Porous composite membranes based on cellulose acetate and cellulose nanocrystals via electrospinning and electrospraying (original) (raw)
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Journal of Polymers and the Environment
Water-stable and eco-friendly membranes were fabricated from carboxymethyl cellulose (CMC) acting as anionic adsorbent and cellulose nanofibrils (CNFs) as strengthening filler by solvent-and unidirectional freeze-casting processes, both supported with simultaneous citric acid (CA) mediated cross-linking. Spectroscopic, thermogravimetric and potentiometric titration techniques were applied to evaluate the efficacy of the cross-linking as well as to quantify the processing-dependant surface charge. In addition, the CMC/CNF assembling and membrane porosity were identified microscopically as the combinatorial effect of components ratio and the applied fabrication technique. Finally, the membrane's cationic dyes adsorption capacity and kinetic were evaluated depending on the dyes ionization constants, solution pH, and the contact time using batch equilibrium experiment, and further evaluated for filtration performance at optimal pH. The resulting, freeze-casted membranes demonstrate anisotropic to isotropic and highly (> 90%) porous structures with gradient pore sizes (from few nm up to 200 µm range). This provides relatively high and stable flux rates (150-190 kL/m 2 h MPa) with ~ 100% cationic dye adsorption, fast dynamic (8.536-5.446 kg/g min) and capacity (1828-1398 g/kg), which highlight their potential in dead-end filtration technologies without need for additional separation step. The similar dye adsorption capacity was assessed for denser and nano-porous (< 50 nm) solvent-casted membranes, however, with much lower and time-declining flux rates (100-10 L/m 2 h MPa), demonstrating their potential usage in spiral wound-cross-flow modules. Both types of membranes anyhow showed high dye removal capacity (≥ 90%) even after 4th (solvent-casted) and 50th (freeze-casted) reusing cycle, present a highvalue alternative to commercial activated carbons or other bio-nano-absorbents.
2018
Disposal of dyestuff into rivers or other water can disrupt the aquatic biota ecosystem in it. Thus the pollution of dyes in the aquatic environment needs to be overcome. One effort to reduce the dye content in water is by making adsorbent membranes based of cellulose which are biomaterials of chitosan and alginate. This aims of study was to make polyelectrolyte membranes from chitosan and alginate which will be applied as adsorbents of textile dyestuffs. The research was done by mixing chitosan gel in 2,5% acetic acid solution with alginat gel in water for 3 h stirring. The solution then was printed out into a polypropylene container and dried. The formed membrane was characterized using FTIR to identify functional groups, XRD and SEM to analyze their physical characteristic. The results showed that the Chi-Alg membrane adsorbent had stability and resistance to the acidic environment. Characterization results using FTIR showed that the adsorbent has functional group of amine, carbo...
Oriental Journal of Chemistry
Disposal of dyestuff into rivers or other water can disrupt the aquatic biota ecosystem in it. Thus the pollution of dyes in the aquatic environment needs to be overcome. One effort to reduce the dye content in water is by making adsorbent membranes based of cellulose which are biomaterials of chitosan and alginate. This aims of study was to make polyelectrolyte membranes from chitosan and alginate which will be applied as adsorbents of textile dyestuffs. The research was done by mixing chitosan gel in 2,5% acetic acid solution with alginat gel in water for 3 hours stirring. The solution then was printed out into a polypropylene container and dried. The formed membrane was characterized using FTIR to identify functional groups, XRD and SEM to analyze their physical characteristic. The results showed that the Chi-Alg membrane adsorbent had stability and resistance to the acidic environment. Characterization results using FTIR showed that the adsorbent has functional group of amine, c...
Enhancement of Dye Separation Performance of Eco-Friendly Cellulose Acetate-Based Membranes
Sustainability
Many reasons have caused a worldwide water stress problem. Thus, the recycling of wastewater streams has been extensively studied. In this work, eco-friendly mixed matrix membranes (MMMs) were fabricated, characterized, and tested for the removal of two separate dyes from simulated waste streams. The environmentally friendly nano activated carbon (NAC) was extracted from water hyacinth to be impregnated as a membrane nano-filler to enhance the neat membrane performance. The extracted NAC was further studied and characterized. Cellulose acetate (CA)-based membranes were obtained by phase inversion and electrospinning mechanisms. All four synthesized blank and MMMs were characterized via scanning electron microscope (SEM) and contact angle to study their structure and hydrophilic nature, respectively. However, the membrane with optimum performance was further characterized using Fourier transfer infrared (FTIR) and X-ray diffraction (XRD). The four prepared cast and electro-spun, blan...
Scientific Reports
The present study fabricated regenerated cellulose nanofiber incorporated with activated carbon and functionalized rC/AC3.7 with EDTA reagent for methylene blue (MB) dye removal. The rC/AC3.7 was fabricated by electrospinning cellulose acetate (CA) with activated carbon (AC) solution followed by deacetylation. FT-IR spectroscopy was applied to prove the chemical structures. In contrast, BET, SEM, TGA and DSC analyses were applied to study the fiber diameter and structure morphology, the thermal properties and the surface properties of rC/AC3.7-EDTA. The CA was successfully deacetylated to give regenerated cellulose nanofiber/activated carbon, and then ethylenediaminetetraacetic acid dianhydride was used to functionalize the fabricated nanofiber composite. The rC/AC3.7-EDTA, rC/AC5.5-EDTA and rC/AC6.7-EDTA were tested for adsorption of MB dye with maximum removal percentages reaching 97.48, 90.44 and 94.17%, respectively. The best circumstances for batch absorption experiments of MB ...
All cellulose electrospun water purification membranes nanotextured using cellulose nanocrystals
Cellulose, 2018
Cellulose acetate (CA) fibers were electrospun on a mesh template to create specific surface and pore structures for membrane applications. The mesh template CA fiber mats were impregnated with cellulose nanocrystals at varying weight percentages. The membranes showed nanotextured surfaces and improved mechanical properties post impregnation. More importantly, the hydrophilicity of the original CA fibers was increased from a hydrophobic contact angle of 102°-0°thereby creating an anti-fouling membrane surface structure. The membranes showed rejection of 20-56% for particles of 0.5-2.0 lm, indicating potential of these membranes in rejecting microorganisms from water. Furthermore, high rejection of dyes (80-99%) by adsorption and potential application as highly functional affinity membranes was demonstrated. These membranes can therefore be utilized as all-cellulose, green, scalable and low cost high flux membranes ([ 20,000 LMH) for water cleaning applications in food industry where microorganisms and charged contaminants are to be removed.
Cellulose, 2018
In order to annul the toxic dye contaminants which are being heavily discharged into the water bodies, the present study emphasizes on the fabrication of pristine and functionalized cellulose nanofibres derived from two distinct lignocellulosic biomass sources i.e. sugarcane bagasse and pine needles. Pine needles proved to be a better source than sugarcane bagasse in terms of high adsorption capacity of the adsorbents which may be due to the difference in the nanofibrillar arrangement based on source. The developed adsorbents were characterized for their structural, morphological and other physicochemical properties with the help of FT-IR, Powder XRD, FE-SEM and EDX spectroscopic techniques. Outstanding adsorption properties of modified cellulose nanofibres were explored for the eradication of Safranin O and Methylene blue from the polluted wastewater. Structural differences based on origin resulted in the variable adsorption characteristics over functionalized adsorbents. Among all, esterified cellulose nanofibres presented best adsorption capacity for the removal of toxic colorants. Incorporation of different isotherms and kinetic models provided the deep insights of the adsorption mechanism.
Cellulose nanocrystals as promising adsorbents for the removal of cationic dyes
Cellulose nanocrystals (CNCs) prepared from cellulose fibre via sulfuric acid hydrolysis was used as an adsorbent for the removal of methylene blue (MB) from aqueous solution. The effects of pH, adsorbent dosage, temperature, ionic strength, initial dye concentration were studied to optimize the conditions for the maximum adsorption of dye. Adsorption equilibrium data was fitted to both Langmuir and Freundlich isotherm models, where the Langmuir model better described the adsorption process. The maximum adsorption capacity was 118 mg dye/g CNC at 25 °C and pH 9. Calculated thermodynamic parameters , such as free energy change (DG =-20.8 kJ/mol), enthalpy change (DH =-3.45 kJ/mol), and entropy change (DS = 0.58 kJ/mol K) indicates that MB adsorption on CNCs is a spontaneous exothermic process. Tunability of the adsorption capacity by surface modification of CNCs was shown by oxidizing the primary hydroxyl groups on the CNC surface with TEMPO reagent and the adsorption capacity was increased from 118 to 769 mg dye/g CNC.
Journal of Applied Polymer Science, 2012
The electrospinning of cellulose acetate (CA) was investigated to develop biodegradable nanostructured membranes for the controlled release of drugs used to treat skin wounds. CA nanofibers were successfully prepared via the electrospinning in the four mixed solvents acetic acid : water; acetone : water; DMAc : acetone; DMAc : acetone : water. Design of experiments (DOE) was applied to see what combinations of parameters could affect the production of electrospun microfibers and nanofibers to optimize the process. The results of this work indicated that both the processing parameters and the solvent mixtures were responsible for the fiber diameter and nanostructure membrane appearance. The optimized condition for each solvent mixture was obtained and compared with each one of the others. The best conditions achieved were dimethylacetamida (DMAc) : acetone with 17% of CA, which provided homogeneous and free bead fibers with an average diameter of 295 nm. V C 2012 Wiley Periodicals, Inc. J Appl Polym Sci 000: 000-000, 2012
Membranes
Commercially available ultrafiltration membranes were coated with cellulose nanofibers (CNFs) produced from softwood pulp by a two-step process: a non-derivatizing DES treatment and a simple mechanical treatment (high-speed homogenization and sonification). The CNFs coating aimed at enhancement of the removal of methylene blue (MB) from water and was investigated at different concentrations of the coating, quantified in grams of CNFs per square meter of the membrane (1.3, 6.5, 13, and 19.5 g/m2). The pure water permeability (PWP) was unaffected up to the concentration of 6.5 g/m2 but the dye retention increased approximately 2.5-fold. Even higher improvement of MB removal, about 4-fold, was observed when 19.5 g/m2 were used, however, the pure water permeability also decreased by about 30%. In addition, it was proved that the coating can be removed and created again several times which shows that the concept could be used to improve the retention of organic compounds when high permea...