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Cellulose Acetate Membranes (cellulose + acetate_membrane)
Selected AbstractsCoconut water as a potential resource for cellulose acetate membrane preparationPOLYMER INTERNATIONAL, Issue 3 2008Cynthia Radiman Abstract BACKGROUND: Cellulose acetate membranes are frequently used for pressure-driven membrane processes. The aim of this work was to prepare cellulose acetate membranes from nata-de-coco using coconut water as starting material. The use of this lignin-free material will certainly minimize the use of chemicals usually needed in the traditional pulps and substitute for the use of wood, which helps prevent global warming and preserves nature as well. RESULTS: Coconut water was fermented by Acetobacter xylinum for 6 days to produce nata-de-coco, which was then acetylated to produce cellulose diacetate with an acetyl content of 39.6%. Fourier transform infrared analysis showed characteristic peaks for the acetyl group at 1748 and 1236 cm,1. The resulting membranes made from the hydrolysis product showed a water flux of 210.5 L m,2 h,1 under an applied pressure of 2 kg cm,2 while the rejection coefficients of dextran T-500 and T-2000 solutions were 78 and 93.7%, respectively. CONCLUSION: Coconut water has a potential to be used in the fabrication of membranes by converting it to nata-de-coco and then to cellulose diacetate which gives an added value to its original nature. It is also highly competitive compared to the traditional pulps, by which acetylation decreases the degree of crystallinity of nata-de-coco resulting in higher membrane permeability. Copyright © 2007 Society of Chemical Industry [source] Tailoring surface properties of cellulose acetate membranes by low-pressure plasma processingJOURNAL OF APPLIED POLYMER SCIENCE, Issue 6 2010Chun Huang Abstract The aim of this study was to tailor the surface properties of cellulose acetate membranes using low-pressure plasma processing. Argon (Ar) plasma and Difluoromethane (CH2F2) plasma were used to control the surface wettabilities of cellulose acetate membranes. Optical emission spectroscopy was used to examine the various chemical species of low-pressure plasma processing. In this investigation, the plasma-treated surfaces were analyzed by X-ray photoelectron spectroscopy, while changes in morphology and surface roughness were determined with confocal laser scanning microscopy. Ar plasma activation resulted in hydrophilic surface. CH2F2 plasma deposited hydrophobic layer onto the cellulose acetate membrane because of strong fluorination of the top layer. The results reveal low-pressure plasma processing is an effective method to control the surface properties of cellulose acetate membranes. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source] Urinary protein fraction in healthy subjects using cellulose acetate membrane electrophoresis followed by colloidal silver stainingJOURNAL OF CLINICAL LABORATORY ANALYSIS, Issue 4 2004Ryoko Machii Abstract We previously reported a rapid and highly sensitive colloidal silver staining solution suitable for the cellulose acetate membrane. This method was useful for detecting even very small amounts of urinary protein. In the present study, we examined urinary protein fractions in healthy subjects, using cellulose acetate membrane electrophoresis (CAE) with a highly sensitive colloidal silver staining, in an attempt to determine the clinical relevance of urinary protein fractions. Sixty unconcentrated spot urine specimens were analyzed by CAE and calculated by densitometry. All of the samples were separated into five fractions by CAE. The mean±1 SD of the percentage of five fractions was 28.37±8.51 in albumin, 4.30±4.19 in ,1 -globulin, 14.41±6.14 in ,2 -globulin, 19.45±7.10 in ,-globulin, and 33.46±8.24 in ,-globulin. The albumin/globulin (A/G) ratio was 0.41±0.17. These six items and the concentrations of total protein, albumin, and ,- N -acetyl- D -glucosaminidase (NAG) did not significantly differ between males and females. NAG is the marker of tubulointerstitial nephropathy. The results suggest that there are no gender-dependent differences in the urinary protein fractions of healthy subjects. J. Clin. Lab. Anal. 18:231,236, 2004. © 2004 Wiley-Liss, Inc. [source] Semiquantitative analysis of urinary low protein levels using silver dot blot assayJOURNAL OF CLINICAL LABORATORY ANALYSIS, Issue 4 2001Kazuyuki Matsuda Abstract We designed a semiquantitative analysis of urinary low protein levels using silver dot blot assay. In this method, 3 ,l of urine are blotted to one dot onto a cellulose acetate membrane, which is stained by a colloidal silver staining reagent, and the optical density of the silver stained urinary protein is measured at 500 nm using a densitometer. There was a good linearity between 2.5 mg/L and 100 mg/L and a gentle linearity between 100 mg/L and 200 mg/L, and the minimum sensitivity was 2.5 mg/L. This method is suitable for semiquantitative analysis of urinary protein levels less than 300 mg/L, which can not be determined precisely by dipstick. J. Clin. Lab. Anal. 15:171,174, 2001. © 2001 Wiley-Liss, Inc. [source] The Use of Electrolyzed Solutions for the Cleaning and Disinfecting of DialyzersARTIFICIAL ORGANS, Issue 12 2000Noriaki Tanaka Abstract: Recently, the use of electrolyzed solutions has attracted considerable interest in Japan. This study investigates the efficiency of electrolyzed solutions as disinfecting agents (DA) in the reuse of dialyzers and compares their efficiency to that of other disinfectants currently in use. The following 3 methods were employed. First, the rinsing time and rebound release of reused dialyzers were measured and compared after electrolyzed solutions, electrolyzed strong acid aqueous solution (ESAAS) and electrolyzed strong basic aqueous solution (ESBAS), made from reverse osmosis (RO) water (ESAAS, ESBAS; Generating apparatuses: Super Oxseed , 1000, Amano Corporation, Yokohama, Japan), 2% Dialox-cj (Teijin Gambro Medical, Tokyo, Japan), and 3.8% formalin were used as DAs. This involved performing dialysis with 2 types of dialyzers: a cellulose acetate membrane (CAM) dialyzer and a polysulfone membrane (PSM) dialyzer. The dialyzers were cleaned and disinfected using the different DA and left for 48 h. Next, after performing dialysis the dialyzer membranes were cleaned with a saline solution (0.9% NaCl) and RO water and then cleaned with the various DA. These membranes were observed using a scanning electron microscope (SEM) to check for the presence of physical and biological contaminants. Finally, in vitro tests were performed to determine the level of dialyzer clearance when PSM dialyzers were reused after having been cleaned and disinfected with the electrolyzed solutions. The rinsing time results for both the CAM and PSM dialyzers showed the electrolyzed solutions (ESBAS and ESAAS) as being undetectable within 10 min. With regard to the rebound release, for both the CAM and PSM dialyzers, the electrolyzed solutions were undetectable at all checking times between 30 and 240 min. Observation by SEM showed that cleaning with both ESAAS and ESBAS left the fewest contaminants, and cleaning with 2% Dialox-cj left the highest level of contaminants in the CAM dialyzers. With regard to experiments concerning use in vitro, no major changes in the dialyzer clearance were noticed after 6 uses. In every experiment, the previous investigations showed the electrolyzed solutions to be superior to 3.8% formalin and 2% Dialox-cj DA for the reuse of dialyzers. [source] Tailoring surface properties of cellulose acetate membranes by low-pressure plasma processingJOURNAL OF APPLIED POLYMER SCIENCE, Issue 6 2010Chun Huang Abstract The aim of this study was to tailor the surface properties of cellulose acetate membranes using low-pressure plasma processing. Argon (Ar) plasma and Difluoromethane (CH2F2) plasma were used to control the surface wettabilities of cellulose acetate membranes. Optical emission spectroscopy was used to examine the various chemical species of low-pressure plasma processing. In this investigation, the plasma-treated surfaces were analyzed by X-ray photoelectron spectroscopy, while changes in morphology and surface roughness were determined with confocal laser scanning microscopy. Ar plasma activation resulted in hydrophilic surface. CH2F2 plasma deposited hydrophobic layer onto the cellulose acetate membrane because of strong fluorination of the top layer. The results reveal low-pressure plasma processing is an effective method to control the surface properties of cellulose acetate membranes. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source] Preparation and study of cellulose acetate membranes modified with linear polymers covalently bonded to Starburst polyamidoamine dendrimersJOURNAL OF APPLIED POLYMER SCIENCE, Issue 5 2008J. Ledesma-García Abstract Novel ion-selective membranes were prepared by means of the noncovalent modification of a cellulose acetate (CA) polymer with either poly(ethylene- alt -maleic anhydride) or poly(allylamine hydrochloride) chains covalently linked to Starburst amine-terminated polyamidoamine (PAMAM) dendrimers generations 4 and 3.5, respectively. Linear polymer incorporation within the porous CA membrane was performed with mechanical forces, which resulted in modified substrates susceptible to covalent adsorption of the relevant dendritic materials via the formation of amide bonds with a carbodiimide activation agent. The membranes thus prepared were characterized by chemical, physical, and spectroscopic measurements, and the results indicate that the dendrimer peripheral functional groups were the species that participated in the ion-exchange events. The prepared materials were also evaluated for their ion-exchange permeability with sampled current voltammetry experiments involving cationic and anionic species {[Ru(NH3)6]3+ and [Fe(CN6)]3,, respectively} as redox probe molecules under different pH conditions. As expected, although permeability was favored by opposite charges between the dendrimer and the electroactive probe, a clear blocking effect took place when the charge in the dendritic polymer and the electroactive complex was the same. Electrochemical impedance spectroscopy measurements, on the other hand, showed that the PAMAM-modified membranes were characterized by good selectivity and low resistance values for multivalent ions compared to a couple of commercial ion-exchange membranes. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source] Coconut water as a potential resource for cellulose acetate membrane preparationPOLYMER INTERNATIONAL, Issue 3 2008Cynthia Radiman Abstract BACKGROUND: Cellulose acetate membranes are frequently used for pressure-driven membrane processes. The aim of this work was to prepare cellulose acetate membranes from nata-de-coco using coconut water as starting material. The use of this lignin-free material will certainly minimize the use of chemicals usually needed in the traditional pulps and substitute for the use of wood, which helps prevent global warming and preserves nature as well. RESULTS: Coconut water was fermented by Acetobacter xylinum for 6 days to produce nata-de-coco, which was then acetylated to produce cellulose diacetate with an acetyl content of 39.6%. Fourier transform infrared analysis showed characteristic peaks for the acetyl group at 1748 and 1236 cm,1. The resulting membranes made from the hydrolysis product showed a water flux of 210.5 L m,2 h,1 under an applied pressure of 2 kg cm,2 while the rejection coefficients of dextran T-500 and T-2000 solutions were 78 and 93.7%, respectively. CONCLUSION: Coconut water has a potential to be used in the fabrication of membranes by converting it to nata-de-coco and then to cellulose diacetate which gives an added value to its original nature. It is also highly competitive compared to the traditional pulps, by which acetylation decreases the degree of crystallinity of nata-de-coco resulting in higher membrane permeability. Copyright © 2007 Society of Chemical Industry [source] Production of a Polyester Degrading Extracellular Hydrolase from Thermomonospora fuscaBIOTECHNOLOGY PROGRESS, Issue 5 2002Mona K. Gouda The production of a polyester-degrading hydrolase from the thermophilic actinomycete Thermomonospora fusca was investigated with regard to its potential technical application. Only in the presence of a polyester (random aliphatic-aromatic copolyester from 1,4-butanediol, terephthalic acid, and adipic acid with around 40,50 mol % terephthalic acid in the acid component), the excretion of the extracellular enzyme could be achieved with an optimized synthetic medium using pectin and NH4Cl as nitrogen source. Compared to complex media, a significantly higher specific activity at comparable volumetric yields could be obtained, thus reducing the expenditure for purification. The activity profile in the medium is controlled by a complex process involving (1) induction of enzyme excretion, (2) enzyme adsorption on the hydrophobic polyester surface, (3) inhibition of enzyme generation by monomers produced by polyester cleavage, and (4) enzyme denaturation. Diafiltration with cellulose acetate membranes as the sole downstream processing step led to a product of high purity and with sufficient yield (60% of total activity). Scaling-up from shaking flasks to a fermentor scale of 100 L revealed no specific problems. However, the excretion of the hydrolase by the actinomycete turned out to be inhibited by the degradation products (monomers) of the aliphatic-aromatic copolyester used as inductor for the enzyme production. The crude enzyme exhibited generally similar properties (temperature and pH optimum) as the highly purified hydrolase described previously; however, the storage capability and thermal stability is improved when the crude enzyme solution is diafiltrated. [source] | |||||||||||||