.

The demand for efficient and effective water purification processes encompasses a breadth of industries. As such, a multitude of filtration technologies and unique approaches have been developed. Adoption of an appropriate filtration technology depends on the nature of the water to be treated and the desired finished water quality. The aim of this work was to evaluate a select set of novel membrane filtration technologies and approaches for their efficiency and applicability. Processes evaluated include (1) electrofiltration utilizing a novel inorganic membrane, (2) a couple forward osmosis – membrane distillation for brine treatment, and (3) a novel in-situ ultrasonic self-cleaning membrane.The application of an electrical potential across a membrane during filtration results in unique effects, dependent on the feed water parameters, the membrane properties and system design. Of particular interest is the production of electroosmotic flow. Electroosmotic flow is the movement of water through the membrane, induced by an electrical potential. This effect is independent of transmembrane pressure. This phenomenon appears to be particularly outspoken in dilute acidic and basic aqueous solutions in oxidic membrane structures. Electroosmotic flow, and the associate specific energy consumption, was studied for electrofiltration of acidified DI water with a 2 mm thick high purity α-Al2O3 membrane with a porosity of 35%, and a narrow pore size distribution around 700 nm. It was found that at a temperature of 23°C, a pH of 4 and a pressure difference, Δp, of 15 kPa, the membrane flux increased from 3.7x10-9 to 5.2x10-9 m/s (59 to 82 LMH) after application of a voltage, ΔΦ, of 10 V. This 38% increase at pH 4 required a total electrical SECEOF of 1.5 MJ/m3 (0.43 kWh/m3). Since the electro-filtration proper requires a minimal SECminEF of only ~23 kJ/m3 (6 Wh/m3), the observed SECEOF is ascribed almost entirely to electrode losses and ionic and molecular transport resistance. Under the pH 10 condition, the membrane flux decreased from 4.0x10-9 to 3.0x10-9 m/s (63 to 47 LMH) after application of a voltage, ΔΦ, of 10 V, corresponding to a 29% decrease in water flux. At a minimum Δp =1.5 kPa and conditions otherwise the same, the membrane flux increased from 4.9x10-6 to 1x10-5 m/s (18 to 37 LMH) after application of ΔΦ = 10 V. The total electrical SEC, associated with this increase was 1.2 MJ/m3 (0.22 kWh/m3). The energy efficient use of electrofiltration to generate water flux without moving parts, along with reversibility of the flow direction, has immense potential for membrane filtration.Following this, a bench-scale forward osmosis – membrane distillation (FO-MD) system was applied to flue gas desulfurization (FGD) wastewater generated at coal fired power plants (CFPPs) focusing on water recovery, salt rejection, thermal energy demands, and potential for harvesting low-grade waste heat. Using flat sheet cellulose triacetate (CTA) and polytetrafluoroethylene (PTFE) membranes, treatment of synthetic and collected FGD wastewater was evaluated across a range of applicable temperatures (43.3 – 65.5°C) and draw solutions (NaCl, CaCl2, PAA-Na). Highest water fluxes were observed at the highest NaCl and CaCl2 draw solution concentrations (3.4M) and temperatures (65.5°C) evaluated, with FO and MD fluxes reaching 37 and 25 LMH, respectively. The FO-MD system achieved over 99.8% rejection of all surveyed components (Na, K, Ca, Mg, B, Cl-, SO42-), producing permeate with conductivities below 105 μS/cm. An 89% water recovery occurred using a 3.4 M sodium chloride draw solution. While the FO-MD process is capable of treating FGD wastewater, basic osmotic backwashing was insufficient at restoring the FO membrane water flux. Further investigation of membrane fouling and scaling is warranted. Investigation of the required heat for MD indicates that adequate low-grade waste heat sources are available on-site, suggesting the FO-MD process can be an effective, energy efficient and sustainable treatment technology for FGD wastewater.Lastly, membrane filtration of municipal wastewater, often termed a membrane bioreactor (MBR), can obtain a high quality effluent that surpasses conventional treatment capabilities. Yet, activated sludge filtration results in biofilm growth and a build-up of extracellular polymeric substances (EPS) on the membrane surface, reducing filtration efficiency and requiring cleaning. Ultrasound is a potential cleaning method that has been shown to be effective at removing biofilm formations. Utilizing piezoelectric lead zirconate titanate (PZT) membranes, ultrasound was produced in-situ, during filtration of 0.95 mM KCl and 0.05 mM KHCO3 buffered DI water and activated sludge wastewater solutions. Impacts of the membrane poling process, the applied electric field and in-situ ultrasound were studied. Residual oil from poling the PZT membrane resulted in a more hydrophobic membrane with reduced permeability. The application of an 80 Vpp, 45kHz AC signal had no impact on unpoled or poled PZT membranes when filtering the buffered DI feed solution. When applied to filtration of activated sludge wastewater, the 80 Vpp, 45kHz AC signal resulted in a greater retention of 72-hr normalized water flux for the poled PZT membrane, when compared to a non-active poled membrane over 7 days of filtration. Thus, in-situ ultrasound is a potential online fouling prevention technique.As explored, these membrane filtration technologies and approaches result in energy reductions and fouling mitigation. Through continued development, these processes evaluated at bench scale may advance the membrane filtration industry as a whole.

Substrate Design and Membrane Stability of Multilayer Composite Membrane for CO2 Separation

Wu, Dongzhu The Ohio State University ProQuest Dissertations & 2017 해외박사(DDOD)

소속기관이 구독 중이 아닌 경우 오후 4시부터 익일 오전 9시까지 원문보기가 가능합니다.

Membrane process for CO2 separation has gained interest due to its system compactness, high energy efficiency, operational and maintenance simplicity, and ability to overcome thermodynamic limitations. Flue gas decarbonization is an important approach to control the increasing atmospheric CO2 level. Membranes with exceptional separation performance are required to perform such capture. In this research, a multilayer composite membrane, consisting of a polyethersulfone (PES) substrate, a Zeolite-Y (ZY) nanoparticle gutter layer (optional), and an amine-containing polymer selective layer, was synthesized for CO2 separation from power plant flue gas and other sources with even lower CO2 concentrations. The PES substrate was fabricated in lab and pilot scales. The membrane morphology was optimized by adjusting the preparation parameters. 14-inch wide PES substrate with reproducible morphology was fabricated successfully by using a continuous casting machine. Moreover, a continuous pilot-scale vacuum-assisted nanoparticle deposition process was developed to deposit an inorganic ZY gutter layer to minimize the selective layer penetration. Additionally, hydrophilic moieties were incorporated in the PES substrate to modify the hydrophilicity of the substrate and reduce the substrate permeation resistance. Both ZY deposition and PES modification improved the separation performance of the composite membrane.There was a concern that the minor contaminant components in flue gas, e.g., SO2, may react with amines in the selective layer, which would affect the long-term membrane stability. The membrane stability in the presence of 1-3 ppm SO2 at 57°C was investigated. Upon exposure to ppm levels of SO2, stable separation performances with minor permeance reduction were obtained for the synthesized facilitated transport membranes.The composite membrane synthesized in this research was also employed for CO2 separation from the residual flue gas containing a CO2 concentration of ~ 1%. Capturing the CO2 from residual flue gas after a primary capture system can further reduce the CO2 emission to the atmosphere. The synthesized membrane showed promising separation performance and membrane stability for such separation.

Organic control by hybrid UF membrane with PAC : bench and pilotscale evaluation

Oh, Hee Kyong The University of Seoul 2004 국내박사

Membrane filtration technology has been rapidly accepted in drinking water treatment in order to retrofit existing water treatment and to apply for advanced treatment. Due to its superior rejection of microbial contaminants, taste and odor, disinfection by-product forming potential (DBPFP) and synthetic organic compound (SOC), it has been demonstrated to be competitive with conventional treatment processes. Ultrafiltration (UF) as low-pressure membrane filtration has consistently proven effective for the removal of Giardia and Cryptosporidium and has been applied as an alternate filtration technology. However, UF membrane with low removal in dissolved organic matter is required to combine with other treatment processes in order to achieve advanced water treatment. Therefore, powdered activated carbon (PAC) adsorption was selected as a pretreatment process prior to the UF membrane in treating surface water of Han River. In this study, PAC effect on the UF membrane performance was investigated, evaluation criteria for membrane performance was provided, and applicability of the hybrid PAC-UF membrane was evaluated for drinking water treatment. For this research, bench-scale and pilot-scale UF membrane equipment were operated and PAC adsorption prior to the UF membrane was combined in both membrane tests. During the bench and pilot PAC-UF membrane tests, performance of the PAC-UF membrane was compared with the UF membrane, in terms of contaminant removal and flux behavior. Aromaticity and humification degree of NOM from Han River were moderate by less than 2.45±0.735 L/mgm of SUVA. Specific THM, HAA and TOX yields from DOC were 46.1±7.9, 22.8±10.4 and 66.2±10.6 ?g/mg, respectively and those from SUVA were 53.1±19.2, 20.7±9.9 and 95.2±17.9 (?g/L)/(L/mmg), respectively. When 85~92% of CHCl3 composition ratio was considered, DOC goal of finished water is recommended by less than 1 mg/L to satisfy 80 ?g/L of CHCl3 standard. Suspended organic matter as TOC produced DBP by chlorination, therefore, pretreatment process such as oxidation prior to the UF membrane should be carefully introduced not to increase DBP concentration. Seasonal variation in molecular weight distribution (MWD) of NOM from raw water was minor and NOM was mainly distributed in low and medium molecular weight range of less than 30,000 dalton, occupying 67~80% of total NOM, which can not be rejected by the UF membrane alone. Hydrophilic NOM of raw water was higher than hydrophobic NOM in the most of seasons and was more than 1 mg/L of DOC. However, the hydrophobic fraction of NOM through four seasons was less than 1 mg/L of DOC, with the composition of 17~58%. These results were in agreement with the hydrophilic fractions of lower MW trend. The NOM characterization suggested that pretreatment process prior to the UF membrane should control low and medium molecular weight fraction and hydrophobic NOM with high yield of DBP. Thus PAC addition prior to the UF membrane was introduced for this purpose. The hydrophilic NOM of more than 1 mg/L in raw water should be also investigated to be controlled through the hybrid PAC-UF membrane. PAC addition in bench-scale hybrid PAC-UF membrane could improve NOM removal, especially hydrophobic NOM. As PAC particle size decreased and PAC dose increased, DOC removal increased, forming lower DBP in permeate. 7 ?m PAC addition of 10 mg/L could produce DOC of 1 mg/L and THMFP of 50 ?g/L in the permeate. It would be achieved by complementary PAC adsorption of hydrophobic NOM with hundreds of dalton molecular weight and mechanical sieving of hydrophilic UF membrane for less hydrophobic NOM with higher molecular weight dalton. Effect of PAC addition prior to UF membrane on flux behavior was investigated. As PAC particle size decreased and PAC dose increased, decrease of permeate flux mitigated. It might be considered that PAC of smaller particle size had higher adsorption capacity of NOM and could reduce the organic foulant loading toward the UF membrane surface. From the results of bench-scale experiment, 10~20 mg/L of carbon dose with 7 ?m PAC might be an optimum condition for the hybrid PAC-UF membrane, in order to maintain DOC of permeate less than 1 mg/L and to improve permeate flux of the UF membrane. In addition, future work requires to investigate the effect of PAC contact time on membrane performance. In operation of the pilot PAC-UF membrane, turbidity and particle removals were improved by the carbon cake formation on the membrane surface. However, turbidity and particle count monitoring of permeate in the PAC-UF membrane showed that initial peaks of turbidity and particle counts happened at the beginning of filtration cycle. Therefore, flushing step with volume of more than membrane hold-up right after backwashing was required to produce the permeate safely for the beginning period of filtration. When the pilot-scale hybrid PAC-UF membrane was operated in a batch mode, PAC addition with 20 mg/L of carbon dose could produce less than 1 mg/L of DOC in permeate and remove effectively Geosmin and 2-MIB to meet the taste and odor threshold. Continuous operation of the pilot-scale hybrid membrane presented that hydrophobic NOM was mainly removed and transphilic NOM was slightly removed. Furthermore, all permeate could meet THM (100 ?g/L) and HAA (100 ?g/L) standard of KDWS (Korean Drinking Water Standard). It could be considered that DBPFP removal might be improved by the complementary cooperation between carbon adsorption and UF membrane rejection. Finally, additional treatment process should be researched in order to control the NOM which cannot be rejected even by the hybrid PAC-UF membrane. PAC addition in the hybrid PAC-UF membrane could improve the productivity of UF membrane, thus resulting in increasing the normalized cumulative production up to 15~41% than the UF membrane during the same operation period. However, as conversion ratio was higher, flux decline in the PAC-UF membrane was slightly higher than in the UF membrane. Higher permeation rate induced increase of PAC particle loading on the UF membrane surface, thus might deteriorate the permeate flux than the UF membrane. Therefore, less than 10% of conversion ratio, more than 0.5 kg/cm2 of transmembrane pressure (TMP) and higher cross-flow velocity was recommendable for preventing excess PAC accumulation. In addition, membrane operation conditions such as TMP, cross-flow velocity and backwashing condition should be well designed specific to the hybrid PAC-UF membrane under optimized condition of PAC dose. Monitoring of particle counts in the permeate can identify PAC leak from permeate as well as removal of larger pathogens such as Giardia and Cryptosporidium. Continuous PAC accumulation in the hybrid membrane should be supervised not to increase the particle loading to the UF membrane, thus monitor of turbidity in the circulation loop can be an evaluation indicator for accumulated PAC concentration and can diagnose the carbon feed system. Backwashing condition should be optimized since the varied and deteriorated membrane surface through long-term membrane filtration affects the backwashing efficiency. Thus, turbidity profile of backwashing waste solution against time is recommendable to evaluate for backwash efficiency, and peak of turbidity should happen early within the given backwashing duration. Also monitoring of UV254 could give information on the PAC drain time from the membrane system as well as evaluation of backwashing efficiency. Total TOC amount of whole cleaning solutions in the hybrid PAC-UF membrane was lower than that of all cleaning solutions in the UF membrane, which could testify that PAC adsorbed portion of organic foulants in bulk solution prior to UF, thus reducing organic foulant loading to the membrane surface. Si and Ca were mainly detected as inorganic membrane foulants the all waste cleaning solutions. Acid cleaning showed most efficient removal of Fe, and alkaline cleaning could remove residual inorganic foulant of Ca from the membrane surface, through dissolution of the metal NOM complexes. Visual inspection of membrane fiber surface through transparent casing of membrane module showed that hollow-fiber of the UF membrane was more yellowish than that of the PAC-UF membrane, but residual PAC particles on the membrane surface made the appearance of PAC-UF membrane fiber light gray. Therefore, the surface of polysulphone UF membrane was directly affected by hydrophobic NOM such as humic acid, but PAC addition in the hybrid membrane prevented fiber surface from being directly colored by NOM and may reduce the membrane aging due to organic fouling. In the future, the residual PAC on the membrane surface should be investigated to understand whether it affects the effective pore of UF membrane. PAC particles were accumulated in the inlet and outlet of the UF membrane module and might cause the flow channel to decrease. It not only increased hydrodynamic resistance to permeation but also reduced effective adsorption capacity of PAC. Therefore, hydraulic conditions of recirculation loop should be optimized not to accumulate PAC in the membrane module. Specific module design might be required to minimize the dead-end zone, which was not available for membrane filtration. Finally, backwashing pressure should be enough to detach the residual PAC from the membrane surface. SEM images showed that organic and inorganic matters fouled the UF membrane in treating surface water, gel layer formed on the top nearest to the membrane surface or between tiny spaces, and the amorphous large lumps unevenly formed on the upper side of membrane. Acid cleaning was effective in dissolving the linkage between inorganic and organic matters as well as metal oxide precipitates. Final alkaline cleaning could remove mainly organic foulant attached on the UF membrane surface and within the membrane pore. On the other hand, thick deposit layer composed of around 10 ?m particle size covered the whole surface of the hybrid membrane. The morphology of deposits was more homogeneous than that of the UF membrane, however upper crumbles on the cake layer were loosely deposited. Even after all cleaning procedures, no pores of membrane were visible due to carbon residual on the membrane surface. Based on the above discussion, the hybrid PAC-UF membrane can be an effective advanced treatment processes in controlling DOC and taste and odor problem. PAC addition could improve productivity of the UF membrane, due to reduction of organic foulant loading prior to the UF membrane and might be capable of reducing the membrane aging from organic foulant. Also monitor of turbidity and SUVA in the recirculation loop might be avaliable for evaluating the PAC behavior through the hybrid membrane system. In the future, evaluation indices should be more practically established to decide PAC drain time from the membrane system and process development should be researched for recycle of PAC drained from backwashing cycle.

A framework for designing spiral-wound osmotic membrane module in consideration of membrane and flow channel deformation

Chulmin Lee 광주과학기술원 대학원 2021 국내박사

Membrane module design plays key roles in terms of membrane performance, operations and maintenance (O&M), and resulted overall economics of plant implementation. Although the design of the conventional spiral-wound membrane (SWM) element has been constantly developed since the origination and implementation of the RO process mainly in the industrial area, research attention on the development of the SWM element for osmotically driven membrane process (ODMP) is still severely limited. In this study, structural characteristics of all the parts within the ODMP SWM element and their effects on the process performance of during operation will be thoroughly investigated using both experimental and simulation methods for validity and applicability of the research outcome. In the first and second chapters of the dissertation, alteration of membrane transport properties under hydraulic pressure and mechanical compression have been investigated using experimental and theoretical methods. Significant variations of major membrane properties such as water permeability and selectivity by transmembrane pressure and spacer configuration have been identified to provide a basis in the prediction of spatial membrane performance in module-scale process operation. The critical mechanical compression ratio, determined by the membrane’s selectivity loss by mechanical compression, can also contribute to the membrane structural design of ODMP modules. In the third chapter, the Fluid-structure interaction (FSI) technique has been employed for geometric and hydrodynamic evaluation in the deformation of the spacer-filled channel. The study successfully provided polynomial relation of unit channel pressure to superficial velocity, allowing large-scale membrane envelope CFD simulation without tremendous computational power requirement for complicated spacer-filled channel geometry. As the final task of the dissertation, profile of membrane transport properties from the first chapter and polynomial relation of unit pressure drop from the third chapter was employed in the CFD evaluation to optimize membrane leaf geometry such as leaf length and the ratio of central glue line to leaf length for each ODMPs, forward osmosis (FO), pressureassisted forward osmosis (PAFO), and pressure-retarded osmosis (PRO). The results highlighted the importance of the internal design of the membrane module since they have significant impacts on major process performance indicators such as water flux, specific energy consumption, and power density. Ultimately, this study is aimed to provide a reliable, accessible, and practical framework for developing ODMP SWM modules. Suggested work in this thesis potentially can be applied for developing all types of flat-sheet membrane modules in a cost-efficient manner.

Fabrication and Application of Forward Osmosis Membranes using a modified molecular layer-by-layer method

Soon-Bum Kwon 고려대학교 그린스쿨대학원 2024 국내박사

This dissertation delves into the manufacturing method and the application process of a separation membrane tailored for the forward osmosis procedure. In this study, efforts were made to overcome the limitations of conventional membrane formation technologies by establishing a high-performance composite membrane. This involves a different approach compared to the conventional method of creating a selective layer directly on a support layer to form the entire membrane. Instead, it involves independently fabricating a complete selective layer and subsequently combining it with a support layer to manufacture a unified whole membrane. This paper emphasizes the research findings presented in Chapters 3 and 4. In chapter 3, the support-free assembled molecular layer-by-layer (SF-mLbL) was suggested to manufacture the thin-film composite (TFC) membrane by combining the separately fabricated polyamide (PA) selective layer with a tunable thickness and the highly porous support layer. The PA layer manufactured by SF-mLbL technique exhibited a thin and dense structure. The PAN support layer manufactured at a low concentration can alleviate the internal concentration polymerization (ICP) phenomenon through the porous support layer structure. The SF-mLbL (8 wt%) membrane prepared under these optimal conditions had higher water flow and selectivity (43.52±0.89 LMH/0.15±0.01 g L-1) than 7.41±0.18 (43.52±0.89 LMH/0.15±0.01 g L-1). ). LMH/0.81 ± 0.01 g L−1) IP-PA and commercial cellulose triacetate membranes were used with 0.5 M NaCl draw solution in FO mode. As a result, the SF-mLbL membrane showed significant improvement in the FO process through balanced permselectivity. In chapter 4, the novel support-free molecular layer-by-layer (SF-mLbL) technique using a microfiltration (MF)-grade support layer for minimum ICP was applied to produce a robust and uniform active layer, even on large pores of the support layer. Based on the location of graphene oxide (GO) nanoparticles, thin-film nanocomposite (TFN) and thin-film nanocomposite-interlayer (TFNi) membranes were fabricated. Among these, the TFNi membrane with the highest performance contained 0.7 wt% GO nanoparticles and was stacked in 15 cycles. The 0.7 wt%-15 cycles TFNi membrane showed high water flux (87.18 ± 0.15 LMH) and low reverse salt flux (5.06 ± 0.11 gMH) when deionized (DI) water and 0.5M NaCl solution were used as feed and draw solutions, respectively, in FO mode. This study demonstrates that the TFNi method is suitable for manufacturing high-performance FO membranes.

Correlation between membrane fouling and the ratio of particle to pattern size

장준희 서울대학교 대학원 2014 국내석사

Membrane fouling remains as one of the critical problems which drastically reduce filtration performance of membrane in water and wastewater treatment. Among various studies attempted to solve this problem, patterned membrane has proven the positive effects on membrane fouling. However, the ratio of particle size to pattern size in view point of fouling still remains unclear. In this study, we prepared new nano- and micro-scale patterned membranes and investigated the correlation between membrane fouling and the ratio of particle to pattern size. Through SEM and AFM imaging, it was confirmed that successful transfer of nano- and micro-scale features with size of 110 nm and 2 µm respectively was made onto the surface of PES UF membrane via hot-embossing NIL method. Although all the membranes have similar pore size, which is approximately 10 nm, regardless of existence of pattern or pattern size, patterned membrane showed 10 – 30 % higher water permeability than flat membrane due to increased effective surface area of patterned surface. Finally, the effect of particle to pattern ratio on membrane fouling in patterned membrane system was investigated through conducting ultrafiltration of various sized colloidal latex particles. The new parameter, the ratio of particle size to pattern size (Rp), was defined to accurately describe anti-fouling performance of patterned membrane. Also, the extent of membrane fouling was plotted against Rp value and it was found that the range of optimal Rp value was located around 5 when using particles with size from 0.1 to 6 µm. This range of optimal Rp value is expected to provide a useful guide line when selecting effective pattern size to remove specific sizes of foulants in future research or industrial application.

IER3IP1-Mediated ER-to-Golgi Trafficking Expands the Functional Landscape of the ER Membrane Complex

신예진 울산대학교 일반대학원 2026 국내박사

Membrane proteins are synthesized and targeted to the endoplasmic reticulum (ER), where their transmembrane domains (TMDs) are accurately inserted into the lipid bilayer. The proper folding and topology of membrane proteins are fundamental prerequisites for their functional maturation, and these processes are primarily governed by dedicated insertional machineries such as the translocon. Among these machineries, the ER membrane complex (EMC) has emerged as an insertase and molecular chaperone that primarily assists in the biogenesis of multi-pass membrane proteins. Although its contribution to membrane protein insertion is well established, the mechanisms by which EMC influences ER homeostasis and broader membrane trafficking processes remain to be elucidated. To explore how EMC contributes to the maintenance of ER function, we sought to identify its client proteins that might illuminate downstream physiological roles. Using TurboID-based proximity labeling combined with quantitative mass spectrometry, we identified immediate early response3 interacting protein1 (IER3IP1) as an ER protein whose expression was markedly reduced under EMC-deficient conditions. Insertion assays demonstrated that EMC promotes membrane integration of IER3IP1’s TMD, and that the characteristically low hydrophobicity of this domain determines its dependence on EMC for proper insertion. Given the previously reported role of IER3IP1 in modulating ER-to-Golgi trafficking, we further investigated its functional consequences using both fluorogenic and biochemical analyses through the Retention Using selective Hooks (RUSH) assay. Loss of IER3IP1 led to a pronounced delay in the Golgi transport of the secretory protein clusterin (CLU). Consistently, parallel defects in CLU trafficking were also observed in EMC-deficient cells, and this defect was rescued by re-expression of IER3IP1. Additionally, crosslinking experiments revealed the presence of a small membrane- associated protein within the ER that specifically binds to the N-terminal TMD of IER3IP1. Mutational disruption of this region abolished complex formation, and notably, the pathogenic A18V mutation within this TMD not only disrupted the specific interaction but also impaired ER-to-Golgi transport of CLU. Together, our findings demonstrate that IER3IP1 is inserted into the ER membrane via the EMC, forms a defined complex with a small membrane protein through its N-terminal TMD, and thereby modulates the kinetics of ER-to-Golgi trafficking. This work reveals a dual role for the EMC: first, to ensure the stable biogenesis of membrane proteins with marginally hydrophobic TMDs, and second, to maintain the fidelity of the secretory pathway through client-specific regulatory mechanisms. We propose that the EMC contributes to ER homeostasis by integrating its function in membrane protein biogenesis with the control of subsequent post-ER trafficking events. 막단백질은 소포체에서 합성되며, 지질 이중층 내로 막관통영역이 정확히 삽입되는 과정을 거친다. 막단백질의 올바른 위상과 접힘은 기능적 성숙을 위한 필수 조건이며, 이 과정은 주로 translocon과 같은 삽입 장치에 의해 조절된다. 특히, ER membrane complex (EMC)는 다중 막관통영역을 가진 막단백질의 생합성을 돕는 insertase이자 분자 샤페론으로서 중요한 역할을 한다. EMC가 막단백질 삽입에 미치는 기능은 잘 알려져 있으나, 소포체 항상성 유지 및 단백질 수송 과정에서의 역할은 아직 명확히 밝혀지지 않았다. 본 연구에서는 EMC가 소포체 기능 유지에 기여하는 새로운 생리적 메커니즘을 규명하기 위해, EMC에 의해 삽입되는 막단백질을 탐색하였다. TurboID 기반 근접 바이오틴화와 정량적 질량분석을 활용한 결과, EMC 결핍 조건에서 발현이 현저히 감소하는 막단백질로 immediate early response 3 interacting protein 1(IER3IP1)을 확인하였다. 추가적으로, IER3IP1의 막관통영역은 낮은 소수성을 특징으로 하며, EMC의 도움 없이는 정상적으로 삽입되지 않음을 실험적으로 입증하였다. IER3IP1이 소포체-골지체 단백질 수송에 관여한다는 선행 연구를 바탕으로, 형광 및 생화학적 분석을 포함한 RUSH(Retention Using Selective Hooks) 실험을 수행하였다. 그 결과, IER3IP1의 결핍은 분비단백질인 clusterin의 골지체 수송을 유의미하게 지연시켰으며, 이 현상은 EMC 결핍에서도 동일하게 관찰되었다. 또한, IER3IP1의 재발현을 통해 clusterin의 수송 속도가 회복됨을 확인하였다. 교차결합 실험을 통해 IER3IP1의 N-말단 막관통영역에 특이적으로 결합하는 소형 막단백질이 존재함을 밝혔으며, 해당 영역의 돌연변이가 복합체 형성과 소포체-골지체 수송 모두를 저해함을 확인하였습니다. 특히, 병원성 돌연변이인 A18V는 복합체 형성과 단백질 수송 모두에 결함을 유발하였다. 종합적으로, EMC는 IER3IP1의 막관통영역 삽입을 매개함으로써 안정적인 생합성을 보장하고, IER3IP1을 통해 소형 막단백질과 복합체를 형성함으로써 소포체-골지체 단백질 수송의 동역학을 조절하는 이중적 역할을 수행한다. 본 연구는 EMC가 소수성이 낮은 막관통영역을 가진 막단백질의 삽입뿐 아니라, 그 기질 단백질을 매개로 한 후속 단백질 수송 경로의 안정성 유지에도 기여함을 보여주며, EMC가 소포체 항상성 유지에 핵심적인 역할을 함을 제시한다.