Cellulose Acetate Sheets Research Articles

Cellulose acetate sheet supported gold nanoparticles for the catalytic reduction of toxic organic pollutants

Abstract Water contamination by toxic organic dyes represents a significant global challenge necessitating effective remediation strategies. Due to their high catalytic activity, considerable attention has been gained to metal-based nanocatalysts. Cellulose acetate sheets supported by gold nanoparticles through a reduction method were synthesized. The composite synthesized material presents a compelling platform for catalytic reduction in the remediation of toxic organic pollutants, ensuring controlled particle size and stability. In this study, the prepared cellulose acetate sheet (CAsheet) was dipped in a 0.001 M aqueous chloroauric acid (HAuCl4) solution and reduced by immersion in a 0.1 M sodium borohydride (NaBH4) aqueous solution. After the successful preparation of virgin cellulose acetate sheet (CAsheet) and gold-supported cellulose acetate sheet (Au-CAsheet) samples were assessed by scanning electron microscopy (SEM), X-ray crystallography (XRD), energy dispersive X-rays spectroscopy (EDX), and Fourier transform infrared spectroscopy (FTIR) analysis. The catalytic reduction reaction of toxic compounds i.e. reduction of 4-nitroaniline (4-NA), Congo red (CR), and reactive yellow (RY-42) by using NaBH4. The catalytic activity of the Au-CAsheet was exhibited by the reaction rate constant (k app) values 0.3189, 0.1596, and 0.1593 min−1 for CR, 4-NA, and RY-42 respectively. This kind of procedure for Au-CAsheet synthesis may be valid for different applications in catalysis, sensing, and environmental application.

Synthesis and antibacterial activity of cellulose acetate sheets modified with flower-shaped AlOOH/Ag

Modified cellulose acetate antibacterial material was obtained by immobilizing Al/Ag nanoparticles on fabric fibres in water and subsequent hydrolysis of this nanoparticles under mild reaction condition. AlOOH/Ag self-assembled flower-shaped nanostructures consist of AlOOH nanoplates and Ag inclusions. The AlOOH nanosheets size is of 150–300 nm, thickness is 5–7 nm. The silver inclusions were from 5 to 30 nm in size. Flower-shaped AlOOH/Ag nanostructures change the charge of fibres and stabilize Ag nanoparticles against agglomeration. The positive charge of the modified fibres improves the bacteria adsorption due to electrostatic interaction. The antibacterial activity of the nanoparticles and modified material arise due to the slow Ag+ migration into the medium from stabilized Ag nanoparticles. The nanoparticles and modified cellulose acetate sheets were characterized by transmission and scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction analysis, FTIR spectroscopy. The release of silver ions to the medium remains low for 70 h with AlOOH/Ag@CA reducing all the tested bacterial strains below the limit of detection (102 CFU/mL) within 3 h for Escherichia coli and 6 h for MRSA due to local effects of silver on adsorbed bacteria. The antibacterial activity of modified cellulose acetate fabric allows this method of modification to be exploited to produce materials for biomedical applications.

The application of forward osmosis to dairy processing

This work assesses the feasibility for concentrating process streams within dairy processing facilities using commercial forward osmosis membranes; to increase their total solids concentrations before entering energy intensive unit operations including thermal evaporators and spray dryers. These streams include demineralised whey, lactose, whey protein concentrate, sweet whey and skim milk. FTSH2O cellulose acetate (CTA) and Aquaporin flat sheet membranes are used with magnesium chloride concentrations of 1.66 ± 0.12 M as the draw solution. The experimental data are fitted to conventional mathematical models for forward osmosis, further modified by considering the nonlinear relationship between osmotic pressure and solute concentration. The diffusion coefficients of magnesium chloride in 1.6 M solutions at 10 °C, 20 °C and 50 °C are obtained and reported for the first time. Minimal fouling and a significantly smaller degree of concentration polarisation was observed on the membrane surface during lactose concentration compared to the concentration of other dairy solutions, due to the absence of proteins and calcium phosphate salts. The transfer of magnesium into the concentrated products was monitored and shown to be below 100 mg per 100 g dry powder. Acid cleaning alone was not effective in recovering pure water flux, and enzyme cleaners at neutral pH were needed given the limited pH tolerance (3–8) of the CTA membranes. Total solids concentrations of the concentrated dairy streams by forward osmosis (up to 40%) exceed those which can be achieved by nanofiltration and reverse osmosis (i.e., 15–20%). This study shows that forward osmosis is an effective approach to concentrate relevant dairy streams to achieve high concentration factors (e.g. >4 for sweet whey samples) without jeopardising product quality.

A diagnostic tool for assessing the conservation condition of cellulose nitrate and acetate in heritage collections: quantifying the degree of substitution by infrared spectroscopy

Cellulose nitrate and acetate are materials at risk in heritage collections because it is not possible to predict the evolution of their conservation state over time. Knowing that the degree of substitution (DS) of these materials correlates with their state of conservation because the fundamental degradation mechanism is hydrolysis, in this work, DS was measured in historical objects and artworks. Infrared spectra were used to develop and optimize calibration curves for cellulose nitrate and acetate references that were next applied to calculate DS values of heritage objects. The extent of hydrolysis measured, with this tool, correlated well with the physical deterioration assessed through the sample hardness (Shore A) which was measured with a Durometer. Calibration curves were optimized in reference materials by Attenuated Total Reflectance (ATR-FTIR) and Micro Fourier Transform Infrared Spectroscopy (μFTIR). The DS values of the AC reference materials was previously calculated by nuclear magnetic resonance spectroscopy. The calibration curves were obtained plotting DS as a function of the ratio between a reference peak (which does not suffer relevant changes during degradation) and selected peaks that monitor the degradation for cellulose acetate and nitrate polymers (avoiding the interference of plasticizers). The reference peak for both was the COC stretching mode (νCOC). The probe peak was, for cellulose nitrate, the NO2 asymmetric stretching (νaNO2) and, for cellulose acetate, the OH stretching mode (νOH). This ratio was then applied to calculate DS values of historical materials, in good and poor conservation condition; in situ by ATR, and in micro-samples collected from artworks by μFTIR. This selection comprises cinematographic and photographic films dated from the 1890s to the 1960s, and contemporary works of art made with cellulose acetate sheets by Portuguese artist José Escada dated from the 1960s. Finally, by comparison with the original estimated DS values, we show how this tool permits to define the state of degradation of these complex polymer matrixes. Thus, establishing the quantification of the DS as a novel tool to monitor the degradation of cellulose ester plastics, contributing in this way for a sustainable preservation of an irreplaceable heritage.

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.

Extrusion foaming of thermoplastic cellulose acetate sheets with HFO‐1234ze and co‐blowing agents

Cellulose acetate is a bio‐based plastic which can be used to produce foam sheets through the extrusion process. In this study, different co‐blowing agents (BAs) were added to the foaming process in order to improve the extrusion foaming behavior and cell density of sheets foamed with HFO‐1234ze. The effect of co‐BAs on the melt viscosity was investigated with an inline extrusion rheometer. Furthermore, the resulting cell morphology of foam sheets was studied. While the plasticizing effect of the co‐BA is similar to HFO‐1234ze, the cell density of the foam sheets could be improved by adding co‐BAs in concentrations between 0.04 and 0.16 mol/kg. Adding 0.06 mol/kg of ethanol increased the cell density from approximately 1 to 12 × 105 1/cm³ at an invariant density of ∼130 kg/m³. The density reduction of the foam sheets can be calculated in good agreement from the molar concentration of the BAs. However, high amounts of co‐BA slightly reduce the BA yield. POLYM. ENG. SCI., 58:E182–E188, 2018. © 2018 Society of Plastics Engineers

Synthesis and catalytic properties of silver nanoparticles supported on porous cellulose acetate sheets and wet-spun fibers

Cellulose acetate fibers (CAfiber), and sheets (CAsheet) were prepared by wet-spinning, and doctor blade methods, respectively. For CAfiber, the CA-acetone solution was pushed through narrow orifice of the medical syringe into a coagulating bath containing water. The same polymer solution was used for the fabrication of CAsheet. The prepared CAfiber and CAsheet were dipped in a 0.1M aqueous AgNO3 solution followed by treatment with 0.1M NaBH4 aqueous solution to synthesize the Ag nanoparticles over stated substrates. The virgin CAfiber and CAsheet as well as Ag nanoparticles containing samples (Ag/CAfiber and Ag/CAsheet) were characterized by FE-SEM, XRD, FTIR, and TGA. These materials were tested as catalysts in hydrogenation of the 2,6-dinitrophenol (2,6-DNP) by NaBH4. The Ag/CAfiber played better catalytic role in the hydrogenation of 2,6-DNP as compared to the Ag/CAsheet. Moreover, the catalyst amount effect on the reaction rate constant, ease of separation and reusability of the prepared materials were discussed.

Surface roughness and foam morphology of cellulose acetate sheets foamed with 1,3,3,3‐tetrafluoropropene

Cellulose acetate (CA) is a bio‐based polymer suitable to replace foamed polystyrene (PS) in packaging applications. Foam trays can be produced by thermoforming of extruded sheets foamed with physical blowing agents. In this paper, the effects of various process settings and the calibration of the sheet on foam morphology and surface quality of extruded CA sheets are presented. Different contact cooling options were applied in order to investigate their influence on surface roughness, density, and morphology of the sheets. By adjusting cooling parameters, blowing agent formulation, and process settings, smooth foam sheets with a surface roughness below 10 µm and a density in the range of 150 kg m−3 were produced. POLYM. ENG. SCI., 57:441–449, 2017. © 2016 Society of Plastics Engineers

Intensification of heterogeneous TiO2 photocatalysis using an innovative micro-meso-structured-photoreactor for n-decane oxidation at gas phase

The main goal of this work is to overcome barriers in heterogeneous TiO2 photocatalysis application towards indoor air decontamination by process intensification. The photocatalytic oxidation (PCO) of gas-phase n-decane was studied using a micro-meso-structured-photoreactor irradiated by simulated solar light, consisting of chambers and channels mechanically engraved in an acrylic slab. The network of chambers and channels is sealed with a borosilicate slab, allowing a good light penetration through the entire reactor depth. A sheet of cellulose acetate (CA) coated, in one side, with TiO2-P25 was assembled between the two slabs, allowing high spatial illumination homogeneity over the catalyst surface. The P25 thin film was in contact with the air stream flowing in the network. The reactor contains 1.95g of TiO2 in contact with the air stream per liter of reactor volume and the illuminated catalyst surface area, in contact with the gas phase, per reactor volume was calculated to be 349m2m−3, which is ∼1.4 times higher than that obtained for an annular photoreactor packed with CA monolithic structures coated with TiO2-P25. The PCO reaction rate, rdec, was assessed under different experimental conditions: amount of TiO2 supported in CA sheets, n-decane feed concentration, feed flow rate, relative humidity and UV irradiance. The highest rdec value (0.82μmolmin−1) was achieved when the following conditions were employed: mTiO2=75mg, Cdec,feed=1.31×10−2molm−3, Qfeed=220cm3min−1 and I=38.4Wm−2. The maximum reactivity of photocatalyst in combination with the photoreactor was 6.93×10−4molm−3reactor s−1, which is a 21.4 fold increase when compared with the annular photoreactor, highlighting the enhancement of mass and photons transfer.

Intensification of heterogeneous TiO2 photocatalysis using an innovative micro–meso-structured-reactor for Cr(VI) reduction under simulated solar light

Process intensification of heterogeneous TiO2 photocatalysis using a new type of static mixer micro–meso-structured-reactor, based on the NETmix reactor, was evaluated to promote the hexavalent chromium reduction to its trivalent state, in the presence of sacrificial agents. The photocatalytic micro–meso-structured reactor comprises a back acrylic slab where chambers and channels are imprinted and a frontal borosilicate slab with especially high UV transparency, irradiated by simulated solar light. An UV transparent cellulose acetate (CA) sheet coated with TiO2-P25 by a simple spray method was assembled between the two slabs of the photoreactor. The reactor geometry provides an efficient exposure of TiO2-P25 CA sheets to radiation, with an illuminated surface per unit of volume inside the reactor of 470m2m−3 and 1.36g TiO2 per liter of liquid inside the reactor. Beyond that, it provides a good degree of mixing using a laminar flow, maximizing heterogeneous and homogeneous Cr(VI) reduction reactions. Firstly, different organic species were tested as hole scavengers in order to avoid the Cr(III) re-oxidation. The effect of the degree of mixing inside the photoreactor, according to the Reynolds number, on the Cr(VI) photocatalytic reduction was then evaluated. Following, operating conditions such as TiO2 mass, tartaric acid concentration, pH value, temperature and initial Cr(VI) concentration were analyzed. Results indicate high reduction rates (1mmolCr(VI)m−3illuminated volumes−1) and a photonic efficiency of 3.96% for Re=830, 30mg TiO2 and a Cr(VI):tartaric acid molar ratio of 1:90 at pH 3.0 and 25°C. Finally, the CA sheets coated with thin films of TiO2-P25 showed to be suitable for continuous Cr(VI) reduction, without losing efficiency during 3 consecutive photocatalytic cycles.

Application of white cellulose acetate sheets on fossil wood investigation

Generally, transparent cellulose acetate sheets as a peel technique material are used in the identification of fossils, whereas white cellulose acetate sheets as a biochemistry technique material are applied in serum protein electrophoresis (SPE). Here we report the application of white cellulose acetate sheets for identifying a polished fossil wood from the Upper Mesozoic of West Liaoning, China. Based on the characters of transverse, radial, and tangential sections, the fossil wood is ascribed to a taxon of Protoglyptostroboxylon sp. Compared with transparent cellulose acetate sheets, white cellulose acetate sheets not only provide the similar information as that of the former, but also are more easily acquired in the Chinese market than the former. Because peel technique supported by white cellulose acetate sheets has the advantages of simple, time-saving, safe, reliable, and practical operation with lower material loss, it is a very good choice for the polished fossil wood investigation in labs, museums, geological parks, and handicraft shops. It is also a convenient approach to training students to learn the anatomic structure of fossil wood.

Evaluation of dentoskeletal parameters in Senegalese subjects using orthodontic architectural analysis

The aim of this study was to determine the morphological characteristics of a Senegalese population based on an architectural cephalometric analysis. One hundred and five lateral cephalograms of Senegalese patients were assessed in a cross-sectional study. All lateral cephalometric films were traced on a transparent cellulose acetate sheet by the same operator. Danguy architectural analysis was performed with 11 measurements (seven linear and four angular). T-test was used to assess differences in cephalometric variables between subjects grouped according to gender (male and female) and age bracket (<12 years and ≥12 years). Significance was set at p≤0.05. This study shows that this Senegalese sample had a skeletal class II tendency associated with backward mandibular rotation. The divergence of masticatory corner appears to be greater than in Caucasians with more vertical facial growth. No statistically significant differences were found between men and women. As compared to the under 12 years subgroup, the over 12 years subgroup shows significant increase in maxillary and mandibular lengths whereas skeletal divergence evidenced the opposite tendency and the difference with the under 12 subgroup was significant. Lastly, the first molar underwent significantly greater mesial drift in the 12 and over sub-group. Danguy architectural analysis provides a good reliable comparative assessment of facial structures and offers an addition to conventional dimensional or typological analytical methods.

Titanium-coating of stainless steel as an aid to improved cleanability

In the food industry, wear of surfaces provides numerous topographical features in which microorganisms may be retained. We hypothesise that by modifying the surface chemistry, this effect may be decreased. Cellulose acetate sheets softened with acetone were pressed onto both new fine polished and used stainless steel surfaces in order to take impressions of surface features for subsequent visualisation and characterisation in the laboratory, using scanning electron microscopy, atomic force microscopy ( R a) and white light profilometry ( S a ). The method gives high resolution negative replicas of the surface, can be used quickly, safely and efficiently, and enables investigations into surface wear over time, and the effect of defined topographic features on surface hygiene and cleanability. Subsequently, the retention of microorganisms on fine polished stainless steel and titanium coated fine polished stainless steel was assessed in the presence and absence of a meat conditioning film. The titanium coating discouraged the retention and enhanced the removal of both Escherichia coli and the meat conditioning film.

Nanofabrication in cellulose acetate

We have demonstrated nanofabrication with commercialized cellulose acetate. Cellulose acetate is used for bulk nanofabrication and surface nanofabrication. In bulk nanofabrication, cellulose acetate reacts with an e-beam and permanent patterns are formed in it instead of being transferred to other substrates. We have studied the nano relief modulation performance of cellulose acetate before and after development. The depth of the nanopatterns is magnified after development, and is varied by exposing dosage and line width of the pattern. The thinnest 65 nm wide line is achieved in the bulk fabrication. We also demonstrate a binary phase Fresnel lens array which is directly patterned in a cellulose acetate sheet. Because of its unique mechanical and optical properties, cellulose is a good candidate for a template material for soft imprinting lithography. In the surface nanofabrication, cellulose acetate thin film spin-coated on silicon wafers is employed as a new resist for e-beam lithography. We achieved 50 nm lines with 100 nm pitches, dots 50 nm in diameter, and single lines with the smallest width of 20 nm. As a new resist of e-beam lithography, cellulose acetate has high resolution comparable with conventional resists, while having several advantages such as low cost, long stock time and less harmfulness to human health.

Cellulose acetate electrophoresis of glycosaminoglycans.

Electrophoresis on cellulose acetate membrane (zone electrophoresis) is a common method for qualitative and semiquantitative analysis of glycosaminoglycan (GAG) mixtures. The advantage of this method is its simplicity, rapidity, the possibility of processing several samples at the same time, and the low cost of analysis. Apart from cellulose acetate strips and electrophoresis apparatus, usually applied in diagnostic laboratories for serum protein electrophoresis, no special equipment is needed (see Note 1). Several original papers and book chapters describe this technique in different running conditions; the most common is a monodimensional electrophoresis in bivalent cation buffer or pyridine/formiate buffer (13). However, no simple system can separate all known GAGs in one run. The separation of different GAGs in one dimension can be done by a several steps method described by Hopwood and Harrison (), requiring careful temperature control and selective ethanol precipitation after each run. Alternatively, the GAGs can be separated by a two-dimensional method (), but only one sample at once may be applied on the cellulose acetate sheet. The scope of this chapter is to describe a simple method for rapid separation and visualization of the most common GAGs from tissue or cell culture. Comparison of electrophoretic profiles before and after selective enzymatic treatment (see Chapter 32– Chapter 36) or HNO2 depolymerization of heparin/heparan sulfate () allows characterization in a single run of the major fractions of GAGs in a given sample.

Bisalbuminemia in Two Croatian Families

Background Bisalbuminemia is a dysproteinemia characterized by the occurrence of two albumin fractions on serum protein separation by electrophoresis on cellulose acetate sheets. Bisalbuminemia may occur as a hereditary trait or as analytical interference with some drugs, especially penicillin. Methods Two patients with the finding of bisalbuminemia are presented. Both patients (patient 1 was a 4-1/2-month-old male infant, and patient 2 was a 15-year-old boy) were admitted for respiratory infection. Results Bisalbuminemia was detected by serum protein electrophoresis and confirmed by isoelectric focusing in pH gradient gel (pH range 4.0–6.5). This finding was supported by simultaneous detection of abnormal albumin in the mother of patient 1, while the father had normal albumin. The abnormal fast albumin in both patients had an increased relative mobility of 1.08 when measured from the sample application position. Conclusions The results presented are the first description of albumin mutations in Croatia (that according to the CISMEL group could be classified as ZC/HZ), and present the first step in identification prior to determination of structural change and amino acid sequence in the albumin molecule.

Hyperdermium: a new clavicipitalean genus for some tropical epibionts of dicotyledonous plants

The morphological characteristics of two tropical clavicipitalean fungi on species of the plant family Asteraceae were examined. These species were found to be superficial on the stems of living plants but early stages of infection involve necrotrophy of scale insects. These fungi are distinct from other Clavicipitaceae by possession of anamorphs producing multiseptate conidia. A new genus, Hyperdermium, was proposed to accommodate these two species. In cultures on potato dextrose agar overlaid with cellulose acetate sheets, both species produced colonies resembling those on plant tissues. Hyperdermium bertonii produced conidia in culture but not perithecia. Hyperdermium pulvinatum produced both conidia and perithecia in culture. Phylogenetic analysis using large subunit rDNA sequences placed Hyperdermium in the subfamily Cordycipitoideae. A study was made of perithecial ontogeny in H. pulvinatum. Centrum development was of the Epichloë-type.

Biophysical Differences Among Prunus Necrotic Ringspot Ilarviruses

Intact nucleoproteins of several isolates of Prunus necrotic ringspot virus (PNRSV) from cherry, peach, almond, and hop resolved as three components in rate-zonal sucrose density gradients and as two or three components on electrophoresis in agarose slab gels. Electrophoretic mobilities of the various nucleoprotein components differed among isolates. When electrophoresis was conducted on cellulose acetate sheets, PNRSV nucleoproteins resolved as single bands with marked differences in mobility noted among isolates (...)

Intracavitary hyperthermia: Construction and heat patterns of individualized vaginal prototype applicators

Patients who have inoperable or previously irradiated cervical recurrences, especially if very confined and alone, pose a challenging problem to the clinician. Low-dose irradiation and hyperthermia seems to be a promising method for salvage treatments in previously treated patients. In order to heat the vaginal apex, individualized prototype applicators utilizing commercial microwave antennas were constructed and tested in muscle equivalent phantom. The technical construction of vaginal applicators followed Pierquin's procedure for gynaecological brachy-therapy moulds: (1) a true negative vaginal print in alginate was made; (2) a positive mould in plaster of Paris was then constructed; (3) a negative vaginal print was produced in plaster of Paris and (4) heat moulding of a 0.1 cm thick sheet of cellulose acetate on the plaster mould was accomplished. Interstitial microwave antennas were inserted within the applicator and kept in place using silk wires or Teflon rings. The external part of the applicator was thermally sealed and protected with silicone. This was particularly useful in cases where an inner cooling system was required. Heat patterns in tissue equivalent phantom materials were determined using non-perturbing probes and infrared thermography. An illustrative clinical case is described.

A sensitive and efficient isoenzyme technique for small arthropods and other invertebrates

AbstractAn electrophoretic method for the study of enzyme variation, which uses cellulose acetate sheets with an agar overlay for staining, the use of a very good general purpose buffer (citric-aminopropyldiethanol amine) and the use of sodium azide as a bacteriocide to allow long term storage of chemicals as solutions are described. Tests are reported of the technique onTetranychus urticaeKoch,Aedes aegypti(L.) and several species ofDrosophila. The results demonstrate that the technique offers sensitivity equal to or greater than starch or polyacrylamide gel electrophoresis and that it is applicable to very small organisms, allowing either the testing of single individuals for large numbers of enzymes or the testing of fewer enzymes under different electrophoretic conditions (i.e. to detect cryptic variation under a single condition). The technique is efficient of time and materials, and safer than conventional methods.