Pub Date : 2020-04-01DOI: 10.22079/JMSR.2019.115517.1298
Rodrigo J. Martinez, Yingying Chen, D. Gervasio, J. Baygents, J. Farrell
This research investigated stability of two novel aminated polyphenylene polymers as anion exchange layers in bipolar membranes. Bipolar membrane stability was tested under operating conditions of 50 mA/cm2, and under conditions of soaking in room temperature 1 M NaOH. The stability of the custom made bipolar membranes was compared with those for two commercial membranes. For the polyphenylene-based membranes, there was no measurable increase in operating voltage when run continuously at a current density of 50 mA/cm2. For the two commercial membranes, the operating voltages increased by 3.2 to 4.4 mV per day when operated continuously over an 85 day testing period. Commercial membrane degradation in 1 M NaOH was similar to that under real operating conditions, with average rates of voltage increase of 3.2 to 3.5 mV/d. The custom made membrane containing a quaternary ammonium-tethered poly(biphenylalkylene) (PBPA) anion exchange layer did not show any loss in performance in either stability test. Density functional theory (DFT) simulations were used to calculate activation barriers and reaction energies for nucleophilic attack on the polymer backbones and cation functional groups on each of the four anion exchange polymers. Cation loss from all four polymers was thermodynamically favorable, with activation barriers ranging from 64 to 138 kJ/mol. The two commercial polysulfone-based anion exchange membranes were susceptible to cleavage of the ether bonds. However, the polyphenylene-based anion exchange polymers were considerably more stable with respect to backbone cleavage. The DFT calculations showing that the PBPA polymer was the most stable confirmed the results of the stability tests.
{"title":"Alkaline Stability of Novel Aminated Polyphenylene-Based Polymers in Bipolar Membranes","authors":"Rodrigo J. Martinez, Yingying Chen, D. Gervasio, J. Baygents, J. Farrell","doi":"10.22079/JMSR.2019.115517.1298","DOIUrl":"https://doi.org/10.22079/JMSR.2019.115517.1298","url":null,"abstract":"This research investigated stability of two novel aminated polyphenylene polymers as anion exchange layers in bipolar membranes. Bipolar membrane stability was tested under operating conditions of 50 mA/cm2, and under conditions of soaking in room temperature 1 M NaOH. The stability of the custom made bipolar membranes was compared with those for two commercial membranes. For the polyphenylene-based membranes, there was no measurable increase in operating voltage when run continuously at a current density of 50 mA/cm2. For the two commercial membranes, the operating voltages increased by 3.2 to 4.4 mV per day when operated continuously over an 85 day testing period. Commercial membrane degradation in 1 M NaOH was similar to that under real operating conditions, with average rates of voltage increase of 3.2 to 3.5 mV/d. The custom made membrane containing a quaternary ammonium-tethered poly(biphenylalkylene) (PBPA) anion exchange layer did not show any loss in performance in either stability test. Density functional theory (DFT) simulations were used to calculate activation barriers and reaction energies for nucleophilic attack on the polymer backbones and cation functional groups on each of the four anion exchange polymers. Cation loss from all four polymers was thermodynamically favorable, with activation barriers ranging from 64 to 138 kJ/mol. The two commercial polysulfone-based anion exchange membranes were susceptible to cleavage of the ether bonds. However, the polyphenylene-based anion exchange polymers were considerably more stable with respect to backbone cleavage. The DFT calculations showing that the PBPA polymer was the most stable confirmed the results of the stability tests.","PeriodicalId":16427,"journal":{"name":"Journal of Membrane Science and Research","volume":"6 1","pages":"218-225"},"PeriodicalIF":0.0,"publicationDate":"2020-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49316335","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-04-01DOI: 10.22079/JMSR.2020.118838.1314
Andrea Molina, Mónica Faria, Gladis Judith Labrada Delgado, M. D. Pinho, M. G. S. Loredo
The present work reports on the synthesis of cellulose acetate (CA) asymmetric membranes with the incorporation of inorganic fluorides, CaF2 particles. These fillers of polymeric composites can, according to the literature, promote the ordering of the polymer matrix, which can lead to interesting permeation properties. In order to achieve that, fluorite (CaF2 ) fine particles were prepared by a double jet injection method using CaCl2 and NaF solutions as precursors and polyvinylpyrrolidone as a stabilizing agent. The fluorite particles were incorporated in the casting solutions of cellulose acetate/acetone/formamide. Dynamic light scattering measurements showed that formamide acting as the poor solvent in the membrane casting solutions can lead to some agglomeration of the fluorite particles and evident changes in structure and permeation properties. The CA/CaF2 composite membranes were casted by the phase inversion method at different solvent evaporation times. The permeation experiments indicated that the active layer of the membranes prepared with shorter solvent evaporation times is composed of an organic-inorganic network with bigger pores, which allows the permeation of molecules approximately two times the size of those retained by the CA membranes. Further increase in the solvent evaporation time has the opposite effect, as particle agglomerates may be formed.
{"title":"Synthesis of Calcium Fluoride Ultrafine Particles for the Preparation of Integral Asymmetric Cellulose Acetate/Calcium Fluoride Membranes","authors":"Andrea Molina, Mónica Faria, Gladis Judith Labrada Delgado, M. D. Pinho, M. G. S. Loredo","doi":"10.22079/JMSR.2020.118838.1314","DOIUrl":"https://doi.org/10.22079/JMSR.2020.118838.1314","url":null,"abstract":"The present work reports on the synthesis of cellulose acetate (CA) asymmetric membranes with the incorporation of inorganic fluorides, CaF2 particles. These fillers of polymeric composites can, according to the literature, promote the ordering of the polymer matrix, which can lead to interesting permeation properties. In order to achieve that, fluorite (CaF2 ) fine particles were prepared by a double jet injection method using CaCl2 and NaF solutions as precursors and polyvinylpyrrolidone as a stabilizing agent. The fluorite particles were incorporated in the casting solutions of cellulose acetate/acetone/formamide. Dynamic light scattering measurements showed that formamide acting as the poor solvent in the membrane casting solutions can lead to some agglomeration of the fluorite particles and evident changes in structure and permeation properties. The CA/CaF2 composite membranes were casted by the phase inversion method at different solvent evaporation times. The permeation experiments indicated that the active layer of the membranes prepared with shorter solvent evaporation times is composed of an organic-inorganic network with bigger pores, which allows the permeation of molecules approximately two times the size of those retained by the CA membranes. Further increase in the solvent evaporation time has the opposite effect, as particle agglomerates may be formed.","PeriodicalId":16427,"journal":{"name":"Journal of Membrane Science and Research","volume":"6 1","pages":"147-157"},"PeriodicalIF":0.0,"publicationDate":"2020-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47372033","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-04-01DOI: 10.22079/JMSR.2019.115152.1295
Sama A. Al-Mutwalli, Mehmet Dilaver, D. Y. Koseoglu-Imer
The recovery of high-quality, valuable end products from cheese whey is a very important industrial process. The aim of this study is to improve the recovered protein content of concentrate stream in cheese whey. The experiments were conducted by using ceramic ultrafiltration (UF) membrane followed by diafiltration (DF) process with a 15kDa molecular weight cut-off (MWCO). The volume concentration factor (VCF) was set as 1.4, 2.0 and 3.3 by controlling the permeate and concentrate volume. It was observed that the protein concentration increased from 1.4 g/l in the feed solution to 9.9 g/l in the concentrate stream. After VCF optimization, two intermittent feed diafiltration (IFD) cycles were performed experimentally and a mathematical model with real-time function was applied for DF yield calculation. The maximum yield was found as 88% at the end of the second DF cycle. The protein content reached to 33% in the concentrate stream after applying the IFD process. During the fouling experiments of DF process, the indicative parameters were calculated with three different fouling models. Total resistance (RT), membrane fouling index (MFI), and unified membrane fouling index (UMFI) were found as 5.15x1014 m-1, 25x106, and 344 respectively. IFD process enhanced the overall performance of whey processing compared to normal UF process.
{"title":"Performance Evaluation of Ceramic Membrane on Ultrafiltration and Diafiltration Modes for Efficient Recovery of Whey Protein","authors":"Sama A. Al-Mutwalli, Mehmet Dilaver, D. Y. Koseoglu-Imer","doi":"10.22079/JMSR.2019.115152.1295","DOIUrl":"https://doi.org/10.22079/JMSR.2019.115152.1295","url":null,"abstract":"The recovery of high-quality, valuable end products from cheese whey is a very important industrial process. The aim of this study is to improve the recovered protein content of concentrate stream in cheese whey. The experiments were conducted by using ceramic ultrafiltration (UF) membrane followed by diafiltration (DF) process with a 15kDa molecular weight cut-off (MWCO). The volume concentration factor (VCF) was set as 1.4, 2.0 and 3.3 by controlling the permeate and concentrate volume. It was observed that the protein concentration increased from 1.4 g/l in the feed solution to 9.9 g/l in the concentrate stream. After VCF optimization, two intermittent feed diafiltration (IFD) cycles were performed experimentally and a mathematical model with real-time function was applied for DF yield calculation. The maximum yield was found as 88% at the end of the second DF cycle. The protein content reached to 33% in the concentrate stream after applying the IFD process. During the fouling experiments of DF process, the indicative parameters were calculated with three different fouling models. Total resistance (RT), membrane fouling index (MFI), and unified membrane fouling index (UMFI) were found as 5.15x1014 m-1, 25x106, and 344 respectively. IFD process enhanced the overall performance of whey processing compared to normal UF process.","PeriodicalId":16427,"journal":{"name":"Journal of Membrane Science and Research","volume":"6 1","pages":"138-146"},"PeriodicalIF":0.0,"publicationDate":"2020-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48525719","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-04-01DOI: 10.22079/JMSR.2019.110904.1273
Rajesha Kumar, Mansour Ahmed, Garudachari Bhadrachari, A. Al-Mesri, Juergen Thomas
In this work, the hydrophobic modification of TiO2 nanoparticles (HTiO2) was carried out by reacting with dodecylphosphonic acid (DDPA) and hexylamine solution. A facile approach of the self-assembly technique was used for the coating of hydrophobic HTiO2 layer over the microporous polypropylene (PP) membrane. The self-assembled layer was formed between the interface of trimesoyl chloride (TMC) (in hexane) and trimethylamine (in water) solutions. The high porosity for the coated membranes ascribed to the selfassembled trimesic acid (TMA) layer and its potential to generate open and loosely packed, two-dimensional hydrogen-bond networks on the membrane surface. The dispersion of HTiO2 was accomplished in the TMC in hexane leading hydrophobic and porous surfaces than the neat PP membrane. The initial average pore size of the PP membrane was reduced from 0.4 μm to 0.2 μm with a coating of 2.0 wt% of HTiO2. The new membranes showed high reliability, high rejection, and water flux during the real seawater desalination tested in direct contact membrane distillation (DCMD) configuration. The maximum transmembrane permeate flux of 45.4 kg/m2h with >98% salt rejection was obtained for the coating layer with 2.0 wt% HTiO2 at 80oC demonstrating the future potential application towards seawater desalination.
{"title":"A Facile Approach of Thin Film Coating Consisted of Hydrophobic Titanium Dioxide over Polypropylene Membrane for Membrane Distillation","authors":"Rajesha Kumar, Mansour Ahmed, Garudachari Bhadrachari, A. Al-Mesri, Juergen Thomas","doi":"10.22079/JMSR.2019.110904.1273","DOIUrl":"https://doi.org/10.22079/JMSR.2019.110904.1273","url":null,"abstract":"In this work, the hydrophobic modification of TiO2 nanoparticles (HTiO2) was carried out by reacting with dodecylphosphonic acid (DDPA) and hexylamine solution. A facile approach of the self-assembly technique was used for the coating of hydrophobic HTiO2 layer over the microporous polypropylene (PP) membrane. The self-assembled layer was formed between the interface of trimesoyl chloride (TMC) (in hexane) and trimethylamine (in water) solutions. The high porosity for the coated membranes ascribed to the selfassembled trimesic acid (TMA) layer and its potential to generate open and loosely packed, two-dimensional hydrogen-bond networks on the membrane surface. The dispersion of HTiO2 was accomplished in the TMC in hexane leading hydrophobic and porous surfaces than the neat PP membrane. The initial average pore size of the PP membrane was reduced from 0.4 μm to 0.2 μm with a coating of 2.0 wt% of HTiO2. The new membranes showed high reliability, high rejection, and water flux during the real seawater desalination tested in direct contact membrane distillation (DCMD) configuration. The maximum transmembrane permeate flux of 45.4 kg/m2h with >98% salt rejection was obtained for the coating layer with 2.0 wt% HTiO2 at 80oC demonstrating the future potential application towards seawater desalination.","PeriodicalId":16427,"journal":{"name":"Journal of Membrane Science and Research","volume":"6 1","pages":"196-202"},"PeriodicalIF":0.0,"publicationDate":"2020-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44938628","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-04-01DOI: 10.22079/JMSR.2019.115128.1294
S. I. Sharudin, P. Goh, A. Ismail
Salinity gradient energy (SGE) refers to the energy created from the difference in salt concentration between two streams. There are three types of SGE namely, pressure retarded osmosis (PRO), reverse electrodialysis (RED), and capacitive mixing (CapMix). All these technologies require membrane for the system to be operational. In this short review, the membranes modifications for each principle and its strategies in improving the performance of their membranes are presented. The technological progress of SGE is currently constrained by its ability in generating low power density. Thus, further modifications on every aspect of the systems is needed to overcome this bottleneck. This review focuses on the modifications of polymer-based membranes for salinity gradient energy generation. Finally, some challenges and future perspective of SGE development are discussed.
{"title":"Modification of Polymeric Membrane for Energy Generation through Salinity Gradient: A Short Review","authors":"S. I. Sharudin, P. Goh, A. Ismail","doi":"10.22079/JMSR.2019.115128.1294","DOIUrl":"https://doi.org/10.22079/JMSR.2019.115128.1294","url":null,"abstract":"Salinity gradient energy (SGE) refers to the energy created from the difference in salt concentration between two streams. There are three types of SGE namely, pressure retarded osmosis (PRO), reverse electrodialysis (RED), and capacitive mixing (CapMix). All these technologies require membrane for the system to be operational. In this short review, the membranes modifications for each principle and its strategies in improving the performance of their membranes are presented. The technological progress of SGE is currently constrained by its ability in generating low power density. Thus, further modifications on every aspect of the systems is needed to overcome this bottleneck. This review focuses on the modifications of polymer-based membranes for salinity gradient energy generation. Finally, some challenges and future perspective of SGE development are discussed.","PeriodicalId":16427,"journal":{"name":"Journal of Membrane Science and Research","volume":"6 1","pages":"168-177"},"PeriodicalIF":0.0,"publicationDate":"2020-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43827452","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-04-01DOI: 10.22079/JMSR.2019.106656.1263
Hazlini Dzinun, Y. Ichikawa, Honda Mitsuhiro, Qiyan Zhang
Immobilised titanium dioxide (TiO2) in membrane structures has recently become attractive. This is due to the elimination of the separation step after the process of photocatalytic degradation. The efficiency of the TiO2 surface area exposed to UV light as the main important parameter needs to be considered. The immobilisation of TiO2 nanoparticles in the polyvinylidene fluoride (PVDF) membrane structure with different particle sizes (6 nm and 30 nm) was prepared via various techniques including the tape casting and spin coating methods to study the distribution of TiO2 nanoparticles in the membrane structure. Besides, the effects of the spinning speed in spin coating methods on the membrane structure and photocatalytic performance were investigated. The morphological and physical characteristics were also explored by field emission scanning electron microscope (FESEM) energy dispersion of X-ray (EDX), scanning electron microscopy (SEM) and atomic force microscopy (AFM) analysis. The prepared membranes were tested in a photocatalytic system using methylene blue (MB) as a model pollutant. The results showed that the immobilisation of TiO2 nanoparticles in membrane structure could enhance the rate of MB degradation. The aggregation of the 6 nm and 30 nm TiO2 particle sizes prepared by tape casting method shows similar performance in MB degradation rate but contradict the result of the spin coating method. The good distribution and uniformity of the 6 nm TiO2 particle size exhibit a higher MB degradation rate. The thickness of the membrane can be tailored using the spin coating method and UV penetration towards the photocatalytic membrane up to 55.64 μm of thickness, which could enhance the MB photocatalytic degradation rate.
{"title":"Efficient Immobilised TiO2 in Polyvinylidene fluoride (PVDF) Membrane for Photocatalytic Degradation of Methylene Blue","authors":"Hazlini Dzinun, Y. Ichikawa, Honda Mitsuhiro, Qiyan Zhang","doi":"10.22079/JMSR.2019.106656.1263","DOIUrl":"https://doi.org/10.22079/JMSR.2019.106656.1263","url":null,"abstract":"Immobilised titanium dioxide (TiO2) in membrane structures has recently become attractive. This is due to the elimination of the separation step after the process of photocatalytic degradation. The efficiency of the TiO2 surface area exposed to UV light as the main important parameter needs to be considered. The immobilisation of TiO2 nanoparticles in the polyvinylidene fluoride (PVDF) membrane structure with different particle sizes (6 nm and 30 nm) was prepared via various techniques including the tape casting and spin coating methods to study the distribution of TiO2 nanoparticles in the membrane structure. Besides, the effects of the spinning speed in spin coating methods on the membrane structure and photocatalytic performance were investigated. The morphological and physical characteristics were also explored by field emission scanning electron microscope (FESEM) energy dispersion of X-ray (EDX), scanning electron microscopy (SEM) and atomic force microscopy (AFM) analysis. The prepared membranes were tested in a photocatalytic system using methylene blue (MB) as a model pollutant. The results showed that the immobilisation of TiO2 nanoparticles in membrane structure could enhance the rate of MB degradation. The aggregation of the 6 nm and 30 nm TiO2 particle sizes prepared by tape casting method shows similar performance in MB degradation rate but contradict the result of the spin coating method. The good distribution and uniformity of the 6 nm TiO2 particle size exhibit a higher MB degradation rate. The thickness of the membrane can be tailored using the spin coating method and UV penetration towards the photocatalytic membrane up to 55.64 μm of thickness, which could enhance the MB photocatalytic degradation rate.","PeriodicalId":16427,"journal":{"name":"Journal of Membrane Science and Research","volume":"6 1","pages":"188-195"},"PeriodicalIF":0.0,"publicationDate":"2020-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41859153","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-04-01DOI: 10.22079/JMSR.2020.120669.1336
A. Figoli, C. Ursino, S. Santoro, I. Ounifi, Jalila Chekir, A. Hafiane, E. Ferjani
In this work, cellulose acetate (CA) nanofiltration (NF) membranes were prepared via non-solvent phase inversion technique (NIPS). Polymer concentration was varied from 22 to 25 wt% in order to study its effect on the membrane properties. The fabricated membranes were characterized in terms of morphological analysis using scanning electron microscopy (SEM), contact angle, water content, water permeability and salts retention such as Na2SO4, CaCl2 and NaCl. Membranes performances were evaluated for cadmium Cd2+ removal using three types of cadmium salt: CdCl2, Cd(NO3)2 and CdSO4. The effects of several operating parameters such as the pH of the feed solution (2-12), trans-membrane pressure (0-14 bar), feed concentration (10-4-10-2 mol.L-1) and ionic strength were also studied and investigated. Results evidenced that the prepared CA-NF membranes consists of a sustainable remediation of Cadmium contamination for safe water supply.
{"title":"Cellulose Acetate Nanofiltration Membranes for Cadmium Remediation","authors":"A. Figoli, C. Ursino, S. Santoro, I. Ounifi, Jalila Chekir, A. Hafiane, E. Ferjani","doi":"10.22079/JMSR.2020.120669.1336","DOIUrl":"https://doi.org/10.22079/JMSR.2020.120669.1336","url":null,"abstract":"In this work, cellulose acetate (CA) nanofiltration (NF) membranes were prepared via non-solvent phase inversion technique (NIPS). Polymer concentration was varied from 22 to 25 wt% in order to study its effect on the membrane properties. The fabricated membranes were characterized in terms of morphological analysis using scanning electron microscopy (SEM), contact angle, water content, water permeability and salts retention such as Na2SO4, CaCl2 and NaCl. Membranes performances were evaluated for cadmium Cd2+ removal using three types of cadmium salt: CdCl2, Cd(NO3)2 and CdSO4. The effects of several operating parameters such as the pH of the feed solution (2-12), trans-membrane pressure (0-14 bar), feed concentration (10-4-10-2 mol.L-1) and ionic strength were also studied and investigated. Results evidenced that the prepared CA-NF membranes consists of a sustainable remediation of Cadmium contamination for safe water supply.","PeriodicalId":16427,"journal":{"name":"Journal of Membrane Science and Research","volume":"6 1","pages":"226-234"},"PeriodicalIF":0.0,"publicationDate":"2020-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41605756","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-03-27DOI: 10.22079/JMSR.2020.119041.1316
Jeein Kim, Taejun Park, E. Chung
The impact of controlling molar ratio of ZIF-8 precursors on Pebax 1657 and Pebax 2533 based Mixed Matrix Membranes (MMMs) on the CO2 permeability and CO2 /N2 ideal selectivity was investigated. Three types of ZIF-8 were synthesized by controlling molar ratio of 2-methylimidazole and zinc nitrate hexahydrate as 2/1, 8/1, and 32/1. The SEM images and XRD patterns of ZIF-8 showed that particle sizes and crystallinity peaks were decreased as molar ratio of ZIF-8 increased. The CO2 permeability of Pebax MMM was improved by filling with the ZIF-8 particles compared to the pure Pebax. At equivalent temperatures, the highest CO2 permeability was shown in Pebax 1657/ZIF-8 with the ZIF8 precursors’ molar ratio of 32/1 and Pebax 2533/ZIF-8 with the molar ratio of 2/1. As molar ratio of ZIF-8 precursors increases, CO2 permeability of Pebax 1657 was increased by excessive sorption of CO2 by imidazolium ions in ZIF-8, whereas CO2 permeability of Pebax 2533 was decreased by decreasing pore size and particle size of ZIF-8. The CO2 permeability was higher in Pebax 2533/ZIF-8 compared to Pebax 1657/ZIF-8, because Pebax 2533 has more concentrations of polar groups in the polymer matrix than Pebax 1657. However, the CO2 /N2 ideal selectivity was higher in Pebax 1657/ZIF-8 compared to Pebax 2533/ZIF-8 because diffusivity of Pebax 1657 compared to Pebax 2533 is lower for nonpolar gases, such as N2 , and the solubility is higher for polarizable gases like CO2 . As increasing temperature, Pebax/ZIF-8 MMMs showed enhancement of CO2 and N2 permeability but decreased in CO2 /N2 ideal selectivity.
{"title":"Effect of 2-MeIM/Zn Molar Ratio on CO2 Permeability of Pebax/ZIF-8 Mixed Matrix Membranes","authors":"Jeein Kim, Taejun Park, E. Chung","doi":"10.22079/JMSR.2020.119041.1316","DOIUrl":"https://doi.org/10.22079/JMSR.2020.119041.1316","url":null,"abstract":"The impact of controlling molar ratio of ZIF-8 precursors on Pebax 1657 and Pebax 2533 based Mixed Matrix Membranes (MMMs) on the CO2 permeability and CO2 /N2 ideal selectivity was investigated. Three types of ZIF-8 were synthesized by controlling molar ratio of 2-methylimidazole and zinc nitrate hexahydrate as 2/1, 8/1, and 32/1. The SEM images and XRD patterns of ZIF-8 showed that particle sizes and crystallinity peaks were decreased as molar ratio of ZIF-8 increased. The CO2 permeability of Pebax MMM was improved by filling with the ZIF-8 particles compared to the pure Pebax. At equivalent temperatures, the highest CO2 permeability was shown in Pebax 1657/ZIF-8 with the ZIF8 precursors’ molar ratio of 32/1 and Pebax 2533/ZIF-8 with the molar ratio of 2/1. As molar ratio of ZIF-8 precursors increases, CO2 permeability of Pebax 1657 was increased by excessive sorption of CO2 by imidazolium ions in ZIF-8, whereas CO2 permeability of Pebax 2533 was decreased by decreasing pore size and particle size of ZIF-8. The CO2 permeability was higher in Pebax 2533/ZIF-8 compared to Pebax 1657/ZIF-8, because Pebax 2533 has more concentrations of polar groups in the polymer matrix than Pebax 1657. However, the CO2 /N2 ideal selectivity was higher in Pebax 1657/ZIF-8 compared to Pebax 2533/ZIF-8 because diffusivity of Pebax 1657 compared to Pebax 2533 is lower for nonpolar gases, such as N2 , and the solubility is higher for polarizable gases like CO2 . As increasing temperature, Pebax/ZIF-8 MMMs showed enhancement of CO2 and N2 permeability but decreased in CO2 /N2 ideal selectivity.","PeriodicalId":16427,"journal":{"name":"Journal of Membrane Science and Research","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-03-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45910380","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-03-13DOI: 10.22079/JMSR.2020.118843.1315
S. Daly, A. J. Semiao
Organic matter leads to one of the biggest problems in membranes: fouling. Developing efficient cleaning processes is therefore crucial. This study systematically examines how alginic acid fouling formed under different physical and chemical conditions affect osmotic backwashing cleaning efficiency in forward osmosis (FO). The fouling layer thickness before and after osmotic backwashing was measured by confocal laser scanning microscopy in order to assess cleaning efficiency, along with pure water flux (PWF) measurements. Osmotic backwashing was found to be very efficient. In the absence of Ca2+ in the feed solution, the alginate fouling thickness was fouling layer thickness down to Backwashing also became less effective when the initial membrane fouling flux increased using a draw solution (DS) of 4 M NaCl, with 91 μm of fouling remaining, despite a fullPWF restoration. The use of Ca2+ in the osmotic backwashing DS caused the fouling layer to expand and not be removed due to flux reversal and the interaction between the alginic acid layer and Ca2+. A reduction in the PWF recovery was obtained, showing the type of salt used for backwashing has a severe influence on cleaning efficiency.
{"title":"Mechanisms Involved in Osmotic Backwashing of Fouled Forward Osmosis (FO) Membranes","authors":"S. Daly, A. J. Semiao","doi":"10.22079/JMSR.2020.118843.1315","DOIUrl":"https://doi.org/10.22079/JMSR.2020.118843.1315","url":null,"abstract":"Organic matter leads to one of the biggest problems in membranes: fouling. Developing efficient cleaning processes is therefore crucial. This study systematically examines how alginic acid fouling formed under different physical and chemical conditions affect osmotic backwashing cleaning efficiency in forward osmosis (FO). The fouling layer thickness before and after osmotic backwashing was measured by confocal laser scanning microscopy in order to assess cleaning efficiency, along with pure water flux (PWF) measurements. Osmotic backwashing was found to be very efficient. In the absence of Ca2+ in the feed solution, the alginate fouling thickness was fouling layer thickness down to Backwashing also became less effective when the initial membrane fouling flux increased using a draw solution (DS) of 4 M NaCl, with 91 μm of fouling remaining, despite a fullPWF restoration. The use of Ca2+ in the osmotic backwashing DS caused the fouling layer to expand and not be removed due to flux reversal and the interaction between the alginic acid layer and Ca2+. A reduction in the PWF recovery was obtained, showing the type of salt used for backwashing has a severe influence on cleaning efficiency.","PeriodicalId":16427,"journal":{"name":"Journal of Membrane Science and Research","volume":"6 1","pages":"158-167"},"PeriodicalIF":0.0,"publicationDate":"2020-03-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44554800","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-02-27DOI: 10.22079/JMSR.2020.112911.1283
M. Zamanian, H. Sadrnia, M. Khojastehpour, J. Thibault, F. Hosseini
Nanocomposites made of nanoparticles embedded in the matrix of polymer membranes have been used in the food packaging industry due to their enhanced barrier and mechanical properties. In this study, nanocomposite films made of polyvinyl alcohol (PVA) and titanium dioxide nanoparticles (size = 20 nm, 1 and 2 wt%) were prepared by the solvent casting method and their mechanical, physical, and barrier properties were determined. Scanning electron microscopy (SEM) and X-ray diffraction analysis (XRD) were performed for characterizing the morphology of PVA/TiO2 nanocomposite films. Water vapor permeability (WVP) and oxygen transmission rate (OTR) were measured for mixed matrix PVA films for two concentrations of TiO2 nanoparticles. The results revealed that OTR and WVP decreased with increasing TiO2 nanoparticle concentration. Elongation at the break point and Young’s modulus both increased whereas strength decreased. XRD measurements confirmed the completely dispersed structure formed in the TiO2 nanocomposites. SEM micrographs showed an identical distribution at 1 and 2 wt% levels of TiO2 nanoparticles.
{"title":"Effect of TiO2 Nanoparticles on Barrier and Mechanical Properties of PVA Films","authors":"M. Zamanian, H. Sadrnia, M. Khojastehpour, J. Thibault, F. Hosseini","doi":"10.22079/JMSR.2020.112911.1283","DOIUrl":"https://doi.org/10.22079/JMSR.2020.112911.1283","url":null,"abstract":"Nanocomposites made of nanoparticles embedded in the matrix of polymer membranes have been used in the food packaging industry due to their enhanced barrier and mechanical properties. In this study, nanocomposite films made of polyvinyl alcohol (PVA) and titanium dioxide nanoparticles (size = 20 nm, 1 and 2 wt%) were prepared by the solvent casting method and their mechanical, physical, and barrier properties were determined. Scanning electron microscopy (SEM) and X-ray diffraction analysis (XRD) were performed for characterizing the morphology of PVA/TiO2 nanocomposite films. Water vapor permeability (WVP) and oxygen transmission rate (OTR) were measured for mixed matrix PVA films for two concentrations of TiO2 nanoparticles. The results revealed that OTR and WVP decreased with increasing TiO2 nanoparticle concentration. Elongation at the break point and Young’s modulus both increased whereas strength decreased. XRD measurements confirmed the completely dispersed structure formed in the TiO2 nanocomposites. SEM micrographs showed an identical distribution at 1 and 2 wt% levels of TiO2 nanoparticles.","PeriodicalId":16427,"journal":{"name":"Journal of Membrane Science and Research","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-02-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45518573","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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