Humic acid removal using cellulose acetate membranes grafted with poly (methyl methacrylate) and aminated using tetraethylenepentamine

Graft copolymerization of cellulose acetate (CA) and poly (methyl methacrylate) (PMMA) was synthesized through free radical polymerization in the presence of cerium sulfate (CS) as initiator under nitrogen atmosphere in an aqueous solution. During the grafting reactions, the effects of polymerization time and temperature on the grafting were investigated. Furthermore, functionalization of the synthesized product was done using amine group (tetraethylenepentamine, TEPA). The results from Nuclear Magnetic Resonance (¹H NMR) spectra confirmed a successful grafting of PMMA on the CA membrane surfaces. Zeta potential (ζ), field emission scanning electron microscopy (FESEM), and atomic absorption spectrophotometer (AAS) characterization studies were done. The maximum removal efficiencies for un-grafted CA (un-g-CA), CA-g-PMMA, and CA-g-PMMA-TEPA membranes at pH of 7.0 were 34.5%, 83.3%, and 99.1%, respectively. The removal percentage results were detected to increase with increasing in the regeneration cycles. At the end of the fourth cycle, the HA removal percentages were 41.6%, 87.4%, and 99.9% for un-g-CA, CA-g-PMMA and CA-g-PMMA-TEPA membranes, respectively.

Electrospun composite cellulose acetate/iron oxide nanoparticles non-woven membranes for magnetic hyperthermia applications

In the present work composite membranes were produced by combining magnetic nanoparticles (NPs) with cellulose acetate (CA) membranes for magnetic hyperthermia applications. The non-woven CA membranes were produced by electrospinning technique, and magnetic NPs were incorporated by adsorption at fibers surface or by addition to the electrospinning solution. Therefore, different designs of composite membranes were obtained. Superparamagnetic NPs synthesized by chemical precipitation were stabilized either with oleic acid (OA) or dimercaptosuccinic acid (DMSA) to obtain stable suspensions at physiological pH. The incorporation of magnetic NP into CA matrix was confirmed by scanning and transmission electron microscopy. The results showed that adsorption of magnetic NPs at fibers' surface originates composite membranes with higher heating ability than those produced by incorporation of magnetic NPs inside the fibers. However, adsorption of magnetic NPs at fibers' surface can cause cytotoxicity depending on the NPs concentration. Tensile tests demonstrated a reinforcement effect caused by the incorporation of magnetic NPs in the non-woven membrane.

Adsorption of Soluble Immunoglobulin-Type Adhesion Molecules to Cellulose Acetate Beads

Circulating levels of soluble intercellular adhesion molecule-1 (sICAM-1) and vascular adhesion molecule-1 (sVCAM-1) are elevated in patients with inflammatory bowel disease. Cellulose acetate (CA) beads are used as carriers for granulocyte and monocyte (GM) adsorptive apheresis (GMA). We investigated the effect of CA beads on sICAM-1 and sVCAM-1 plasma concentrations in vitro. Because GM adsorption to CA beads increased with a rise in the incubation temperature in our previous study, peripheral blood was incubated with and without CA beads at 5, 25, 37, or 43 °C and plasma sICAM-1 and sVCAM-1 was measured. The sICAM-1 and sVCAM-1 concentrations in samples incubated with CA beads were significantly lower than those without CA beads at all four temperatures. However, no significant differences were observed both sICAM-1 and sVCAM-1 plasma levels at the four different temperatures after incubation with CA beads. These results suggest that independent of incubation temperature, sICAM-1 and sVCAM-1 are likely to adsorb CA beads. These molecules may be a new index for predicting the therapeutic effects of GMA.

Multi-hierarchical tissue-engineering ECM-like scaffolds based on cellulose acetate with collagen and chitosan fillers

A novel high-tech composite biomimetic matrixes for a wide range of medical purposes were prepared. The structure of scaffolds was inspired by the architecture of native decellularized tissue: material consists of a sponge and fibrous components of different spatial geometry based on cellulose acetate with collagen or chitosan filler. The fibrous component was prepared by electrospinning, the sponge - freeze-drying technique. The influence of main technological parameters, such as freeze mode, polymer type and concentration, etc. on the fiber-sponge architecture and properties was examined. It was shown that scaffolds with different types of microstructure can be obtained employing this technique. The impregnation of chitosan or collagen filler in fiber matrix also significantly improves mechanical properties up to 40 MPa for strength and 600 MPa for Young's modulus.

Fabrication of cellulose acetate nanocomposite membranes using 2D layered nanomaterials for macromolecular separation

Cellulose acetate (CA) nanocomposite ultrafiltration (UF) membranes were fabricated using 2D layered nanosheets such as graphene oxide (GO) and exfoliated molybdenum disulfide (E-MoS₂) and effectively used for the removal of macromolecular protein. The GO and E-MoS₂ nanosheets were prepared and characterized by FT-IR and XRD respectively. GO and E-MoS₂ (0.5wt.%) were blended individually with CA. The assenting changes generated by the incorporation of GO and E-MoS₂ in terms of surface hydrophilicity of the nanocomposite membrane were analyzed by pure water flux (PWF) and contact angle measurement. The influence of 2D nanosheets on the morphology of CA are studied by scanning electron microscopy (SEM). Mechanical strength and hydraulic resistance of the nanocomposite membranes were found to be improved compared to bare CA membrane. The separation and antifouling performance of the nanocomposite membranes were studied using macromolecular bovine serum albumin (BSA). From the results, it was observed that a CA/GO-0.5 membrane exhibited the highest PWF (125.4±1.7Lm^-2h^-1), water content (70.6±1.2%), porosity (34.6±1.7%), flux recovery ratio (FRR) (88.8±1.6%) and lowest contact angle (63.9±2.5°), hydraulic resistance (4.3±0.67kPa/Lm^-2h ^-1) than pure CA and CA/E-MoS₂-0.5 membranes. CA/GO-0.5 membrane displayed superior UF and antifouling performance due to the greater affinity of GO nanoparticles towards water.

Fabrication of cellulose acetate/polybenzoxazine cross-linked electrospun nanofibrous membrane for water treatment

Herein, polybenzoxazine based cross-linked cellulose acetate nanofibrous membrane exhibiting enhanced thermal/mechanical properties and improved adsorption efficiency was successfully produced via electrospinning and thermal curing. Initially, suitable solution composition was determined by varying the amount of the benzoxazine (BA-a) resin, cellulose acetate (CA) and citric acid (CTR) to obtain uniform nanofibrous membrane via electrospinning. Subsequently, thermal curing was performed by step-wise at 150, 175, 200 and 225°C to obtain cross-linked composite nanofibrous membranes. SEM images and solubility experiments demonstrated that most favorable result was obtained from the 10% (w/v) CA, 5% (w/v) BA-a and 1% (w/v) CTR composition and cross-linked nanofibrous membrane (CA10/PolyBA-a5/CTR1) was obtained after the thermal curing. Chemical structural changes (ring opening) occurred by thermal curing revealed successful cross-linking of BA-a in the composite nanofibrous membrane. Thermal, mechanical and adsorption performance of pristine CA and CA10/PolyBA-a5/CTR1 nanofibrous membranes were studied. Char yield of the pristine CA nanofibrous membrane has increased notably from 12 to 24.7% for composite CA10/PolyBA-a5/CTR1 membrane. When compared to pristine CA membrane, CA10/PolyBA-a5/CTR1 nanofibrous membrane has shown superior mechanical properties having tensile strength and Young's modulus of 8.64±0.63MPa and 213.87±30.79MPa, respectively. Finally, adsorption performance of pristine CA and CA10/PolyBA-a5/CTR1 nanofibrous membranes was examined by a model polycyclic aromatic hydrocarbon (PAH) compound (i.e. phenanthrene) in aqueous solution, in which CA10/PolyBA-a5/CTR1 nanofibrous membrane has shown better removal efficiency (98.5%) and adsorption capacity (592μg/g).

Nanocrystalline cellulose isolated from discarded cigarette filters

We report the isolation of nanocrystalline cellulose (NCC) produced from discarded cigarette filters (DCF). The DCF were processed into cellulose via ethanolic extraction, hypochlorite bleaching, alkaline deacetylation, and then converted into NCC by sulfuric acid hydrolysis. The morphological structures of the isolated NCC established with TEM showed that the nanocrystals were needle-like with a mean length of 143nm. FEGSEM showed the morphological transition of the micro-sized DCF to self-assembled NCC while EDX revealed the presence of Ti (as TiO₂) in DCF, which was retained in the NCC. A NCC sample was freeze-dried and showed a specific surface area of 7.78m²/g. The crystallinity of the NCC film and freeze-dried samples were 96.77% and 94.47%, respectively. Crystallite sizes of the freeze-dried (8.4nm) and film (7.6nm) samples correlated with the mean width (8.3nm) of the NCC observed under TEM.

New polylactic acid/ cellulose acetate-based antimicrobial interactive single dose nanofibrous wound dressing mats

New single dose interactive extracellular matrix (ECM) mimicking nanofibrous wound dressings based on polylactic acid (PLA) and cellulose acetate (CA) were developed, characterized and investigated for wound treatment. The antimicrobial agent, thymoquinone (TQ) was selected and incorporated into the scaffolds for preventing common clinical infections, and to accelerate the rate of wound closure and re-epithelialization. The newly fabricated TQ-loaded PLA/CA wound dressings offered many advantages such as mimicking the ECM via the 3D nanofibrous structure, and promoted the cell proliferation due to the hydrophilicity and bioactivity of CA. The wound dressings also prevented the bacterial infection in the early stages due to presence of TQ, and maintained the minimum possible bacterial load in the wound area through the sustained release of the drug for 9days. In vivo assessment demonstrated that TQ-loaded PLA: CA (7:3) scaffolds significantly promoted the wound healing process by increasing re-epithelialization and controlling the formation of granulation tissue. The obtained results suggest that the developed TQ-loaded PLA/CA nanofibrous mats could be ideal for wound dressing applications.

Br-PADAP embedded in cellulose acetate electrospun nanofibers: Colorimetric sensor strips for visual uranyl recognition

In this work, a new visual colorimetric strip based on cellulose acetate nanofiber mats modified by 2-(5-Bromo-2-pyridylazo)-5-(diethylamino) phenol was successfully prepared via electrospinning technology. The prepared colorimetric strip showed high sensitivity towards UO₂²⁺ with the yellow-to-purple color change signal. Upon the optimal conditions of solution pH at 6.0 and response time for 80min, the detection limit for UO₂²⁺ can reach 50 ppb. Moreover, the strip also exhibited excellent anti-interference ability in the presence of other metal ions. In order to achieve the quantitative detection for UO₂²⁺, a color-differentiation map was established, which was prepared from converted H values. Finally, the strip was also used to detect UO₂²⁺ in the seawater and showed high sensitivity.

Ultrasonic-assisted deacetylation of cellulose acetate nanofibers: A rapid method to produce cellulose nanofibers

Herein we report a rapid method for deacetylation of cellulose acetate (CA) nanofibers in order to produce cellulose nanofibers using ultrasonic energy. The CA nanofibers were fabricated via electrospinning thereby treated with NaOH and NaOH/EtOH solutions at various pH levels for 30, 60 and 90min assisted by ultrasonic energy. The nanofiber webs were optimized by degree of deacetylation (DD%) and wicking behavior. The resultant nanofibers were further characterized by FTIR, SEM, WAXD, DSC analysis. The DD% and FTIR results confirmed a complete conversion of CA nanofibers to cellulose nanofibers within 1h with substantial increase of wicking height. Nanofibers morphology under SEM showed slightly swelling and no damage of nanofibers observed by use of ultrasonic energy. The results of ultrasonic-assisted deacetylation are comparable with the conventional deacetylation. Our rapid method offers substantially reduced deacetylation time from 30h to just 1h, thanks to the ultrasonic energy.

Nanosized sustained-release drug depots fabricated using modified tri-axial electrospinning

Nanoscale drug depots, comprising a drug reservoir surrounded by a carrier membrane, are much sought after in contemporary pharmaceutical research. Using cellulose acetate (CA) as a filament-forming polymeric matrix and ferulic acid (FA) as a model drug, nanoscale drug depots in the form of core-shell fibers were designed and fabricated using a modified tri-axial electrospinning process. This employed a solvent mixture as the outer working fluid, as a result of which a robust and continuous preparation process could be achieved. The fiber-based depots had a linear morphology, smooth surfaces, and an average diameter of 0.62±0.07μm. Electron microscopy data showed them to have clear core-shell structures, with the FA encapsulated inside a CA shell. X-ray diffraction and IR spectroscopy results verified that FA was present in the crystalline physical form. In vitro dissolution tests revealed that the fibers were able to provide close to zero-order release over 36h, with no initial burst release and minimal tailing-off. The release properties of the depot systems were much improved over monolithic CA/FA fibers, which exhibited a significant burst release and also considerable tailing-off at the end of the release experiment. Here we thus demonstrate the concept of using modified tri-axial electrospinning to design and develop new types of heterogeneous nanoscale biomaterials.

STATEMENT OF SIGNIFICANCE

Nanoscale drug depots with a drug reservoir surrounded by a carrier are highly attractive in biomedicine. A cellulose acetate based drug depot was investigated in detail, starting with the design of the nanostructure, and moving through its fabrication using a modified tri-axial electrospinning process and a series of characterizations. The core-shell fiber-based drug depots can provide a more sustained release profile with no initial burst effect and less tailing-off than equivalent monolithic drug-loaded fibers. The drug release mechanisms are also distinct in the two systems. This proof-of-concept work can be further expanded to conceive a series of new structural biomaterials with improved or new functional performance.

Granulocyte and monocyte adsorptive apheresis ameliorates sepsis in rats

Background

Overwhelming activation of granulocytes and monocytes is central to inflammatory responses during sepsis. Granulocyte and monocyte adsorptive apheresis (GMA) is an extracorporeal leukocyte apheresis device filled with cellulose acetate beads and selectively adsorbs granulocytes and monocytes from the peripheral blood.

Methods

In this study, septic rats received the GMA treatment for 2 h at 18 h after cecal ligation and puncture.

Results

GMA selectively adsorbed activated neutrophils and monocytes from the peripheral blood, reduced serum inflammatory cytokine expression, and seemed to improve organ injuries and animal survival. GMA potentially reduced lung injury by alleviating the infiltration of inflammatory cells and the secretion of cytokines.

Conclusions

This study showed that selective granulocyte and monocyte adsorption with cellulose acetate beads might ameliorate cecal ligation and puncture (CLP)-induced sepsis and improve survival and organ function.

Electrospun H4SiW12O40/cellulose acetate composite nanofibrous membrane for photocatalytic degradation of tetracycline and methyl orange with different mechanism

H₄SiW₁₂O₄₀ (SiW₁₂)/cellulose acetate (CA) composite nanofibrous membrane was prepared by electrospinning in which CA was employed as the support of SiW₁₂. Characterization with Fourier transformation infrared spectroscopy (FT-IR), Energy-dispersive X-ray spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS) indicated that SiW₁₂ has been successfully loaded into the CA membrane and its Keggin structure remained intact. The as-prepared composite membrane exhibited enhanced photocatalytic activity in the decomposition of tetracycline (TC) and methyl orange (MO) compared with pure SiW₁₂ under ultraviolet irradiation. The optimal mass ratio of SiW₁₂ to CA was 1:4, and the corresponding degradation efficiency for TC and MO was 63.8% and 94.6%, respectively. It is noteworthy that the degradation rate of MO increased more evidently than that of TC under the same conditions, which may be attributed to the different role that CA nanofibrous membrane played in the TC and MO photodegradation process. Besides providing more contact area between SiW₁₂ and the pollutant in TC photodegradation, CA membrane played an additional role that donated electron to SiW₁₂ in the MO degradation process, leading to a different photocatalytic mechanism with greatly enhanced degradation rate. Moreover, the composite membrane presented an excellent reusability, which was mainly ascribed to the water-insolubility of CA and the hydrogen bonds between CA and SiW₁₂. This work will be useful for the design of biopolymer-based membrane photocatalysts applied to antibiotics and dyes wastewater treatment.

Process development for cigarette butts recycling into cellulose pulp

Cigarette butts, which are usually thrown on the ground or into ordinary bins, have been recognized as toxic residues since may contain cigarette contaminants and chemicals produced during combustion. Therefore, contaminants in cigarette butts can be leached by rain into surface water and thereby contaminate the environment. In Brazil, according to the National Policy on Solid Waste, all residues must be disposed of in an environmentally friendly manner. Although cigarette butts are not mentioned in the law, due to their characteristics, they may be classified as hazardous waste. At the University of Brasilia, a cellulose pulp production process from cigarette butts has been developed employing alkaline pulping. This process is presented as an alternative to environmentally friendly final disposal of this residue. During the process, a dark liquor is generated, which was found to contain lignin, carbonyls, metals, nicotine and specific tobacco nitrosamines. The dark liquor was treated by acidification to promote lignin precipitation, coagulation with chitosan and Al₂(SO₄)₃ to remove metals and organic compounds and ozonized to oxidize resistant chemicals. The dark liquor presented a high chemical oxygen demand (COD; 29,986mg/L), which was partially removed by precipitation (20%), chitosan coagulation (66%) and ozonation (45.8%). As the remaining COD was still high, we proposed reusing the clarified effluent in alkaline pulping, which seemed to be the easiest and most efficient procedure with the lowest cost.

Electrospun cellulose acetate composites containing supported metal nanoparticles for antifungal membranes

Electrospun cellulose acetate composites containing silver and copper nanoparticles supported in sepiolite and mesoporous silica were prepared and tested as fungistatic membranes against the fungus Aspergillus niger. The nanoparticles were in the 3-50nm range for sepiolite supported materials and limited by the size of mesopores (5-8nm) in the case of mesoporous silica. Sepiolite and silica were well dispersed within the fibers, with larger aggregates in the micrometer range, and allowed a controlled release of metals to create a fungistatic environment. The effect was assessed using digital image analysis to evaluate fungal growth rate and fluorescence readings using a viability stain. The results showed that silver and copper nanomaterials significantly impaired the growth of fungi when the spores were incubated either in direct contact with particles or included in cellulose acetate composite membranes. The fungistatic effect took place on germinating spores before hyphae growth conidiophore formation. After 24h the cultures were separated from fungistatic materials and showed growth impairment only due to the prior exposure. Growth reduction was important for all the particles and membranes with respect to non-exposed controls. The effect of copper and silver loaded materials was not significantly different from each other with average reductions around 70% for bare particles and 50% for membranes. Copper on sepiolite was particularly efficient with a decrease of metabolic activity of up to 80% with respect to controls. Copper materials induced rapid maturation and conidiation with fungi splitting in sets of subcolonies. Metal-loaded nanomaterials acted as reservoirs for the controlled release of metals. The amount of silver or copper released daily by composite membranes represented roughly 1% of their total load of metals. Supported nanomaterials encapsulated in nanofibers allow formulating active membranes with high antifungal performance at the same time minimizing the risk of nanoparticle release into the environment.

Crosslinked pullulan/cellulose acetate fibrous scaffolds for bone tissue engineering

Natural polymer based fibrous scaffolds have been explored for bone tissue engineering applications; however, their inadequate 3-dimensionality and poor mechanical properties are among the concerns for their use as bone substitutes. In this study, pullulan (P) and cellulose acetate (CA), two polysaccharides, were electrospun at various P/CA ratios (P80/CA20, P50/CA50, and P20/CA80%) to develop 3D fibrous network. The scaffolds were then crosslinked with trisodium trimetaphosphate (STMP) to improve the mechanical properties and to delay fast weight loss. The lowest weight loss was observed for the groups that were crosslinked with P/STMP 2/1 for 10min. Fiber morphologies of P50/CA50 were more uniform without phase separation and this group was crosslinked most efficiently among groups. It was found that mechanical properties of P20/CA80 and P50/CA50 were higher than that of P80/CA20. After crosslinking strain values of P50/CA50 scaffolds were improved and these scaffolds became more stable. Unlike P80/CA20, uncrosslinked P50/CA50 and P20/CA80 were not lost in PBS. Among all groups, crosslinked P50/CA50 scaffolds had more uniform pores; therefore this group was used for bioactivity and cell culture studies. Apatite-like structures were observed on fibers after SBF incubation. Human Osteogenic Sarcoma Cell Line (Saos-2) seeded onto crosslinked P50/CA50 scaffolds adhered and proliferated. The functionality of cells was tested by measuring ALP activity of the cells and the results indicated their osteoblastic differentiation. In vitro tests showed that scaffolds were cytocompatible. To sum up, crosslinked P50/CA50 scaffolds were proposed as candidate cell carriers for bone tissue engineering applications.

Fabrication and performance of PET mesh enhanced cellulose acetate membranes for forward osmosis

Polyethylene terephthalate mesh (PET) enhanced cellulose acetate membranes were fabricated via a phase inversion process. The membrane fabrication parameters that may affect the membrane performance were systematically evaluated including the concentration and temperature of the casting polymer solution and the temperature and time of the evaporation, coagulation and annealing processes. The water permeability and reverse salt flux were measured in forward osmosis (FO) mode for determination of the optimal membrane fabrication conditions. The optimal FO membrane shows a typical asymmetric sandwich structure with a mean thickness of about 148.2μm. The performance of the optimal FO membrane was tested using 0.2mol/L NaCl as the feed solution and 1.5mol/L glucose as the draw solution. The membrane displayed a water flux of 3.47L/(m(2)·hr) and salt rejection of 95.48% in FO mode. While in pressure retarded osmosis (PRO) mode, the water flux was 4.74L/(m(2)·hr) and salt rejection 96.03%. The high ratio of water flux in FO mode to that in PRO mode indicates that the fabricated membrane has a lower degree of internal concentration polarization than comparable membranes.

Application of cellulose acetate for controlled release of thymol

Cellulose acetate (CA) was investigated as a carrier towards development of material with controlled release of thymol as a natural substance with strong antibacterial properties using high pressure techniques. Effect of thymol content on CA was confirmed by SEM, FTIR and DSC methods. Kinetic of thymol release from CA was tested using simulated gastric and intestinal fluids (hydrochloric acid and phosphate buffer saline). Results were correlated with Korsmeyer-Peppas and Weibull model. Depending on the thymol content and chemical nature of the release medium, the time of thymol release varied from one to three days indicating CA as a promising carrier of thymol with potential uses from medicine to agriculture. The impregnated CA showed antibacterial activity against 23 tested bacterial strains including methicillin-resistant Staphylococcus aureus (MRSA) which is particularly important bearing in mind that this strain causes fatal infections in humans and animals.

Tortoiseshell or Polymer? Spectroscopic Analysis to Redefine a Purported Tortoiseshell Box with Gold Decorations as a Plastic Box with Brass

The study and preservation of museum collections requires complete knowledge and understanding of constituent materials that can be natural, synthetic, or semi-synthetic polymers. In former times, objects were incorporated in museum collections and classified solely by their appearance. New studies, prompted by severe degradation processes or conservation-restoration actions, help shed light on the materiality of objects that can contradict the original information or assumptions. The selected case study presented here is of a box dating from the beginning of the 20th century that belongs to the Portuguese National Ancient Art Museum. Museum curators classified it as a tortoiseshell box decorated with gold applications solely on the basis of visual inspection and the information provided by the donor. This box has visible signs of degradation with white veils, initially assumed to be the result of biological degradation of a proteinaceous matrix. This paper presents the methodological rationale behind this study and proposes a totally non-invasive methodology for the identification of polymeric materials in museum artifacts. The analysis of surface leachates using (1)H and (13)C nuclear magnetic resonance (NMR) complemented by in situ attenuated total reflection infrared spectroscopy (ATR FT-IR) allowed for full characterization of the object s substratum. The NMR technique unequivocally identified a great number of additives and ATR FT-IR provided information about the polymer structure and while also confirming the presence of additives. The pressure applied during ATR FT-IR spectroscopy did not cause any physical change in the structure of the material at the level of the surface (e.g., color, texture, brightness, etc.). In this study, variable pressure scanning electron microscopy (VP-SEM-EDS) was also used to obtain the elemental composition of the metallic decorations. Additionally, microbiologic and enzymatic assays were performed in order to identify the possible biofilm composition and understand the role of microorganisms in the biodeterioration process. Using these methodologies, the box was correctly identified as being made of cellulose acetate plastic with brass decorations and the white film was identified as being composed mainly of polymer exudates, namely sulphonamides and triphenyl phosphate.

Preparation and evaluation of water-in-soybean oil-in-water emulsions by repeated premix membrane emulsification method using cellulose acetate membrane

The purpose of this study was to investigate the preparation of formulated water- in-soybean oil-in-water emulsions by repeated premix membrane emulsification method using a cellulose acetate membrane. The effect of selective membrane emulsification process parameters (concentration of the emulsifiers, number of passes of the emulsions through the membrane and storage temperature) on the properties and stability of the developed emulsions were also investigated. 1, 3, 6, 8-pyrenetetrasulfonic acid tetrasodium salt (PTSA) was used as a hydrophilic model ingredient for the encapsulation of bioactive substances. W/O emulsions with 7 wt% (weight percentage) PGPR displays homogeneous and very fine dispersions, with the median diameter at 0.640 μm. Meanwhile, emulsions prepared by membrane emulsification (fine W/O/W) showed the highest stability at Tween 80 concentrations of 0.5 wt.% (weight percentage). It concluded that at 7 wt.% (weight percentage) PGPR concentration and 0.5 wt.% (weight percentage) Tween 80 concentrations, the most uniform particles with minimum mean size of oil drops (9.926 μm) were obtained after four passes through the membrane. Thus, cellulose acetate membrane can be used for preparing a stable W/O/W emulsions by repeated premix ME due to low cost and relatively easy to handle.

Controlled release of drugs from cellulose acetate matrices produced from sugarcane bagasse: monitoring by square-wave voltammetry

In this paper, cellulose triacetate (CTA) was produced from sugarcane bagasse and used as matrices for controlled release of paracetamol. Symmetric and asymmetric membranes were obtained by formulations of CTA/dichloromethane/drug and CTA/dichloromethane/water/drug, respectively, and they were characterized by scanning electron microscopy (SEM) and differential scanning calorimetry (DSC). Different morphologies of membranes were observed by SEM, and the incorporation of paracetamol was confirmed by lowering of the glass transition temperature (Tg) in the DSC curves. This indicates the existence of interactions between the matrix and the drug. The evaluation of drug release was based on the electrochemical monitoring of paracetamol through its oxidation at a glassy carbon electrode surface using square-wave voltammetry (SWV), which provides fast, precise and accurate in situ measurements. The studies showed a content release of 27% and 45% by the symmetric and asymmetric membranes, respectively, during 8 h.

CO2 adsorption using TiO2 composite polymeric membranes: A kinetic study

CO2 is the main greenhouse gas which causes global climatic changes on larger scale. Many techniques have been utilised to capture CO2. Membrane gas separation is a fast growing CO2 capture technique, particularly gas separation by composite membranes. The separation of CO2 by a membrane is not just a process to physically sieve out of CO2 through the controlled membrane pore size. It mainly depends upon diffusion and solubility of gases, particularly for composite dense membranes. The blended components in composite membranes have a high capability to adsorb CO2. The adsorption kinetics of the gases may directly affect diffusion and solubility. In this study, we have investigated the adsorption behaviour of CO2 in pure and composite membranes to explore the complete understanding of diffusion and solubility of CO2 through membranes. Pure cellulose acetate (CA) and cellulose acetate-titania nanoparticle (CA-TiO2) composite membranes were fabricated and characterised using SEM and FTIR analysis. The results indicated that the blended CA-TiO2 membrane adsorbed more quantity of CO2 gas as compared to pure CA membrane. The high CO2 adsorption capacity may enhance the diffusion and solubility of CO2 in the CA-TiO2 composite membrane, which results in a better CO2 separation. The experimental data was modelled by Pseudo first-order, pseudo second order and intra particle diffusion models. According to correlation factor R(2), the Pseudo second order model was fitted well with experimental data. The intra particle diffusion model revealed that adsorption in dense membranes was not solely consisting of intra particle diffusion.

The PGI enzyme system and fitness response to temperature as a measure of environmental tolerance in an invasive species

In the field of invasion ecology, the determination of a species’ environmental tolerance, is a key parameter in the prediction of its potential distribution, particularly in the context of global warming. In poikilothermic species such as insects, temperature is often considered the most important abiotic factor that affects numerous life-history and fitness traits through its effect on metabolic rate. Therefore the response of an insect to challenging temperatures may provide key information as to its climatic and therefore spatial distribution. Variation in the phosphoglucose-6-isomerase (PGI) metabolic enzyme-system has been proposed in some insects to underlie their relative fitness, and is recognised as a key enzyme in their thermal adaptation. However, in this context it has not been considered as a potential mechanism contributing to a species invasive cability. The present study aimed to compare the thermal tolerance of an invasive scarabaeid beetle, Costelytra zealandica (White) with that of the closely related, and in part sympatrically occurring, congeneric non-invasive species C. brunneum (Broun), and to consider whether any correlation with particular PGI genotypes was apparent. Third instar larvae of each species were exposed to one of three different temperatures (10, 15 and 20 °C) over six weeks and their fitness (survival and growth rate) measured and PGI phenotyping performed via cellulose acetate electrophoresis. No consistent relationship between PGI genotypes and fitness was detected, suggesting that PGI may not be contributing to the invasion success and pest status of C. zealandica.

Uniaxially aligned electrospun cellulose acetate nanofibers for thin layer chromatographic screening of hydroquinone and retinoic acid adulterated in cosmetics

Uniaxially aligned cellulose acetate (CA) nanofibers were successfully fabricated by electrospinning and applied to use as stationary phase for thin layer chromatography. The control of alignment was achieved by using a drum collector rotating at a high speed of 6000 rpm. Spin time of 6h was used to produce the fiber thickness of about 10 μm which was adequate for good separation. Without any chemical modification after the electrospinning process, CA nanofibers could be readily devised for screening hydroquinone (HQ) and retinoic acid (RA) adulterated in cosmetics using the mobile phase consisting of 65:35:2.5 methanol/water/acetic acid. It was found that the separation run on the aligned nanofibers over a distance of 5 cm took less than 15 min which was two to three times faster than that on the non-aligned ones. On the aligned nanofibers, the masses of HQ and RA which could be visualized were 10 and 25 ng, respectively, which were two times lower than those on the non-aligned CA fibers and five times lower than those on conventional silica plates due to the appearance of darker and sharper of spots on the aligned nanofibers. Furthermore, the proposed method efficiently resolved HQ from RA and ingredients commonly found in cosmetic creams. Due to the satisfactory analytical performance, facile and inexpensive production process, uniaxially aligned electrospun CA nanofibers are promising alternative media for planar chromatography.

Removal of aqueous Hg(II) and Cr(VI) using phytic acid doped polyaniline/cellulose acetate composite membrane

Conductive composite membrane-phytic acid (PA) doped polyaniline (PANI)/cellulose acetate (CA) (PANI-PA/CA) was prepared in a simple and environmental-friendly method, in which aniline was blended with CA/PA solution and polymerized before the phase conversion. The resultant composite membranes were characterized by SEM, EDX, FTIR-ATR, BET and electrical resistance measurements. When used as adsorbent for Hg(II) and Cr(VI) ions, the prepared composite membrane exhibits excellent adsorption capability. The adsorption of Hg(II) and Cr(VI) follows a pseudo-second-order kinetic model and best fits the Langmuir isotherm model, with the maximum adsorption capacity reaching 280.11 and 94.34 mg g(-1), respectively. The heavy metal loaded composite membrane can be regenerated and reused after treatment with acid or alkali solution, making it a promising and practical adsorbent for Hg(II) and Cr(VI) removal. Tests with river water were also carried out, indicating good performance and application.