How solute-membrane interaction influences foulant formation in polymeric catalytic membrane: Competitive and sequential reactions

Ian Keen Koo,Poh Teck Lim,Xiao Chen,K.B. Goh 한국공업화학회 2023 Journal of Industrial and Engineering Chemistry Vol.123 No.-

Foulant-induced deactivation usually limits polymeric catalytic membrane performance, but the mechanismsgoverning foulant formation remain poorly understood. Recent research suggests that the interactionbetween solutes and the membrane plays a crucial role in foulant formation. This paper proposes amolecular theory to explain how reactant/product-membrane interactions influence foulant formation. This theoretical approach allows us to untangle the coupled competitive/sequential reaction–non-idealdiffusion phenomena in deactivating polymeric catalytic membranes. In other words, we include thereactant and product molecular information when describing their non-ideal reaction–diffusion behaviorin confined polymeric environments; that is, they can interact (i) catalytically and (ii) non-catalyticallywith the membranes. We demonstrate how the non-catalytic reactant/product-membrane interactionscontrol the partitioning process between the membranes and bulk solutions, allowing us to capturethe formation of foulant locally and the global deactivation process. In our observations, we have foundthat attractive reactant-membrane interactions can enhance diffusion within the membrane, but this cancome at the cost of reduced catalytic activity. Conversely, with the repulsive pair interaction, the reactantsmust overcome a more significant energy barrier to penetrate the membranes, simultaneously limitingthe polymeric catalytic membrane performance and hindering foulant formation. In conclusion, ourtheory establishes a detailed understanding of reaction–diffusion phenomena governing foulant formationin polymeric catalytic membranes, considering the direct interaction between active reactants/productsand reactive membranes.

PES-TiO2 복합막의 제조 및 막 특성 평가

염경호,이미선 한국막학회 2007 멤브레인 Vol.17 No.3

침지침강 상변환법으로 폴리에테르설폰(PES)-TiO2 복합막을 제조하였다. 14 wt% 및 20 wt%의 PES/NMP 기준 고분자 용액에 TiO2 나노입자를 PES에 대해 0~60 wt%로 첨가량을 달리하여 복합막 제조에 사용될 캐스팅 용액을 준비하였다. 제조된 PES-TiO2 복합막의 막 특성과 몰폴로지를 TiO2 첨가량에 따른 캐스팅 용액의 점도, coagulation value, 광투과도와 복합막의 인장강도, 세공크기 및 접촉각, 표면 및 단면 SEM 사진, BSA 용액의 한외여과 실험을 통해 규명하였다. 캐스팅 용액에 첨가시킨 TiO2 입자의 함유량이 증가함에 따라 점도는 증가하고 coagulation value는 낮아져 캐스팅 용액의 열역학적 불안정성이 증가하였다. TiO2 입자의 첨가량이 증가함에 따라 1) 순간분리의 침강형식을 유지하면서 침강속도가 빨라졌으며, 2) 순수투과량, 세공크기 및 압밀화 안정성이 증가하며, 3) 인장강도와 접촉각은 감소하였다. PES-TiO2 복합막의 BSA 용액에 대한 전량여과식 한외여과 실험결과 TiO2 입자의 함유량이 증가함에 따라 막의 친수화 특성이 증가하여 투과플럭스가 증가하였으며, TiO2가 첨가되지 않은 막과 비교하여 최대 7배까지 투과 플럭스가 향상되었다. The polyethersulfone(PES)-titanium oxide(TiO2) hybrid membranes were prepared by immersion precipitation phase inversion method. The casting solution for the preparation of PES-TiO2 hybrid membrane was provided by adding TiO2 nano particles into the basis polymer solution of 14 wt% and 20 wt% PES/N-methyl-2-pyrrolidone(NMP). The TiO2 loading [wt% (TiO2/NMP)] in eating solution was varied from 0 to 60 wt%. Membrane performance and morphological change of the resulting PES-TiO2 hybrid membranes were discussed in aspect of TiO2 loading, by viscosity, coagulation value and light transmittance of the casting solution, measurement of tensile strength, pore size and contact angle, surface and cross sectional SEM images of the hybrid membrane, and ultrafiltration experiments using the hybrid membrane. According as increase of TiO2 loading in the casting solution, viscosity is increased and coagulation value becomes lower, therefore the thermodynamic instability of the casting solution is increased. It is found that when TiO2 loading is increased, 1) precipitation rate becomes faster while instantaneous demixing is maintained, 2) pure water flux, membrane pore size and compaction stability of the resulting membranes are increased, 3) tensile strength and contact angle are decreased. Dead-end ultrafiltration of bovine serum albumin(BSA) solution using the hybrid membrane shows that membrane performance(flux of BSA solution) enhanced up to 7 times compared with the results obtained using the pure PES membrane(not containing TiO2 particle), due to the increase of hydrophilicity.

Enhancement Effects of Cationic Contaminants from Bacteria on Cake Layer Formation and Biofouling on an RO Membrane

Shun Yamanouchi,Eri Nasuno,Masaki Ohno,Chigusa Okano,Ken-ichi Iimura,Tetsuji Okuda,Wataru Nishijima,Norihiro Kato 한국생물공학회 2017 Biotechnology and Bioprocess Engineering Vol.22 No.3

The model cationic molecule prodigiosin interacted with a polyamide/polysulfone composite reverse osmosis (RO) membrane, resulting in a reduction of the membrane permeation rate. Prodigiosin is an antibacterial agent produced by Serratia marcescens that is frequently isolated from activated sludge of domestic or industrial wastewater. Such molecules respectively secreted or leaked from live or dead cells are thought to affect membrane biofouling. In this study, a cell suspension containing prodigiosin-producing S. marcescens AS-1 wild-type or the non-producing AS-1ΔspnI strain was fed to the thin RO membrane to determine the occlusion ratio on the membrane. Cationic prodigiosin enhanced membrane biofouling by clogging the pores and enhanced the accumulation of the cake layer. The effects remarkably recovered the occlusion ratio after removing the cake layer by feeding with water. After temporary pressure relief, the occlusion ratios for AS-1 and AS-1ΔspnI were recovered to stable levels from approximately 70 to 49% and 23%, respectively. Zetapotential analysis supported the neutralization effects leading to the accumulation of bacterial cells under applied high pressure for RO membrane permeation.

스트렙토조토신 유도 당뇨백서의 골조직 재생에 흡수성 차폐막이 미치는 영향

양병근,이학철,이지영,손강배,설양조,이상철,계승범,정종평,한수부,Yang, Byung-Kun,Lee, Hak-Churl,Lee, Ji-Young,Son, Kang-Bae,Seol, Yang-Jo,Lee, Sang-Cheol,Kye, Seung-Beom,Chung, Chong-Pyoung,Han, Soo-Boo 대한치주과학회 2000 Journal of Periodontal & Implant Science Vol.30 No.2

The purpose of this study is to evaluate the effects of bioresorbable membranes in guided bone regeneration of streptozotocin induced diabetic rats. 50 Sprague-Dawley rats were randomly categorized into 4 groups: Group 1 & 2 had 10 normal rats each and group 3 & 4 included 15 streptozotocin induced diabetic rats each. Defect measuring 7mm in diameter was formed on every rat calvarium. No membrane was used in groups 1 & 3 and membranes were used in groups 2 & 4. The rates were sacrificed at 2 and 4 weeks after defect formation. Routine histological specimens were prepared. Masson-trichrome and HE stain were done before light microscopy. Guided regenerative potential was evaluated by measuring the amount of new bone formation in the calvarial defect by histomorphometry. Following results were obtained. 1. New bone formation in the diabetic groups was significantly less that than in the normal groups regardless of membrane use(p<0.05). 2. In the comparison of new bone formation in the normal groups, membrane group showed significantly more bone formation(p<0.1). 3. When the amount of new bone formation was compared in the diabetic groups, more bone was formed in the membrane groups but the difference was not statistically significant.4. In the normal groups the amount of new bone formation was significantly greater at 4 weeks compared to that at2 weeks(p<0.05) but amount of bone regeneration at 4 weeks was not significantly greater than that at 2 weeks in both diabetic groups.

Structurally ordered nanofiltration membranes prepared by spatially anchoring interfacial polymerization for highly efficient separation properties

Ao Sheng,Hao Wang,Haoji Jiang,Yaxin Zhao,Hao Li,Hao Jia,Zhong Wei,Heyun Wang 한국화학공학회 2021 Korean Journal of Chemical Engineering Vol.38 No.9

The incorporation of various nanofillers into the interfacial polymerization (IP) process is widely applied to prepare higher performance NF membranes. However, few studies have reported the influence of nanofillers on nanocomposite membrane formation in the IP process. Here, an optical microscope was employed to study the change rule in the 8-NH2-POSS/PSA nanocomposite membrane formation process due to the addition of 8-NH2-POSS nanoparticles. First, the addition of 8-NH2-POSS reduced the diffusion rate of the polyacrylamide hydrochloride (PAH) water phase on the surface against the oil phase because of the interaction with the PAH molecules. Furthermore, the 8-NH2- POSS/PSA nanocomposite membrane structure was more homogeneous and exhibited uniform pinhole defects distribution due to the interaction of the 8-NH2-POSS nanoparticles to the PAH segment. A significant separation performance was observed in the 8-NH2-POSS/PSA nanocomposite membrane due to the hydrophilicity and positive charge of the 8-NH2-POSS nanoparticles. The permeation flux and MgCl2 rejection of the 8-NH2-POSS/PSA nanocomposite membrane increased up to 50.5 L/m2 h at 0.5MPa and 94.8%, respectively, which corresponded to increases of 73.5% and 8.7% as compared to the pristine PSA membrane. 8-NH2-POSS/PSA nanocomposite membranes have great application potential in the water softening and treatment of divalent metals ions under acidic conditions.

무기인산염이 외방성 수직골 형성에 미치는 영향

이진,박준봉,허익,정종혁,권영혁,Lee, Jean,Park, Joon-Bong,Herr, Yeek,Chung, Jong-Hyuk,Kwon, Young-Hyuk 대한치주과학회 2008 Journal of Periodontal & Implant Science Vol.38 No.1

Purpose: It has been shown that the inorganic polyphosphate is effective for the regeneration of bones through the preliminary animal test of rabbits. The most effective concentration of the polyphosphate, however, is not known yet. Moreover, the effectiveness of carriers inside human body is not confirmed.. Materials and Methods: In this study, we examined the effect of the concentration of the inorganic polyphosphate on the process of the bone regeneration using the 6 weeks old rabbits with the weight of 2.0 kg in average. We performed the experiment using TR-ePTFE membrane(membrane) filled with collagen immersed in 4%, 8% of inorganic polyphosphate, respectively, following removal of the proper sized cortical bones from the rabbit calvaria. The experimental results were compared with the one of the following four groups: The negative control group for membrane only, the positive control group for membrane filled with collagen, the first experimental group for membrane filled with collagen immersed in 4% of inorganic polyphosphate, and the second experimental group for membrane filled with collagen immerse in 8% of inorganic polyphosphate. The fragments of the tissue with membrane obtained from each group of the sacrificed rabbits for 8 or 16 weeks sustained after surgery were then prestained by the Hematoxylin-Eosin stain and coated by resin to form non-decalcified specimens for the histologic examination and analysis. New bone formation was assessed by histomorphometric and statistical analysis. Results: 1. All groups have shown better bone regeneration at 16weeks than 8weeks. 2. Negative control group has shown more bone regeneration relative to the other groups at 8 and 16 weeks. 3. All experimental groups have shown better bone regeneration relative to positive control group. 4. At 16 weeks, the first experimental group has shown more bone regeneration compared to the second experimental group. Exophytic bone formation is not good at the first and the second experimental groups compared with negative control group. But, the use of 4% inorganic polyphosphate was more effective to bone formation than the use of 8% inorganic polyphosphate. Conclusion: With above results, it is suggested the use of inorganic polyphosphate with vehicle under TR-ePTFE membrane.

고분자 변형으로 가능해진 MOF의 원위치 형성을 이용한 혼합기질 기체분리막의 대면적화 가능한 제막

박성환 ( Sunghwan Park ),이영세 ( Young-sei Lee ) 한국공업화학회 2023 공업화학 Vol.34 No.3

혼합기질막(mixed-matrix membrane, MMM)은 고성능 충전제가 고분자 기질에 분산된 구조로, 지난 30년간 이를 이용한 기체분리 연구가 집중적으로 수행되었다. 일반적으로 MMM은 고분자 막보다 우수한 기체 분리 성능을 가지고 있으며, 다결정 막에 비해 좋은 확장성을 보인다. 그러나 이러한 잠재성에도 불구하고, MMM의 상용화는 여러 가지 어려운 문제들로 인해 지연되고 있다. MMM의 주요 문제 중 하나는 충전제와 고분자 사이의 부적절한 계면 상호작용으로 결함(즉, 개면 공극 등)이 형성될 수 있다는 것이다. 따라서 많은 MMM 연구에서 이러한 계면의 문제를 해결하기 위한 전략이 제시되었다. 하지만 계면상의 상호작용으로 MMM이 가진 문제점들을 해결하려는 과학적 접근에 비해 손쉽고 효과적으로 대면적의 MMM을 제조하기 위한 공학적 접근은 상대적으로 간과되어 왔다. 본 총설에서는 MMM의 대면적화를 위한 공학적인 접근 중 하나인 고분자 변형을 통해 가능해진 금속-유기 골격체(metal-organic framework, MOF)의 원위치 형성을 이용한 MMM 제막 방법을 소개하고자 한다. 이 새로운 제막법은 현재 MMM이 직면하고 있는 문제들을 공학적인 접근으로 효과적으로 해결하여 MMM의 상용화를 촉진시킬 수 있다. Mixed-matrix membranes (MMMs), which are composed of a polymer matrix filled with high-performance fillers as a dispersed phase, have been intensively studied for gas separations for the past 30 years. It has been demonstrated that MMMs exhibit superior gas separation performance compared to polymer membranes and are more scalable than polycrystalline membranes. Despite their potential, the commercialization of MMMs has yet to be reported due to several challenging issues. One of the major challenges of MMMs is the non-ideal interface between the continuous polymer phase and dispersed phase, which can result in defect formation (i.e., interfacial voids, etc.). With respect, many MMM studies have focused on addressing the issues through scientific approaches. The engineering approaches for facile and effective large-scale fabrication of MMMs, however, have been relatively underestimated. In this review paper, a novel strategy for fabricating MMMs in a facile and scalable manner using in situ metal-organic framework (MOF) formation is introduced. This new MMM fabrication methodology can effectively address the issues facing current MMMs, likely facilitating the commercialization of MMMs.

Effects of alginate immobilization on dynamic membrane formation and H₂ fermentation from galactose

Park, Jong–,Hun,Sim, Young–,Bo,Kim, Jun Seok,Kim, Sang–,Hyoun Elsevier 2020 International journal of hydrogen energy Vol.45 No.10

<P><B>Abstract</B></P> <P>A dynamic membrane (DM) is a biofilm that forms on a support material, acting as a filter to retain high-density biomass. This study aims to explain the effects of alginate immobilization on DM formation during dark-H<SUB>2</SUB> fermentation. Galactose is used as a model substrate. Heat-treated anaerobic sludge, with and without immobilization, is used for an inoculum for two identical lab-scale DM bioreactors (DMBR). The DMBRs are continuously operated for more than 40 days by changing the hydraulic retention time (HRT) from 12 to 3 h. Biomass retention and H<SUB>2</SUB> production performance are significantly improved at an HRT of 3 h with immobilization. The alginate-added bioreactor shows higher extracellular polymeric substance content both in the mixed liquor and the DM. At an HRT of 3 h with immobilization, the fraction of <I>Sporolactobacillus</I> spp. and <I>Lactobacillus</I> spp. increases, possibly contributing to DM formation. However, lactic-acid concentration does not increase, implying it can be further consumed by the dominant bacteria, <I>Clostridium butyricum</I>.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Dynamic membrane (DM) was established in H<SUB>2</SUB> production from galactose. </LI> <LI> Inoculation with alginate facilitated DM formation and H<SUB>2</SUB> production. </LI> <LI> <I>Sporolactobacillus</I> and <I>Lactobacillus</I> increased along with the DM formation. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

분리막 혐기성 반응조를 이용한 하수슬러지로부터의 VFA 생성과 수소생성 가능성 평가

차기철 ( Cha Gi Cheol ),정태영 ( Jeong Tae Yeong ),정형근 ( Jeong Hyeong Geun ) 한국물환경학회 2003 한국물환경학회지 Vol.19 No.6

Characteristics for hydrogen and VFA production (volatile fatty acid) from waste activated sludge was investigated using two stage reactor (acid formation reactor; first stage, photosynthetic reactor; second stage). The acid reactor used Submerged and external separation membrane. The photosynthetic reactor connected with the acid reactor. The COD removal rate in acid formation reactor with submerged and external separation membrane showed about 55% and 75%, respectively. The total VFA produced more in acid reactor with external separation membrane than in acid reactor with submerged separation membrane. The influent COD removal rate per total VFA production rate showed about 11% and 18%, respectively. Hydrogen gas production was not showed in acid reactor but showed in photosynthetic reactor. The hydrogen production per T-VFA in photosynthetic reactor connected with submerged and external separation membrane acid reactor showed about 50.1 ㎖ H₂/g T-VFA and 160.5 ㎖ H₂/g T-VFA, respectively. The Y value in steady state condition of photosynthetic reactor connected with submerged and external separation membrane acid reactor showed about 0.0028 ㎎-biomass ㎎-substrate- and 0.0004㎎-biomass . ㎎-substrate-` , respectively.

Novel Preparation and Characterization of the α4-loop-α5 Membrane-perturbing Peptide from the Bacillus thuringiensis Cry4Ba δ-endotoxin

Leetachewa, Somphob,Katzenmeier, Gerd,Angsuthanasombat, Chanan Korean Society for Biochemistry and Molecular Biol 2006 Journal of biochemistry and molecular biology Vol.39 No.3

Helices 4 and 5 of the Bacillus thuringiensis Cry4Ba $\delta$-endotoxin have been shown to be important determinants for mosquito-larvicidal activity, likely being involved in membrane-pore formation. In this study, the Cry4Ba mutant protein containing an additional engineered tryptic cleavage site was used to produce the $\alpha4$-$\alpha5$ hairpin peptide by an efficient alternative strategy. Upon solubilization of toxin inclusions expressed in Escherichia coli and subsequent digestion with trypsin, the 130-kDa mutant protoxin was processed to protease-resistant fragments of ca. 47, 10 and 7 kDa. The 7-kDa fragment was identified as the $\alpha4$-loop-$\alpha5$ hairpin via N-terminal sequencing and mass spectrometry, and was successfully purified by size-exclusion FPLC and reversed-phase HPLC. Using circular dichroism spectroscopy, the 7-kDa peptide was found to exist predominantly as an $\alpha$-helical structure. Membrane perturbation studies by using fluorimetric calcein-release assays revealed that the 7-kDa helical hairpin is highly active against unilamellar liposomes compared with the 65-kDa activated full-length toxin. These results directly support the role of the $\alpha4$-loop-$\alpha5$ hairpin in membrane perturbation and pore formation of the full-length Cry4Ba toxin.