Letteratura scientifica selezionata sul tema "Membrane"
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Articoli di riviste sul tema "Membrane"
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Arahman, Nasrul, Bastian Arifin e Fachrul Razi. "Profil Permeabilitas Berdasarkan Struktur Morfologi Membran Polietersulfon pada Pemekatan Larutan Tokoferol (Permeability Profile based on Morphology Structure of Polyethersulfone Membrane on Concentrating the Tocopherol Solution)". Agritech 36, n. 4 (25 febbraio 2017): 416. http://dx.doi.org/10.22146/agritech.16765.
Testo completoAbstract (sommario):
Separation technique by membrane technology has been widely applied for separation and purification of minor components from vegetable oil. Membrane was prepared and modified in several way in order to improve the filtration performance in purification process of vegetable oil. In this work, the filtration performance of three types of polyethersulfone hollow fiber membrane was investigated. The main objective of this research was to study the effect of membranes type on the filtration performance of tocopherol solution. Three series of filtration experiment were conducted by using fabricated membrane by dissolving of polyethersulfone (PES) in N-methyl pyrrolydone (NMP) with different polymer composition. The membranes was M1 = PES 20 % + NMP, M2 = PES 18 % + NMP, and M3= PES 20 %+ Polyvinyl pyrrolidone (PVP 5 %) + NMP. The difference structure of membrans was confirmed by scanning electron microscopy measurement. The permeability profile of tocopherol solution of 500 ppm was observed by using a single module of hollow fiber membrane with filtration flow of pressure driven inside (PDI). It is shown that, the permeability of tocopherol solution was maximum and stable using PES membrane was composed by M3 system. Moreover, the improvement of tocopherol concentration in retentate solution was about two times higher than that the original solution that was obtained from filtration system of M1 membrane.ABSTRAKTeknik separasi dengan membran teknologi telah diaplikasikan secara luas untuk pemisahan dan pemurnian komponen minor dari minyak tumbuh-tumbuhan. Membran telah dibuat dan dimodifikasikan dengan berbagai cara untuk meningkatkan kinerja filtrasi pada proses pemurnian minyak tumbuh-tumbuhan. Pada penelitian ini, dipelajari kinerja filtrasi tiga jenis membran hollow fiber yang terbuat dari polimer polietersulfon. Tujuan utama penelitian adalah untuk melihat pengaruh jenis membran terhadap kinerja filtrasi larutan tokoferol. Tiga seri penelitian ultrafiltrasi telah dirancang dengan menggunakan membran yang dibuat dengan melarutkan polietersulfon (PES) dalam N-metil pirolidon (NMP) dengan komposisi polimer yang berbeda. Ketiga jenis membran yang digunakan adalah M1 = PES 20 % + NMP, M2 = PES 18 % + NMP, dan M3 = PES 20 % + Polivinil pirolidon (PVP 5 %) + NMP. Perbedaan struktur morfologi membran telah dikonfirmasikan dengan analisis scanning electron microscopy. Profil permeabilitas larutan tokoferol 500 ppm diobservasi menggunakan modul tunggal membran hollow fiber dengan tipe aliran pressure driven inside (PDI). Hasil penelitian menunjukkan bahwa permeabilitas larutan tokoferol tertinggi dihasilkan dengan menggunakan membran M3. Lebih lanjut, peningkatan konsentrasi larutan tokoferol sekitar dua kali lebih tinggi dari konsentrasi awal dicapai dari proses filtrasi dengan membran M1.
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Maslahat, Mamay, e Agung Abadi Kiswandono. "STUDI TRANSPOR SENYAWA FENOL MENGGUNAKAN MEMBRAN CAIR POLIEUGENOL DENGAN PELARUT DIKLOROMETANA". Jurnal Sains Natural 1, n. 2 (25 novembre 2017): 145. http://dx.doi.org/10.31938/jsn.v1i2.24.
Testo completoAbstract (sommario):
Study on Phenol Compound Transport using Polieugenol Liquid Membrane with Dichloromrthane Solven Phenol is a component in waste water that is very dangerous, because it is toxic, corosif on skins and carcinogenics. It can be separated by using liquid membranes. Membrane can be a very specific filter. Liquid membrans transport technique used three phase. The phase are donor phase that contain substance to be separated, membrane phase that contains ligan in the organic solvents, and aceptore phase that contain base as release agent of ligans complex. Polyeugenol have a condition as a ligan that is capable as selective chelate agent for phenol coumpounds. In this research, polieugenol were used with dichloromethane solvents as a membrane for separating and transporting phenol separated, NaOH as release phase with variating pHs, concentrations of release phase, transport time and membrane concentrations. The result showed that liquid membrane of polieugenol in dichloromethane solvent can transport phenol at source phase pH 6.5, at optimum released concentration was 0.75 M, optimum transport times was 72 hours, and optimum membran concentrations was 1,5×10-3 with % transport was 65.2%.Keywords : Liquid membrane, polyeugenol, dichlorometane, phenol ABSTRAK Fenol merupakan salah satu komponen dalam air limbah yang sangat berbahaya, karena beracun dan bersifat korosif terhadap kulit serta karsinogenik. Fenol dapat dipisahkan dengan menggunakan membran cair. Membran dapat bertindak sebagai filter yang sangat spesifik. Teknik transpor membran cair melibatkan tiga fasa yaitu fasa donor, mengandung bahan yang akan dipisahkan, fasa membran berisi ligan dalam pelarut organik dan fasa akseptor yang berisi basa sebagai agen pelepas dari kompleks ligan.Polieugenol mempunyai syarat sebagai ligan sehingga mampu berfungsi sebagai agen pengkhelat yang selektif untuk senyawa fenol. Pada penelitian ini digunakan polieugenol dengan pelarut diklorometana sebagai membran untuk pemisahan dan transpor senyawa fenol, dan NaOH sebagai fasa pelucut dengan memvariasikan pH, konsentrasi fasa pelucut, waktu transpor dan konsentrasi membran. Hasil penelitian menunjukan bahwa membran cair polieugenol dalam pelarut diklorometana dapat mentranspor fenol pada pH fasa sumber optimum 6,5, pada konsentrasi pelucut optimum 0,75 M, waktu transpor optimum 72 jam, dan pada konsentrasi membran optimum 1,5×10-3 dengan % transpor 65,2%.Kata kunci : membran cair, polieugenol, diklorometana, fenol
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As'adah, Anis, e Munasir MUNASIR. "REVIEW : PERFORMA MEMBRAN KOMPOSIT MENGGUNAKAN ALIRAN DEAD-END FILTRATION". Inovasi Fisika Indonesia 12, n. 2 (4 luglio 2023): 92–102. http://dx.doi.org/10.26740/ifi.v12n2.p92-102.
Testo completoAbstract (sommario):
Teknologi berbasis membran merupakan salah satu teknologi pengolahan air yang paling banyak diminati saat ini karena memiliki beberapa manfaat seperti konsumsi energi yang begitu relatif rendah dan operasi yang sederhana. Membran Graphene Oxide (GO) termasuk membran yang banyak diminati karena memiliki porositas GO yang tinggi serta ukuran pori nano yang baik. Sehingga dilakukan review artikel tentang performa membran komposit menggunakan aliran dead-end filtration. Bahan-bahan lain yang dapat dikompositkan dengan membran GO seperti Ti3C2Tx, Ni, Isophorone Diisocyanate (IPDI), TiO2, Ag, PAM, Attapulgite (ATP) dan SiO2 yang memiliki potensi untuk filtrasi yang berbeda-bedaseperti untuk filtrasi pada pemisahan molekul dan pengolahan air, filtrasi untuk zat pewarna dan lain-lain. Dalam proses filtrasi membran untuk aliran dead-end filtration merupakan aliran yang secara keseluruhannya akan melewati suatu membran serta partikel akan tertahan pada membran tersebut. Pada review artikel ini didapatkan membran komposit GO/SiO2 yang memiliki performa baik dilihat dari nilai fluks tertinggi sebesar 229.15 L/m2.h.bar di antara membran komposit yang lain dan berpotensi untuk filtrasi pencemaran air.
Kata Kunci: Membran Komposit, Graphene Oxide, Dead-End Filtration
Abstract
Membrane-based technology is one of the most popular water treatment technologies today because it has several benefits such as relatively low energy consumption and simple operation. Graphene Oxide (GO) membranes are among the membranes that are in great demand because they have high GO porosity and good nano pore sizes. Therefore, a review of articles on the performance of composite membranes using dead-end filtration was carried out. Other materials that can be composited with GO membranes such as Ti3C2Tx, Ni, Isophorone Diisocyanate (IPDI), TiO2, Ag, PAM, Attapulgite (ATP) and SiO2 which have different potential for filtration such as for filtration in molecular separation and water treatment , filtration for dyes and others. In the membrane filtration process for dead-end filtration flow is a flow that as a whole will pass through a membrane and the particles will be stuck on the membrane. In this review article, it was found that the GO/SiO2 composite membrane had good performance in terms of the highest flux value of 229.15 L/m2.h.bar among other composite membranes and has the potential to filter water pollution.
Keywords: Composite Membrane, Graphene Oxide, Dead-End Filtration
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Efome, Johnson E., Fan Yang, Dipak Rana, Takeshi Matsuura e Christopher Lan. "Functionalized PVDF Nanofiber Membranes for Desalination by Direct Contact Membrane Distillation". International Journal of Materials Science and Engineering 6, n. 2 (giugno 2018): 67–71. http://dx.doi.org/10.17706/ijmse.2018.6.2.67-71.
Testo completo
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Notriawan, Doni, Nesbah Nesbah, Gustria Ernis, Muhammad Adeng Fadhila, Risky Hadi Wibowo, Reza Pertiwi e Vinolla Ilfanisari. "Aktivitas Antibakteri Membran Nanokomposit Kitosan/Nanopartikel Perak". ALCHEMY 9, n. 1 (30 marzo 2021): 26–31. http://dx.doi.org/10.18860/al.v9i1.11146.
Testo completoAbstract (sommario):
The aim of this study was to make and test the antibacterial activity of chitosan/silver nanoparticles nanocomposite membranes. Nanocomposite membranes were synthesized by chitosan with pluronic using acetic acid as a solvent. Silver nanoparticles were synthesized using the green synthesis method and the makasar fruit (Brucea javanica L. Merr) peel extract as a bioreductor. The silver nanoparticles were composited with a chitosan/pluronic mixture and printed on a glass plate. Nanocomposite membranes were characterized using the FTIR spectrophotometer and the scanning electron microscope (SEM). Nanocomposite membrane were tested for antibacterial activity against Escherechia coli. The UV-Vis spectra showed the formation of silver nanoparticles which were indicated by the absorption at 454 nm and the absorbance value of 0.405. Characterization using FTIR showed no new functional groups formed in the composites of chitosan and pluronic. SEM results showed the difference between the chitosan membrane and the nanocomposite membrane. The surface of nanocomposite membrane showed uneven compared to the chitosan membrane. Nanocomposite membranes have antibacterial activity to inhibit E. coli growth. Keywords: nanocomposite, chitosan/silver nanoparticles, antibacterial Penelitian ini bertujuan untuk membuat dan menguji aktivitas antibakteri membran nanokomposit kitosan/nanopartikel perak. Membran nanokomposit dibuat dengan mensintesis kitosan dengan pluronik menggunakan pelarut asam asetat. Nanopartikel perak disintesis menggunakan metode green synthesis dengan ekstrak kulit buah makasar (Brucea javanica L. Merr) sebagai bioreduktor. Nanopartikel perak dikompositkan dengan campuran kitosan/pluronik dan dicetak di atas plat kaca. Membran nanokomposit dikarakterisasi menggunakan spektrofotometer FTIR dan scanning electron microscope (SEM). Membran nanokomposit dilakukan uji aktivitas antibakteri terhadap Escherechia coli. Spektra UV-Vis menunjukkan terbentuknya nanopartikel perak yang ditandai adanya serapan pada panjang gelombang 454 nm dan absorbansi 0,405. Karakterisasi dengan FTIR menunjukkan tidak adanya gugus fungsi baru yang terbentuk pada komposit dari kitosan dan pluronik. Hasil SEM menunjukkan adanya perbedaan antara membran kitosan dengan membran nanokomposit. Permukaan membran nanokomposit terlihat tidak rata dibandingkan membran kitosan. Membran nanokomposit memiliki aktivitas bakteri sehingga dapat mengambat pertumbuhan bakteri E. coli. Kata kunci: nanokomposit, kitosan/nanopartikel perak, antibakteri
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Indriyani, Vera, Yunita Novianty e Agus Mirwan. "PEMBUATAN MEMBRAN ULTRAFILTRASI DARI POLIMER SELULOSA ASETAT DENGAN METODE INVERSI FASA". Konversi 6, n. 1 (1 aprile 2017): 11. http://dx.doi.org/10.20527/k.v6i1.2994.
Testo completoAbstract (sommario):
Abstrak- Pengolahan air bersih dengan teknologi membran merupakan proses pengolahan air dengan kualitas yang sangat baik dan sesuai untuk pengolahan air minum di negara-negara berkembang karena membran memiliki banyak sekali keunggulan. Salah satu jenis operasi pemisahan membran adalah dengan membran ultrafiltrasi. Ultrafiltrasi merupakan proses penyaringan partikel-partikel dalam rentang ukuran koloid, yaitu larutan dan molekul besar ditahan dipermukaan membran dan zat terlarut dengan ukuran sangat kecil dapat melewati membran. Tujuan dari penelitian ini adalah untuk menentukan komposisi % berat dimetilformamida pada pembuatan membran ultrafiltrasi yang terbaik. Membran ultrafiltrasi ini dibuat dengan memvariasikan konsentrasi aditif dimetilformamida yang berfungsi untuk penentuan ukuran pori membran dan konsentrasi aseton. Pencampuran bahan dilakukan dengan pengadukan selama ± 6 jam, hasil cetakan film polimer dikoagulasi selama 1 jam dalam air es (± 4°C) kemudian dicuci dengan air mengalir dan disimpan dalam wadah yang diberi formalin. Kemudian dilakukan pengujian pada membran tersebut menggunakan air gambut dimana permeat yang dihasilkan di ukur volumenya setiap selang waktu 5 menit untuk menentukan fluks membrannya. Kemudian dilakukan analisa terhadap konsentrasi permeat untuk menentukan koefisien rejeksi, di mana rejeksi yang diharapkan adalah > 90%. Berdasarkan hasil penelitian, membran ultrafiltrasi yang terbaik adalah membran dengan komposisi % berat dimetilformamida 20; 24 dan 28 dimana koefisien rejeksi rata-rata yang diperoleh masing-masing adalah 98,15; 92,80 dan 95,41%. Kata kunci: dimetilformamida, koefisien rejeksi, fluks Abstract-Clean water treatment with membrane technology is a water treatment process with very good quality and suitable for drinking water treatment in developing countries because the membrane has a lot of advantages. One type of membrane separation operation is with ultrafiltration membranes. Ultrafiltration is a process of filtering particles in the size range of colloids, namely liquid while large molecules detained on the surface of the membrane and the solute with very small size can pass through the membrane. The purpose of this study was to determine the best composition of %wt of dimethylformamide in the manufacture of ultrafiltration membranes. Ultrafiltration membrane is made by varying the concentration of the additive of dimethylformamide which serves for the determination of membrane pore size and the concentration of acetone. Mixing materials done by stirring for ± 6 hours, polymer film printouts is coagulated for 1 hour in ice water (± 4 ° C) and then washed with running water and stored in a container containing formalin. Then conducted testing on the membrane using peat water where permeate that generated is measured the volume of each interval of 5 minutes to determine the membrane flux. Then analyzing the concentration of permeate to determine the coefficient of rejection, where the expected rejection is> 90%. Based on the research results, the best ultrafiltration membrane was membrane with composition wt% of dimethylformamide of 20; 24 and 28, where rejection coefficient average respectively was 98.15; 92.80 and 95.41%. Keywords: dimethylformamide, rejection coefficient, flux
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Mirwan, Agus, Vera Indriyani e Yunita Novianty. "PEMBUATAN MEMBRAN ULTRAFILTRASI DARI POLIMER SELULOSA ASETAT DENGAN METODE INVERSI FASA". Konversi 6, n. 1 (28 marzo 2018): 11. http://dx.doi.org/10.31213/k.v6i1.14.
Testo completoAbstract (sommario):
Abstrak- Pengolahan air bersih dengan teknologi membran merupakan proses pengolahan air dengan kualitas yang sangat baik dan sesuai untuk pengolahan air minum di negara-negara berkembang karena membran memiliki banyak sekali keunggulan. Salah satu jenis operasi pemisahan membran adalah dengan membran ultrafiltrasi. Ultrafiltrasi merupakan proses penyaringan partikel-partikel dalam rentang ukuran koloid, yaitu larutan dan molekul besar ditahan dipermukaan membran dan zat terlarut dengan ukuran sangat kecil dapat melewati membran. Tujuan dari penelitian ini adalah untuk menentukan komposisi % berat dimetilformamida pada pembuatan membran ultrafiltrasi yang terbaik. Membran ultrafiltrasi ini dibuat dengan memvariasikan konsentrasi aditif dimetilformamida yang berfungsi untuk penentuan ukuran pori membran dan konsentrasi aseton. Pencampuran bahan dilakukan dengan pengadukan selama ± 6 jam, hasil cetakan film polimer dikoagulasi selama 1 jam dalam air es (± 4°C) kemudian dicuci dengan air mengalir dan disimpan dalam wadah yang diberi formalin. Kemudian dilakukan pengujian pada membran tersebut menggunakan air gambut dimana permeat yang dihasilkan di ukur volumenya setiap selang waktu 5 menit untuk menentukan fluks membrannya. Kemudian dilakukan analisa terhadap konsentrasi permeat untuk menentukan koefisien rejeksi, di mana rejeksi yang diharapkan adalah > 90%. Berdasarkan hasil penelitian, membran ultrafiltrasi yang terbaik adalah membran dengan komposisi % berat dimetilformamida 20; 24 dan 28 dimana koefisien rejeksi rata-rata yang diperoleh masing-masing adalah 98,15; 92,80 dan 95,41%. Kata kunci: dimetilformamida, koefisien rejeksi, fluks Abstract-Clean water treatment with membrane technology is a water treatment process with very good quality and suitable for drinking water treatment in developing countries because the membrane has a lot of advantages. One type of membrane separation operation is with ultrafiltration membranes. Ultrafiltration is a process of filtering particles in the size range of colloids, namely liquid while large molecules detained on the surface of the membrane and the solute with very small size can pass through the membrane. The purpose of this study was to determine the best composition of %wt of dimethylformamide in the manufacture of ultrafiltration membranes. Ultrafiltration membrane is made by varying the concentration of the additive of dimethylformamide which serves for the determination of membrane pore size and the concentration of acetone. Mixing materials done by stirring for ± 6 hours, polymer film printouts is coagulated for 1 hour in ice water (± 4 ° C) and then washed with running water and stored in a container containing formalin. Then conducted testing on the membrane using peat water where permeate that generated is measured the volume of each interval of 5 minutes to determine the membrane flux. Then analyzing the concentration of permeate to determine the coefficient of rejection, where the expected rejection is> 90%. Based on the research results, the best ultrafiltration membrane was membrane with composition wt% of dimethylformamide of 20; 24 and 28, where rejection coefficient average respectively was 98.15; 92.80 and 95.41%. Keywords: dimethylformamide, rejection coefficient, flux
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Noezar, I. "Membran PVA-chitosan crosslinked untuk pemisahan campuran etanol-air secara pervaporasi". Jurnal Teknik Kimia Indonesia 7, n. 1 (9 ottobre 2018): 724. http://dx.doi.org/10.5614/jtki.2008.7.1.3.
Testo completoAbstract (sommario):
One of the technologies for ethanol-water separation is pervaporation. The principles of pervaporation is based on the difference in diffusional rate and solubility of the solution components in membranes. The performance of the membrane, in terms of flux and selectivity, is influenced by the swelling of the membrane due to the interaction between the solution components and the membrane materials. Membrane modification is done by forming chemical bonding between PVA and chitosan, using glutaraldehyde as crosslinking agent. The performance of the PVA-chitosan crosslinked membrane for ethanol-water separation is characterized by high mass flux and reasonably high selectivity. Pressure observed on the permeate side was 0.5 mbar, with a feed ethanol concentration of 93%. Experimental results indicate that the PVA membrane has a higher degree of swelling compared to the crosslinked PVA-chitosan membrane. The PVA-chitosan crosslinked membrane has a higher selectivity compared to the PVA membrane. The highest flux of 0.833 kgm-2hour-1 was produced by the PVA membrane. The highest selectivity of 2.820 was obtained using a 1:1 PVA-chitosan crosslinked membrane.Keywords: PVA-chitosan; crosslinked; pervaporation Abstrak Salah satu teknologi untuk pemisahan etanol-air adalah pervaporasi. Prinsip pemisahan pervaporasi adalah dengan perbedaan laju difusi dan kelarutan komponen campuran pada membran. Kinerja membran berupa fluks dan selektivitas dipengaruhi oleh kondisi swelling membran akibat interaksi komponen dengan material membran. Modifikasi membran dilakukan dengan membentuk ikatan kimia antara PVA dan chitosan dengan glutaraldehid sebagai crosslinking agent. Kinerja membran PVA-Chitosan crosslinked dalam pemisahan campuran etanol-air berupa fluks massa yang tinggi dan selektivitas yang cukup besar. Tekanan pada sisi permeat 0,5 mbar dengan konsentrasi etanol umpan 93%. Hasil penelitian menunjukkan membran PVA memiliki nilai derajat swelling lebih tinggi (0,088) daripada membran PVA-Chitosan crosslinked. Membran PVA-Chitosan crosslinked memiliki selektivitas lebih tinggi daripada membran PVA. Fluks terbesar dimiliki oleh membran PVA senilai 0,833 kgm-2jam-1membran PVA-Chitosan crosslinked 1:1 sebesar 2.820.Kata Kunci : PVA-Chitosan; crosslinked; pervaporasi
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Li, Xue, Jun Pan, Francesca Macedonio, Claudia Ursino, Mauro Carraro, Marcella Bonchio, Enrico Drioli, Alberto Figoli, Zhaohui Wang e Zhaoliang Cui. "Fluoropolymer Membranes for Membrane Distillation and Membrane Crystallization". Polymers 14, n. 24 (12 dicembre 2022): 5439. http://dx.doi.org/10.3390/polym14245439.
Testo completoAbstract (sommario):
Fluoropolymer membranes are applied in membrane operations such as membrane distillation and membrane crystallization where hydrophobic porous membranes act as a physical barrier separating two phases. Due to their hydrophobic nature, only gaseous molecules are allowed to pass through the membrane and are collected on the permeate side, while the aqueous solution cannot penetrate. However, these two processes suffer problems such as membrane wetting, fouling or scaling. Membrane wetting is a common and undesired phenomenon, which is caused by the loss of hydrophobicity of the porous membrane employed. This greatly affects the mass transfer efficiency and separation efficiency. Simultaneously, membrane fouling occurs, along with membrane wetting and scaling, which greatly reduces the lifespan of the membranes. Therefore, strategies to improve the hydrophobicity of membranes have been widely investigated by researchers. In this direction, hydrophobic fluoropolymer membrane materials are employed more and more for membrane distillation and membrane crystallization thanks to their high chemical and thermal resistance. This paper summarizes different preparation methods of these fluoropolymer membrane, such as non-solvent-induced phase separation (NIPS), thermally-induced phase separation (TIPS), vapor-induced phase separation (VIPS), etc. Hydrophobic modification methods, including surface coating, surface grafting and blending, etc., are also introduced. Moreover, the research advances on the application of less toxic solvents for preparing these membranes are herein reviewed. This review aims to provide guidance to researchers for their future membrane development in membrane distillation and membrane crystallization, using fluoropolymer materials.
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Saputra, Hens. "Pembuatan dan Karakteristik Membran Reaktor Zeolit". Majalah Ilmiah Pengkajian Industri 8, n. 1 (29 luglio 2019): 11–16. http://dx.doi.org/10.29122/mipi.v8i1.3643.
Testo completoAbstract (sommario):
Membran reaktor merupakan konsep perpaduan dari sistem reaksi dan proses pemisahan/pemurnian. Membran ini disebut juga sebagai membran katalis atau sistem katalis-membran. Dengan membran reaktor ini diharapkan konversi suatu reaksi dapat ditingkatkan dan diperoleh suatu produk yang memiliki tingkat kemurnian lebih tinggi. Sebagai katalis digunakan silica alumina yang berukuran 1,0 mm. Membran anorganik zeolit MFI dilapiskan menutupi seluruh permukaan katalis. Bahan baku yang digunakan antara lain tetraethylortosilikat (TEOS) sebagai sumber silikat dan template organik tetraprophyl ammonium bromide (TPABr). Proses kristalisasi dilakukan pada temperatur 453 K di dalam autogeneous autoclave, dilanjutkan dengan kalsinasi pada temperatur 873 K selama 1 jam. Karakterisasi membran zeolit yang dihasilkan dilakukan dengan X-ray diffraction (XRD) dan pengamatan dengan Scanning Electron Mycroscope (SEM). Karakteristik pori dipelajari menggunakan metode physisorption dan BJH pore size distribution. Selain itu dilakukan pula uji selektifitas dan alkilasi toluena dan xylene. Berdasarkan pengamatan menggunakan XRD mengindikasikan adanya struktur zeolit MFI pada sampel membrane katalis yang dihasilkan. Diperkuat dengan obserbasi SEM menunjukkan bahwa membran zeolit MFI melapisi seluruh permukaan pelet silika alumina dan terdapat indikasi terjadinya komposit terhadap silika alumina pada daerah perbatasan antara membran zeolit atau lapisan bagian luar dengan katalis silika alumina. Hasil pengujian menunjukkan hasil bahwa membran reaktor zeolit MFI berpotensi untuk diaplikasikan sebagai membran katalis yang bersifat sangat selektif terhadap bentuk suatu molekul. Sebagai contoh kasus, suatu isomer dapat dipisahkan satu sama lain secara selektif, sehingga dapat meningkatkan konversi reaksi.Kata kunci : Membran reaktor, isomer, xylene, zeolit, silika alumina, hydrothermal.AbstractMembrane fusion reactor is the concept of the reaction system and the process of separation/purification . These membranes are called also as membrane catalysts or catalyst - membrane system . With the membrane reactor is expected conversion reaction can be improved and obtained a product which has a higher degree of purity . As used silica alumina catalyst measuring 1.0 mm . MFI zeolite coated inorganic membranes covering the entire surface of the catalyst . The raw materials used include tetraethylortosilikat (TEOS ) as a source of silicate and organic template tetraprophyl ammonium bromide ( TPABr ) . Crystallization process carried out at a temperature of 453 K in the autogeneous autoclave , followed by calcination at a temperature of 873 K for 1 hour . Characterization of zeolite membranes produced by X - ray done diffraction ( XRD ) and scanning electron observations with Mycroscope ( SEM ) . Pore characteristics studied physisorption using BJH pore size and distribution . Test will be conducted and the selectivity of toluene and xylene alkylation . Based on observations using XRD indicates the MFI zeolite structure on the resulting catalyst membrane samples . Reinforced with obserbasi SEM showed that the MFI zeolite membrane coating the entire surface of the silica- alumina pellets and there are indications of the silica- alumina composite in the border area between the zeolite membrane or outer layer of silica alumina catalyst . The results show that the results of the MFI zeolite membrane reactor has the potential to be applied as the membrane is highly selective catalyst to form a molecule . As an example case , an isomer can be separated from each other selectively , so as to increase the reaction conversionKeywords : Membrane reactors, isomers, xylene, zeolite, silica alumina, hydrothermal.
Tesi sul tema "Membrane"
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PAGLIERO, MARCELLO. "New membranes for membrane distillation process". Doctoral thesis, Università degli studi di Genova, 2021. http://hdl.handle.net/11567/1046350.
Testo completoAbstract (sommario):
The PhD research program was focused of the development of new hydrophobic membranes suitable for membrane distillation (MD) operation. In particular, the preparation of polymeric flat sheet membranes via nonsolvent induced phase separation (NIPS) technique was investigated. This method allows to fine-tune a large number of variables in order to obtain membranes with an ample variety of different morphologies and properties. Therefore, a systematic study on the important factors affecting the membrane structure, which in turn determines the distillation performance, was carried out. The selected polymer was polyvinylidene fluoride (PVDF), the solvent was dimethylformamide (DMF).
First, the effect of the dope solution composition was evaluated. The polymer amount was found to be a key element in defining the porosity and the pore size of the final membrane. Moreover, a minimum critical concentration required to obtain a proper structure was identified on the basis of the dope solution viscosity. In fact, at lower concentrations brittle or defective films were produced.
Another important preparation parameter thoroughly investigated was the coagulation bath strength. Harsh nonsolvents induce fast precipitation creating a dense skin above a macrovoid-dominated layer, while weak coagulation media promote a delayed demixing and generate uniform and symmetric structures. Using a semi crystalline polymer such as PVDF, the precipitation rate becomes even more important because it also influences the crystallization of the polymer. The strength of the coagulation bath was regulated by adding different amounts of ethanol to the water bath, from 0% up to 96% v/v. Optimization of this parameter allowed to prepare almost superhydrophobic membranes that were able to withstand the pressure and temperature conditions during vacuum membrane distillation (VMD) tests and to deliver high distillate fluxes and total salt rejection when treating a concentrated NaCl solution.
A different approach to improve the membrane performance was exploited in further phase of activity. Different kinds of pore forming agents – such as polyethylene glycols and lithium chloride – were added to the dope solution in order to enhance the porosity and control the pore size. Since the support material can act as an added mass transfer resistance, it was decided to cast these membranes without any reinforcement. However, the absence of any rigid support caused severe shrinkage phenomena during the drying of the membranes leading to an almost complete collapse of the porous structure. It was found that the structure could be preserved by simply clamping the wet membrane on a stiff planar surface and leaving it to dry at room temperature.
The amount and type of the additive had impacts on both kinetic and thermodynamic factors governing the phase separation process. By adjusting the dope solution composition, it was possible to favour one or the other to obtain membranes with the desired structure and performance. These unsupported membranes were not able to bear the pressure difference normally applied during VMD, therefore they were tested using a direct contact membrane distillation (DCMD) setup.
Since the presence of the support material is mandatory for VMD application, the effect of different kinds of supports was investigated. In particular, several commercial nonwovens were used to prepare PVDF membranes based on the knowledge acquired during the first phase of the PhD activity. Moreover, along with the nonwovens, three polymeric nets, characterized by different structure and made with different polymers, were tested as possible supports. While the commercial nonwovens did not alter too much the performance and morphology of the PVDF membranes, using the nets some remarkable effects were registered. The alternation between holes and crests of the nets caused the formation of membranes with zones having different porosities. The VMD tests highlighted the better performance of the nonwoven casted membranes. However, the patterned surface of the net supported membranes resulted in lower flux decline when a concentrated NaCl solution was used as feed.
Polymeric membranes are the most studied type for MD application both for the easy processability and the low production costs. Moreover, the commonly used polymers can withstand the normal operation conditions for desalination or wastewater treatment applications. However, the possibility of producing membranes able to resist higher temperatures and pressures would open the way to new MD applications. One of the possible paths to reach this goal is the exploitation of ceramic membranes. Ceramic material are nevertheless naturally hydrophilic and surface modification procedures must be carried out in order to turn such membranes hydrophobic. Therefore, the reaction between the surface hydroxyl groups of alumina commercial membranes and a silanizing agent was exploited. By changing the reaction conditions, it was possible to obtain highly hydrophobic membranes without affecting the initial pore size and porosity. This functionalizing surface layer proved to be stable up to 400°C which would allow to cover any possible MD operation condition.
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Fawzy, Mohamed Khaled Adel <1990>. "Innovative Ceramic Membranes for Sweeping Gas Membrane Distillation: Membrane Characterization and Process Development". Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2020. http://amsdottorato.unibo.it/9284/1/PhD_Thesis_Mohamed_Fawzy.pdf.
Testo completoAbstract (sommario):
The employment of tubular hydrophobic carbon-based titania membranes in sweeping gas membrane distillation (SGMD) was studied in this PhD thesis. The characterization of some of the membrane morphological properties was implemented by experimental and modeled results of gas permeation tests. The dusty gas model was adopted in gas permeation modeling. Two different approaches were followed during modeling. The first approach considered the morphological properties of each single membrane layer. As for the second approach, average membrane morphological properties were characterized without considering the unique contribution of each layer.
The investigation of the module performance during SGMD operations was achieved by experimental and modeling studies for NaCl (aq.). The model considered the Knudsen and molecular diffusion mechanisms. The module was capable of undergoing experiments at temperatures up to 110°C. Experimental flux results went in agreement with the modeled values obtained on using the morphological properties of each membrane layer. On the contrary, the modeled values obtained on considering average membrane morphological properties deviated significantly from the experimental results. The model was also used to estimate the effect of the operating conditions and flow configuration on water flux. Other modeling studies of the modules were performed for ethanol (aq.) to predict the effect of the operating conditions on the membrane selectivity. The Maxwell-Stefan approach was followed in this case.
Eventually, a hypothetical sweater desalination process was proposed incorporating SGMD (using the modules studied in this thesis) as the desalination unit. Process development and optimization were carried out. The optimized case corresponded to SGMD liquid inlet temperature of 107°C for an SGMD vessel having a length of 5.4 m. This corresponded to a water production cost of 20.9 $/m3 such that the feed heating was the determinant cost item. This cost could be mitigated in case of using a waste heat source.
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Rane, Mahendra. "Porous Membrane". Doctoral thesis, Universitätsbibliothek Chemnitz, 2010. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-201000336.
Testo completoAbstract (sommario):
Membrane processes can cover a wide range of separation problems [with a
specific membrane (membrane structure) required for every problem]. Thus,
there are membranes available that differ in their structure and consequently in
the functionality. Therefore membrane characterization is necessary to ascertain,
which membrane may be used for a certain separation. Membranes of pore size
ranging from 100nm to 1μm with a uniform pore size are very important in
membrane technology. An optimum performance is achieved when the
membrane is as thin as possible having a uniform pore size.
Here in this thesis, membranes were synthesized by particle assisted wetting
using mono-layers of silica colloids as templates for pores along with
polymerizable organic liquids on water surface. The pore size reflects the
original shape of the particles. Thus it is possible to tune the pore size by
varying the particle size. This method is effective to control pore sizes of
membranes by choosing silica particles of suitable size.
This approach gives a porous structure that is very thin, but unfortunately
limited in mechanical stability. Thus there is a need for support which is robust
and can withstand the various mechanical stresses. A small change in the
membrane or defect in the layered structure during the membrane formation can
have drastic effect on the assembly. Lateral homogeneity of the layer generated
by the particle assisted wetting can be judged by examination of its reflectivity,
but once it is transferred on any solid support this option is no more.
So a method is needed to detect the cracks or the inhomogenity of the
membrane which can be detected even after the transfer. To tackle this problem
a very simple and novel technique for characterizing the membrane by
fluorescence labeling and optical inspection was developed in this thesis. The
idea was to add a fluorescent dye which is poorly water soluble to the spreading
solution comprising of the particles and the monomer. If the dye survived the
photo-cross linking, then it would be embedded in the cross-linked polymer and
would serve as a marker. Defects and inhomogenity would show up as cracks
and spots. By the method that we have developed, we can detect our membrane
from the support and spot defects.
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Shi, Jinjun. "Composite Membranes for Proton Exchange Membrane Fuel Cells". Wright State University / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=wright1214964058.
Testo completo
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Roselló, Busquets Cristina. "Paper de la Sintaxina-1 i els lipid rafts en guia axonal i regeneració neural". Doctoral thesis, Universitat de Barcelona, 2019. http://hdl.handle.net/10803/668211.
Testo completoAbstract (sommario):
Durant el desenvolupament del sistema nerviós cal que les cèl·lules formades a una zona concreta migrin fins a la seva posició final o bé que projectin els seus axons per tal de contactar amb les seves cèl·lules diana. En aquest procés participen multitud de molècules de guia axonal i els seus receptors, que produiran l’atracció o la repulsió de l’axó, guiant-lo fins a la seva posició final. En aquest procés el conus de creixement té un paper clau ja que és on es localitzen la majoria d’aquests receptors i on es dona el recanvi de membrana a través de l’exocitosi i endocitosi, necessàries pel creixement de l’axó. En aquests processos de fusió de membrana participen les proteïnes SNARE, entre elles la Sintaxina-1. Una de les molècules guia més importants durant el desenvolupament del sistema nerviós és la Netrina-1. Aquesta molècula té diferents receptors i segons al receptor que s’uneixi provocarà atracció o repulsió. Estudis previs demostren que la la Sintaxina-1 interacciona amb un dels receptors de la Netrina-1, el DCC, i que aquesta interacció és necessària, durant el desenvolupament de la medul·la espinal, per a l’atracció de les neurones comissurals in vitro. Hi ha pocs estudis on s’investigui el paper de les proteïnes SNARE en guia axonal in vivo. Per aquesta raó, en aquesta tesi estudiem el paper de les proteïnes SNARE, específicament de la Sintaxina-1, en la guia axonal de les neurones comissurals, durant el desenvolupament de la línia mitja i la medul·la espinal, en tres models animals diferents (mosca, pollastre i ratolí). Per mitjà de la supressió dels gens de diferents proteïnes SNARE, demostrem que la Sintaxina-1 és necessària per la correcta guia axonal de les neurones comissurals i el correcte desenvolupament de la medul·la a les tres espècies. A més, confirmem que la pèrdua de funció de la Sintaxina-1 comporta una pèrdua de la sensibilitat de les neurones comissurals a les molècules de guia axonal Netrina-1 i Slit-2 i que la funció de la Sintaxina-1 està conservada en diferents processos de guia axonal com la repulsió depenent de Slit/ROBO a les neurones comissurals, i la repulsió depenent de Netrina-1/UNC5 a les neurones de la EGL.
La majoria dels mecanismes involucrats en la guia axonal durant el desenvolupament són molt similars als processos que es donen durant la regeneració. Gran part dels receptors que participen en guia axonal i creixement estan localitzats en microdominis de membrana rics en esfingolípids i colesterol, anomenats lipid rafts, i la seva funcionalitat depèn de la correcta localització en aquests microdominis. A més el colesterol proporciona ordre i rigidesa a les membranes. Aquí demostrem com al disminuir el colesterol de les membranes incrementem el creixement neurític, l’àrea dels conus de creixement, la densitat dels fil·lopodis i la ramificació de neurones immadures del sistema nerviós central i perifèric cultivats in vitro. A més, demostrem que la pèrdua de colesterol afavoreix la regeneració de neurones hipocampals axotomitzades in vitro, de la via perforant en cultius organotípics i del nervi ciàtic in vivo. Finalment, també demostrem que la Nistatina, una droga àmpliament utilitzada per eliminar els lipid rafts de les membranes, incrementa la regeneració in vitro de neurones d’hipocamp activant l’enzim òxid nítric sintasa i, en conseqüència, incrementant els nivells d’òxid nítric.During the nervous system development neurons have to migrate and extend their axons to connect with their targets. In this process a huge amount of axon guidance molecules and their receptors participate to produce axon attraction or repulsion, guiding them to their final position. The growth cone has a key role in this process because the majority of receptors are localized in its surface and is where membrane turnover takes place. SNARE proteins are important components for membrane fusion in both, exocytosis and endocytosis, and their participation in axon guidance has been recently described. One important molecule during the nervous system development is Netrin-1. This guidance cue has different receptors and has the ability to produce attraction or repulsion depending on the receptor it binds. Recent studies have demonstrated that one of the SNARE proteins, Syntaxin-1, interacts with the Netrin-1 receptor DCC and that this interaction is necessary for the attraction of the commissural neurons. In this thesis we study the role of Syntaxin-1 during the commissural neuron guidance in three different animal models (fly, chicken and mouse). Deleting SNARE genes, we demonstrate that Syntaxin-1 is necessary for the correct commissural axon guidance and the correct spinal cord development in the three species. The mechanisms that regulate axon growth during development are very similar to processes that take place during axon regeneration. A variety of axon guidance receptors are localized in membrane microdomains enriched in cholesterol, termed lipid rafts, whose functionality depends on the proper localization within these microdomains. Here, we demonstrate that cholesterol depletion increases neurite growth, growth cone area, filopodia density and branching in immature neurons of the central and peripheral nervous system in vitro. Moreover, cholesterol depletion enhances axon regeneration after axotomy in vitro in dissociated hippocampal neurons, in slice organotypic cultures and in sciatic nerve in vivo. Finally, we also demonstrate that hippocampal regeneration in vitro is increased when nitric oxide synthase is activated by Nystatin treatments, a well-known drug used to disrupt lipid rafts from the cell membrane.
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Whitehead, L. "Computer simulation of biological membranes and membrane bound proteins". Thesis, University of Southampton, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.297412.
Testo completo
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Dickson, Callum. "In silico modelling of membranes and drug membrane interactions". Thesis, Imperial College London, 2014. http://hdl.handle.net/10044/1/25070.
Testo completoAbstract (sommario):
A new all-atom force field for the simulation of phospholipid bilayers using the AMBER molecular dynamics package has been developed, which is compatible with other AMBER protein, nucleic acid, carbohydrate and small molecule force fields. The force field has been validated by simulating bilayers of six different lipid types, finding favourable comparison to experiment for properties such as area per lipid, volume per lipid, bilayer thickness, NMR order parameters, scattering data, and lipid lateral diffusion. The modular nature of this force field allows numerous combinations of head and tail groups to create different lipid types, enabling the easy insertion of new lipid species. The lipid bilayer model has then been applied to the study of the interaction between radioimaging agents and membranes in an effort to understand the phenomena of non-specific binding, which remains poorly understood yet of serious detrimental consequence to the development of new imaging tracers. The effect of different concentrations of imaging agent on a homogeneous membrane has been examined using unbiased simulations, whilst the permeability coefficient of each imaging agent through a membrane has been calculated using biased simulations. It is found that radiotracers with low non-specific binding must adopt a certain orientation to cross the head group region of a membrane - this requirement may act as a barrier to membrane entry. Furthermore, once partitioned into the membrane, simulations predict that those radiotracers displaying a high degree of non-specific binding act to order lipid tail groups to a greater extent than those with low non-specific binding, reducing the permeability of the membrane and possibly acting to 'trap' radiotracer in the membrane. These simulations also predict that non-specific binding is not related to radiotracer membrane permeability through a homogeneous bilayer.
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Ma, Yaning. "Characterization of Membrane Permeability and Polymer-Stabilized Model Membranes". Thesis, The University of Arizona, 2007. http://hdl.handle.net/10150/193347.
Testo completoAbstract (sommario):
The permeability of lipid bilayer membranes to glucose and carboxyfluorescein has been studied in model membranes. Using an enzyme assay, the permeability of glucose was monitored spectrometrically with both large and giant unilamellar vesicles (LUVs and GUVs). The permeability of carboxyfluorescein was studied by entrapping the dye and monitoring its leakage over time from a single GUV. Permeability study using GUVs may provide new information that cannot be obtained from LUVs.The stability of lipid membranes was enhanced by incorporating polymer scaffold. LUVs were prepared with hydrophobic monomers partitioned and then polymerized inside the hydrophobic interior of the lipid bilayers. The sizes of the formed polymers were characterized using gel permeation chromatography and mass spectrometry. This study suggests that large molecular weight polymers were formed inside the lipid bilayers and that the stability of the membranes is related to the size of the polymers.
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Lycon, David Steven. "Flux enhancement and fouling reduction in a centrifugal membrane process". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape8/PQDD_0021/NQ44796.pdf.
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Keuler, Johan Nico. "Optimising catalyst and membrane performance and performing a fundamental analysis on the dehydrogenation of ethanol and 2-butanol in a catalytic membrane reactor". Thesis, Link to the online version, 2000. http://hdl.handle.net/10019.1/1277.
Testo completoLibri sul tema "Membrane"
1
H, Maddy A., e Harris J. R, a cura di. Membrane biogenesis. New York: Plenum Press, 1994.
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Graham, J. M. Membrane analysis. Oxford, UK: BIOS Scientific Publishers, 1997.
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Basile, Angelo, e Fausto Gallucci, a cura di. Membranes for Membrane Reactors. Chichester, UK: John Wiley & Sons, Ltd, 2011. http://dx.doi.org/10.1002/9780470977569.
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Drioli, Enrico, e Masayuki Nakagaki, a cura di. Membranes and Membrane Processes. Boston, MA: Springer US, 1986. http://dx.doi.org/10.1007/978-1-4899-2019-5.
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E, Drioli, e Nakagaki Masayuki 1923-, a cura di. Membranes and membrane processes. New York: Plenum Press, 1986.
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Harris, Maddy Alun, e Harris James R, a cura di. Subcellular Biochemistry. New York: Plenum, 1994.
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Thomas, Tsotsis Theodore, a cura di. Catalytic membranes and membrane reactors. Weinheim: Wiley-VCH, 2002.
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NATO, Advanced Study Institute on New Perspectives in the Dynamics of Assembly of Biomembranes (1987 Cargèse France). Membrane biogenesis. Berlin: Springer-Verlag, 1988.
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1950-, Gomez-Fernandez J. C., Chapman Dennis 1927- e Packer Lester, a cura di. Progress in membrane biotechnology. Basel: Birkhäuser Verlag, 1991.
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J, Hilderson Herwig, e Ralston Gregory B, a cura di. Physicochemical methods in the study of biomembranes. New York: Plenum Press, 1994.
Cerca il testo completoCapitoli di libri sul tema "Membrane"
1
Téllez, Carlos, e Miguel Menéndez. "Zeolite Membrane Reactors". In Membranes for Membrane Reactors, 243–73. Chichester, UK: John Wiley & Sons, Ltd, 2011. http://dx.doi.org/10.1002/9780470977569.ch8.
Testo completo
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Hori, Ryohei, Ken-ichi Inui, Mikihisa Takano e Tomonobu Okano. "Transport Mechanisms of Organic Ions in Rat Renal Brush Border and Basolateral Membrane Vesicles". In Membranes and Membrane Processes, 1–7. Boston, MA: Springer US, 1986. http://dx.doi.org/10.1007/978-1-4899-2019-5_1.
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Kimizuka, H., Y. Nagata e W. Yang. "Ion and Solvent Transports Through Amphoteric Ion Exchange Membrane". In Membranes and Membrane Processes, 85–92. Boston, MA: Springer US, 1986. http://dx.doi.org/10.1007/978-1-4899-2019-5_10.
Testo completo
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Hernandez, A., J. A. Ibañez e A. F. Tejerina. "A Selective Parameter for Ionic Membrane Transport Selectivity and Porosity of Several Passive Membranes". In Membranes and Membrane Processes, 93–99. Boston, MA: Springer US, 1986. http://dx.doi.org/10.1007/978-1-4899-2019-5_11.
Testo completo
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Lindheimer, A., D. Cros, B. Brun e C. Gavach. "Ionic Permeability of the S18 Saft Carboxylic Membrane". In Membranes and Membrane Processes, 101–13. Boston, MA: Springer US, 1986. http://dx.doi.org/10.1007/978-1-4899-2019-5_12.
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Strathmann, H. "Preparation of Microporous Membranes by Phase Inversion Processes". In Membranes and Membrane Processes, 115–35. Boston, MA: Springer US, 1986. http://dx.doi.org/10.1007/978-1-4899-2019-5_13.
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Pittalis, F., e F. Bartoli. "Chitosan Hollow Fibers: Preparation and Properties". In Membranes and Membrane Processes, 137–42. Boston, MA: Springer US, 1986. http://dx.doi.org/10.1007/978-1-4899-2019-5_14.
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Han, S. J., K. F. Wu, G. X. Wu e Y. B. Wang. "Research on the Preparation of a New Type of Polyarylsulfone Membrane for Ultrafiltration". In Membranes and Membrane Processes, 143–49. Boston, MA: Springer US, 1986. http://dx.doi.org/10.1007/978-1-4899-2019-5_15.
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Espenan, J. M., e P. Aptel. "Outer Skinned Hollow-Fibers-Spinning and Properties". In Membranes and Membrane Processes, 151–61. Boston, MA: Springer US, 1986. http://dx.doi.org/10.1007/978-1-4899-2019-5_16.
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Bottino, A., G. Capannelli e S. Munari. "Factors Affecting the Structure and Properties of Asymmetric Polymeric Membranes". In Membranes and Membrane Processes, 163–78. Boston, MA: Springer US, 1986. http://dx.doi.org/10.1007/978-1-4899-2019-5_17.
Testo completoAtti di convegni sul tema "Membrane"
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Bradenburg, Frank. "Architectural Membranes Used for Tensile Membrane Structures". In Structures Congress 2009. Reston, VA: American Society of Civil Engineers, 2009. http://dx.doi.org/10.1061/41031(341)100.
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Oviroh, Peter Ozaveshe, Rokhsareh Akbarzadeh e Tien-Chien Jen. "Biomimetic Membrane Simulation for Water Desalination". In ASME 2018 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/imece2018-86664.
Testo completoAbstract (sommario):
Reverse Osmosis (RO) for the desalination of saline water is associated with tremendous energy costs and low efficiency. Improvements in nanotechnology have led to the development of a variety of nanoporous membranes for water purification. Biomimetic membrane is an emerging new technology for water purification. Consequently, there is still much to study about the function and structure of these kinds of membranes. The purpose of this work was to determine which factors influence membrane performance. The focus was on those factors affecting membranes in pure water. Biomimetic membrane using MoS2 which has a higher rate of ion rejection and higher water permeability was studied through molecular dynamics simulations using reactive force fields (ReaxFF). The behaviour of the membrane before subjecting it to desalination was studied. The effect of water temperature, atmospheric pressure and membrane thickness on performance of membrane was studied. The permeability flux was calculated and compared in different conditions and the relation between these factors was revealed.
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Yamamoto, Takao. "Membrane-Membrane Interaction and Free Energy of Multilayer Membrane System". In SLOW DYNAMICS IN COMPLEX SYSTEMS: 3rd International Symposium on Slow Dynamics in Complex Systems. AIP, 2004. http://dx.doi.org/10.1063/1.1764092.
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"2014 Asian conference on membrane computing [Copyright]". In 2014 Asian Conference on Membrane Computing (ACMC). IEEE, 2014. http://dx.doi.org/10.1109/acmc.2014.7065808.
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Jahangiri Mamouri, Sina, Volodymyr V. Tarabara e André Bénard. "Numerical Simulation of Filtration of Charged Oil Particles in Stationary and Rotating Tubular Membranes". In ASME 2015 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/imece2015-52038.
Testo completoAbstract (sommario):
Cross flow filtration (CFF) is a common membrane separation process with applications in food, biochemical and petroleum industries. In particular, membranes can be used for liquid-liquid separation processes such as needed in oil-water separation. A major challenge in cross flow filtration is membrane fouling. It can decrease significantly the permeate flux and a membrane’s efficiency. Membrane fouling can be mitigated by inducing shear on the membrane’s surface and this can be enhanced by inducing a swirl in the flow. In addition, a possible approach to improve membrane efficiency consists of repelling droplets/particles from the porous surface toward the centerline using a repulsive electric force. For this purpose, the surface of the membrane can be exposed to electric potential and droplets/particles are also induced to have the same electric charge. In this work, numerical simulations of charged non-deformable droplets moving within an axially rotating charged tubular membrane are performed. The results show that by increasing the electric potential on the membrane surface, the repelling force increases which obviously improves the grade efficiency of the membrane. However, the electric field gradients found in the flow field require large potentials on the membrane surface to observe a noticeable effect. Hence, a smaller solid cylinder is located in the centerline of the flow channel with zero potential. This solid cylinder enhances the electric field gradient in the domain which results in higher repelling forces and larger grade efficiency of the membrane at small potentials. The addition of a small cylinder in the flow field also improves the grade efficiency increases due to the higher shear stress near the membrane surface.
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Faiz, Mehwish, Areej Ahmed e Sumaya Abid. "Discriminating plasma membrane, internal membrane, and organelle membrane proteins by SVM". In 2021 4th International Conference on Computing & Information Sciences (ICCIS). IEEE, 2021. http://dx.doi.org/10.1109/iccis54243.2021.9676407.
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Gao, Jia, Seungbae Park, James Pitarresi e Dorel Homentcovschi. "Wrinkling of Thin Membrane Under Thermal Loading". In ASME 2006 International Mechanical Engineering Congress and Exposition. ASMEDC, 2006. http://dx.doi.org/10.1115/imece2006-16256.
Testo completoAbstract (sommario):
There has been an increasing interest in the applications of thin membrane in space application, flexible electronic display, manufacturing of glass displays and growth of film on materials at elevated temperatures. Because of the negligible bending stiffness of thin membranes, membranes are lack of resistance to compressive stress. For the applications at high temperatures, the thermal expansion coefficient mismatch between membrane and substrate materials may generate compressive stress that causes the membrane buckling. The study of thermal buckling of isotropic elastic plate in the context of the large - deflection theory was the subject of a series of papers[1-5]. However, it has been noted that none of these papers has considered the second buckling of the membrane resulting in membrane wrinkling. The presence of wrinkles may significantly change deflection and stress profile of membranes. So, it is important to develop an effective analysis method to investigate the wrinkle formation and evolution in membrane subjected the elevated temperature. This paper presents the experiment work to investigate wrinkle formation and evolution in membranes heated from room temperature up to 170 °C. The specimens consist of polymer and metal membranes with steel and silicon substrate respectively. A wide range of membrane shapes and aspect ratios are considered in this work. An experiment set up is developed to study the deflection profiles of membranes at discrete temperatures. The information gained from this experiment work is used to validate numerical modeling results. The Finite Element Analysis results using nonlinear post-buckling analysis are also included in this paper. The nonlinear post-buckling analysis provides a good understanding of the mechanism of wrinkle generation and evolution as temperature increased. It is shown that the first buckling of membrane significantly reduces bending stiffness thus to create localized buckling modes accounting for the wrinkle generation. The wrinkle pattern is stable until the temperature reaches the next critical value. After this critical temperature, the wrinkle pattern is changed until temperature reaches the next critical value. The new wrinkle pattern is keeping evolved until the final temperature is reached. The finite element analysis results are in good agreement with experimental observations.
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Mateus, Marilia, Luis Raiado-Pereira e Miguel Prazeres. "Membrane chromatography for therapeutic DNA production: Adsorption membranes development". In 2011 1st Portuguese Meeting in Bioengineering ¿ The Challenge of the XXI Century (ENBENG). IEEE, 2011. http://dx.doi.org/10.1109/enbeng.2011.6026054.
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Soares, T. A., T. P. Straatsma, Theodore E. Simos e George Maroulis. "Towards Simulations of Outer Membrane Proteins in Lipopolysaccharide Membranes". In COMPUTATIONAL METHODS IN SCIENCE AND ENGINEERING: Theory and Computation: Old Problems and New Challenges. Lectures Presented at the International Conference on Computational Methods in Science and Engineering 2007 (ICCMSE 2007): VOLUME 1. AIP, 2007. http://dx.doi.org/10.1063/1.2836008.
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Chandra, P. Helen, S. M. Saroja Theerdus Kalavathy e M. Nithya Kalyani. "Simple test tube splicing on images". In 2014 Asian Conference on Membrane Computing (ACMC). IEEE, 2014. http://dx.doi.org/10.1109/acmc.2014.7065797.
Testo completoRapporti di organizzazioni sul tema "Membrane"
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Husson, Scott M., Viatcheslav Freger e Moshe Herzberg. Antimicrobial and fouling-resistant membranes for treatment of agricultural and municipal wastewater. United States Department of Agriculture, gennaio 2013. http://dx.doi.org/10.32747/2013.7598151.bard.
Testo completoAbstract (sommario):
This research project introduced a novel membrane coating strategy to combat biofouling, which is a major problem for the membrane-based treatment of agricultural and municipal wastewaters. The novelty of the strategy is that the membrane coatings have the unique ability to switch reversibly between passive (antifouling) and active (antimicrobial) fouling control mechanisms. This dual-mode approach differs fundamentally from other coating strategies that rely solely on one mode of fouling control. The research project had two complementary objectives: (1) preparation, characterization, and testing of dual-mode polymer nanolayers on planar surfaces and (2) evaluation of these nanolayers as membrane modifiers. The first objective was designed to provide a fundamental understanding of how polymer nanolayer chemistry and structure affect bacterial deposition and to demonstrate the reversibility of chemical switching. The second objective, which focused on membrane development, characterization, and testing, was designed to demonstrate methods for the production of water treatment membranes that couple passive and active biofouling control mechanisms. Both objectives were attained through synergistic collaboration among the three research groups. Using planar silicon and glass surfaces, we demonstrated using infrared spectroscopy that this new polymer coating can switch reversibly between the anti-fouling, zwitterion mode and an anti-microbial, quaternary amine mode. We showed that switching could be done more than 50 times without loss of activity and that the kinetics for switching from a low fouling zwitterion surface to an antimicrobial quaternary amine surface is practical for use. While a low pH was required for switching in the original polymer, we illustrated that by slightly altering the chemistry, it is possible to adjust the pH at which the switching occurs. A method was developed for applying the new zwitterionic surface chemistry onto polyethersulfone (PES) ultrafiltration membranes. Bacteria deposition studies showed that the new chemistry performed better than other common anti-fouling chemistries. Biofilm studies showed that PESultrafiltration membranes coated with the new chemistry accumulated half the biomass volume as unmodified membranes. Biofilm studies also showed that PES membranes coated with the new chemistry in the anti-microbial mode attained higher biofilm mortality than PES membranes coated with a common, non-switchablezwitterionic polymer. Results from our research are expected to improve membrane performance for the purification of wastewaters prior to use in irrigation. Since reduction in flux due to biofouling is one of the largest costs associated with membrane processes in water treatment, using dual-mode nanolayer coatings that switch between passive and active control of biofouling and enable detachment of attached biofoulants would have significant economic and societal impacts. Specifically, this research program developed and tested advanced ultrafiltration membranes for the treatment of wastewaters. Such membranes could find use in membrane bioreactors treating municipal wastewater, a slightly upgraded version of what presently is used in Israel for irrigation. They also may find use for pretreatment of agricultural wastewaters, e.g., rendering facility wastewater, prior to reverse osmosis for desalination. The need to desalinate such impaired waters water for unlimited agricultural use is likely in the near future.
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Buxbaum, Robert. High Flux Metallic Membranes for Hydrogen Recovery and Membrane Reactors. Office of Scientific and Technical Information (OSTI), giugno 2010. http://dx.doi.org/10.2172/1126695.
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EVANS, LINDSEY, e JAMES E. MILLER. Sweeping Gas Membrane Desalination Using Commercial Hydrophobic Hollow Fiber Membranes. Office of Scientific and Technical Information (OSTI), gennaio 2002. http://dx.doi.org/10.2172/793312.
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Frederick F Stewart. NHI-Acid Concentration Membranes -- Membrane Recommendations for the S-I Cycle. Office of Scientific and Technical Information (OSTI), marzo 2007. http://dx.doi.org/10.2172/915523.
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William A. Greene, Patricia A. Kirk, Richard Hayes e Joshua Riley. CENTRIFUGAL MEMBRANE FILTRATION. Office of Scientific and Technical Information (OSTI), ottobre 2005. http://dx.doi.org/10.2172/859218.
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Boyle, T. J., C. J. Brinker, T. J. Gardner, R. C. Hughes e A. G. Sault. Catalytic Membrane Sensors. Office of Scientific and Technical Information (OSTI), dicembre 1998. http://dx.doi.org/10.2172/2882.
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Liu, Paul K. T. Catalytic Membrane Program. Office of Scientific and Technical Information (OSTI), gennaio 2000. http://dx.doi.org/10.2172/764722.
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Hobbs, D. T. Membrane Stability Testing. Office of Scientific and Technical Information (OSTI), settembre 1997. http://dx.doi.org/10.2172/586971.
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Daniel J. Stepan, Bradley G. Stevens e Melanie D. Hetland. CENTRIFUGAL MEMBRANE FILTRATION. Office of Scientific and Technical Information (OSTI), ottobre 1999. http://dx.doi.org/10.2172/761675.
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Hunt, C. Silicon membrane formation. Office of Scientific and Technical Information (OSTI), maggio 1989. http://dx.doi.org/10.2172/5370108.
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