Preparation Of Cellulose Acetate Membranes Research Articles

Characterization of Cellulose Acetate Membrane at Different Thicknesses on Sucrose Concentration by Forward Osmosis

Forward osmosis (FO) requires a specific membrane structure for applications like juice concentration. The phase inversion method was used to make cellulose acetate (CA) FO membranes. The solvents used were acetone and 1,4-dioxane. Additives included polyvinylpyrrolidone (PVP), methanol, and maleic acid were used in the preparation of CA membrane, which make it easier to improve a FO membrane's permeability. The performance of fabricated FO membrane and their morphology were evaluaed with different casting thicknesses of 150, 200, and 250 µm. Experiment works begins with an hour of membrane flux testing, deionized water was used as feed solution and 1 M NaCl as draw solution. The membrane was then used to concentrate 0.5 M sucrose with NaCl for 240 minutes (2 M). Contact angle, porosity, and scanning electron miscroscopy (SEM) were used to characterize membrane properties and morphology. High water flux (2.25 L/m2hr) and high porosity (75.86%) were found at 200 µm casting thickness. Water permeability of sucrose concentration at 200 µm casting thickness had the highest flux (2.39 L/m2hr). The results also show that flux values vary with membrane thickness. All membranes were hydrophilic with contact angles below 90°. A 200 µm casting thickness produces a membrane with smooth and evenly distributed pores, according to morphology analysis. Structural parameter (S) values had a proportional relationship with the FO membrane thickness, which thinner membrane potentially reduces the internal concentration polarization (ICP).

Preparation of cellulose acetate membrane coated by PVA/Fe3O4 nanocomposite thin film: an in situ procedure

The surface modification of porous cellulose acetate (CA) flat sheet membranes containing 8-hydroxyquinoline (as ligand) was carried out by coating with poly(vinyl alcohol) (PVA)/Fe3O4 nanocomposite solution. Nanocomposite solution was provided by in situ formation of Fe3O4 nanostructures in a polymeric solution containing poly(vinyl alcohol) via a facile chemical procedure. The provided membranes were used for Ni(II) and Cd(II) ion removal from aqueous solutions. The influences of membrane modification, initial feed concentration, and filler loading on the membrane performance for removal of the mentioned ions were investigated. The results showed that ion rejection was enhanced by addition of magnetite nanostructures and 8-hydroxyquinoline to the membrane matrix. Several techniques including IR spectroscopy, X-ray diffraction, SEM, water contact angle, and overall porosity measurements were used to characterize the prepared samples. Morphological studies showed appropriate distribution of magnetite nanostructures in the polymeric backbone of nanocomposite membrane. The filtration/regeneration tests were sequentially performed and confirmed the facile regeneration of the nanocomposite membranes.

Selective adsorption of gold and silver in bromine solutions by acetate cellulose composite membranes coated with polyaniline or polypyrrole

This paper presents the selective adsorption of bromine-metallic complexes of Au and Ag on composite membranes, as well as the desorption process and redoping of the conducting polymers. The polyaniline (PANI) and polypyrrole (PPy) membranes exhibited relevant adsorption properties. 72% for gold and 98% for silver with PANI, 50% for gold and 97% for silver with PPy, in bromine complexes. The adsorption capabilities of the composite membranes were attributed to the ion exchange between the dopant and the AuBr 4 − or AgBr 2 − complexes. Both materials fitted to a Langmuir isotherm. PANI-based membranes reached 31.4% of gold and 54.4% of silver desorption whereas PPy-based membranes reached 54% of gold and 28.8% of silver. Redoping studies suggested the potential reuse of the PANI-based membranes at least for six cycles of the adsorption/desorption process. The preparation of cellulose acetate membranes modified with poly (acrylic acid) and triphenyl phosphate and coated with the conducting polymers, PANI or PPy was in accordance to our previously reported method. The composite membranes were characterized by FT-IR, scanning electron microscopy, electrical conductivity measurements, I–V, mechanical tests, contact angle measurements, XRD and energy disperse spectroscopy. The novelty of the present work is the combination of electroconductive polymers, for the recovery of metals, and bromide as a leachate, less harmful than the traditionally used leachers.

셀룰로오스 아세테이트 분리막 제조 및 정삼투 성능 평가

셀룰로오스 아세테이트 분리막 제조 및 정삼투 성능 평가

Preparation of Cellulose acetate membrane by phase inversion technique and modification of surface by Copper Ferro cyanide multilayers

Cellulose acetate (CA) membranes were prepared by wet phase inversion technique from acetone/formamide (2/1 wt/wt). The casting solution using a 20 weight-percentage polymer concentration was used for phase inversion. The solution of Potassium Ferro cyanide and Copper sulphate having molar concentration 0.1m, 0.01m, 0.001m, 0.2m, 0.02m, 0.002m were used for deposition on the surface of Cellulose acetate (CA) membrane by alternate changing the two solutions in a special cell. Values of membrane potential were measured and the transport number, fixed charged density and the permselectivity values were calculated for the electrolytes NaCl and KCl. Scanning electron micrographs (SEM) were taken for simple Cellulose acetate (CA) membrane and surface modified multilayers Cellulose acetate (CA) membrane which showed the fine deposition of multilayers of Copper Ferro Cyanide which reduced the pore size ofCellulose acetate(CA) membrane up to nano order. The values of membrane potential (with and without deposition of inorganic multilayers) slightly decreased with time reaching to a constant value, which showed initial accumulation of solution fluid within transmembrane region and saturation thereafter. The values of membrane potential increased with the deposition of multilayers showing decrease in pore size of membrane which has become of the order of nanosize. The values of transport number of cations of (K+ and Na+) were calculated using membrane potential data, which was foundin good resemblance of the ionic size of trace metal ions.

Influence of humidity, temperature, and the addition of activated carbon on the preparation of cellulose acetate membranes and their ability to remove arsenic from water

ABSTRACTSeveral composite membranes have been prepared from cellulose triacetate (CTA) and activated carbon (AC) by solvent casting, varying temperature from 35 to 55°C and relative humidity (RH): 10–70%. Some conditions promoted AC particle agglomeration which is evidenced by SEM and IFME® program. In those membranes, where homogeneity is attained, a deep characterization has been carried out by DMA, MDSC, thermoporometry, solute transport, and AFM. When AC is added in films, Tg is lowered and the fraction of pores with bigger size is augmented. Molecular weight cut off calculated by solute transport, increases from 801.15 to 1194.29 kDa using 1% AC at RH 70% and T 35°C. Water flux is of 5.23 Lm−2 h−1 bar−1. Arsenic removal has been performed, achieving a 45% tested from a 500 ppb arsenic solution, where several factors such as electrical rejection, adsorption and exclusion, could contribute to the total membrane nanofiltration process. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40134.

Preparation of cellulose acetate membrane filled with metal oxide particles for the pervaporation separation of methanol/methyl tert-butyl ether mixtures

In this work, a new pervaporation cellulose acetate (CA) membrane filled with metal oxide particles was prepared to intensify the separation of methyl tert-butyl ether (MTBE)/methanol mixtures. The SEM and Raman spectrometry revealed that the particles of metal oxide were evenly dispersed in the membrane matrix and made a denser membrane. When the content of Al2O3 and ZnO was 1.98 wt% and 4 wt%, respectively, both the permeation flux and separation factor of blended CA membrane were higher than those of pure CA membrane. In comparison with the pure CA membrane, the maximum flux of blended membrane filled with Al2O3 and ZnO improved 96.5% and 111.1%, respectively; the maximum separation factor improved 48.0% and 37.8%, respectively. In addition to the substantially improved permeation flux and selectivity, the CA membrane filled with metal oxide was found easy to prepare and with low cost. © 2008 Elsevier B.V. All rights reserved.

Rapid Quantification of DNase I Activity in One-Microliter Serum Samples

Deoxyribonuclease I (DNase I; EC 3.1.21.1) is genetically polymorphic (1), and has been postulated to be a candidate molecule for the endonucleolytic activity involved in apoptosis or programmed cell death (2) and involved in the initiation of systemic lupus erythematosus (3). We have reported the presence of high DNase I activity and its gene expression in the anterior lobe of the pituitary gland of both sexes and the abrupt increase in its gene expression at the onset of puberty (4). These findings suggest that DNase I has other, unknown biological roles as well as a digestive role. The single radial enzyme diffusion (SRED) method (5)(6) has been used to quantify DNase I activity and allows the measurement of very low DNase I activity in serum samples, although it requires a long incubation period (10–20 h). Recently we proposed that determination of serum DNase I activity is useful in the diagnosis of acute myocardial infarction (AMI) in the early phase after onset (7). However, the present SRED assay takes too long to be useful in the emergency room, and the development of a more rapid assay for DNase I is desirable for therapeutic decision-making. In this report, we describe a novel assay method that can be used to quantify DNase I activity in 1-μL serum samples within 30 min. Human DNase I was purified from urine as described previously (8). Antibodies specific to human DNase I and II were produced in rabbits (8)(9)(10). Cellulose acetate membrane (CAM) was purchased from Sartorius, SYBR Green I (SG) was from Cambrex, and salmon testicular DNA (type III) was from Sigma. An assay reagent set for DNase I activity was prepared in two steps: production of a gel plate for keeping the CAM wet, and preparation of CAM containing …

Formation of micro- and nano-spheric particles (filter dust) during the preparation of cellulose acetate membranes

Membranes were prepared from six samples of cellulose acetate (CA) differing in their average molecular weight (75–260 kg/mole) and molecular weight distribution using methyl acetate as solvent and 2-propanole as precipitant. The routes through the phase diagram and the evaporation times were varied in these experiments. Electron microscopy demonstrates that the amount of filter dust (CA particles deposited on the membrane surface) decreases as the fraction of low molecular weight material in the starting polymer becomes less. For low average molar mass of CA and moderate polymer concentrations in the casting solution the dust consists of individual spheres of relatively uniform size (1–2 μm) which cover the surface in a number of layers. With rising molar mass of the polymer the dust particles consist increasingly of strings of cohering and deformed beads of comparable size. Under these condition, some considerably smaller particles (≤0.1 μm) are also formed. Possible mechanisms of filter dust formation are discussed and measures for its prevention are proposed.

The role of formamide in the preparation of cellulose acetate membranes by the phase inversion process

By varying the concentration of formamide within the acetone solutions from which cellulose acetate membranes were fabricated, a series of membranes exhibiting a wide range of performance characteristics was prepared. The morphological, optical, swelling and water transport properties of these membrane gels have been interpreted with reference to a phase inversion in their sol precursors.