Cellulose Acetate Blend Research Articles

Efficacy of synthesis conditions on functionalized carbon nanotube blended cellulose acetate membrane for desalination

Cellulose acetate membrane has been applied to reverse osmosis for desalination due to chlorine tolerance and biofouling resistance. Since it requires optimized synthesis condition for application, we investigated the effect of different conditions on membrane performances. It was found that polymer concentration, solvent ratio, and evaporation time were critical to determine membrane selectivity and permeability. Based on the study, optimized conditions were obtained, which were 14 wt% of polymer concentration, 1:2.9 of ratio of 1,4-dioxane to acetone, and 30 s of evaporation time. Further, functionalized multi-walled carbon nanotubes (MWCNTs) were applied to the optimized bare membrane in order to enhance the performances. The composite membranes were characterized by fourier transform infrared spectroscopy, scanning electron microscopy, and contact angle measurement. It was found that the MWCNTs influenced the morphology and surface chemistry of the membrane. This study could contribute to develop a commercial composite RO membrane with nanomaterial for desalination application.

Fabrication of new cellulose acetate blend imprinted membrane assisted with ionic liquid ([BMIM]Cl) for selective adsorption of salicylic acid from industrial wastewater

Highly selective cellulose acetate (CA) blend imprinted membranes for salicylic acid (SA) was prepared by using phase inversion technique with sulfonated polysulfone (SPS) as a functional polymer, polyethylene glycol-4000 (PEG 4000) and ionic liquid 1-butyl-3-methylimidazolium chloride ([BMIM]Cl) as the additives. The membranes were characterized by several techniques including SEM, Raman, contact angle, membrane flux, and SA adsorption–desorption techniques. The SEM micrographs showed that the cross-sectional morphology of CA membranes was affected by polymer blend composition and applications of additives. Compared with the pure CA membrane the CA/SPS(90/10)+[BMIM]Cl membranes showed low contact angle, high membrane flux, strong adsorption capacity and high permeation selectivity. The experimental data of adsorption kinetic for CA/SPS(90/10)+[BMIM]Cl were well fitted to the pseudo-second-order kinetic model using multiple regression analysis. The selectivity coefficients of CA/SPS(90/10)+[BMIM]Cl-MIM for SA in relation to competition analogs p-hydroxybenzoic acid (p-HB) and phenol were 5.8549 and 5.9062, respectively, which suggested that CA/SPS(90/10)+[BMIM]Cl-MIM had high selectivity and binding affinity for the template SA. Overall results suggest that [BMIM]Cl can be considered as an effective additive for CA imprinted membranes in the treatment of SA-contained water.

Studies on Concentration of Simulated Ammonium-diuranate Filtered Effluent Solution by Forward Osmosis Using Indigenously Developed Cellulosic Osmosis Membranes

In this study, we discuss the preparations of cellulosic membranes from cellulose acetate (CA), cellulose triacetate (CTA) and cellulose acetate blend (CAB) [blending of CA and CTA] systems and their potential for concentration of simulated ammonium-diuranate (ADU) effluent solution (only uranium and ammonium nitrate) by FO. The membranes are prepared using casting solution of polymers in mixed solvent systems with gelling in ice-cold water followed by annealing in 80°C hot water. Prepared membranes are characterized in terms of separation performance (tested under brackish water reverse osmosis test condition), water contact angle and surface average roughness. The performance of the membranes are evaluated in terms of volume reduction factor using solution of 40,000 ppm of NH4NO3 and 20 ppm uranium as feed and 320000ppm of NH4NO3 as draw solution. It is found that the volume reduction factor increases in the order of CTA<CAB<CA membranes. The effect of different draw solutions on volume reduction for the same system using CA membrane is also evaluated. Almost no leaching of uranium is found to the draw solution side for all the membranes. Possibility of using the FO process in a simpler way (as membrane pouch) to concentrate this simulated ADU filtered solution has been ascertained.

Study of sustained release drug-loaded nanofibers of cellulose acetate and ethyl cellulose polymer blends prepared by electrospinning and their in-vitro drug release profiles

Sustained release cellulose acetate (CA) and ethyl cellulose (EC) polymer blend nanofibers loaded with ketoprofen (KET) were successfully prepared by electrospinning. Successful fiber formation has been investigated by using two different binary solvent systems, i.e., acetic acid + distilled water (2:1 v/v) and acetone + N,N-DMAc + ethanol (2:1:1 v/v). Scanning electron microscopy (SEM) images showed that morphological features gradually change as the ratio of both polymers change. Nanofiber diameter also decreases as the CA content is increased in the polymer blend solution from 77.25 ±27 to 72.39 ±30 nm. Drug release profiles were evaluated by in-vitro drug release experiments. Drug release follows a pseudo-Fickian behavior of diffusion and shows a sustained release mechanism. Nanofibers containing more CA show greater controlled release capacity as compared to EC. X-ray diffraction (XRD) patterns of CA and EC polymer blend nanocomposites show that crystalline ketoprofen has changed into an amorphous state. Fourier transform Infrared (FTIR) analysis indicates hydrogen bonding occurs between the drug and the polymer, accounting for molecular integration of the two components. The thermal stability of the prepared polymer blend was also studied using thermo-gravimetric analysis (TGA). A polymer blend sustained release drug delivery system prepared by electrospinning make it possible to fabricate other novel drug releasing systems.

Cellulose Acetate Blends - Effect of Plasticizers on Properties and Biodegradability

Cellulose Acetate Blends - Effect of Plasticizers on Properties and Biodegradability

Thermodynamic modeling of polyamide-6 (PA-6)/cellulose acetate (CA) blend membrane prepared via casting technique

Abstract Thermodynamic behavior of a ternary system with one low molecular weight component, formic acid (FA) as the solvent, water (non-solvent), and two high molecular weight polymers [polyamide-6 (PA-6) and cellulose acetate (CA)] was investigated using an extended modified Flory-Huggins model. Where, all chemicals were purchased from Leuna Werke AG (Germany). The model was solved by MATLAB SIMULINK software manufactured in the USA. The predicted results from the model explained that the miscibility of the two blend polymers, PA-6 and CA, completed over all compositions at room temperature, and the minimum point where the miscibility of the two polymers completed was in the composition of 0.2 volume fraction of PA-6 at Gibbs free energy change on mixing (ΔGm) of -1.74015 kJ/mole. The critical temperature (Tc) for superiority properties of the polymer blend solution are in the range between the upper critical saturation temperature (UCST) 323K and the lower critical saturation temperature (LCST) 338K. The diffusion model on the solution of the immersion precipitation process in the coagulation bath indicates that the solvent volume fractions increase with time, while the polymer solution volume fraction decreases, due to solvent removal from the polymer solution and membrane formation. According to the mathematical model, it was found that the annealing temperature can affect the densification of the membrane top layer. However, the heat treatment process leads to a decrease in thickness of the membrane bottom layer, as a result of reduced and distributed membrane pores.

Concentration of ammonium diuranate effluent by reverse osmosis and forward osmosis membrane processes

In this study, both reverse osmosis (RO) and forward osmosis (FO) experiments are conducted to concentrate simulated inactive ammonium diuranate (ADU) filtered effluent solution (by mixing uranyl nitrate and ammonium nitrate) using indigenously developed cellulose acetate blend (CAB) and thin-film composite polyamide (TFCP) membranes. Both the membranes are prepared and characterized in terms of pure water permeability and solute rejection for 2000 ppm NaCl feed, water contact angle and surface average roughness. Subsequently, testing of volume reduction and concentration of simulated ADU effluent solution are carried out using custom made RO and FO testing systems. It is found that in RO process, the performance in terms of volume reduction factor and concentration factor with respect to uranium for both CAB and TFCP membranes are comparable but the CAB membranes show better performance than the TFCP membranes in FO modes. The concentration of ammonium nitrate is less in RO concentrate than in the FO concentrates. Similar experiments with the feed solution having different concentration of uranium (1–20 ppm) with same concentration of ammonium nitrate show that in FO, almost no leaching of uranium is found to the draw solution side but in RO, some of the uranium starts passing to the permeate side, particularly at lower concentration of uranium in the feed.

Miscibility, water uptake, ion exchange capacity, conductivity and dielectric studies of poly(methyl methacrylate) and cellulose acetate blends

ABSTRACTIn the last few decades, polymer blends with good miscibility and conductivity have been the focus of study for material scientists. Here, polymer blends of Poly(methyl methacrylate) (PMMA) and Cellulose acetate (CA) of varying blend compositions have been prepared by solution casting method and their miscibility, water uptake, ion exchange capacity (IEC) proton conductivity, and dielectric properties have been studied. Dimethyl formamide (DMF) was used as solvent. Fourier transform infrared spectra (FTIR) and Differential scanning calorimetry (DSC) measurements have been used to analyze the miscibility of the blends. Up to 50/50 PMMA/CA, water uptake showed an increasing trend and for other compositions the value decreased. Ion exchange capacity and conductivity of the blends decreased with increase in PMMA content of the blends. The variations in the blend properties have been attributed to the presence of specific interactions and exchangeable groups in the blend system. The proton conductivity of the blends is in the order of 10−3 S cm−1. Impedance analysis of the blends indicated the absence of any relaxation phenomenon in the blend system. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 3074–3081, 2013

Hydrophilic Nanofibers as New Supports for Thin Film Composite Membranes for Engineered Osmosis

Engineered osmosis (e.g., forward osmosis, pressure-retarded osmosis, direct osmosis) has emerged as a new platform for applications to water production, sustainable energy, and resource recovery. The lack of an adequately designed membrane has been the major challenge that hinders engineered osmosis (EO) development. In this study, nanotechnology has been integrated with membrane science to build a next generation membrane for engineered osmosis. Specifically, hydrophilic nanofiber, fabricated from different blends of polyacrylonitrile and cellulose acetate via electrospinning, was found to be an effective support for EO thin film composite membranes due to its intrinsically wetted open pore structure with superior interconnectivity. The resulting composite membrane exhibits excellent permselectivity while also showing a reduced resistance to mass transfer that commonly impacts EO processes due to its thin, highly porous nanofiber support layer. Our best membrane exhibited a two to three times enhanced water flux and 90% reduction in salt passage when compared to a standard commercial FO membrane. Furthermore, our membrane exhibited one of the lowest structural parameters reported in the open literature. These results indicate that hydrophilic nanofiber supported thin film composite membranes have the potential to be a next generation membrane for engineered osmosis.

Effect of chain structure on the miscibility of cellulose acetate blends: a small-angle neutron scattering study

The miscibility of cellulose ester blends with varying degree of substitution (DS) of acetates along the chain backbone has been investigated using small-angle neutron scattering. The difference in degree of substitution (ΔDS) between the two components in the blend was systematically varied from 0.06 to 0.63 where each blend was found to be a partially miscible, two-phase system. Miscibility between the two components initially decreases as ΔDS of the blends increases. The Flory interaction parameter, χ, concurrently increases with increasing ΔDS as a result of diminishing van der Waals forces between components. The cellulose acetates with lower degree of substitution, which contain more hydroxyl substituents, however, demonstrate greater miscibility even at higher ΔDS. This is interpreted to be the result of favorable hydrogen bonding between blend components that are possible in the presence of more hydroxyl groups. FT-IR data support this interpretation, indicating an increase in hydrogen bonding in a blend having a lower DS component. These results indicate that while an increase in structural differences between cellulose acetate blend components limits miscibility, the presence of hydroxyl groups on the chain promotes mixing. This competition accentuates the significant impact specific interactions have on blend miscibility for these copolymers.

Synthesis and Characterization of Cellulose Acetate Blend Ultrafiltration Membranes： The Effect of Degrees of Substitution

Cellulose acetate (CA), a hydrophilic membrane material, was selected to prepare ultrafiltration membrane for the aim of achieving high-performance membranes with respect to flux and rejection characteristics. In order to prepare membranes with improved properties, blending of cellulose acetates with different degrees of substititution(DS) has been attempted. In this study, polymeric blend ultrafiltration membranes based on cellulose acetate with different DS were prepared by phase inversion technique. Scanning electron microscopy (SEM), atomic force microscopy (AFM), and contact angle are used to understand the influence of DS on the properties of modified membranes. The blend membranes prepared were subjected to the separation of egg albumin (EA). The separation and permeate flux efficiencies of the blend membranes were discussed.

Preparation and characterization of cellulose acetate/carboxymethyl cellulose acetate blend ultrafiltration membranes

A carboxymethyl cellulose acetate (CMCA)/cellulose acetate (CA) blend ultrafiltration (UF) membrane was prepared via phase inversion in the absence and presence of 2.5wt.% additive, namely polyethylene glycol 600 (PEG 600). CMCA was firstly synthesized from carboxymethyl cellulose sodium (CMC-Na) by acidifying and esterifying. The as-prepared blend membranes were characterized using scanning electron microscopy (SEM), atomic force microscopy (AFM), mechanical analysis, contact angle, pure water flux (PWF), water content (WC), rejection and molecular weight cut off (MWCO) to understand the influence of polymer blend composition and additive on the properties of the modified membranes. SEM and AFM surface roughness analysis showed that CA/CMCA blend membranes possessed large size pore in the top layer and porous structures in the cross-section. Compared to the pure CA membrane, blending of CA with CMCA resulted in novel blend membranes with enhanced ultrafitration membrane characteristics such as lower contact angle and higher PWF coupled with higher water content. Bovine serum albumin (BSA) was subjected to rejection by the blend membranes. Meanwhile, the fouling resistant ability was studied and the UF experiments suggested that the modified membranes had more positive influence on membrane anti-fouling performance.

Fabrication of (polyvinyl chloride/cellulose acetate) electrodialysis heterogeneous cation exchange membrane: Characterization and performance in desalination process

In this research, polyvinylchloride (PVC)/cellulose acetate (CA) blend heterogeneous cation exchange membranes were prepared by solution casting technique using tetrahydrofuran as solvent and cation exchange resin powder as functional groups agent. CA was employed in membrane fabrication to improve the hydrophilicity of membranes. The effect of blend ratio of polymers binder (PVC to CA) on physico-chemical characteristics of home-made membranes was studied. Scanning optical microscopy (SOM) images showed uniform particles distribution and relatively uniform surfaces for the membranes. Membrane water content and surface hydrophilicity were enhanced with increase of CA blend ratio in casting solution. Membrane ion exchange capacity was also improved slightly with increase of CA ratio in prepared membranes. Membrane fixed ion concentration, membrane potential, charge density, permselectivity, transport number and areal electrical resistance all showed decreasing trends by the increase in CA blend ratio in casting solution. Results revealed that ionic permeability and flux were initially enhanced by the increase of CA concentration up to 20%wt in casting solution and then showed decreasing trend by more CA loading from 20 to 50%wt. These parameters were enhanced again by more increase in CA ratio from 50 to 100%wt in prepared membranes.

Development of membrane blend using casting technique for water desalination

Membrane separation technologies have some of advantages are considered a better alternative to traditional methods. Research of novel membranes is very vital for covering the higher required of membrane in several purposes like water desalting technology. In this work polyamide-6/cellulose acetate (PA-6/CA) blend membrane was developed according to the wet phase inversion system. The structures of the prepared membranes were examined by scanning electron microscopy (SEM). SEM images showed uniform particles distribution in the prepared membranes. Moreover, SEM images revealed that the membranes have relatively uniform surface (PA-6/CA). PA-6/CA blend membranes systems are evaluated by using synthetic NaCl solution. The separation performance showed that salt rejection increased with increasing of heat treatment of the casted films and it was improved with increasing of operating pressure.

Recent advances in (reactive) melt processing of cellulose acetate and related biodegradable bio-compositions

Cellulose esters, where thermoplastic cellulose acetate is the most industrially relevant derivative, have become highly significant as biodegradable materials issued from renewable bio-feedstock. This contribution highlights some of the main achievements in blending and functionalization of cellulose acetate through (reactive) melt processing with a view to produce environmentally friendly products. Biodegradation aspects of these cellulosic derivatives are also raised.

Study of the optimization factors for preparation of heterogeneous reverse osmosis membranes

The influence of the preparation factors such as casting solution composition, different methods of coal modification, evaporation time of solvent and their optimization on performance of cellulose acetate heterogeneous reverse osmosis membranes have been studied. Three types of membranes were made from a blend of cellulose acetate (CA) and coal by weight ratios 1:1.5, 1:1.75 and 1:2. The powdered coal was modified with nitric acid and aryl diazonium salts in acetonitrile medium at constant modification time. The membranes were prepared by phase inversion process from a casting solution of cellulose acetate-coal and magnesium perchlorate in acetone water mixture at varying evaporation time of solvent at constant temperature using the same gelation medium. The composition of raw and modified coals was examined by IR spectroscopy. Membranes obtained with a casting solution composition of cellulose acetate-coal in weight ratios of 1:1.5 and 1:1.75, modified coals and longer evaporation time of solvent showed the best performance.

Preparation of electrospun silk fibroin/Cellulose Acetate blend nanofibers and their applications to heavy metal ions adsorption

Silk fibroin (SF)/Cellulose Acetate (CA) blend nanofibrous membranes were prepared by electrospinning and their heavy metal absorbabilities were examined in an aqueous solution after ethanol treatment. The electrospun nanofibrous membranes were comprised of randomly oriented ultrafine fibers of 100–600 nm diameters. As a result of field emission electron microscope (FEEM), the anti-felting properties of the blend nanofibrous membranes were markedly improved after treatment with 100 % ethanol when SF was blended with CA. Metal ion adsorption test was performed with Cu2+ as a model heavy metal ion in a stock solution. The SF/CA blend nanofiber membranes showed higher affinity for Cu2+ in an aqueous solution than pure SF and pure CA nanofiber membranes. Especially, the blend nanofibrous membranes with 20 % content of CA had an exceptional performance for the adsorption of Cu2+, and the maximum milligrams per gram of Cu2+ adsorbed reached 22.8 mg/g. This indicated that SF and CA had synergetic effect. Furthermore, the parameters affecting the metal ions adsorption, such as running time and initial concentration of Cu2+, had been investigated. The results showed that the adsorption of the Cu2+ sharply increased during the first 60 min, the amount of metal ions adsorbed increased rapidly as the initial concentration increased and then slope of the increase decreased as the concentration further increased. This study provides the relatively comprehensive data for the SF/CA blend nanofibrous membranes application to the removal of heavy metal ion in wastewater.

Electrospun phase change fibers based on polyethylene glycol/cellulose acetate blends

Ultrafine phase change fibers based on polyethylene glycol (PEG)/cellulose acetate (CA) blends in which PEG acts as a model phase change material (PCM) and CA acts as a supporting material, were successfully prepared via electrospinning. The effect of PEG content on the morphology, crystalline properties, phase change behaviors and tensile properties of the composite fibers was studied systematically by field-emission scanning electron microscopy (FE-SEM), wide-angle X-ray diffraction (WAXD), differential scanning calorimetry (DSC) and a tensile tester, respectively. The SEM observation indicates that maximum PEG content in the fibers could reach up to 70 wt%, and the morphology and average diameter of the composite fibers vary with PEG content. Thermal analysis results show that the latent heats of the phase change fibers increase with the increasing of PEG content in the fibers, and the PEG/CA fibers with high enthalpies have a good capability to regulate their interior temperature as the ambient temperature alters. Therefore, the developed phase change fibers have enormous applicable potentials in thermal energy storage and temperature regulation.

Novel multifunctional membrane technology for visual detection and enhanced adsorptive removal of lead ions in water and wastewater

A multifunctional membrane for visual detection and enhanced adsorptive removal of lead ions in aqueous solution was prepared by immobilizing lead sensitive ligand, dithizone (DZ), on chitosan (CS) /cellulose acetate (CA) blend membrane. The prepared membrane can display visible color change (from yellow to red) as a response to lead ions in solutions; and at the same time, lead ions can be adsorptively removed by the amine groups on the membrane surface. Thus, the development provides a truly multifunctional membrane technology that can achieve optical warning as well as removal of lead ions simultaneously. Experimental results showed that the prepared membrane exhibited the advantages of quick response, easy naked-eye recognition and improved lead uptake capacity.

Study on the control of pore sizes of membranes using chemical methods: Part III. The performance of carbonates and bicarbonates in the membrane-making process by the chemical reaction

In this paper, polyvinylidene fluoride (PVDF)/polymethyl acrilate (PMMA)/cellulose acetate (CA) blend UF membranes were prepared by chemical reaction introduced phase-inversion method. The results of the experiment show that: (1) The membrane pore size distribution is more uniform due to the presence of carbonates or bicarbonates in the coagulation bath; (2) No more than the stoichiometric ratio amount of carbonates or bicarbonates in the coagulation bath can effectively improve the membrane pore size distribution and make the pore size of membrane more uniform; (3) The membrane prepared by carbonates solution as a working solution in coagulation bath possess superior performance than that by bicarbonates.