Ultrafiltration Research Papers - Academia.edu (original) (raw)

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- Chemical Engineering, Materials Science, Ultrafiltration, Porosity
- by Jose coca prados
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- Engineering, Materials Science, Ultrafiltration, Desalination
- by Mohamed Naceur Belgacem
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- Materials Science, Polymer science, Elastomers, Lignin
- by Mohamed Naceur Belgacem
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- Materials Science, Synthesis, Characterization, Lignin
- by Mohamed Naceur Belgacem
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- Ultrafiltração, Compostos Fenólicos

Soda lignin precipitated from black liquor of Stipa tenacissima L. cooking was converted into polyols by a chain extension reaction with propylene oxide (PO). It was oxypropylated in a batch reactor in the presence of potassium hydroxide (KOH) as a catalyst. The reaction conditions were optimized by modifying the lignin/propylene oxide ratio [L/PO (w/v)], the temperature and the catalyst content. L/PO ratios of 20/80, 30/70 and 40/60 and catalyst contents from 3% to 5% were used. The temperature of the reaction was varied from 120 to 140 °C. The ensuing polyols were characterized by FTIR, H-NMR spectroscopy and size exclusion chromatography. Also, their viscosity and hydroxyl index were determined. A decrease in the molecular weight was observed after the oxypropylation reaction, which was explained by lignin depolymerisation. The viscosity and the hydroxyl index of the polyols ranged from 0.48 to 4.2 Pa.s and 150 to 375, depending on the lignin/PO ratio. Rigid polyurethane foam (RP...

- by Mohamed Naceur Belgacem
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- by Paula García
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- Chemistry, Food Science, Food Chemistry, Medicine
- by Raja Ghosh
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- Chemistry, Chromatography, Biotechnology, Medicine

Fractionation of proteins by ultrafiltration is an interesting challenge. With a particular membrane, the protein – protein and protein – membrane interactions largely decide which protein passes through and which is retained. System hydrodynamics also affects protein fractionation as the transmission behavior of a protein is altered by concentration polarization. Therefore, disruption of the concentration polarization layer would help to maintain the native selectivity of the membrane and hence aid in protein fractionation. An attempt is made to use gas sparging, a technique proven effective in controlling concentration polarization to enhance the selectivity of separation of BSA (MW 67,000) and lysozyme (MW 14,100). The effects of gas flow rate, liquid flow rate and feed concentration on the selectivity of fractionation are examined. Gas sparging enhances protein fractionation; under suitable solution conditions, nearly complete separation of BSA and lysozyme was achieved with gas...

- by Raja Ghosh
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- Engineering, Chemical Engineering, Chemistry, Chromatography
- by NGM Miranda
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- Membrana, Fenólicos Totais, Atividade antioxidante
- by riazul haque
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- Medical Microbiology, Biology, Medicine, Ultrafiltration

R G filters in Indian scenario - There are conflicting specifications in government tenders of various states in India . Apart from this C P H E E O manual has some different specifications in some aspects . Designers try to follow in toto specifications of concerned departments , even though they are out dated . Some designers while detailing make blunders . An effort is made to elaborate on these and mistakes in detailing .

- by Ravindra Pathak
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- Water Treatment
- by Angel Perez
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- Materials Science, Environmental Management, Medicine, Multidisciplinary
- by Wai-yee Chan
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- Biochemistry, Chemistry, Biology, Medicine
- by Dante Moraes
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- Environmental Science, Chemistry, Technology, Bioremediation
- by Sebastian Delgado
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- Chemistry, Water Purification, Medicine, Ultrafiltration
- by faten kamil
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- Materials Science, Ceramic, Membrane, Ceramic Membrane

The clearance of a dialyzer is calculated under the most general conditions, allowing not only for a mixed diffusive and convective mass transfer, but also for a variation along the membrane of the local ultrafiltration, the membrane permeability and the sieving coefficient. The study is then carried on for the case in which these are all constant, to reach a relatively simple expression for the influence of a low ultrafiltration rate on the clearance. In this study, the permeabilities of the boundary layers on both sides are treated as included in the (equivalent) membrane. In an appendix, the stacking of membranes is studied, giving a general law for the calculation of overall permeabilities of a stack of individual membranes, regarded as one (equivalent) membrane (such as a physical membrane with two boundary layers). Permeability data for boundary layers are quoted from earlier works. In other appendices, the variation of the local ultrafiltration along the dialysis path is stud...

- by Jan Erik Sigdell
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- Mathematics, Physics, Chemistry, Biomedical Engineering
- by Jan Erik Sigdell
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- Biomedical Engineering, Artificial Organs, Medicine, Ultrafiltration
- by Jan Erik Sigdell
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- Biomedical Engineering, Artificial Organs, Medicine, Ultrafiltration
- by Ana Elias
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- Engineering, Environmental Science, Carbon, Biotechnology

Poliovirus (PV) is on the verge of global eradication. Due to asymptomatic shedding, eradication certification requires environmental and clinical surveillance. Current environmental surveillance methods involve collection and processing of 400-mL to 1-L grab samples by a two-phase separation method, where sample volume limits detection sensitivity. Filtration of larger sample volumes facilitates increased detection sensitivity. This study describes development of a pumpless in-field filtration system for poliovirus recovery from environmental waters. Recovery of PV types 1, 2, and 3 were compared for glass wool, ViroCap, and NanoCeram (PV1 only) filters. Seeded experiments were performed using 10(5) plaque forming units of PV inoculated into 10-L volumes of secondary effluent, surface water, or a 50:50 mixture of each at pH 7.0. Filter eluates were plated onto buffalo green monkey kidney cells for virus enumeration by plaque assay. Across all water types, recovery from glass wool f...

- by John Scott Meschke
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- Biology, Environmental Monitoring, Medicine, Multidisciplinary
- by amit kumar
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- Geochemistry, Chemistry, Arsenic, Hydrogels

Background Malnutrition is a common condition in pediatric chronic kidney disease patients, and it is more complex as it could interfere with their growth and development potential. Nevertheless, classic nutritional status monitoring using anthropometric measurements is challenging due to its limitations. Normalized protein catabolic rate (nPCR) is a recent parameter that has already been recommended as a tool for monitoring nutritional status in the pediatric population with end-stage kidney disease that has undergone hemodialysis. However, it is still rarely used in Indonesia. We investigated the value and role of nPCR in the pediatric end-stage kidney with hemodialysis. Methods We conducted a cross-sectional study in patients 3–18 years old at Pediatric Hemodialysis Center Cipto Mangunkusumo Hospital. Inclusion criteria were end-stage kidney disease patients who underwent routine hemodialysis for at least three months and were free of infection and hospitalization within the last...

- by Eka Laksmi Hidayati
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- Anthropometry, Medicine, Malnutrition, Population

- by Eka Laksmi Hidayati
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- Anthropometry, Medicine, Malnutrition, Population
- by laurence lavenant
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- Chemistry, Microalgae, Ultrafiltration, Fractionation

Chemical modification of polymer and blending of suitable additives are the common methods used to improve the properties of polyethersulfone (PES) based hemodialysis membranes. In this research work, both methods are adopted and novel nanocomposite based additives were synthesized and blended with PES alone; and then with chemically modified PES (sulfonated PES (S-PES)). The whole research work was divided into three phases. In the first phase, the nanocomposites (NCs) were formed by mixing together the acid functionalized multiwall carbon nanotubes (f-MWCNT) and two different grades of polyvinylpyrrolidone (PVP-k90 and PVP-k30) in dimethylformamide and subsequently blended with PES. The f-MWCNT contained some hydrophilic functional groups (–COOH, and –OH) and heredity hydrophobic carbon part, which made it dual nature. On one side, it carbon part created sites for attachment for the hydrophobic polymer (PES) by hydrophobic–hydrophobic interaction and p–p stacking, whereas on the o...

- by Muhammad Irfan
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- Chemical Engineering, Materials Science, Chemistry, Carbon Nanotube

This study was carried out to determine the effect of ultrafiltration permeate recycling on deinking efficiency of flexo-printed newspapers. Wash filtrate effluents generated from various mixtures of old flexographic and offset newspapers and old maga-zines were clarified using ultrafiltration and sedi-mentation processes. Clarified waters were mixed with a deinked pulp sample to simulate a recircu-lation loop around the thickening stage. The effect of recycling water was assessed from brightness and effective residual ink concentration (ERIC) of washed pulp samples. Various deinking processes were also compared. Results show that ultrafiltra-tion permeate did not decrease pulp quality while clarified water from sedimentation significantly affected both brightness and ERIC values especially for high flexo-printed levels in recovered paper fur-nishes.

- by Bruno Chabot
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- Environmental Science, Waste Management, Newspaper, Deinking

BACKGROUNDCork processing wastewater is an environmental problem due to its high content of organic matter, such as sugars and non‐biodegradable compounds such as polyphenols (PPs), namely tannins. Membrane technology aimed at valorisation of the wastewaters components, concentrate stream, and simultaneously offer a pre‐treatment of the wastewater, permeate stream. In this work, the identification of bioactive PPs was also envisaged. Several fractions of cork processing wastewaters were generated using two cellulose acetate ultrafiltration membranes of 3 kDa and 74 kDa for PPs isolation according to nature and molecular weights. The membranes were prepared by the phase inversion method and fractionation was made in concentration and diafiltration modes. The wastewater and the fractions were analyzed in terms of total organic carbon, total phenols, tannins and total polysaccharides content and the compounds present were identified by FTIR, LC–MS and quantified by HPLC‐DAD.RESULTSComp...

- by Maria Serralheiro
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- Chemistry, Chromatography, Multidisciplinary, Ultrafiltration
- by Berna Kırıl Mert and +1
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Developments in industrial activities around the world lead to increase water consumption and to become widespread industrial water pollution problems. This situation accompanied by increasing water shortage issues needs to be realized technological applications which include recovering water in reusable quality from wastewaters of excessive water-consuming industries. In this study, recovering water in reusable quality from textile washing wastewaters having 6.22±0.03 pH, 1130±321 mg TDS/L, 2362±727 mg COD/L and 744±234 mg TOC/L was aimed using ultrafiltration (UF), nanofiltration (NF) and reverse osmosis (RO) membrane processes. In this respect, effect of membrane type as the main parameter for real-scale installations on reusable water quality was examined. Experiments were performed using four membranes each for UF and NF and five for RO at the conditions of original pH, 25 oC and 300 rpm cross-flow rate in trans-membrane pressures of 8, 12 and 40 bar for UF, NF and RO, respecti...

- by Berna Kırıl Mert
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- Chemistry, Water quality, Membrane Technology, Ultrafiltration
- by Peter Vollaard
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- Chemical Engineering, Chemistry, Analytical Chemistry, Arsenic
- by Kimberly Gray
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- Engineering, Chemical Engineering, Materials Science, Chemistry
- by Kimberly Gray
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- Engineering, Chemical Engineering, Materials Science, Chemistry
- by HAROLD G MONBOUQUETTE
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- Engineering, Membrane Science, Ultrafiltration, Surface modification
- by Valentina Lavarias
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- Medicine, Ultrafiltration, Humans, Hemodynamics

Background: This study aimed at the possibility of concentrating milk in the laboratory using ultra-filtration technology instead of the traditional evaporation method that is still used in Iraq. Methods: Therefore, 5 litres of raw, cow milk were taken from a reliable source and two different concentrations of lemongrass were added as a preservative to observe the changes occurring during concentration, chemically and microbial. The best conditions were found to concentrate the milk 2.7 once and improve it over many days with the addition of lemongrass extract as a preservative. A material with a flat membrane polyethyle-solphen with a measurement of 10 kdalton (Snyder USA) was selected. Throughout the duration of the more than three-hour experiment, the measurements were taken. Two sets of data were examined: in the first set, the flow rate was varied between 0.15 and 0.25 L/min while the trans membrane pressure (TMP) was kept constant at 2 bar. The value of 0.15 L/min was determined to be the ideal flux. In the second group, the trans membrane pressure was varied between 0.5 and 1,2 bar while the flow rate was kept constant at 0.15 L/min. At TMP 2 bar, the ideal flux value was discovered at 35C, the permeate flux was around 5-7 L/m2.hr. Result: It was found the change of the total solid and protein were excellent percentages with time of filtration. The total number of bacteria at both concentrations decreased significantly (p<0.05) in the biological test results.

- by Arcc Journals
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- Dairy Technology
- by Soner Duman
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- Mortality, Medicine, Ultrafiltration, Cardiorenal Syndrome

- by Muhammad Irfan
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- Chemical Engineering, Materials Science, Chemistry, Carbon Nanotube

Background Hypervolemia is a risk factor for left ventricular hypertrophy and hypertension in peritoneal dialysis patients. Icodextrin improves volume control by increasing ultrafiltration in peritoneal dialysis patients. Aim To examine the effects of twice-daily icodextrin administration on blood pressure and left ventricular hypertrophy in peritoneal dialysis patients with hypervolemia and ultrafiltration failure. Method and Results Administration of icodextrin twice daily resulted in a significant reduction in the left ventricular mass index (LVMI) of patients by the end of the third month ( p < 0.05). The reduction in LVMI was also significant for the once-daily icodextrin group ( p < 0.05). Mean blood pressure of patients receiving icodextrin twice daily was significantly reduced ( p < 0.05). By the end of the third month no significant changes were observed in mean blood pressure of the patients using once-daily icodextrin ( p > 0.05). No statistically significant ...

- by Oktay Oymak
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- Treatment Outcome, Medicine, Ultrafiltration, Echocardiography

Informations concernant cette traductionDans le cadre d’un accord de partenariat entre l’ISPD et le RDPLF, le RDPLF est le traducteur français officiel des recommandations de l’ISPD. La traduction ne donne lieu à aucune compensation financière de la part de chaque société et le RDPLF s’est engagé à traduire fidèlement le texte original sous la responsabilité de deux néphrologues connus pour leur expertise dans le domaine. Avant publication le texte a été soumis à l’accord de l’ISPD. La traduction est disponible sur le site de l’ISPD et dans le Bulletin de la Dialyse à Domicile.Le texte est, comme l’original, libremement téléchargeable sous licence copyright CC By 4.0https://creativecommons.org/licenses/by/4.0/Cette traduction est destinée à aider les professionnels de la communauté francophone à prendre connaissance des recommandations de l’ISPD dans leur langue maternelle. Toute référence dans un article doit se faire au texte original en accès libre :Peritoneal Dialysis Internatio...

- by Christian Verger
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- Humanities, Ultrafiltration, Peritoneal Dialysis

This work investigates the separation of soybean oil/compressed n‐butane and soybean oil/liquefied petroleum gas (LPG) mixtures, using ultra‐ and nanofiltration membranes. For this purpose, soybean oil/n‐butane and soybean oil/LPG in the mass ratio of 1:3 were continuously fed into a flat sheet module without the recycle. The effects of the feed pressure (10, 20, and 30 bar), the pressure difference (1, 5, and 10 bar) and the pre‐treatment with ethanol and n‐propanol on the oil permeate flux and oil retention were investigated. The membranes with best performance (higher oil retention combined with high solvent permeate flux) were Sepa GM (4 kDa) and Sepa HL (98 % MgSO4), previously conditioned in ethanol. The Sepa GM membrane showed oil retention between 95 to 99 %. The Sepa HL membrane showed oil retention between 83 to 97 %. The pre‐treatment with ethanol improved the permeate flux. In most of the experimental conditions severe membrane fouling was observed. A change in the perme...

- by Zuleica Novello
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- Chemical Engineering, Chemistry, Ultrafiltration, Nanofiltration
- by Peter Tromp
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- Environmental Science, Electron Microscopy, Nanoparticles, Environmental Chemistry
- by Jorge Luis Litardo Velásquez
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- Chemistry, Kinetics, Water Purification, Minerals

5 paginas, 3 tablas, 3 figuras.-- Poster presentado al FOODSIM 2010, June 24-26, 2010, CIMO Research Centre, Braganca, Portugal

- by Nelson Pérez
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- Chemistry, Tuna
- by Diep Dinh Phong
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- Environmental Engineering, Chemical Engineering, Chemistry, Analytical Chemistry
- by Urs von Stockar
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- Kinetics, Biology, Biological Chemistry, Medicine
- by Urs von Stockar
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- Chemistry, Mass Transfer, Chromatography, Kinetics

A novel in situ product removal (ISPR) method that uses microcapsules to extract inhibitory products from the reaction suspension is introduced into fermentation technology. More specifically, L‐phenylalanine (L‐Phe) was transformed by Saccharomyces cerevisiae to 2‐phenylethanol (PEA), which is inhibitory toward the yeast. In order to continuously remove PEA from the vicinity of the cells, the reaction suspension was brought into contact with capsules of 2.2‐mm diameter that had a hydrophobic core of dibutyl sebacate and an alginate‐based wall. This novel process combines the advantages of a normal in situ extraction process (fast mass transfer and simple process set‐up) with the benefits of a membrane‐based process (reduction of the solvent toxicity and avoidance of stable emulsions). In particular, the microbial cells are shielded from the phase toxicity of the organic solvent by a hydrogel layer surrounding the organic core. By placing the microcapsules into the fermenter, the fi...

- by Urs von Stockar
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- Chemistry, Chromatography, Biotechnology, Medicine