Direct molecular interaction of CO2 with KTFSI dissolved in Pebax 2533 and their use in facilitated CO2 transport membranes J. Membr. Sci. (IF 6.035) Pub Date : 2017-11-20 Sungjin Lee, Seul Chan Park, Tea-Yon Kim, Sang Wook Kang, Yong Soo Kang
Polymer electrolyte membrane containing potassium bis(trifluoromethanesulfonyl)imide (KTFSI) dissolved in a polymeric solvent of Pebax 2533 demonstrated facilitated transport for effective CO2 separation. Reversible interactions of CO2 with both K+ and TFSI- dissolved in Pebax 2533 were directly observed by both solid state 39K and 13C NMR and FT-IR spectroscopy for the first time, inducing the CO2 carrier activity for the facilitated transport. Additionally, through comparing the CO2 separation performance of LiTF2N, NaTF2N and KTF2N, it was concluded that alkali cation has play an important role in helping to interact with CO2 for the CO2 carrier activity and that K+ was the best as a CO2 carrier among alkali metals used. Consequently, the KTFSI/Pebax 2533 polymer electrolyte membrane showed significant improvement of the CO2 separation performance due to the carrier action of both K+ and TFSI- in the solid state with long-term stability.
Module scale-up and performance evaluation of thin film composite hollow fiber membranes for pressure retarded osmosis J. Membr. Sci. (IF 6.035) Pub Date : 2017-11-20 Yunfeng Chen, Chun Heng Loh, Lizhi Zhang, Laurentia Setiawan, Qianhong She, Wangxi Fang, Xiao Hu, Rong Wang
Pressure retarded osmosis (PRO) demonstrates great potential in energy harvesting when combining with seawater reverse osmosis. However, the lack of suitable membrane modules and the issue caused by the membrane fouling greatly impede the practical application of PRO to a larger scale. In this study, two-inch thin film composite hollow fiber modules were fabricated by using in-house developed PRO membranes. The produced PRO modules have a maximum effective area of 0.5 m2. By assessing the PRO performances of the modules with different sizes, external concentration polarization (ECP) was found to have significant impact on the flux reduction during module scale-up. Different module designs, including fiber bundles, distribution baffles and distribution tubes, were thus adopted as an attempt to boost the membrane performance. A power density of 8.9 W/m2 at 15 bar was obtained using tap water as feed and 1 M NaCl solution as draw solution. PRO performance tests were also carried out using the developed two-inch modules on a pilot-scale setup with actual wastewater retentate as feed solution. Low pressure nanofiltration was selected as the pretreatment of the wastewater retentate to mitigate fouling. A power density of larger than 8 W/m2 was obtained when pretreated wastewater retentate was used as the feed solution, implying high potential of PRO in the pilot scale. Nevertheless, full potential of PRO can only be realized by mitigating ECP, which could be achieved by improving the module design in the further endeavor.
Numerical simulation of kinetic demixing and decomposition in a LaCoO3-δ oxygen membrane under an oxygen potential gradient J. Membr. Sci. (IF 6.035) Pub Date : 2017-11-16 Na Ta, Ming Chen, Lijun Zhang, Christodoulos Chatzichristodoulou, Weimin Chen, Peter Vang Hendriksen, Yong Du
A composition- and temperature-dependent mobility database of all ionic species in the LaCoO3-δ phase was developed and combined with a La-Co-O thermodynamic database to simulate kinetic demixing and partial decomposition in LaCoO3-δ oxygen membranes operated under a 0.0001/0.21 bar oxygen partial pressure difference at 1073 K for 1 year. Formation of La2O3, Co3O4 and CoO phases across the membrane is predicted. The kinetic demixing process can be divided into two stages, namely, establishment of the oxygen potential gradient (fast) and demixing of the cations (slow); the former is controlled by the mobility of oxygen ions, and the latter is determined by the higher mobility of Co ions as compared to the La ion in the ABO3-type perovskite. A drift motion of both oxide surfaces towards the high PO2 side occurs with the movement of cations.
Does pre-ozonation or in-situ ozonation really mitigate the protein-based ceramic membrane fouling in the integrated process of ozonation coupled with ceramic membrane filtration? J. Membr. Sci. (IF 6.035) Pub Date : 2017-11-15 Jia Song, Zhenghua Zhang, Shengyin Tang, Yu Tan, Xihui Zhang
The integrated process of ozonation coupled with ceramic membrane filtration has been actively utilized to alleviate membrane fouling in water/wastewater treatment, however, the effect of ozonation on protein-based ceramic membrane fouling is still contradictory. Herein, for the first time, we reported the severe protein-based ceramic membrane fouling at high ozone dosage in the integrated process of ozonation coupled with ceramic membrane filtration and the related fouling mechanism was systematically explored. Ozonation at low dosage slightly mitigated membrane fouling, whereas severe membrane fouling occurred at high ozone dosage (10 mg/L for pre-ozonation; 4 and 10 mg/L for in-situ ozonation). At high ozone dosage, the trans-membrane pressure (TMP) remarkably increased (> 40 kPa) within 90 min and both hydraulically reversible and irreversible fouling contributed to the total membrane fouling resistance. Electro kinetic potential and particle size of the bovine serum albumin (BSA) solution were not the key factors affecting the aggravated membrane fouling at high ozone dosage. The remarkably deteriorated membrane fouling at high ozone dosage can be accounted for the formation of BSA crosslinks ascribed to the oligomerization and agglomeration of BSA and the intermolecular disulfide bridge formation with the crosslinks progressively accumulating on the membrane surface and in the membrane pores during filtration. The modeling results confirmed that the BSA-based membrane fouling mechanism was changed from cake-intermediate to cake-standard with ozonation at high ozone dosage. Meanwhile, the cake layer and/or gel layer played a more important role for the aggravated membrane fouling at high ozone dosage even though the contribution of pore blocking was also significant.
A multifunctional separator modified with cobalt and nitrogen co-doped porous carbon nanofibers for Li–S batteries J. Membr. Sci. (IF 6.035) Pub Date : 2017-11-15 Guoping Chen, Xiong Song, Suqing Wang, Ying Wang, Tuo Gao, Liang-Xin Ding, Haihui Wang
Lithium–sulfur (Li–S) battery is considered as one of the most promising advanced energy storage devices. However, several critical issues remain which restrict their practical applications, especially the shuttle effect of soluble lithium polysulfides. Herein, we designed a lightweight multifunctional layer comprising reduced graphene oxide (rGO) and cobalt/nitrogen co-doped carbon nanofibers (Co-N-C) to modified the polypropylene (PP) separator to facilitate the electrochemical performance of Li–S batteries. The Co-N-C/rGO layer with abundant mesopores possesses strong immobilization ability of polysulfides and high electronic conductivity, which could work as an intrinsic physical/chemical frame work barrier and an upper current collector to trap and reutilize the polysulfides. Consequently, the Li–S battery with the modified Co-N-C/rGO/PP separator exhibits excellent cycling performance and good rate capability. A high discharge capacity of 1344 mAh g–1 at 0.1 C, 658 mAh g–1 at 5 C and a low capacity degradation rate of 28.8% after 500 cycles at 0.5 C were obtained. These exciting results indicate that this multifunctional Co-N-C/rGO/PP separator could be a promising separator candidate for Li–S batteries.
Removal of PhACs and their impacts on membrane fouling in NF/RO membrane filtration of various matrices J. Membr. Sci. (IF 6.035) Pub Date : 2017-11-14 Chen Li, Yu Yang, Ye Liu, Li-an Hou
The removal of pharmaceutically active compounds (PhACs) by fouled nanofiltration (NF) and reverse osmosis (RO) membranes has been extensively studied. Investigations on the effects of PhACs on organic fouling or biofouling in the NF/RO membrane application are still lacking. In this study, NF/RO membranes were fed with both synthetic (SRNOM solution and synthetic wastewater containing pure culture inoculum) and real (secondary effluent) water matrices spiked with three PhACs to elucidate the impact of PhACs on membrane fouling in comparison with control experiments in the absence of PhACs. Results showed that the PhACs mitigated flux decline during NF/RO filtration of SRNOM solution. The total organic foulants on both membrane surfaces decreased in the presence of PhACs due to the increased negative charges of the membranes and the enhanced size and charge effects of PhAC–macromolecule complexes in SRNOM solution. PhACs appeared to inhibit cell growth in the early stages of biofouling, causing a decline in total biomass, and then induced cell lysis, releasing EPS to protect from chemical stress in the later stages of biofouling, especially protein-like materials, causing more severe biofouling. The alleviation of declines in flux and salt rejection during the filtration of secondary effluent were found in the presence of PhACs. Therefore, we hypothesized that organic fouling or early-stage biofouling occurred during 100 h of filtration of secondary effluent. The decrease in PhAC retention was more obvious due to the higher ionic strength in the secondary effluent. This study may aid understanding of PhAC removal from various matrices and the effects of PhAC mixtures on membrane fouling by in practical NF/RO membranes applications.
Development of polymer-polymer type charge-transfer blend membranes for fuel cell application J. Membr. Sci. (IF 6.035) Pub Date : 2017-11-14 Shiyan Feng, Shoichi Kondo, Takahiro Kaseyama, Taichi Nakazawa, Takamasa Kikuchi, Roman Selyanchyn, Shigenori Fujikawa, Liana Christiani, Kazunari Sasaki, Masamichi Nishihara
We have prepared new charge-transfer (CT) complex polymer blend membranes (CT membranes), for use as high performance polymer electrolyte membranes (PEMs); with a simple and easy preparation method for application in PEFCs. In this study, electron-accepting sulfonated polyimide (SPI) and electron-donating polyether (PE), were used to develop polymer-polymer type CT membranes. The formation of CT complex in the obtained SPI/PE membranes was confirmed by visible spectroscopy. The use of flexible spacers in the PE and heat treatment of the CT membranes, enhanced the CT complex formation. SPI/PE CT membranes showed 1.9–2.2 times higher mechanical strength than the original SPI, while SPI/PE 0.33 CT membrane with heat treatment at 130 °C for 2 hours showed 4.3 times higher mechanical strength than the original SPI. Hydrogen permeability through SPI/PE CT membranes was 4.1–5.4 times lower than Nafion 212 and 1.4–1.9 times lower than the original SPI membrane. We have prepared a thin SPI/PE CT membrane (10 μm thickness), that showed comparable OCV (0.88 V), similar resistance compared to Nafion 212 and demonstrated more than 10 hours of durability in a fuel cell test; suggesting that SPI/PE thin CT membrane can be applied for PEFC application.
Ultrafiltration based on various polymeric membranes for recovery of spent tungsten slurry for reuse in chemical mechanical polishing process J. Membr. Sci. (IF 6.035) Pub Date : 2017-11-14 Nur Fatin Amalina Muhammad Sanusi, Mohd Hizami Mohd Yusoff, Ooi Boon Seng, Mohd Sabirin Marzuki, Ahmad Zuhairi Abdullah
Membrane separation based on ultrafiltration for the recovery of spent tungsten slurry from chemical mechanical polishing (CMP) process has been investigated. Five polymeric membranes with different molecular weight cut-off (MWCO) i.e. 10 kDa PES, 30 kDa PES, 100 kDa PES, 50 kDa PS and 50 kDa PVDF were successfully applied. Flux analysis was conducted to study the fouling phenomena and the fouling effects on membrane surface were elucidated by means of SEM and AFM analyses. Almost steady fluxes were reached after about 60 min of filtration process. Meanwhile, the membrane fouling was mainly due to the formation of cake layer on the membrane surface leading to blockage of membrane pores. On top of that, 50 kDa PS membrane showed the highest potential in filtrating and concentrating the CMP spent tungsten slurry with 92% retention of silica particles and 42% retention of tungsten. Furthermore, it also achieved the lowest mean size particle of 126 nm in the retentate which were significantly different from that of the original spent tungsten slurry.
Effect of Temperature Gradients in (Reverse) Electrodialysis in the Ohmic Regime J. Membr. Sci. (IF 6.035) Pub Date : 2017-11-13 Anne M. Benneker, Timon Rijnaarts, Rob G.H. Lammertink, Jeffery A. Wood
Electrodialysis (ED) and reverse electrodialysis (RED) are processes for the production of desalinated water (ED) and power (RED). Temperature of the feed streams can strongly influence the performance of both processes. In this research, commercial membranes are used for the investigation of temperature and temperature gradients on ED and RED processes. We find that the energy required for ED processes can be reduced by 9% if the temperature of one of the feed streams is increased by 20 °C, while maintaining the charge-selectivity of the membranes. The direction of the temperature gradient did not have a significant influence on the efficiency and selectivity of ED in the Ohmic regime. In RED, we find an increase in obtained gross power density over 25% for the process when one feed stream is heated to 40 °C instead of 20 °C. This work experimentally demonstrates that utilization of low-grade waste heat from industrial processes can yield significant reduction of energy costs in ED processes, or result in higher power densities for RED systems where the increase in temperature of a single feed stream already yields significant efficiency improvements.
Submerged or sidestream? The influence of module configuration on fouling and salinity in osmotic membrane bioreactors J. Membr. Sci. (IF 6.035) Pub Date : 2017-11-13 Christopher P. Morrow, Allyson L. McGaughey, Sage R. Hiibel, Amy E. Childress
The role of submerged and sidestream forward osmosis (FO) membrane module configuration in osmotic membrane bioreactors (OMBRs) was investigated. Experiments were performed under identical (solids retention time, bioreactor volume, feed solution, draw solute, and draw solution concentration) conditions to isolate the effect of FO module configuration and associated hydrodynamics on water flux, reverse salt flux, and membrane fouling. Steady-state water flux of fouled membranes was the same for submerged and sidestream configurations and two draw solution concentrations, leading to the concept of a homeostatic flux in OMBRs similar to the critical flux in conventional membrane bioreactors. Despite a significant increase in driving force, fouled membranes did not have higher steady-state water flux; instead, the higher draw solution concentration resulted in higher specific reverse salt flux (SRSF) and increased fouling. For the 35 g/L NaCl draw solution, SRSF was 1.61 ± 0.01 and 0.59 ± 0.07 g L−1 for submerged and sidestream configurations, respectively and for the 100 g/L NaCl draw solution, SRSF was 2.22 ± 0.25 and 1.05 ± 0.35 g L−1 for submerged and sidestream configurations, respectively. With 100 g/L draw solution, foulant cake layers were 2–4 times thicker, likely due to higher initial water flux that resulted in more foulants being transported to the membrane surface. Experimental results were used as model inputs to predict results for a larger scale system. Model results predicted lower steady-state bioreactor salinities in the sidestream configuration, particularly when longer solids retention times were used.
Magnetic field induced orderly arrangement of Fe3O4/GO composite particles for preparation of Fe3O4/GO/PVDF membrane J. Membr. Sci. (IF 6.035) Pub Date : 2017-11-13 Yan Huang, Chang-fa Xiao, Qing-lin Huang, Hai-liang Liu, Jun-qiang Hao, Liang Song
Magnetic Fe3O4/graphene oxide (GO) composite particles with excellent properties of magnetic susceptibility and hydrophilicity were synthesized by a facile one-step chemical coprecipitation method. Then the prepared magnetic Fe3O4/graphene oxide (MGO) particles were introduced to polyvinylidene fluoride (PVDF) casting solution to fabricated PVDF/MGO hybrid membrane under the magnetic field. The directional migration and ordered arrangement of MGO sheets in magnetic field were investigated. The preparation of multilayer composite membrane was in the form of functional layer and support substrate in series, in which the functional layer with MGO orderly embedded into the membrane surface was prepared via magnetic field induced MGO sheets to the membrane surface during the phase inversion process. There was obvious effects of this novel structure on the pure water flux, hydrophilicity and antifouling properties of the membranes. The PVDF/MGO membranes showed high pure water flux (484 L·m−2·h−1) and high flux recovery ratio (up to 83.0%).
Slug Bubbling in Flat Sheet MBRs: Hydrodynamic Optimization of Membrane Design Variables through Computational and Experimental Studies J. Membr. Sci. (IF 6.035) Pub Date : 2017-11-11 Bing Wang, Kaisong Zhang, Robert W. Field
Slug bubbling in flat sheet MBRs (FSMBR) is of interest in water treatment industry to effectively control fouling. In this work, a novel bubbling method is introduced to produce slug bubbles into all channels between every pair of membranes for a large-scale 100-sheets commercial FSMBR. Below the membrane plates, coalescent bubbles formed and these developed into large-sized bubbles, which eventually distributed between channels as a set of slug bubbles. Computational Fluid Dynamics (CFD) was used to predict the bubble size and distribution among different channels, and associated hydrodynamic features. Substantial agreement was observed with the experiment results. The configuration of membrane plate centrally located above the aeration nozzles was determined to have superior hydrodynamic performance of high shear stress on the membrane surfaces. The effect of membrane plate and channel dimensions were studied to identify the optimized design for hydrodynamics enhancement on fouling control. The combination of membrane thickness at 5 mm and channel gap at 6 mm was verified to be the optimal configuration, which would give uniform distribution of slug bubbles and provide high shear stress in the channels. The optimized air flow rate was successfully reduced to 4.7 L/min•m2, which corresponds to a 53% reduction compared with traditional usage (10 L/min•m2) in industry.
Selective-exhaust gas recirculation for CO2 capture using membrane technology J. Membr. Sci. (IF 6.035) Pub Date : 2017-11-10 Giuseppe Russo, George Prpich, Edward J. Anthony, Fabio Montagnaro, Neila Jurado, Giuseppina Di Lorenzo, Hamidreza G. Darabkhani
Membranes can potentially offer low-cost CO2 capture from post-combustion flue gas. However, the low partial pressure of CO2 in flue gases can inhibit their effectiveness unless methods are employed to increase their partial pressure. Selective-Exhaust Gas Recirculation (S-EGR) has recently received considerable attention. In this study, the performance of a dense polydimethylsiloxane (PDMS) membrane for the separation of CO2/N2 binary model mixtures for S-EGR application was investigated using a bench-scale experimental rig. Measurements at different pressures, at different feeding concentrations and with nitrogen as sweep gas revealed an average carbon dioxide permeability of 2943 ± 4.1%RSD Barrer. The bench-scale membrane module showed high potential to separate binary mixtures of N2 and CO2 containing 5–20% CO2. The permeability was slightly affected by feed pressures ranging from 1 to 2.4 bar. Furthermore, the separation selectivity for a CO2/N2 mixture of 10%/90% (by volume) reached a maximum of 10.55 at 1.8 bar. Based on the results from the bench-scale experiments, a pilot-scale PDMS membrane module was tested for the first time using a real flue gas mixture taken from the combustion of natural gas. Results from the pilot-scale experiments confirmed the potential of the PDMS membrane system to be used in an S-EGR configuration for capture of CO2.
Microporous polypropylene membrane prepared via TIPS using environment-friendly binary diluents and its VMD performance J. Membr. Sci. (IF 6.035) Pub Date : 2017-11-10 Yu-Jie Wang, Zhi-Ping Zhao, Zhen-Yu Xi, Su-Ying Yan
Growing attention given to non-toxic solvents for membrane preparation has been the motivation for membrane scientists to develop future generation membranes due to increasing concerns for environmental impacts and strict rules. In this study, a novel preparation approach for polypropylene (PP) membranes via TIPS using non-toxic binary diluents consisting of carnauba wax as latent solvent and soybean oil as good solvent was developed successfully. Water and ethanol were used as a quenching bath and extractant of diluents in the membrane, respectively. Impacts of both polymer weight fraction and carnauba wax weight fraction on the phase diagram (phase separation behaviors) of the PP/binary diluents system were investigated firstly. The liquid-liquid (L-L) phase separation region can be enlarged with the continuously increasing of carnauba wax. The effect of adding the second latent diluent on the structures and properties of PP membranes was also studied. The morphology of membranes was further controlled by adjusting the composition of binary diluents. The inter-connected spongelike structure was achieved successfully, which greatly increased the membrane elongation at break. Moreover, vacuum membrane distillation (VMD) desalination experiments showed that the PP membranes produced have the potentiality in VMD desalination application. The carnauba wax after extraction by boiling ethanol could be easily crystallized, separated and recycled by cooling.
Sterile filtration of oncolytic viruses: an analysis of effects of membrane morphology on fouling and product recovery J. Membr. Sci. (IF 6.035) Pub Date : 2017-11-10 Shabnam Shoaebargh, Ian Gough, Maria Fe Medina, Adam Smith, Joris van der Heijden, Brian Lichty, John Bell, David R. Latulippe
Oncolytic viruses (OVs) are an emerging class of bio-therapeutics that have attracted significant interest due to their inherent specificity for targeting malignant tissues in cancer immunotherapy. One of the main challenges in many OVs manufacturing processes is the dead-end sterile filtration step that is highly desirable from a safety and regulatory perspective. The primary issue is the severe membrane fouling, as indicated by a dramatic and uncontrollable transmembrane pressure (TMP) increase in constant flux experiments, and low recovery of the desired final product. While previous studies have mostly focused on selective retention or removal of viruses during the production of smaller biologics, this study is the first to obtain quantitative data for the fouling propensity of microfiltration filters and recovery of viral vectors in a sterile filtration process. The performance of four 0.2/0.22 μm commercial sterile filters was evaluated in constant flux filtration tests with a promising OV candidate (Rhabdovirus Maraba). Among the tested sterile filters, two-layered sterile filters (i.e. Fluorodyne EX EDF and MiniSart Plus) indicated slower transmembrane pressure (TMP) increase along with a higher filtered viral volume. For all four filters, the total viral recovery was quite low (less than 25%) – this significant amount of loss of a valuable therapeutic product is of particular concern. These results provide important insights into the development of new sterile filtration membranes and processes that are critically needed for the large-scale production of OVs.
Effect of humidity and nanocellulose content on Polyvinylamine-nanocellulose hybrid membranes for CO2 capture J. Membr. Sci. (IF 6.035) Pub Date : 2017-11-10 Davide Venturi, Deana Grupkovic, Marco Giacinti Baschetti, Laura Sisti
In order to address the need for more efficient technologies for carbon capture applications, a novel type of nanocellulose based hybrid membrane has been successfully prepared by blending the commercial Polyvinylamine solution Lupamin® 9095 (BASF) with Nano Fibrillated Cellulose (NFC) to improve its mechanical and separation capabilities. Self-standing films with different nanocellulose loading (from 30 to 70 wt%) have been prepared and characterized at 35 °C through water vapor sorption experiments and humid gas permeation tests.As expected, membrane permeability consistently increased with increasing water vapor and a higher presence of Lupamin in the film resulted in an increment of both gas permeability and selectivity. In particular blends with a NFC content of 70 wt% Lupamin reached an ideal selectivity of 135 for the separation of CO2/CH4 and 218 for CO2/N2, at 60 RH%, while the maximum permeability in the order of 187 Barrer was instead reached at 80% RH.Water vapor solubility was also measured and modeled through Park Model to correlate the gas separation properties with the effective content of water present in the membrane matrix. As expected, a higher content of the hydrophilic polymer resulted in a larger water uptake, which at medium to high humidity appeared to trigger a water clustering phenomenon in the matrix. This fact was accompanied by a substantial relaxation of the polymer network, causing a marked reduction of selectivity, which dropped, at the highest RH investigated, to values in the order of 30 and 80 towards CH4 and N2 respectively. Despite this loss in performance, most materials tested still showed very interesting properties, well above Robeson's 2008 Upper Bound, making them an interesting alternative for traditional gas separation processes.
Dissipative particle dynamics simulation on the membrane formation of polymer–solvent system via nonsolvent induced phase separation J. Membr. Sci. (IF 6.035) Pub Date : 2017-11-08 Han-han Lin, Yuan-hui Tang, Hideto Matsuyama, Xiao-lin Wang
A new dissipative particle dynamics (DPD) simulation methodology adopting a mass transfer algorithm was established to investigate the membrane formation process via nonsolvent induced phase separation (NIPS). The effect of the interphase mass transfer between the casting solution and the nonsolvent bath on the membrane formation process and the membrane morphology was elaborately analyzed. Factors including the solvent–nonsolvent interaction, the polymer concentration and the nonsolvent temperature were considered. The results showed that as the solvent-nonsolvent interaction got better, the mass transfer was intensified which contributed to an intense phase separation. Thereby asymmetric membrane structure with a thick dense surface layer and a porous sub-layer would be formed. With the nonsolvent temperature raising, the relatively symmetric structure with small pores was obtained due to the declined polymer aggregation rate and the increased phase separation rate caused by the accelerated mass transfer. As the polymer concentration increased, the flexibility of the system reduced. Thereby the phase separation slowed down, resulting in highly asymmetric structure with a thicker and denser surface layer and a more porous sub-layer. The analysis of the phase separation in this study benefits to a better understanding on the mechanism of the membrane structure via NIPS.
Porous membranes prepared by a combined crystallisation and diffusion (CCD) method: study on formation mechanisms J. Membr. Sci. (IF 6.035) Pub Date : 2017-11-08 Bo Wang, Jing Ji, Congcong Chen, K. Li
Currently, porous polymeric membranes are mainly produced by the NIPS and TIPS techniques, but both have intrinsic technical limitations in terms of effective control of membrane structures. Recently, a novel Combined solvent Crystallisation and polymer Diffusion (CCD) method has been established to produce high-performance membranes with a unique asymmetric structure, where solvent nucleation and crystallisation in a binary polymer-solvent system are utilised to serve as the pore-forming mechanism. However, the membrane formation mechanism of the CCD method has yet been understood fully. In this work, the formation mechanism is proposed based on the widely acknowledged principles of nucleation and crystal growth. A typical and commonly used amorphous polymer, polyethersulfone (PES) is employed as a sample membrane material to prepare microfiltration/ultrafiltration membranes using the CCD method and the effect of cooling rate on the membrane structure is investigated. The structural features of the membranes can be well explained using the proposed membrane formation mechanism, where the effect of cooling rate is rationalised. Pristine PES membranes with pore sizes < 20 nm and narrow pore size distribution can be achieved when a fast cooling rate is applied. Such membranes show a high pure water permeation flux, which is comparable to the nominal flux of commercial hydrophilic PES membranes with similar pore size.
Fouling mechanism of hydrophobic polytetrafluoroethylene (PTFE) membrane by differently charged organics during direct contact membrane distillation (DCMD) process: an especial interest in the feed properties J. Membr. Sci. (IF 6.035) Pub Date : 2017-11-08 Chang Liu, Lin Chen, Liang Zhu
The growing attention to membrane distillation (MD) processes from various disciplines raises the demand for systematic research on MD membrane fouling. This study investigates the role of feed properties, such as feed compositions, charge properties, particle size, hydrophobicity/hydrophilcity, thermal stability and intermolecular interactions, in organic fouling of direct contact membrane distillation (DCMD). The differently charged lysozyme (LYS), sodium alginate (SA), and bovine serum albumin (BSA) were chosen as model organic foulants. The fouling data showed that the feed containing LYS and SA displayed a more severe flux decline compared to the BSA/SA solution, which was highly associated with the charge interaction. Additionally, the flux performance for the mixed foulants was partly affected by the proportion of protein (BSA or LYS) to polysaccharide (SA). It was found that the mixed feed containing less BSA caused a faster flux decline, whereas the feed containing higher amounts of LYS exhibited a more severe membrane fouling. Based on the membrane characterization analysis using FTIR, the BSA and SA showed significant conformational changes during the feed heating process, which largely aggravated the membrane fouling rate. Furthermore, the membrane fouling degree was proven to be distinctly affected by the sites where fouling occurred according to the SEM-EDX analysis. The results exhibited that SA was primarily deposited on the membrane surface, while the LYS largely penetrated into the pores, causing a more severe membrane fouling. Finally, two different fouling patterns including “egg-box model” and “multi-layer model” were suggested for the BSA/SA and LYS/SA feeds during the DCMD operation process, respectively.
PVDF/PBSA membranes with strongly coupled phosphonium derivatives and graphene oxide on the surface towards antibacterial and antifouling activities J. Membr. Sci. (IF 6.035) Pub Date : 2017-11-08 Paresh Kumar Samantaray, Giridhar Madras, Suryasarathi Bose
Poly (vinylidene fluoride) (PVDF) based membranes are inert and hydrophobic, which makes them susceptible to biofouling. Blending it with a biopolymer like Poly (butylene succinate-co-adipate) (PBSA) can offer functional sites to tether anti-microbial and anti-fouling agents to improvise the anti-bacterial and anti-fouling properties of PVDF. In this study porous PVDF/PBSA membranes were obtained using non-solvent induced phase separation and modified by a unique phosphonium chloride trihexyltetradecylphosphonium chloride by two approaches. In the first approach; phosphonium chloride was immobilized onto the porous membrane while in the second, the membrane was tethered with graphene oxide initially and then immobilized by phosphonium chloride leading to synergistic performance towards excellent antibacterial and antifouling characteristics. The antimicrobial action manifested by the modifications was assessed by standard plate count taking E.coli and S.aureus as model bacterial organisms. To understand the antimicrobial mechanism, outer membrane permeabilization studies with N-Phenyl-1-naphthylamine assay, intracellular leakage of K+ ion and nucleic acids in metabolic pool and intracellular Reactive oxygen species (ROS) generation studies were assessed. The antifouling study was also carried out by using Bovine serum albumin (BSA) as a model biofoulant. This study demonstrated high distilled water flux, excellent fouling resistance, impressive 7-fold reduction of bacteria and stable flux performance.
Facilitated Olefin Transport through Membranes Consisting of Partially Polarized Silver Nanoparticles and PEMA-g-PPG Graft Copolymer J. Membr. Sci. (IF 6.035) Pub Date : 2017-11-07 Jung Pyo Jung, Cheol Hun Park, Jae Hun Lee, Jung Tae Park, Jeong-Hoon Kim, Jong Hak Kim
We report the preparation of solid-state facilitated olefin transport membranes based on a low-cost, one-pot, room-temperature synthesized graft copolymer, i.e., poly(ethylene-alt-maleic anhydride)-g-O-(2-aminopropyl)-O’-(2-methoxyethyl) polypropylene glycol (PEMA-g-PPG). An electron acceptor, 7,7,8,8-tetracyanoquinodimethane (TCNQ), was employed to activate the surface of the silver nanoparticles (AgNPs), leading to partial polarization. The AgNPs interacted with TCNQ as well as the PEMA-g-PPG graft copolymer to form facilitated olefin transport membranes, as characterized by Fourier transform infrared spectroscopy, UV-vis spectroscopy, and X-ray photoelectron spectroscopy. The PEMA-g-PPG/AgNP membrane activated by TCNQ showed long-term stability (with a mixed gas permeance of 7.8 GPU and propylene/propane selectivity of 17.5) of up to 100 h, while that without TCNQ showed poor stability. The membrane based on PEMA-g-PPG showed better performance than those based on conventional matrices of poly(ethylene oxide) (PEO), poly(vinyl pyrrolidone) (PVP), or poly(ether-block-amide) (PEBAX).
Effect of the Surface Charge of Monodisperse Particulate Foulants on Cake Formation J. Membr. Sci. (IF 6.035) Pub Date : 2017-11-06 Qi Han, Weiyi Li, Thien An Trinh, Anthony G. Fane, Jia Wei Chew
In microfiltration and ultrafiltration, particulate foulants are inevitably deposited on the membrane surface, forming a cake whose structure and behavior play crucial roles in the subsequent filterability of the suspensions. This study investigated the impact of fouling by three types of latex particulate foulants, which were of the same size (3 μm) but with different surface charges. Surprisingly, although the positively charged aminated latex was expected to perform the worst in the flux-decline experiments due to attractive electrostatic interaction with the negatively charged membrane, this latex displayed the best performance relative to the two negatively charged latex. To understand these counter-intuitive results, a novel network model  and three-dimensional (3D) optical coherence tomography (OCT) image analysis  were employed to reveal the underlying reasons for the different fouling behaviors. Two mechanisms were found to contribute to the worse performance of the negatively charged latex. Firstly, these particles tended to deposit on the pore rather than non-pore region of the membrane due to the repulsive particle-membrane electrostatic interactions, which led to a more complete pore blockage and thereby greater initial cake resistance. Secondly, these particles had a greater tendency to cluster and deposit on other deposited latex due to similarly repulsive particle-membrane and particle-particle interactions, which led to a more inhomogeneous cake and thereby greater specific cake resistance.
Treatment and Energy Utilization of oily water via integrated Ultrafiltration-Forward Osmosis–Membrane Distillation (UF-FO-MD) System J. Membr. Sci. (IF 6.035) Pub Date : 2017-11-06 Dongwei Lu, Qianliang Liu, Yumeng Zhao, Huiling Liu, Jun Ma
Oily water of high salinity and temperature causes challenges to eco-environment. Instead of being considered as only pollutants treated by integrated membrane system, oily water was also considered and utilizied as driving-energy resource for the system in this work. This paper proposed and studied integrated UF-FO-MD system for not only treatment of oily water but also utilization of its high salinity and temperature (i.e., osmotic and thermal energies). 50 KDa ceramic membrane was selected for oily water treatment because of high oil recovery rate, low flux decline rate and great reduction of downstream FO-MD fouling, and corresponding membrane fouling mechanism was proposed. After UF, oily water was simultaneously used as FO draw (sewage as FO feed) and MD feed to utilize its osmotic and thermal energies for FO-MD running. Oil content largely influenced FO-MD fouling, while temperature and salt content had little influence. Three scenarios of dynamic mass-transfer process and temperature-salt content equilibrium curve for FO-MD were proposed, which provide guidance for oily water utilization to control mass-transfer process. UF-FO-MD system efficiently treated both oily water and sewage, and recovered high-quality water by utilization of oily water energies at low-energy cost. Oily water after treatment and utilization met reinjection standard. This work helps for oil-field wastewater treatment and utilization to realize water recovery, energy utilization and pollution reduction.
Micropore structure stabilization in organosilica membranes by gaseous catalyst post-treatment J. Membr. Sci. (IF 6.035) Pub Date : 2017-11-06 A. Petra Dral, Ernst R.H. van Eck, Louis Winnubst, Johan E. ten Elshof
A post-treatment involving repeated exposure to gaseous HCl alternated with heating is demonstrated to strongly accelerate the recently reported structural evolution in organically bridged silica networks. Films, powders and membranes derived from 1,2-bis(triethoxysilyl)ethane were exposed to in-situ synthesized HCl gas, alternated with heat treatments at 150–300 °C in air or N2. The film thickness, network condensation, chemical integrity and micropore structure were monitored with X-ray reflectivity, 29Si direct excitation magic angle spinning nuclear magnetic resonance, Fourier-transform infrared spectroscopy and gas permeation. Treatment with HCl was found to predominantly catalyze hydrolysis, enabling network optimization via iterative bond breakage and reformation. Network shrinkage, widening or opening of the smallest pores and densification of the overall pore structure were accelerated while the ethylene bridges remained intact. The achieved acceleration of material evolution makes iterative hydrolysis and condensation a promising approach for increasing the long-term micropore stability of molecular sieving membranes.
Enhanced butanol selectivity of pervaporation membrane with fluorinated monolayer on polydimethylsiloxane surface J. Membr. Sci. (IF 6.035) Pub Date : 2017-11-06 Pei-Yao Zheng, Xiao-Qing Li, Jia-Kai Wu, Nai-Xin Wang, Jie Li, Quan-Fu An
A facile approach to fabricate fluorinated molecular monolayer on the surface of polydimethylsiloxane (PDMS) membrane was conducted using fluoroalkylsilane (FAS) as cross-linking agent. In detail, hydroxyl terminated PDMS were cross-linked with 1 H,1 H,2 H,2H-Perfluorodecyltriethoxysilane and cast on porous polysulfone support to prepare PDMS membranes. X-ray photoelectron spectroscopy showed that fluorinated alkyl chains were enriched at the surface of the membranes. Moreover, the surface fluorine concentration increased with the increasing of FAS and plateaued at around 55 at% (close to that of FAS molecules) when the surface was fully covered by fluorinated monolayers. The surface hydrophobicity was proportional to the surface fluorine content as revealed by water contact angle measurement. When applied in pervaporation separation of 1 wt% n-butanol/water mixture at 60 °C, the membrane prepared with a FAS ethoxy to PDMS hydroxyl equivalents ratio of 35 (PDMS-FAS-35) exhibited a flux of 843 g−2h−1 and an enhanced permeate n-butanol concentration of 34.3 wt% compared with PDMS cross-linked with traditional TEOS (1375 g−2h−1, 24.4 wt%). The decrease of permeate flux was because of the reduced water partial flux without sacrificing the butanol partial flux on the consequence of water repellency of FAS monolayer. The results indicated that the FAS cross-linked PDMS could increase the separation efficiency of the membrane, thereby reducing the cost and energy consumption of the pervaporation process.
Cardo-type random co-polyimide membranes for high pressure pure and mixed sour gas feed separations J. Membr. Sci. (IF 6.035) Pub Date : 2017-11-01 Garba O. Yahaya, Ilham Mokhtari, Afnan A. Alghannam, Seung-Hak Choi, Husnul Maab, Ahmad A. Bahamdan
A series of aromatic random co-polyimide membranes based on 6FDA-Durene/CARDO backbone with varying content of CARDO moiety (3:1; 1:1 and 1:3) were synthesized for enhanced acid gas separation performance. Gas transport properties of pure and mixed gas streams consisting of H2S, CO2, He, CH4, N2 and C2H6 through the dense films of the co-polyimide were studied. Mixed sweet gas tests were done with feeds containing no H2S up to 55 bar, while mixed sour gas measurements were conducted with feeds containing H2S up to 34 bar for 10% H2S and 20% H2S. The membranes exhibit very attractive pure gas transport properties, as CO2 permeability and CO2/CH4 selectivity are up to 323 barrer and 35 respectively. Furthermore, the transport properties of sour gas mixture consisting of five gases were also found attractive, as the CO2/CH4 and H2S/CH4 ideal selectivities are in the range of 18–23 and 19–21 respectively; while CO2 and H2S permeabilities are in the range of 38–51 and 40–47 barrers respectively for 20% H2S in the gas mixture. These values and separation performance exhibited by the co-polyimide are comparable and very competitive even, as compared to the values obtained in some of the high performance polymeric membranes that have been reported in the literature. The stability of the random co-polyimide 6FDA-Durene/CARDO membrane under these aggressive environments is quite remarkable.
Zwitterionic functionalized “cage-like” porous organic frameworks for nanofiltration membrane with high efficiency water transport channels and anti-fouling property J. Membr. Sci. (IF 6.035) Pub Date : 2017-11-05 Chongbin Wang, Zhiyuan Li, Jianxin Chen, Yunlong Zhong, Yongheng Yin, Li Cao, Hong Wu
Nanofiltration membranes bearing high separation and anti-fouling performances represent an efficient separation technology for desalination applications. Although porous organic frameworks (POFs) are considered as a promising candidate for constructing membranes with improved water flux due to their unique advantages such as well-defined pores and tunable functionality, there is still challenge for anti-fouling property of the membranes. Zwitterions possessing balanced charge groups are very attractive for preparing anti-fouling membranes owe to their high hydration capacity. In this study, nanocomposite membranes were prepared by embedding the zwitterionic functionalized “cage-like” POFs (Z-PAF-C) into polyamide (PA) layer. The POFs blended within polymeric membranes could provide more and shorter channels for water molecules through the hybrid membranes, attributing to the novel porous structure of POFs. The zwitterionic groups derived from Z-PAF-C could enhance the hydrophilicity of membrane surface, rendering the membranes promising anti-fouling properties. The water flux of the membrane was increased distinctly from 24 L m−2 h−1 to 42.6 L m−2 h−1 under 0.2 MPa with the loading of Z-PAF-C ranged from 0 g/m2 to 0.85 g/m2 while the retention for Na2SO4 (1 g/L) was maintained at 90.6%. This study demonstrated that the introduction of the zwitterionic functionalized POFs can improve the hydrophilicity and charge negativity of membrane surface, resulting in an enhanced water flux and anti-fouling property.
Preparation of high strength poly(vinylidene fluoride) porous membranes with cellular structure via vapor-induced phase separation J. Membr. Sci. (IF 6.035) Pub Date : 2017-11-04 Qian Zhao, Rui Xie, Feng Luo, Yousef Faraj, Zhuang Liu, Xiao-Jie Ju, Wei Wang, Liang-Yin Chu
Catalytic effect of iron on the tolerance of thin-film composite polyamide reverse osmosis membranes to hydrogen peroxide J. Membr. Sci. (IF 6.035) Pub Date : 2017-11-04 Ran Ling, Ling Yu, Thi Phuong Thuy Pham, Jiahui Shao, J. Paul Chen, Martin Reinhard
Hydrogen peroxide (H2O2) is potentially an attractive alternative to chlorine-based (hypochlorous acid and monochloramine) antifouling agent in reverse osmosis (RO) because H2O2 does not form toxic disinfection byproducts and is tolerated by polyamide (PA) membranes up to high concentrations. However, aqueous H2O2 solutions are corrosive and iron corrosion products activate H2O2 to reactive oxygen species that degrade the PA separation layer. The impact of iron oxides on membrane stability was studied in the presence of H2O2 in three different systems: in a corrosion-resistant system (constructed with plastic components) and in an all-steel system under corroding conditions. H2O2 concentrations were 2.0 mM (68 mg/L) or 10 mM (340 mg/L) and corrosion was enhanced by adding 10 mM Cl- or suppressed by adding phosphate buffer. Membrane performance was evaluated by determining salt rejection and the water flux. Under corrosion-suppressed conditions, membranes were stable during the 8-d test. In a conventional all-steel testing system containing 10 mM Cl- ion as corrosion promoter, the membrane tolerance was significantly diminished. Kinetic data of pCBA degradation indicated that membrane damage was caused by ·OH radicals. Quenching of the ·OH radical by methanol, and X-ray photoelectron spectroscopy (XPS) and Scanning Electron Microscopy (SEM) data are consistent with the hypothesis that Fenton reactions promoted by iron oxides caused PA oxidation cleavage of the polyamide cross-linkages.
Simultaneous permeability, selectivity and antibacterial property improvement of PVC ultrafiltration membranes via in-situ quaternization J. Membr. Sci. (IF 6.035) Pub Date : 2017-11-04 Chunrui Wu, Zhongyang Wang, Sihua Liu, Zongli Xie, Huayan Chen, Xiaolong Lu
Effect of heat treatment and pH on the efficiency of micro-diafiltration in the separation of native fat globules from cream in butter production J. Membr. Sci. (IF 6.035) Pub Date : 2017-11-04 Annamari Jukkola, Riitta Partanen, Orlando J. Rojas, Antti Heino
A buttermilk that is rich in functional components from milk fat globule membrane (MFGM) is of great interest to industry and consumers. However, isolation of such components is challenging because of the complexes they form with proteins. In this contribution, we describe a process, the ideal butter process, for separating milk fat globules and proteins in cream prior butter making to enhance MFGM deployment. First, raw and pasteurized bovine creams were micro-diafiltered with water using a tubular ceramic membrane. A 1.4 µm pore size was selected for the membrane to separate proteins and fat globules. Two trans-membrane pressures (0.4 and 0.6 bar) were used to determine the permeate flux and protein mass flow needed in the evaluation of the filtration efficiency. Compared to pasteurized cream, raw cream led to shorter filtration time. Pasteurization induced protein adsorption on the surface of fat globules, thus decreasing separation efficiency. Furthermore, pH was found to fluctuate during the diafiltration, owing to the decrease of buffering capacity by cream in the course of protein and mineral permeation and subsequent equilibration process of colloidal phosphates with serum phase. A relatively higher filtration pH increased filtration efficiency and protected fat globules from coalescence, given the increased osmotic pressure (electrostatic repulsion). Overall, the protein content in cream decreased by ~80% upon microfiltration. Despite the reduced protein concentration in the filtered creams, no negative effects were observed during churning into butter, which resulted in low-protein content buttermilk (~80% protein reduction). Hence, the ideal butter process can be used to facilitate MFGM isolation and better handling of process streams.
Dual-phase membrane based on LaCo0.2Ni0.4Fe0.4O3-x-Ce0.8Gd0.2O2-x composition for oxygen permeation under CO2/SO2-rich gas environments J. Membr. Sci. (IF 6.035) Pub Date : 2017-11-04 Julio Garcia-Fayos, María Balaguer, Stefan Baumann, José M. Serra
Membrane Preparation by Sequential Spray Deposition of Polymer PISA Nanoparticles J. Membr. Sci. (IF 6.035) Pub Date : 2017-11-04 Jie Ma, Henitsoa M. Andriambololona, Damien Quemener, Mona Semsarilar
UV initiated surface grafting on polyethersulfone ultrafiltration membranes via ink-jet printing-assisted modification J. Membr. Sci. (IF 6.035) Pub Date : 2017-11-04 Roy Bernstein, Clare E. Singer, Swatantra P. Singh, Canwei Mao, Christopher J. Arnusch
Functionalization of Polybenzimidazole-crosslinked Poly(vinylbenzyl chloride) with Two Cyclic Quaternary Ammonium Cations for Anion Exchange Membranes J. Membr. Sci. (IF 6.035) Pub Date : 2017-11-03 Jinkai Hao, Yongyi Jiang, Xueqiang Gao, Wangting Lu, Yu Xiao, Zhigang Shao, Baolian Yi
Investigation of alternative supported liquid membranes in electromembrane extraction of basic drugs from human plasma J. Membr. Sci. (IF 6.035) Pub Date : 2017-11-02 Chuixiu Huang, Xiantao Shen, Astrid Gjelstad, Stig Pedersen-Bjergaard
For the first time, supported liquid membranes (SLMs) of phthalate- and nitrile-based organic solvents were investigated for electromembrane extraction (EME) of eleven polar and non-polar basic drugs from human plasma (pH 7.4). Several phthalates and nitriles which possess high hydrogen bond acceptor basicity, zero hydrogen bond donor acidity, and certain level of hydrophobicity (3 < log P < 5.5) were identified as new and efficient SLMs. The new solvents provided low extraction current, and contained no solvent impurities contaminating the acceptor solution when analyzed by HPLC-UV. Extraction recoveries, kinetics, and even selectivity with diallyl phthalate and dodecanenitrile were similar to 2-nitrophenyl octyl ether (NPOE), although they comprised totally different functional groups. Water penetration into the SLM during EME was investigated for the first time and analyzed by Fourier transform infrared spectrometry. Interestingly, no water was observed penetrating into solvents which are only efficient for EME of nonpolar basic drugs, while water was found to penetrate into the SLM solvents which are efficient for EME of polar basic drugs.
Significantly enhanced CO2 capture properties by synergy of zinc ion and sulfonate in Pebax-pitch hybrid membranes J. Membr. Sci. (IF 6.035) Pub Date : 2017-11-01 Ning Zhang, Dongdong Peng, Hong Wu, Yanxiong Ren, Leixin Yang, Xingyu Wu, Yingzhen Wu, Zihan Qu, Zhongyi Jiang, Xingzhong Cao
Strained single-layer C2N membrane for efficient seawater desalination via forward osmosis: a molecular dynamics study J. Membr. Sci. (IF 6.035) Pub Date : 2017-11-02 Bo Liu, Adrian Wing-Keung Law, Kun Zhou
Forward osmosis (FO) has proven to be a promising membrane separation technology for seawater desalination. However, advanced porous membranes are highly demanded to improve the efficiency of FO process. The single-layer C2N, also known as nitrogenated holey graphene, has recently emerged as a promising material for nanofiltration due to its intrinsic porous structure and robust mechanical strength. In this study, molecular dynamics simulations have been conducted to investigate the seawater desalination performance of the single-layer C2N membrane in the FO process by tuning its pore size using tensile strain. The results show that with a biaxial tensile strain larger than 4%, the C2N membrane becomes permeable to the water molecules but completely impermeable to the salt ions. At the strain of 12%, a water flux as high as 14.36 L cm−2 h−1 can be obtained at the moderate temperature of 338 K. Interestingly, the permeation water flux shows a nonmonotonic dependence on the osmosis pressure difference across the membrane. To understand the underlying mechanism, the potential mean force profile, water density distribution and hydrogen bonding dynamics are analyzed to investigate both the diffusion of the water molecules near the membrane and in the bulk salt solution. This study is helpful for the understanding of the water permeation behavior through the C2N membrane and promoting its application in seawater desalination.
Preparation and pervaporation performance of vinyl-functionalized silica membranes J. Membr. Sci. (IF 6.035) Pub Date : 2017-11-01 Sadao Araki, Ami Okabe, Akira Ogawa, Daisuke Gondo, Satoshi Imasaka, Yasuhisa Hasegawa, Koichi Sato, Kang Li, Hideki Yamamoto
Porous and non-porous micrometer-sized glass platelets as separators for lithium-ion batteries J. Membr. Sci. (IF 6.035) Pub Date : 2017-11-01 U. Schadeck, K. Kyrgyzbaev, T. Gerdes, M. Willert-Porada, R. Moos
Custom-made porous and non-porous micrometer-sized glass platelets made of phase-separating sodium borosilicate glass are used as a new type of separator for lithium-ion batteries with liquid electrolytes as a high-temperature stable alternative for polymer-based separators. The production process of glass platelets as well as the preparation of porous glass platelets by the so-called VYCOR®-process is described. The influence of the platelet morphology on the ionic conductivity in a non-aqueous battery electrolyte is shown. Porous glass platelets with a porosity of 52% show an ionic conductivity of 5.5 mS cm-1 in a standard non-aqueous lithium-ion battery electrolyte. The battery performance of porous and non-porous glass platelets as a separator is tested in a graphite/lithium iron phosphate full-cell configuration and is compared to state-of-the-art polymer-based separators. Charge/discharge tests are performed at different current rates. The results clearly show that glass platelets perform excellently with high charge/discharge currents up to a 10 C rate and capacity retention at a 1 C rate compared to polymer based separators.
Enhanced, hydrophobic, fluorine-containing, thermally rearranged (TR) nanofiber membranes for desalination via membrane distillation J. Membr. Sci. (IF 6.035) Pub Date : 2017-10-31 Sang Hyun Park, Ji Hoon Kim, Sun Ju Moon, Enrico Drioli, Young Moo Lee
Elucidating the mechanisms underlying the difference between chloride and nitrate rejection in nanofiltration J. Membr. Sci. (IF 6.035) Pub Date : 2017-10-31 Razi Epsztein, Wei Cheng, Evyatar Shaulsky, Nadir Dizge, Menachem Elimelech
Effects of industrial gas impurities on performance of mixed matrix membranes J. Membr. Sci. (IF 6.035) Pub Date : 2017-10-31 Shinji Kanehashi, Alita Aguiar, Hiep Lu, G. Chen, Sandra Kentish
A series of mixed matrix membranes using a commercially available aromatic polyimide (Matrimid® 5218) with nanoparticles formed from carbon, a porous organic polymer and metal organic frameworks were prepared to investigate the effects of flue gas impurities on gas permeation. We show that common impurities found in power station flue gases (H2S, SO2, and NO) have significant effects upon the performance of these mixed matrix membranes. The effects of NO, SO2 and H2S on the zeolitic imidazolate framework ZIF-8 are all large and rapid and would render these membranes unsuitable for flue gas service that do not use flue gas desulfurisation. Similarly, H2S adsorbs irreversibly into membranes containing copper benzene-1,3,5-tricarboxylate (Cu-BTC), although the impacts of NO and SO2 are less severe. The membranes containing a porous organic polymer or porous carbon are less affected by these contaminants. In particular, the permeability of the membrane containing the porous organic polymer is still significantly above that of the base Matrimid polymer after exposure for 80 days to 1000 ppm of each contaminant. Further, this mixed matrix structure shows enhanced H2S selectivity. These results suggest that MMMs prepared using organic based nanoparticles can be effective in gas separation applications such as natural gas sweetening, biogas purification and post-combustion carbon capture, when acid gases are present as an impurity.
Hydrogen Production from solid Feedstock by using a Nickel Membrane Reformer J. Membr. Sci. (IF 6.035) Pub Date : 2017-10-31 Jonas M. Leimert, Marius Dillig, Jürgen Karl
Development of Pd-based double-skinned membranes for hydrogen production in fluidized bed membrane reactors J. Membr. Sci. (IF 6.035) Pub Date : 2017-10-31 Alba Arratibel, Alfredo Pacheco Tanaka, Iker Laso, Martin van Sint Annaland, Fausto Gallucci
Fabrication of phenolic resin based desalting membrane with ordered mesostructure and excellent chlorine resistance J. Membr. Sci. (IF 6.035) Pub Date : 2017-10-31 Qiang Li, George Chen, Liang Liu, Xuliang Wang
Enhanced Hydrophilicity and Water-permeating of Functionalized Graphene-oxide Nanopores: Molecular Dynamics Simulations J. Membr. Sci. (IF 6.035) Pub Date : 2017-10-31 Tongfei Yu, Zhijun Xu, Shuyan Liu, Hang Liu, Xiaoning Yang
In this work, molecular dynamics simulations were employed to study the permeation of ethanol-water mixtures through single-layer graphene oxide (GO) nanopores functionalized with COOH (carboxyl) and COO- (ionized carboxyl) groups. GO-COOH nanopore shows regular behavior with competitive permeation between the two species in the mixture. However, GO-COO- pore exhibits selective permeation of water, suggesting COO- functionalized GO sheets could provide the initial barrier to block ethanol permeation and enhance dehydration separation in GO-based membranes. Our simulation presents the underlying mechanism of the selective water transport is not determined by the pore-size sieving, but has been ascribed as the strong molecular affinity between water and GO-COO- surface. This interfacial interaction can induce the preferential interfacial adsorption and pore occupation for water, simultaneously impede the transport path of ethanol into the nanopore, and consequently give rise to the selective penetration of water in the mixture. The simulation results provide the direct theoretical evidence that ionization of carboxyl groups on GO sheets can be applied to improve the dehydration permeation of alcohol-water mixtures across GO-based separation membranes.
Development of high performance nanofibrous composite membranes by optimizing polydimethylsiloxane architectures for phenol transport J. Membr. Sci. (IF 6.035) Pub Date : 2017-10-31 Meng-Yi Jin, Yuan Liao, Choon-Hong Tan, Rong Wang
Phenol removal and recovery from wastewaters are highly demanded in industries due to its high toxicity and industrial importance. It can transport through the silicon-based rubber polydimethylsiloxane (PDMS) via the solution-diffusion mechanism. To improve the phenol removal efficiency in extractive processes, dense PDMS membranes with different macromolecular structures have been developed and evaluated in this work. The condensation-cured PDMS membranes (PA) with network architecture exhibited higher phenol partition coefficients (K) than the hydrosilylation-cured PDMS membranes with linear and branch architectures. This was attributed to the four-armed quaternary-siloxy linkages formed in the three-dimensional network structure, increasing the free volume for phenol passage and hydrogen bonding between phenol and PDMS matrix. The K of PA was further enhanced by optimizing the PDMS precursor chain length and cross-linker amount, and the corresponding membrane mechanical properties and phenol overall mass transfer coefficients (k0) were examined. The optimal PA formulation was utilized to fabricate a highly effective nanofibrous composite membrane via spray coating. The resultant composite membrane exhibited a k0 of 18.3 ± 1.3 × 10−7 m/s in an aqueous-aqueous extractive process, significantly outperforming the commercial counterpart with 45% increment. This is the first demonstration of the importance of PDMS macromolecular structures on phenol extraction. The newly-developed condensation-cured PDMS could contribute to the fabrication of highly effective composite membranes for various extractive processes.
A novel strategy to construct highly conductive and stabilized anionic channels by fluorocarbon grafted polymers J. Membr. Sci. (IF 6.035) Pub Date : 2017-10-29 Jin Ran, Liang Ding, Dongbo Yu, Xu Zhang, Min Hu, Liang Wu, Tongwen Xu
Rotating disk-like membrane cell for pressure-driven measurements with equally-accessible membrane surface: numerical simulation and experimental validation J. Membr. Sci. (IF 6.035) Pub Date : 2017-10-28 Marc Fernández de Labastida, Edxon E. Licón, Mykola Bondarenko, Andriy Yaroshchuk
This work presents a new approach to correcting for concentration polarization (CP) in pressure-driven membrane measurements. In the existing test cells (both cross-flow and stirred-batch) there are distributions of extent of CP over membrane surface. This complicates the interpretation of experimental data.A novel design of test cell with equally-accessible membrane surface has been developed based on the classical configuration of rotating disk combined with the possibility of applying trans-membrane hydrostatic pressure differences of up to 20 bar. Due to the equal accessibility, corrections for CP can easily be made even in multi-ionic systems, which would be much more difficult with other membrane test cells.Since the membrane has to be sealed at the edge the geometry somewhat deviates from the ideal case of infinite disk. The impact of these deviations has been quantified via CFD simulations. A major part of the membrane surface is shown to be equally accessible while there are some expectable deviations close to the sealed membrane edge. This zone could be “screened” in the experiments. The approach could also be validated experimentally via studying the dependence of observed rejection on the rotation speed and demonstrating that intrinsic rejection was practically independent of it.Finally, to demonstrate the cell utility, we performed and interpreted a number of experiments using commercial NF270 membrane and various feed solutions (single salts and electrolyte mixtures). We conclude that this cell can be employed for systematic transport characterization of membranes and the obtained information can be used as input in the CFD modelling of membrane modules.
Dual Functional Membrane Capable of Both Visual Sensing and Blocking of Waterborne Virus J. Membr. Sci. (IF 6.035) Pub Date : 2017-10-27 Bom-yi Lee, Jinhwan Kim, Won Jong Kim, Jin Kon Kim
Norovirus, which is transmitted by contact with a contaminated object or person who has a norovirus infection, eating contaminated food, or drinking contaminated water, is a highly contagious virus for humans and animals. Among many infection routes, water supply systems from reservoirs or dams become very important due to the possibility of mass infection. Because only a small amount of norovirus (10~100 particles forming unit) can cause the infection, a rapid and easy detection of the virus is required. Once norovirus is detected, the water supply should be quickly shut down.Here, we introduce a dual functional membrane capable of both easy detecting with the naked eye and blocking noroviruses. We employed an anodized aluminum oxide (AAO) membrane with uniform pores. The top and bottom parts of the membrane were grafted with polydiacetylene (PDA) and poly(N-isopropylacrylamide) (PNIPAM), respectively. The top part was further bioconjugated by antibody for feline calicivirus (FCV), which is a model virus whose structure is similar to norovirus. The membrane showed color change from blue to red when the FCVs were attached to the antibodies. Water flux was controlled (turned on and off) by changing water temperature by using the well-known thermosensitive property of PNIPAM chains. On and off control of water flow was quickly established (less than 5 s) when a laser with near infrared (NIR) wavelength was turned on and off, respectively. In addition, the membrane completely blocked the virus influx into the water system by antibody binding before visual sensing followed by flow control.
Performance enhancement of polybenzimidazole based high temperature proton exchange membranes with multifunctional crosslinker and highly sulfonated polyaniline J. Membr. Sci. (IF 6.035) Pub Date : 2017-10-26 Peng Sun, Zhongfang Li, Suwen Wang, Xiaoyan Yin
Ultrasonic-assisted fabrication of high flux T-type zeolite membranes on alumina hollow fibers J. Membr. Sci. (IF 6.035) Pub Date : 2017-10-25 Rui Wang, Nanke Ma, Yushan Yan, Zhengbao Wang
Ultrasonic-assisted pretreatment prior to hydrothermal synthesis is employed for the first time in the preparation of T-type zeolite membranes on α-Al2O3 hollow fibers by secondary growth. The synthesis time can be shortened from 40 h to 24 h with only 0.5 h ultrasonic pretreatment of the synthesis solution. Elongating ultrasonic treatment time to 1.0 h has no further improvement for the formation of dense membrane. Typically, the pure phase T-type zeolite membrane synthesized in 24 h with 0.5 h ultrasonic pretreatment has a separation factor of >10000 and a flux of 12.2 kg m−2 h−1 for 90.0 wt% isopropanol aqueous solution at 75 °C. When the porosity of the hollow fiber support is 68%, the flux is as high as 14.3 kg m−2 h−1, which is the highest flux ever reported. The high flux of the membrane can be mainly ascribed to the special structure and porosity of the α-Al2O3 hollow fiber support. Finally, a mechanism for ultrasonic-assisted membrane preparation is proposed.
Micropollutants removal from secondary-treated municipal wastewater using weak polyelectrolyte multilayer based nanofiltration membranes J. Membr. Sci. (IF 6.035) Pub Date : 2017-10-25 S. Mehran Abtahi, Shazia Ilyas, Claire Joannis Cassan, Claire Albasi, Wiebe M. de Vos
Nanofiltration (NF) is seen as a very promising technology to remove micropollutants (MPs) from wastewater. Unfortunately this process tends to produce a highly saline concentrate stream, as commercial NF membranes retain both the MPs and most of the ions. The high salinity makes subsequent degradation of the MPs in a bio-reactor very difficult. The main goal of this study is to prepare and study a NF membrane that combines a low salt rejection with a high MPs rejection for the treatment of secondary-treated municipal wastewater. This membrane was prepared using layer by layer (LbL) deposition of the weak polycation poly(allylamine hydrochloride) (PAH), and the weak polyanion poly(acrylic acid) (PAA), on the surface of a hollow fiber dense ultrafiltration (UF) membrane. The ionic strength of the coating solutions was varied and properties of the formed polyelectrolyte multilayers (PEMs), such as hydration, hydrophilicity, hydraulic resistance and ions retention were studied. Subsequently we tested the apparent and steady state rejection of MPs from synthetic wastewater under cross-flow conditions. The synthetic wastewater contained the MPs Diclofenac, Naproxen, Ibuprofen and 4n-Nonylphenol, all under relevant concentrations (0.5–40 µg/L, depending on the MP). PEMs prepared at lower ionic strength showed a lower hydration and consequently a better retention of MPs than PEMs prepared at higher ionic strengths. A strong relationship between the apparent rejection of MPs and their hydrophobicity was observed, likely due to adsorption of the more hydrophobic MPs to the membrane surface. Once saturated (steady state), the molecular size of the MPs showed the best correlation with their rejection, indicating rejection on the basis of size exclusion. In contrast to available commercial NF membranes with both high salt and MP rejection, we have prepared an unique membrane with a very low NaCl retention (around 17%) combined with a very promising removal of MPs, with Diclofenac, Naproxen, Ibuprofen and 4n-Nonylphenol being removed up to 77%, 56%, 44% and 70% respectively. This membrane would allow the treatment of secondary treated municipal wastewater, strongly reducing the load of MPs, without producing a highly saline concentrate stream.
Studying Water and Solute Transport through Desalination Membranes via Neutron Radiography J. Membr. Sci. (IF 6.035) Pub Date : 2017-10-25 Devin L. Shaffer, Jacob M. LaManna, David L. Jacobson, Daniel S. Hussey, Menachem Elimelech, Edwin P. Chan
Analyzing External and Internal Membrane Fouling by Oil Emulsions via 3D Optical Coherence Tomography J. Membr. Sci. (IF 6.035) Pub Date : 2017-10-24 Thien An Trinh, Weiyi Li, Qi Han, Xin Liu, Anthony G. Fane, Jia Wei Chew
Membrane-based filtration is an emerging technique for processing oily wastewater. Improving the efficiency of oil-water separation via membranes entails novel techniques for studying the complex interactions between the oil droplets and membrane underlying fouling. This paper presents the first study that applies optical coherence tomography (OCT) to the characterization of membrane fouling by oil emulsions. A series of dead-end filtration experiments was performed to characterize the rejection of oil droplets (~10 µm; hexadecane) by the membrane structure (0.45 µm PVDF) via three-dimensional (3D) OCT scanning in real time. The experimental results were compared with the control experiments with ~10 µm glass beads to identify the optical artifacts. Both the external and internal fouling by the oil droplets were successfully revealed by analyzing the variation in OCT intensity at various layers that were mathematically defined in terms of the coordinate surfaces parallel to, and above and below, the feed-membrane interface. The evolution of membrane fouling was quantified by evaluating the fraction of fouling voxels as a function of time at varied depths. This study demonstrates that the OCT-based characterization has the potential to shed light on the complex interactions occurring in oil-water separations via membrane filtration, particularly by providing real-time non-invasive monitoring of internal fouling, the understanding of which is valuable for both fundamental research and practical applications.
Analysis of an osmotically-enhanced dewatering process for the treatment of highly saline (waste)waters J. Membr. Sci. (IF 6.035) Pub Date : 2017-10-24 Jungwon Kim, David Inhyuk Kim, Seungkwan Hong
Carboxylic polyethersulfone: a novel pH-responsive modifier in support layer of forward osmosis membrane J. Membr. Sci. (IF 6.035) Pub Date : 2017-10-24 Hasan Salehi, Alireza Shakeri, Masoud Rastgar
Creation of active-passive integrated mechanisms on membrane surfaces for superior antifouling and antibacterial properties J. Membr. Sci. (IF 6.035) Pub Date : 2017-10-23 Kang Gao, Yanlei Su, Linjie Zhou, Mingrui He, Runnan Zhang, Yanan Liu, Zhongyi Jiang
A combined polymerization and self-assembling process for the fouling mitigation of PVDF membranes J. Membr. Sci. (IF 6.035) Pub Date : 2017-10-21 Antoine Venault, Ying-Nien Chou, Yu-Hsiang Wang, Chen-Hua Hsu, Chung-Jung Chou, Denis Bouyer, Kueir-Rarn Lee, Yung Chang
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