Cellulose Triacetate Polymer Research Articles

Facile design of a crown ether-functionalized polymeric membrane for highly efficient lithium and magnesium separation during electrodialysis

Efficient separation of magnesium and lithium is essential for the extraction of lithium resources from salt-lake brines. However, the current membrane separation technologies are challenged by the membrane permeability-selectivity trade-off. Herein, we demonstrated a facile and practical approach to fabricate crown ether-functionalized polymeric membranes with excellent Li+/Mg2+ separation performance by incorporating 12-crown-4 rings into the cellulose triacetate polymer network. The tightly and regularly arranged polymer chains anchored the crown ether rings firmly in the membrane structure, thereby facilitating the formation of stable and highly selective cation transport channels inside the membrane. As a result, the prepared membrane achieved an ultrahigh Li+/Mg2+ separation factor of ∼872 and Li+ flux of 22.6 μmol m−2 s−1, which was much superior to that of commercial CIMS and reported membrane separation technologies. The good long-term stability of the fabricated membrane is promising for achieving efficient magnesium-lithium separation in large-scale industrial applications.

Submicron PAN and nanofiber CTA air filters: Fabrication, optimization, and performance

This study investigates the fabrication, optimization, and performance of submicron polyacrylonitrile (PAN) and nanofiber cellulose triacetate (CTA) air filters produced through electrospinning. PAN fibers with diameters ranging from 379 to 804 nm were generated from PAN/DMF solutions, while genuine CTA nanofibers (65–102 nm) were successfully produced using a recycled CTA polymer and a binary solvent system (DMSO/TCM). The effects of electrospinning parameters, including solution concentration (10–12 wt% for PAN, 8 wt% for CTA), applied voltage (10–16 kV), tip-to-collector distance (16–24 cm), solution supply rate (0.08–0.10 mL/hr), and binary solvent ratio (7:1 to 20:1 DMSO/TCM), on fiber morphology and diameter were systematically examined. Reducing PAN solution concentration and increasing applied voltage effectively decreased fiber diameter, enhancing filtration efficiency. Filtration performance tests revealed that CTA nanofibers outperformed PAN submicron fibers, exhibiting higher quality factors (0.043–0.046 Pa−1) due to their smaller fiber diameters and increased fiber packing density. Decreasing CTA solution supply rate and increasing DMSO/TCM ratio reduced fiber diameter and increased packing density. Longer spinning collection times improved filtration efficiency but increased thickness and pressure drop. The optimization of electrospinning parameters proved crucial for controlling fiber diameter and achieving enhanced filtration efficiency, particularly at the most penetrating particle size (MPPS), which usually covers the ultrafine particle size range. This study provides valuable insights into the development of high-performance air filtration media through the optimization of electrospinning parameters and the utilization of recycled materials.

Detection of Hexavalent Chromium Ion in Water by Optode Membrane

Chromium is a heavy metal that is often found as a water pollutant. High concentrations of hexavalent chromium (Cr(VI)) ion in nature are toxic and carcinogenic, so their presence in water needs to be monitored. Detection of heavy metals in water was carried out using an optical sensor membrane (optode). The optode was fabricated from cellulose triacetate polymer with plasticizers (oleic acid and acetophenone), aliquot 336, and the chromoionophore 1.5-diphenylcarbazide (DPC). The success synthesis of optode was evidenced by FTIR and SEM characterization. The optode performance produces a linear response in detecting Cr(VI) ion in the concentration range of 0.02-0.40 mg/L with an R2 of 0.9930, as well as the best conditioning at pH 3. The detection and quantitation limits are 0.0055 mg/L and 0.0165 mg/L. The sensitivity of the chromium optode was excellence, with a molar absorptivity value of 8.8303 × 106 M-1cm-1. The performance test results of the chromium optode were acceptable because they meet the specified requirements for minimum detection concentration value.

A Sensor (Optode) Based on Cellulose Triacetate Membrane for Fe(III) Detection in Water Samples

Iron is a heavy metal that often contaminates water. High iron concentrations are toxic to human health, so monitoring its presence in water is necessary. Iron in water can be detected using an optical sensor (optode). This research aims to fabricate an optode based on a cellulose triacetate membrane with a selective reagent against Fe(III). The optode was fabricated by mixing cellulose triacetate polymer, a plasticiser (a mixture of oleic acid and acetophenone), aliquot-336, and thiocyanate as a selective reagent. Membrane performance was tested based on working range, linearity, limit of detection and quantitation, precision, and accuracy. The performance of the membrane showed a linear response in the concentration range of 0.1–4 mg/L with a coefficient of determination (R2) of 0.9937, limit of detection of 0.0250 mg/L, limit of quantitation of 0.0757 mg/L, repeatability precision with a relative standard deviation of 3.31%, and an accuracy of 100.49%. Optode selectivity was good for interfering ions Cr(VI) and Pb(II). The colour complex of the optode was stable until the 10th day. The application of iron detection in water samples shows an average concentration of 0.2541 mg/L with good precision and accuracy.

Preliminary study on ZIF-8 containing hollow fiber mixed matrix membranes (HFMMMs) for CO2 and CH4 gas permeation

The advantages in terms of smaller footprint, higher energy efficiency, larger surface-to-volume ratio and higher flux have opened various opportunities for hollow fiber membranes in separation processes especially in carbon dioxide (CO2) capture. Although the development of polymeric hollow fiber membrane has emerged as an important material in membrane technology, currently existing polymeric materials suffer from a limiting trade-off between selectivity and permeability. Recently, it has been reported in the literature that the addition of metal–organic frameworks into polymer matrixes have radically improved the separation performance of CO2 from methane (CH4), as well as enhanced the thermal stability and structural properties of the membrane. In this preliminary study, ZIF-8/cellulose triacetate hollow fiber mixed matrix membranes are fabricated by varying the air gap distances and subsequently, the morphology of the resultant membranes was analysed using a scanning electron microscope while the dispersion of ZIF-8 fillers in the polymer matrix was observed using an energy dispersive X-ray. The results showed that the ZIF-8 fillers were homogeneously distributed into the cellulose triacetate polymer. Then, the performance of the resultant membranes before and after post-treatment with polydimethylsiloxane in CO2 and CH4 gases permeation were evaluated. Due to the presence of multiple defects, the overall performance of the fabricated membranes was low with no significant improvements after post-treatment. Hence, further optimization study on the fabrication process is still required to improve the performance of the ZIF-8/cellulose triacetate hollow fiber mixed matrix membrane in CO2 and CH4 gas permeation.

Composite proton exchange membrane of cellulose triacetate polymer integrated with polyacrylic acid and triazole based copolymer for balanced proton conduction and methanol permeability

AbstractBACKGROUNDProton exchange membranes (PEMs) could prompt proton transport with long‐term oxidative and hydrolytic durability with little methanol crossover under humidified conditions. Cellulose triacetate (CTA)‐based PEMs were fabricated by reinforcing with 4 wt.% of polyacrylic acid (PAA) and polymerized triazole (PTZA) combination of acrylic acid/triazole acrylate copolymer.RESULTSThe presence of PAA and PTZA copolymer in the CTA membrane was confirmed using Fourier transform infrared spectroscopy and X‐ray diffraction. The variations of proton conductivity, methanol crossover and water uptake of the PTZA copolymer‐reinforced CTA matrix were evaluated. Higher proton conductivity of 2.313 × 10−4 S cm−1 and minimal methanol permeability of 1.773 × 10−7 cm2 s−1 were obtained for the CTA/PTZA–20 membrane compared to a pristine CTA membrane. Furthermore, the oxidative tolerability was about 99.6% for CTA/PAA membrane, and hydrolytic stability was 97.78% for the CTA/PTZA–20 membrane, higher than that of the pristine CTA membrane.CONCLUSIONSThe increase in proton conduction compared to pristine CTA membrane could be attributed to the presence of triazole moiety, which acts as a proton facilitator in the conduction process. Additionally, an increase in hydrolytic stability, oxidative tolerability and lower methanol crossover results indicated that the PTZA copolymer‐reinforced CTA PEMs have potential for use in fuel cell applications. © 2021 Society of Chemical Industry (SCI).

CO2/CH4 and H2/CH4 Gas Separation Performance of CTA-TNT@CNT Hybrid Mixed Matrix Membranes.

This study explored the underlying synergy between titanium dioxide nanotube (TNT) and carbon nanotube (CNT) hybrid fillers in cellulose triacetate (CTA)-based mixed matrix membranes (MMMs) for natural gas purification. The CNT@TNT hybrid nanofillers were blended with CTA polymer and cast as a thin film by a facile casting technique, after which they were used for single gas separation. The hybrid filler-based membrane depicted a higher CO2 uptake affinity than the single filler (CNT/TNT)-based membrane. The gas separation results indicate that the hybrid fillers (TNT@CNT) are strongly selective for CO2 over CH4 and H2 over CH4. The increment in the CO2/CH4 and H2/CH4 selectivities compared to the pristine CTA membrane was 42.98 from 25.08 and 48.43 from 36.58, respectively. Similarly, the CO2 and H2 permeability of the CTA-TNT@CNT membrane increased by six- and five-fold, respectively, compared to the pristine CTA membrane. Such significant improvements in CO2/CH4 and H2/CH4 separation performance and thermal and mechanical properties suggest a feasible and practical approach for potential biogas upgrading and natural gas purification.

Sporopollenin supported methylimidazolium ionic liquids based mixed matrix membrane for dispersive membrane micro-extraction of nitro and chloro-substituted phenols from various matrices

The focal point of this study is on the development of sporopollenin supported methylimidazolium ionic liquids (Sp-MIM) based mixed matrix membrane (Sp-MIM-MMM) for simultaneous dispersive membrane microextraction (DMME) of nitro- and chloro-substituted phenols from various matrixes followed by determination using high performance liquid chromatography (HPLC). The Sp-MIM particle phase was incorporated through dispersion onto cellulose triacetate polymer matrix to form Sp-MIM-MMM. Several main variables influencing the Sp-MIM-MMM based DMME efficiency were investigated and optimized in detail, such as polymer phase mass, particle phase loading, number of Sp-MIM-MMM spheres per extraction, solution pH, extraction time, extraction volume, type of desorption solvent, desorption solvent volume, and desorption time. Method validation recorded notable repeatability and reproducibility performance with observed linearity 50–500 ng/mL, the calculated linear regression (R2) was 0.9994–0.9997, relative standard deviation (RSD) was 0.2–0.8%, the limit of detection (LOD) was 0.03–0.06 ng/mL, the limit of quantification (LOQ) was 0.11–0.19 ng/mL while the recovery was 99–119% for all phenol analytes analyzed. Targeted selectivity and sensitivity of the Sp-MIM-MMM towards the phenol analytes were evident in the various sample matrix tested with quantified detection calculated at 14.4–154.7 ng/mL for liquid based-real samples and 17.4–34.4 μg/kg for solid based-real samples. Sp-MIM-MMM too exhibited noteworthy reusability up to 10 cycles, signifying a new venture towards environmentally sustainable technology.

The influence of propane and n-butane on the structure and separation performance of cellulose acetate membranes

This work presents the impact of propane and n-butane on the CO2/CH4 separation performance of both cellulose diacetate (CDA) and cellulose triacetate (CTA) membranes by exposing both pristine membranes to either propane (400 kPa) or n-butane (200 kPa) at room temperature (22 ± 2 °C) for 4 weeks. The propane and n-butane sorption isotherms in both membranes were anomalous at 35 °C. X-ray diffraction (XRD) results indicated that the crystalline nature of both polymers was altered by this exposure, although dynamic scanning calorimetry (DSC) did not detect a significant change in the overall crystallinity. Positron Annihilation Lifetime Spectroscopy (PALS) revealed that the average pore size of the CTA polymer and the number of free volume elements of both membranes also increased, even though the sorption uptake was less than 2 wt%. CO2 and CH4 permeabilities at 35 °C were essentially unaffected by the propane or n-butane exposure, indicating that while the crystalline regions of the polymer were affected, plasticization of the glassy amorphous region did not occur. There was a slight decrease in CH4 permeability for the CDA membrane after n-butane exposure, consistent with a slight decline in the CH4 solubility at this feed pressure. The propane and n-butane permeabilities were 0.029 Barrer at 300 kPa and 0.019 Barrer at 125 kPa for the fresh CTA membrane, but these fell significantly after long term exposure to these gases, possibly due to penetrant clustering.

Cellulose triacetate Polymer Inclusion Membrane (PIM) for dye removal

In this study, polymer inclusion membrane (PIM) made from cellulose triacetate (CTA) and Aliquat 336 is used to extract congo red from aqueous solution. Important parameters such as Aliquat 336 concentration (0, 20, 30, 40 and 50 wt. %), pH of extraction solution (2, 4, 6, 8 and 10), concentration of congo red (2, 4, 6, 8 and 10 ppm), temperature (27, 30, 40, 50 and 60°C) and stirring speed (150, 200, 250,300 and 350 rpm) were studied in order to optimize the extraction capacity. The CTA-PIMs was also characterized by Fourier Infrared Spectroscopy (FTIR) and Scanning Electron Microscopy (SEM) in order to determine the functional group and the morphological structure of the PIMs respectively. From this study, 87% of Congo red was successfully removed after 24 hours by using CTA-PIM with 50 wt.% Aliquat 336. The optimum condition was found to be at pH 2, with temperature and stirring speed of 30 °C and 150 rpm respectively.

Automated Mixed Matrix Membrane Microextraction Prior to Liquid Chromatography for the Determination of Chlorophenoxy Acid Herbicides in Sewage Water Samples

A new automated flow-through adsorption/desorption procedure using a multiwalled carbon nanotube immobilised mixed matrix membrane is described. The membrane consisted of 25% (w/w) multiwall carbon nanotube loading in a cellulose triacetate polymer matrix as support and was cast and embedded in a flow-through cell with a channel of an approximate length of 20 mm, a width of 2 mm, and a depth of 1.5 mm. The membrane immobilised with nanoparticles was activated using 1-octanol as a conditioning solvent. For the analyte adsorption process, 6 mL of the sample was passed through the cell at a flow rate of 0.2 mL min−1. The entrapped target analytes were then desorbed dynamically with 60 µL of 2-propanal at a flow rate of 5 µL min−1 prior to HPLC/UV analysis. The performance of the system was demonstrated for the determination of chlorinated phenoxyacetic acid herbicides in sewage water samples. Under the optimum conditions, the linearity of this method ranged from 50 to 1000 ng mL−1, with a correlation coefficient (r) ≥ 0.993 and a detection limit varying from 15 to 20 ng mL−1. Enrichment factors of up to 55 were achieved with relative recoveries of 95–99% and precision values of 6.1–7.5%.

Preparation and characterization of cellulose triacetate polymer inclusion membrane blended with acetylated kraft lignin: effect of AKL and application to the copper (II) extraction from acidic media

Preparation and characterization of cellulose triacetate polymer inclusion membrane blended with acetylated kraft lignin: effect of AKL and application to the copper (II) extraction from acidic media

Interaction of high-power laser radiation with low-density polymer aerogels**Presented at the ECLIM 2016 conference (Moscow, 18 – 23 September 2016).

The interaction of high-power subnanosecond laser pulses with low-density targets of cellulose triacetate polymer is considered. An Nd-glass laser setup provides a focal spot intensity of over 1014 W cm−2. An investigation is made of absorption of laser radiation, laser-to-X-ray energy conversion, spectra of ions emitted from the plasma, transmission of laser radiation through the target and plasma, as well as volume heating of the target material. It is experimentally determined that the laser energy conversion efficiency to X-rays with photon energies of a few Kiloelectronvolts decreases with increasing target material density. With the use of targets of density 10 mg cm−3 this efficiency is two times lower in comparison to 2 mg cm−3 density targets. The duration and amplitude of laser pulses transmitted through the target decreases with increasing column target density (the product of target material density and its thickness). The spectra of ions emitted from low-density target plasmas are recorded using ion collectors positioned at different angles relative to the direction of laser beam propagation as well as a high-resolution Thomson mass spectrometer. The ion flux and ion energies are found to increase with increasing target material density. The peak of the ion energy spectrum is shifted towards higher energies with increasing laser radiation intensity.

Study of Cylindrical Honeycomb Solar Collector

We present the results of our investigation on cylindrical honeycomb solar collector. The honeycomb has been fabricated with transparent cellulose triacetate polymer sheets. Insulation characteristics of the honeycomb were studied by varying the separation between the honeycomb and the absorber plate. The optimal value of the separation was found to be 3.3 mm for which the heat transfer coefficient is 3.06 W m−2 K−1. This supports result of previous similar experiments. Further we test the honeycomb through a field experiment conducted in Delhi (28.6°N, 77°E) and found that when the incident angle of the solar radiation is within 20° then the performance of the system with the honeycomb is better than the one without the honeycomb.

Spectroscopic and sub-bandgap optical properties of gamma-irradiated cellulose triacetate polymer

The effect of gamma irradiation on the optical and sub-bandgap properties of cellulose triacetate (CTA) films is studied. Sellmeier and Wemple–DiDomenico models are used to study the optical dispersion. The refractive index is decreased with increasing irradiation dose, revealing the existence of chain scission. An increase in Urbach energy is obtained, confirming the existence of bond breaking and chain scission mechanism. Phonon assisted optical transition exists with no appreciable change in the bandgap energy values. Such behaviour indicates that the optical properties of the irradiated CTA polymer are attributable to changes in the linear electronic polarizability of the material rather than its bandgap or electronic structure. The obtained tunability in the optical properties of gamma-irradiated CTA polymer makes it of great interest in a number of optical applications.

Thermal and optical properties of electron beam irradiated cellulose triacetate

Samples from Cellulose triacetate (CTA) sheets were irradiated with electron beam in the dose range 10–200 kGy. Non-isothermal studies were carried out using thermogravimetric analysis (TGA) to obtain the activation energy of thermal decomposition for CTA polymer. The CTA samples decompose in one main break down stage. The results indicate that the irradiation by electron beam in the dose range 80–200 kGy increases the thermal stability of the polymer samples. Also, the variation of melting temperatures with the electron dose has been determined using differential thermal analysis (DTA). The CTA polymer is characterized by the appearance of one endothermic peak due to melting. It is found that the irradiation in the dose range 10–80 kGy causes defects generation that splits the crystals depressing the melting temperature, while at higher doses (80–200 kGy), the thickness of crystalline structure (lamellae) is increased, thus the melting temperature increases. In addition, the transmission of these samples in the wavelength range 200–2500 nm, as well as any color changes, were studied. The color intensity ΔE* was greatly increased on increasing the electron beam dose, and accompanied by a significant increase in the blue color component.

Thermal and optical properties of electron beam irradiated cellulose triacetate

Cellulose triacetate (CTA) is a polymer which is widely used in a variety of applications in the field of radiation dosimetry. In the present work, CTA samples were irradiated by electron beam in the dose range 10–200 kGy. The modifications in the electron irradiated CTA samples as a function of dose have been studied through different characterization techniques such as thermogravimetric analysis, differential thermal analysis and color-difference studies. The electron irradiation in the dose range 80–200 kGy led to a more compact structure of CTA polymer, which resulted in an improvement in its thermal stability with an increase in activation energy of thermal decomposition. Also, the variation of melting temperatures with the electron dose has been determined using differential thermal analysis (DTA). The CTA polymer is characterized by the appearance of one endothermic peak due to melting. The results showed that the irradiation in the dose range 10–80 kGy causes defects generation that splits the crystals depressing the melting temperature, while at higher doses (80–200 kGy), the thickness of crystalline structures (lamellae) is increased, thus the melting temperature increased. In addition, the transmission of these samples in the wavelength range 200–2500 nm, as well as any color changes, was studied. The color intensity Δ E * was greatly increased with increasing the electron beam dose, and accompanied with a significant increase in the blue color component.

Application demonstration and performance of a cellulose triacetate polymer film based transparent insulation wall heating system

For the application demonstration of cellulose triacetate (CTA) polymer film based transparent insulation (TI) structures a technically and ecologically optimized TI facade system was developed and used to equip a south-oriented wall of a solar house meeting passive house standard in Graz, Austria. The demonstration building was equipped with an appropriate data recording system for solar irradiation, temperature, heat flux and humidity. The practical experiences within the heating periods 2002/03 and 2003/04 are reported in this paper. For the optimized TI facade system a solar energy efficiency of about 43% and a U-value of 0.76 W/(m 2 K) were obtained. Although CTA absorbs a high amount of water no adverse condensation phenomena were observable visually. The reasoning for these findings is explained and related to construction details.

Studies on diffusional mobility and selectivity of I− ion in plasticized anion-exchange membrane using radiotracer

Summary Plasticized anion-exchange polymer inclusion membranes (PIM) were prepared by physical immobilization of a liquid anion-exchanger trioctylmethylammonium chloride (Aliquat-336) into the polymer matrix of cellulose triacetate (CTA) plasticized with 2-nitrophenyl octyl ether (NPOE). The self-diffusion coefficients (D m) of I− ion in these PIMs were obtained by analysing the experimental 131I radiotracer exchange rates with an analytical solution of Fick's second law. The D m was found to increase exponentially as a function of volume fraction of liquid (plasticizer) in the membrane, which can be attributed to reduction of physical obstruction in diffusion path of the ions in CTA polymer matrix. The selectivity of PIMs towards different anions, with respect to I− ion, was obtained from a determination of mole fraction of I− ion (ratio of moles of I− ion to total ion-exchange sites) in the membrane as a function of mole fraction of I− ion in the equilibrating aqueous solution containing a competing X− ion (X− = F−/Cl−/Br−/NO3 −/ClO4 −). This study indicated that the PIM has preference for I− ion in the presence of Cl−, Br− and NO3 − ions in equilibrating solution, while ClO4 − ion are preferred over I− ion. The selectivity trend (ClO4 −>I−>NO3 −>Br−>Cl−>F−) in PIM was found to correspond with Hofmeister series.

Molecular Modeling of the Solvent Structuring of Chloroform around Cellulose Triacetate

Abstract A molecular dynamics simulation of the hexamer units of cellulose triacetate (CTA) in chloroform was performed to investigate the solvent structuring and dynamics behavior of chloroform molecules around the CTA polymer. During the simulation, a large fluctuation in the main chain conformation of CTA was observed in this solvent. Moreover, ring puckering of the glucose unit was also observed. In order to investigate the solvent structuring of chloroform around the solute molecule, the site-specified radial distribution function and the average velocity of the solvent atoms were precisely analyzed as a function of the distance from the CTA site. The results were compared with that obtained in our previous simulation of CTA in DMSO. The comparison showed that some DMSO molecules were strongly attracted by CTA sites, such as acetyl methyl residue, while the chloroform molecules were weakly attracted by the carbonyl oxygen of CTA. These differences affect the stability of the conformation of CTA in different solvents. In chloroform, the conformation of acetyl residues, especially at the 6 position, were rotating widely in every monomer unit, which caused a large fluctuation on the main-chain conformation. On the other hand, all acetyl side chains maintained a stable conformation in DMSO because of the strong association of DMSO molecules to the acetyl residue of CTA. The role of the solvent effects on the conformation of the polymer in solution was considered at the molecular level in this work.