Cellulose Acetate Concentration Research Articles

Supercritical Phase Inversion: A Powerful Tool for Generating Cellulose Acetate-AgNO3 Antimicrobial Membranes.

Antimicrobial composite membranes, formed by cellulose acetate loaded with AgNO3 particles, were produced by supercritical phase inversion. Different cellulose acetate concentrations were tested (15%, 20%, 30%(w/w)), whereas the active agent (i.e., silver nitrate) concentration was fixed at 0.1%(w/w) with respect to the quantity of polymer used. To determine the influence of the process parameters on membranes morphology, the pressure and temperature were varied from 150 to 250 bar and from 55 to 35 °C, respectively. In all cases, regularly porous membranes were produced with a uniform AgNO3 distribution in the membrane matrix. Silver release rate depended on membrane pore size, covering a time interval from 8 to 75 h.

On the Synthesis and Characterization of Polylactic Acid, Polyhydroxyalkanoate, Cellulose Acetate, and Their Engineered Blends by Solvent Casting

In this paper, we report the synthesis of polylactic acid (PLA), polyhydroxyalkanoate (PHA), cellulose acetate (CA), and their binary and ternary blends by solvent casting. PLA, PHA, and CA had tensile strengths of ~ 59.4, ~ 17.4 and ~ 23.9 MPa, respectively. Differential scanning calorimetry (DSC) analysis showed that binary blends of PLA and PHA are immiscible in each other. During mechanical testing, 50 PHA–50 PLA showed mild enhancement and had a tensile strength of ~ 37.8 MPa as compared to 75 PLA–25 PHA and 25 PLA–75 PHA, which had tensile strengths of ~ 31.2 and ~ 22.9 MPa, respectively. This may be due to the formation of crystallized PHA in PLA matrix, which was further supported by the DSC results and analysis of fractured surface of 50 PHA–50 PLA. The addition of 24, 49, 74, and 89.5 vol.% CA in the PHA matrix improved the tensile strength to ~ 25.8, ~ 25.9, ~ 44.9, and ~ 42.4 MPa, respectively. Based on DSC results, it is hypothesized that the strength enhancement is due to synergistic effect of crystallization of PHA and plasticizing effect of CA additions. The addition of CA in PLA caused severe demixing, and the strength of PLA matrix reduced to ~ 25.8 and ~ 21.4 MPa after the additions of 24 and 49 vol.% CA in PLA matrix, respectively. In ternary blends, the addition of 5 and 19 vol.% CA degraded the strength of PHA–PLA to ~ 22.6 and ~ 21.8 MPa, respectively. However, after the addition of higher concentrations of CA, for example 32, 59, and 79 vol.% CA additions in PHA–PLA matrix, the strength improved to ~ 32.9, ~ 39.3, and ~ 32.1 MPa, respectively. The enhancement in strength can be explained by the increase in amorphous nature of these blends, which was further supported by the DSC results.

Electrospun Fibrous Mat of Cellulose Acetate: Influence of Solvent System (Acetic Acid/Acetone) on Fibers Morphology

Objectives: Electrospun Cellulose Acetate (CA) fibers system are of high demand due to its desired properties associated with the final fiber features. This polymer inability to dissolve may hinder its electrospinningprocessing. The goal of the current study is to explore the fiber forming ability of solvent mixture of varying ratios of acetone and acetic acid and to derive the optimized formulation that facilitate the continuous and uniform CA fiber formation. Methods: In this study, a new solvent system for electrospinning of cellulose acetate is developed for the preparation of continuous uniform CA fibers. Different concentrations of cellulose acetate are dissolved in solvent system consisting of acetic acid/acetone mixture. The polymer solution prepared was hosted in a mechanical syringe pump, with a stainless-steel blunt end needle fixated to the tip acting as the spraying nozzle. The polymeric cellulose acetate in acetone/acetic acid mixture was examined for its viscosity and electrical conductance. Moreover, the formed cellulose acetate-based fibers were morphologically examined. Results: The solvent system composition as well as the cellulose acetateconcentration affected the final CA fiber morphology, where the 10% cellulose acetate solution in acetone: acetic acid at 9:1 ratio presented uniform fiber morphology with a diameter of 549±45 nm. The solvent systemoptimized preserved continuous and uniform, beads-free CA fibers. Conclusion: In the current study, the different solvent systems studied presented different fiber morphologies and diameter sizes thus preservingthe importance of the solvent system for the cellulose acetate fine fiber production.

Sesamol incorporated cellulose acetate-zein composite nanofiber membrane: An efficient strategy to accelerate diabetic wound healing

Recently, the function of nanofiber membranes prepared from electrospinning in accelerating wound healing has attracted wide attention. In this study, novel nanofiber membranes consisted of cellulose acetate (CA) and zein were fabricated to provide efficient delivery vehicles for sesamol, and then the effect of sesamol-loaded composite nanofiber membranes on the wound healing of diabetic mice was studied. It was found the critical concentration of CA was between 15% and 25% (w/v), and the most suitable concentration of stabilizing fibers was 22.5%. When the CA/zein ratio was 12:8, the fiber obtained small diameter and uniform distribution, stable intermolecular structure, low infiltration speed and high stability in water. The composite nanofiber membrane with high-dose sesamol (5% of total polymer concentration, w/w) promoted formation of myofibroblasts by enhancing TGF-β signaling pathway transduction, and promoted keratinocyte growth by inhibiting chronic inflammation in wounds, thus enhancing wound healing in diabetic mice. This study can further broaden the application range of sesamol, CA and zein, and provide reference for the design and development of new wound dressings in the future.

Purification of water from heavy metal ions by a dynamic membrane with a surface layer of cellulose acetate

To reduce the concentration of heavy metal ions in drinking, natural and wastewater to the established standards, a dynamic membrane with a surface layer of cellulose acetate particles on a nylon substrate was obtained. A dynamic membrane layer was formed from cellulose acetate particles with sizes from 42 to 130 nm. The cellulose acetate content was 14 % by weight, upon receipt from a 10 % solution of cellulose acetate in acetone. After applying a layer of cellulose acetate to the surface of a nylon substrate, a decrease in the specific productivity of the membranes is observed more than 10 times due to the formation of a dynamic layer on the surface and in the pores of the substrate. During the operation of the membrane for 1 hour, there is a decrease in the specific productivity of the membrane by 1.5 times and an increase in the working pressure from 0.35 to 0.41 MPa by 1.2 times. A high selectivity of the dynamic nylon-ACd membrane with respect to iron ions 96%, copper 93% and chromium 93% was established with a specific productivity of 300 dm3/m2·h and a pressure of 0.4 MPa. After purification of tap water with a dynamic membrane, the concentration of heavy metal ions does not exceed the MPC for water bodies for drinking water.

Effect of processing parameters on the electrospinning of cellulose acetate studied by response surface methodology

Cellulose acetate (CA) is the acetate ester of cellulose produced from cellulose via the process of acetylation. Currently, electrospinning has become a widely used technique to produce CA nanofibers for potential applications such as filtration, medical dressings, and food packaging. Being biodegradable and biocompatible, CA nanofibers bring additional advantages for these applications, e.g., high surface area, high porosity, and light weight. The quality of the CA nanofibers, which can be characterized by the prevalence of fiber defects, pore size, and fiber diameter, directly affects their performance. Fiber quality is, in turn, directly determined by the electrospinning process parameters. Therefore, in this project, we aimed to investigate the effect of electrospinning parameters, including CA concentration, voltage, and spinning distance, on the electrospinnability of CA nanofibers and fiber diameter, using process optimization principles and response surface methodology. Certain process parameters, including solvent (acetone), needle diameter (gauge 22, inner diameter 0.413 mm), temperature (20 °C), and feed rate (2 mL/h), were kept constant throughout the experiment. Preliminary experiments were conducted to determine the extreme conditions of each parameter and to define a working boundary. Then, trials of electrospinning CA nanofibers were conducted following a 3-factor, 3-level Box-Behnken design within the predetermined range. CA nanofibers morphology was characterized by scanning electron microscope (SEM) and ImageJ software to obtain their mean diameter. The mean electrospun fiber diameters fell into the range from 404 to 1346 nm and increased with increasing CA concentration. The fiber diameter was impacted less significantly by the other two parameters, i.e., voltage and spinning distance.

Obtaining and properties of a composite membrane with a surface layer of cellulose acetate

AnnotationTo reduce the concentration of dissolved salts in water treatment processes, a composite nanofiltration membrane with a surface layer of cellulose acetate on a polytetrafluoroethylene substrate was obtained. The cellulose acetate content was 17.6% by weight, upon receipt from a 10% solution of cellulose acetate in acetone. An increase in the membrane moisture capacity after modification from 0.6% to 68.5% was established, which is associated with an increase in the hydrophilicity of the membrane. The contact angle of the membrane with a drop of distilled water as a result of the deposition of cellulose acetate particles on the surface of the original membrane decreased from 130º to 53.8º. According to the results of scanning electron microscopy, it was found that the cellulose acetate particles are not located on the surface of the polytetrafluoroethylene substrate, but in the depth of its structure — in the pores, between the fibers, as a result, open pores overlap. After applying a layer of cellulose acetate to the surface of the membrane, the specific productivity of the membrane decreases by 10 times due to the accumulation of particles of cellulose acetate in the pores of the membrane. The maximum specific productivity of the modified membrane 412 dm3/m2 h, is observed when passing distilled water. The retention capacity of the membrane in terms of total salinity in the separation of tap water with an initial salinity of 323 mg/dm3 was 75%.

Development and characterization of electrospun cellulose acetate nanofibers modified by cationic surfactant

Polymeric electrospun nanofibers have been gaining notoriety in the same way as their industrial applications, since the manufacturing of this type of material is simple and low-costed. In order to obtain fibrous polymeric material with small diameters and with reduced beads formation, a 24 factorial experiment with triplicate at center point was performed. Cellulose acetate (CA) and cationic cetylpyridinium bromide (CPB) surfactant nanofibers were made using a homemade electrospinning apparatus. The assessed inputs were as follows: CA%, CPB%, flow rate, and applied voltage. From the analysis of the response surface methodology and scanning electron microscope (SEM), the optimal concentrations of CA and CPB for producing nanofibers were 21 w/v-% and 0.5 w/v-%, respectively, using a flow rate of 0.7 mL h−1 and applied voltage of 18 kV. Fibers mats morphology shows average diameter of 0.2 μm and 7 nm pore size, as well as it was found that the single fiber unit presented nanoheterogeneity. Mechanical resistance of 2.70 MPa was obtained in the tensile strength test. The modification of CA by the addition of surfactant attributed better thermal and mechanical resistances to the nanofibers without, however, affecting their biodegradability and water resistance properties. The morphological characteristics of the newly obtained CA/CPB nanofibers combined with mechanical resistance provided subsidies to suggest that the as-obtained material presents potential to be applied as an air filter.

Electrospinning of cellulose acetate nanofiber membrane using methyl ethyl ketone and N, N-Dimethylacetamide as solvents

Cellulose acetate (CA) nanofiber membrane was prepared by electrospinning method using solvent mixtures of methyl ethyl ketone (MEK) and N, N, - dimethylacetamide (DMAc) in different ratios (2:1, 1:1, 1:2) and also different concentration of CA (7–19%). MEK was selected in place of acetone due to its high boiling point, thereby, minimises the evaporation loss of the solvent enabling the longer duration of electrospinning. The morphology of electrospun nanofibers was observed by Scanning Electron Microscope (SEM). It was observed that cylindrical fibers formed at higher concentration of polymer with increase of DMAc. Fiber diameters were in the range of 40–500 nm with large diameters formed at higher polymer concentration. Contact angle measurement revealed that membranes have good wetting property. The water flux measurements of membranes were carried out under gravity. A water flux of 10,197 Lm−2h−1 was measured initially and was reduced subsequently to 365-200 Lm−2h−1. The membranes could be reused up to four times without rupture. The above experiments suggest that MEK and DMAc could be an alternate solvent system in addition to other systems.

Understanding solubility, spinnability and electrospinning behaviour of cellulose acetate using different solvent systems

The purpose of this study is to understand the solubility and spinnability of cellulose acetate (CA) and its electrospinning behaviour in different solvents. As the process of electrospinning and the corresponding fibre properties are primarily governed by the solvents used, a systematic study of the selection of solvent systems using the solubility parameters of Hildebrand and Hansen along with a Teas chart for a particular polymer is essential for the better optimization of the process. It appeared from the Teas chart that higher dispersion force \((f_{\mathrm{d}})\) and lower hydrogen bonding force \((f_{\mathrm{h}})\) are convenient for both the solubility and spinnability of CA in single solvent of acetone and binary solvent of 2:1 acetone/N,N-dimethylacetamide (DMAc). The viscosity of the solutions escalated with increasing concentration of CA due to polymer chain entanglement which in turn favoured fibre formation. Among the solvent systems used in this work, field emission scanning electron microscopy arrayed the electrospun CA fibres using pure acetone as a solvent produced both cylindrical- and ribbon-shaped fibres of a diameter of 1 \(\upmu \)m, whereas CA in 2:1 acetone/DMAc yielded smooth bead-free cylindrical fibres of diameter in the range of 250–350 nm and CA in 3:1 acetic acid/water formed fibres with beads. Rheological analysis showed that fibre formation improved with increasing viscosity of CA solution. Electrical conductivity measurement of the CA solutions depicted that with an increase in CA concentration, fibre diameters were increased, whereas the conductivity decreased. Also, attenuated total reflectance–Fourier transform infrared spectroscopy confirmed the major peaks of CA for all the electrospun samples.

Two‐stage phase separation of cellulose acetate membranes modified with plasma‐treated natural zeolite: Response surface modeling

Cellulose acetate (CA) microfiltration membranes were prepared by two‐stage vapor‐induced phase separation (VIPS) and immersion precipitation. To improve the hydrophilicity and permeability of the membranes at low operating pressures, plasma‐treated natural zeolite was incorporated into the membranes. A response surface methodology based on the three‐level central composite design (CCD) was used to model and optimize the casting solution composition of the membranes with the aim of maximizing membranes permeability. Three independent variables for CCD optimization were concentration of CA, polyvinylpyrrolidone (PVP) pore former, and plasma‐treated zeolite additive. The results showed that a second‐order polynomial model could properly predict the response (pure water flux) at any input variable values with a satisfying determination coefficient (R2) of 0.954. Also, analysis of variance (ANOVA) confirmed the adequacy of the obtained model. The permeability of the prepared membranes increased by increasing zeolite loading from 0.10 to 0.50 wt%, which was related to the membranes morphology and porosity and confirmed by scanning electron microscopy (SEM) images. Pure water flux of the membranes decreased by increasing CA concentration while an optimum PVP amount was required to reach the maximum flux. The result of the bubble point analysis well matched with surface SEM images of the membranes and permeability trend predicted by CCD model. Also, the prepared CA membranes with different compositions showed no toxicity for mouse L929 fibroblast, which indicated their nontoxic and biocompatible nature.

Fouling resistant functional blend membrane for removal of organic matter and heavy metal ions

This study investigates the removal of heavy metal ions and humic acid using Cellulose acetate (CA) and Poly (methyl vinyl ether-alt-maleic acid) (PMVEMA) blend membranes. Antifouling properties of blend membranes were also investigated. Flat sheet membranes were prepared by phase inversion technique using different concentrations of CA and PMVEMA. The prepared membranes were characterized and their performance was evaluated by measuring pure water flux, water uptake capacity and humic acid removal. Rejection of humic acid (HA) was observed to be around 97% for all the blend membranes because of electrostatic interactions between the functional groups of HA and blends. The fouling characteristics of the membranes was assessed using HA as a foulant and the antifouling capacity of blend membranes was observed to be greater with a flux recovery ratio of almost 95% when compared to bare CA, commercial CA (TechInc) and other reported CA blends used for HA rejection. Also, the blend membranes were very effective in removing heavy metal ions (Pb2+, Cd2+ and Cr+6) and humic acid simultaneously. Overall, the PMVEMA modified CA membranes can open up new possibilities in enhancing the hydrophilicity, permeability and antifouling properties.

Influence of CaCO3 pore-forming agent on porosity and thermal conductivity of cellulose acetate materials prepared by non-solvent induced phase separation

Thermal insulation materials with a low thermal conductivity are indeed demanded because they play the main role in the enhancement of energy conservation in various industries, especially lightweight constructive materials. Therefore, tubular cellulose acetate (CA) materials were firstly prepared by non-solvent induced phase separation (NIPS). In the NIPS process, the concentration of CA was varied in a range of 20–40 wt%. Also, the temperature of water used as a non-solvent was studied from 5 °C up to 50 °C. According to the FE-SEM results, the 30 wt% CA solution at 20 °C provides tubular CA materials with a higher porous structure than an original CA material but the pore size is quite larger than the mean free path of air leading to achieve a material with high thermal conductivity. To overwhelmed such a problem, the calcium carbonate (CaCO3) was used to be pore forming agents in order to decrease pore size of prepared CA sheet materials. The amount of CaCO3 particles in the CA sheet materials was varied as 50 and 60 wt% to investigate its effect on porosity and thermal conductivity of the prepared materials. As the results, the CA sheet materials prepared using NIPS process and after removing 60 vol% CaCO3 have an enlargement of pores with a size lower than the mean free path of air. They exhibit high porous materials leading to the reduction of their thermal conductivity, which has the lowest value about 0.043 W/mK. Consequently, the CA materials are potentially applied for constructive materials in order to reduce energy consumption in buildings.

Electrospun cellulose acetate nanofibers for airborne nanoparticle filtration

Reported in this paper are the effects of tip-to-collector distance, voltage, deposition time and solution concentration on the fiber size distribution and filter quality factor of electrospun cellulose acetate (CA)-based nanofibers. Nanofibrous filter samples were produced by electrospinning in a laboratory setting. The CA solutions were prepared by diluting various concentrations of CA in a 2:1 (w:w) ratio of N,N-dimethylacetamide (concentration 10–20 wt.%). The electrospinning voltages ranged from 8–12 kV, with distances from 10–15 cm and deposition times of up to 30 minutes. The produced nanofibrous filter samples were then analyzed in terms of fiber size distribution and filter quality factor using nanosized sodium chloride particles ranging from 4–240 nm in diameter. The maximum filtration efficiency measured was 99.8% for filter samples obtained with an overall deposition time of 30 minutes. The maximum filter quality factor was 0.14 Pa−1 for a CA concentration of 20 wt.% and a tip-to-collector distance of 15 cm. The average fiber diameters of the fibers were between 175 and 890 nm, and CA concentrations below 15% led to the formation of beads.

Ammonia removal from aquaculture wastewater by high flux and high rejection polysulfone/cellulose acetate blend membrane

Polysulfone (PSf)/cellulose acetate (CA) blend membranes with different compositions (100/0, 90/10, 85/15, 80/20, 75/25 and 70/30) were prepared and characterized for removal of low concentration ammonia (1–10 mg/L) from aquaculture wastewater. The performance of prepared membranes in terms of pure water flux and ammonia removal percentage was analyzed by different experimental variables such as blend membrane compositions, ammonia concentration in feed tank (1, 5 and 10 mg/L) and membrane thickness (80 and 100 µm). The permeability of prepared membranes was examined by pure water flux measurement in feed pressure range of 1–3 bar. The contact angle measurement indicates that the hydrophilicity of PSf/CA blend membranes is enhanced by increasing the CA concentration in the casting solution. This increment improves the pure water flux of blend membranes. The ammonia removal by PSf/CA 80/20 (80 µm) was 79%, 99% and 92% from feed solutions containing 1, 5 and 10 mg/L of ammonia, respectively. The ammonia removal from feed solution containing 1 mg/L of ammonia is improved from 79 to 95% (at 2 bar feed pressure) by increasing the thickness of PSf/CA (80/20) membrane from 80 to 100 µm.

Designing Cellulose Acetate - Polyacrylamide Semi-Interpenetrating Polymer Networks and Evaluation of their Protein Retention Behavior

ABSTRACTIn this work semi-IPNs of cellulose acetate (CA) – N, N’- methylene bisacrylamide (MBA) – crosslinked polyacrylamide (PAM), and native CA gel were prepared and characterized by FTIR, AFM, SEM, XRD, TGA and DSC techniques. The AFM studies revealed that addition of AM increased the symmetry of the semi-IPN surfaces whereas the XRD spectra suggested for a decrease in crystalline nature of CA. The network parameters were changed with change in concentrations of CA and AM. The prepared semi-IPNs were examined for retention of bovine serum albumin (BSA). The mechanical properties, swelling capacity, % porosity and biocompatibility were also investigated.

The Effect of Cellulose Acetate Concentration from Coconut Nira on Ultrafiltration Membrane Characters

Cellulose acetate is one of material in produce ultrafiltration membrane. Many efforts have been done to produce cellulose acetate from natural product to replace commercial one. In this research, ultrafiltration membrane has been produced from coconut flower water (nira). Ultrafiltration membrane is widely used in separation processes. This research aims to determine the characteristics of ultrafiltration membrane at a various concentration of cellulose acetate. The ultrafiltration membrane is conducted by phase inversion method at various concentration of cellulose acetate. The cellulose acetate concentration was 20%, 23% and 25% (w/w) with formamide as additives. The results showed that the greater the concentration of cellulose acetate, the smaller the flux value. The highest flux was a membrane with 20% cellulose acetate concentration with water flux value 55.34 L/(m2. h). But the greater the concentration of cellulose acetate the greater the rejection. The highest rejection value was on a membrane with 25% cellulose acetate concentration of 82.82%. While from the tensile strength test and the pore size analysis, the greater the cellulose acetate concentration the greater the tensile strength and the smaller the pore size

Ethyl cellulose, cellulose acetate and carboxymethyl cellulose microstructures prepared using electrohydrodynamics and green solvents

Cellulose derivatives are an attractive sustainable material used frequently in biomaterials, however their solubility in safe, green solvents is not widely exploited. In this work three cellulose derivatives; ethyl cellulose, cellulose acetate and carboxymethyl cellulose were subjected to electrohydrodynamic processing. All were processed with safe, environmentally friendly solvents; ethanol, acetone and water. Ethyl cellulose was electrospun and an interesting transitional region was identified. The morphological changes from particles with tails to thick fibres were charted from 17 to 25 wt% solutions. The concentration and solvent composition of cellulose acetate (CA) solutions were then changed; increasing the concentration also increased fibre size. At 10 wt% CA, with acetone only, fibres with heavy beading were produced. In an attempt to incorporate water in the binary solvent system to reduce the acetone content, 80:20 acetone/water solvent system was used. It was noted that for the same concentration of CA (10 wt%), the beading was reduced. Finally, carboxymethyl cellulose was electrospun with poly(ethylene oxide), with the molecular weight and polymer compositions changed and the morphology observed.

Behavior of toluene adsorption on activated carbon nanofibers prepared by electrospinning of a polyacrylonitrile-cellulose acetate blending solution

Activated carbon nanofibers were prepared with polymer blends that consisted of polyacrylonitrile (PAN) and cellulose acetate (CA), by electrospinning and subsequent thermal treatment. The average fiber diameter of samples was about 200 nm, ranging from 150 to 400 nm. The specific surface area, total pore volume, and micropore volume increased with increasing CA content. As the CA content was increased up to 20%, the pore characteristics for the adsorption performance were enhanced. However, excess CA content (over 30%) was harmful to volatile organic compounds (VOCs) adsorption ability due to changing morphology of the activated carbon nanofibers. The O/C ratio was increased with increasing CA content. However, the O/C ratios of all activated carbon nanofibers prepared with blends represent small values revealing non-polarity of the surface. The adsorption capacities of PC10, PC09, PC08 and PC07 were 65 g/100 g, 66 g/100 g, 72 g/100 g and 67 g/100 g. The blends of the PAN with CA showed better characteristics than those of PAN alone, but apparently there is an appropriate blending ratio (20%) for high-performance of activated carbonaceous materials.

Effective composite membranes of cellulose acetate for removal of benzophenone-3

In thiswork,Cellulose acetate/Zinc oxide-Zeolite composite membranes were successfully synthesized via a simple DIPS method for the removal of benzophenone- 3 from water.The influence of the different concentrations of cellulose acetate and Zeolites-Zinc Oxide Nano composite particles were prepared and inserted in the membrane matrix. The resulting membrane was characterized by ATR-IR, XRD, SEM, ICP-OES and AFM analysis. The water uptake study was also carried out to know hydrophobicity of the membrane. The membrane performances were significantly improved after the addition of ZnO-Zeolite in the Cellulose acetate solution in ascending order.The concentration of Zeolite ZnO enhances the hydrophilicity of the membranes. The membrane showed 98% rejection of benzophenone-3 in neutral pH. However rejection and permeate flux increases with the concentration of Zeolite ZnO. The effect of applied pressure and feed concentration was studied and discussed with scientific reasons.