Enhanced water flux and bacterial resistance in cellulose acetate membranes with quaternary ammoniumpropylated polysilsesquioxane

An enhanced water flux and anti-fouling nanocomposite ultrafiltration membrane based on quaternary ammoniumpropylated polysilsesquioxane (QAPS)/cellulose acetate (QAPS@CA) was fabricated by in situ sol-gel processing via phase inversion followed by quaternization with methyl iodide (CH₃I). Membrane characterizations were performed based on the contact angle, FTIR, SEM, and TGA properties. Membrane separation performance was assessed in terms of pure water flux, rejection, and fouling resistance. The 7%QAPS@CA nanocomposite membrane showed an increased wettability (46.6° water contact angle), water uptake (113%) and a high pure water permeability of ∼370 L m^-2 h^-1 bar^-1. Furthermore, the 7%QAPS@CA nanocomposite membrane exhibited excellent bactericidal properties (∼97.5% growth inhibition) against Escherichia coli (E. coli) compared to the bare CA membrane (0% growth inhibition). The 7%QAPS@CA nanocomposite membrane can be recommended for water treatment and biomedical applications.

Cellulose acetate fibres loaded with daptomycin for metal implant coatings

Multifunctional polymeric coatings containing drug delivery vehicles can play a key role in preventing/reducing biofilm formation on implant surfaces. Their requirements are biocompatibility, good adhesion, and controllable drug release. Although cellulose acetate (CA) films and membranes are widely studied for scaffolding, their applications as a protective coating and drug delivery vehicle for metal implants are scarce. The reason is that adhesion to stainless steel (SS) substrates is non-trivial. Grinding SS substrates enhances the adhesion of dip-coated CA films while the adhesion of electrospun CA membranes is improved by an electrosprayed chitosan intermediate layer. PMMA microcapsules containing daptomycin have been successfully incorporated into CA films and fibres. The released drug concentration of 3 × 10^-3 mg/mL after 120 min was confirmed from the peak luminescence intensity under UV radiation of simulated body fluid (SBF) after immersion of the fibres.

Quantification of microplastics in sediments from Narragansett Bay, Rhode Island USA using a novel isolation and extraction method

Microplastics are small plastic particles found ubiquitously in marine environments. In this study, a hybridized method was developed for the extraction of microplastics (45-1000 μm) from sediments using sodium bromide solution for density separation. Method development was tested using spiked microplastics as internal standards. The method was then used to extract microplastics from sediments in Narragansett Bay, Rhode Island, USA. Suspect microplastics were analyzed with Raman spectroscopy. Microplastic abundance ranged from 40 particles/100 g sediment to 4.6 million particles/100 g sediment (wet weight). Cellulose acetate fibers were the most abundant microplastic. These results are some of the first data for microplastics in Rhode Island sediments.

Efficient separation of acetylated cellulose from eucalyptus and its enhancement on the mechanical strength of polylactic acid

A simplified and green strategy was provided for the synthesis of cellulose acetate. Cellulose acetate (CA) was isolated from the directly acetylated eucalyptus powder after hydrothermal treatment to selectively remove hemicellulose without delignification. The conversion rate of cellulose (90.75%) and the yield of the acetylated product (61.34%) were greatly improved by hydrothermal treatment, while the re-condensation of lignin during hydrothermal treatment made no adverse difference. The characterization results verified that the acetylated product was cellulose acetate with uniform molecular weight, good thermal stability and semi-crystalline structure. Moreover, CA was used to reinforce polylactic acid (PLA) films prepared by solvent casting. The PLA-CA composite with 5 wt% CA showed an increase of 80.63% in tensile strength and 59.51% in Young's modulus, and their density decreased from 1.2427 g/cm³ to 1.0028 g/cm³. The lightweight and excellent mechanical properties promote the application potential of biodegradable composites to replace petroleum-based plastics.

3D-cellulose acetate-derived hierarchical network with controllable nanopores for superior Li+ transference number, mechanical strength and dendrites hindrance

The dendrites is deemed to be one of the most crucial problems for lithium-ion batteries because it hampers their safety and cycling performance severely. Herein, a cellulose acetate-based separator with uniformly distributed nanopores was engineered and successfully prepared through a simple one-step process. The controlled nanopores promoted uniform transmission of ions and the cellulose acetate backbone inhibited the transference of anions, and prevented large-scale accumulation of lithium ions, thereby restricting the nucleation and growth of dendrites. The 3D-networked separator exhibited capacity retention of 78.6% after 900 cycles at 1C, with the breaking elongation and the strength increased by 620% and 28.4%, respectively, which originated from the porosity controlling of the nanofiber inter-bridging. The nanopore-assembled structure of 3D-hierarchy with MOFs provided the channels for the lithium ions transference through the separator and hence tackled the major challenge of mechanical vulnerability and electrochemical instability, which have never been reported before. Therefore, the developed strategy may offer a powerful and effective alternative for conventional approach of occurring dendrites post-treatments for higher ionic conductivity.

Deacetylated cellulose acetate nanofibrous dressing loaded with chitosan/propolis nanoparticles for the effective treatment of burn wounds

Every year, about 1 out of 9 get burnt in Egypt, with a mortality rate of 37%, and they suffer from physical disfigurement and trauma. For the treatment of second-degree burns, we aim at making a smart bandage provided with control of drug release (using chitosan nanoparticles) to enhance the healing process. This bandage is composed of natural materials; namely, cellulose acetate (CA), chitosan, and propolis (bee resin) as the loaded drug. Cellulose acetate nanofibers were deacetylated by NaOH after optimizing the reaction time and the concentration of NaOH solution, and the product was confirmed with FTIR analysis. Chitosan/propolis nanoparticles were prepared by ion gelation method with size ranging from 100 to 200 nm and a polydispersity index of 0.3. Chitosan/propolis nanoparticles were preloaded in the CA solution to ensure homogeneity. Loaded deacetylated cellulose nanofibers have shown the highest hydrophobicity measured by contact angle. Cytotoxicity of propolis and chitosan/propolis nanoparticles were tested and the experimental IC₅₀ value was about 137.5 and 116.0 μg/mL, respectively, with p-value ≤0.001. In addition, chitosan/propolis nanoparticles loaded into cellulose nanofibers showed a cell viability of 89.46% in the cell viability test. In-vivo experiments showed that after 21 days of treatment with the loaded nanofibers repairing of epithelial cells, hair follicles and sebaceous glands in the skin of the burn wound were found in albino-mice model.

Preparation of bio-based cellulose acetate/chitosan composite film with oxygen and water resistant properties

Plastic pollution has inspired the preparation of environmentally friendly bio-based plastics that can replace petroleum-based plastics. Herein, a composite film with oxygen and water resistant properties was prepared by a fluidized bed method, employing bio-based cellulose acetate (CA) as raw material, glycerol as a plasticizer, and chitosan and silica as additives. The addition of 15% chitosan greatly reduced the oxygen transmission rate of the CA film by 83.5%, and increased the tensile stress and tensile strain of the composite membrane, reaching 26.5 MPa and 22.2%, respectively. The deposition of silica particles is able to compensate for the undesired increase in the hydrophilicity caused by the addition of chitosan, and tune the hydrophilic nature of the surface of the CA/CS films to the hydrophobic nature, which is desirable for water-resistant applications. The prepared composite film displays good oxygen and water resistant properties and can be used for food packaging and related applications.

Cellulose acetate-based membranes by interfacial engineering and integration of ZIF-62 glass nanoparticles for CO2 separation

Composite membranes typically used for gas separation are susceptible to interfacial voids and CO₂ plasticization which adversely affects the gas permeation performance. This paper evaluates routes towards the enhancement of CO₂ permeation performance and CO₂ plasticization resistance of composite membranes using non-stoichiometric ZIF-62 MOF glass and cellulose acetate (CA). Single and mixed gas permeation results, obtained with CO₂ and CH₄, demonstrate that the presence of ZIF-62 glass in CA polymer enhanced the CO₂ permeability and CO₂/CH₄ ideal selectivity from 15.8 to 84.8 Barrer and 12.2-35.3, respectively. The composite membrane loaded with 8 wt% of ZIF-62 glass showed the highest CO₂ permeability and CO₂/CH₄ ideal selectivity of 84.8 Barrer and 35.3, which were 436.7% and 189.3% higher compared to the pristine CA membrane, respectively. A CO₂ plasticization pressure of 26 bar was achieved for the composite membranes, which is 160% higher compared to the pristine CA membranes, at about 10 bar. The mechanisms for the materials stabilization and greater separation performance were attributed to higher pore size (7.3 Å) and significant CO₂ adsorption on the unsaturated metal nodes followed by metal cites electrostatic interaction with CO₂. These findings confirm the potential of ZIF-62 glass materials as promising materials solutions towards the design of composite membranes for CO₂ separation at industrial scale.

Observable removal of pharmaceutical residues by highly porous photoactive cellulose acetate@MIL-MOF film

Pharmaceutical products are used tremendously worldwide and subsequently released into wastewater even at very low concentration caused serious environmental problem due to their high activity. Therefore, the present work focuses on remarkable removal of paracetamol as one from the most used pharmaceutical intermediates, by using porous film based on cellulose acetate@metal organic framework (CA@Ti-MIL-NH₂). The film was designed to achieve extreme removal of paracetamol by action of both of adsorption and degradation. Metal organic frame work was directly synthesized and inserted within the pre-prepared porous CA film to obtain porous CA@Ti-MIL-NH₂ film. The synthesized films were applied in adsorption and photo-degradation of paracetamol separately and together. Due to the photocatalytic activity of Ti-MIL-NH_2, the photo-degradation of paracetamol in visible-light was much effective and considerably high degradation of paracetamol was observed (k₁ = 760.0 m^-1) comparing to the adsorption (k₁ = 160.0 m^-1). The overall removal of paracetamol was significantly enlarged from 82.7 mg/g for CA film to 519.1 mg/g for porous CA@Ti-MIL-NH₂ film. The used film exhibited quite good reusability and the removal of paracetamol was lowered from 96% to 85% after 5 regeneration cycles. Results of total organic carbon confirmed that paracetamol was fully degraded to CO₂ and water.

Cost-effective and recyclable aerogels from cellulose acetate for oil spills clean-up

Cigarette butts are the most known variety of anthropogenic litter on Earth, which consists mainly of cellulose acetate. It can be prepared as aerogel which can be used to remove oil pollution caused by heavy shipping traffic in the Baltic Sea. It is prepared as a solution in acetone which then is poured into water and oven-dried afterwards. The hydrophobicity can be simply improved by wetting with a little amount of oil. Aerogel's sorption capacity, as well as its regeneration for sorption of crude oil, marine diesel oil, and biodiesel sorption from water surface, has been estimated. Their recyclability to fresh samples with re-characterization has been also determined. It has been found that multiple use of cellulose acetate aerogels is not effective because the sorption capacity decreases by up to 80% after a single use. However, the sorption capacity of recycled samples decreases by only 20% on average compared to the samples from the first batch. This capacity could be fully exploited during the life cycle of cellulose acetate.

Antibacterial potency, cell viability and morphological implications of copper oxide nanoparticles encapsulated into cellulose acetate nanofibrous scaffolds

It is generally believed that the most challenging impediment for the utilization of cellulose acetate (CA) in the medical field is its hydrophobicity and disability to poison the harmful microbes. Therefore, in this contribution, we aimed to prepare an environmentally scaffold-based CA loaded with copper nanoparticles (CuONPs), which are expected to not only improve the hydrophilicity of the prepared nanofibers, but also have an effective ability to kill such harmful and infectious microbes that are abundant in wounds. The obtained results attested that the generated nanofibers became thicker with increasing the content of CuONPs in CA nanofibers. The roughness average increased from 143.2 to 157.1 nm, whereas the maximum height of the roughness (Rt) increased from 400.8 to 479.9 nm as going from the lowest to the highest content of CuONPs. Additionally, the contact angle of the prepared nanofibers decreased from 105.3° (CA alone) to 85.4° for CuONPs@CA. Significantly, biological studies revealed that cell viability and anti-bacterial potency were improved upon incorporating CuONPs into CA solution. Correspondingly, their inhibition zones reached 18 ± 3 mm, and 16 ± 2 mm for nanofibrous scaffolds having 12.0CuO@CA, besides raising the cell viability from 91.3 ± 4% to 96.4 ± 4% for 0.0CuO@CA, and 12.0CuO@CA, respectively, thereby implying that the fabricated CuONPs@CA nanocomposite has biocompatibility towards fibroblast cells. Thus, introducing biological activity into CA nanofibers via loading with CuONPs makes it suitable for numerous biomedical applications, particularly as an environmentally benign wound dressing fibers.

Characterizing and modelling the sound absorption of the cellulose acetate fibers coming from cigarette butts

This work deals an experimental and theoretical research about the porous structure and the acoustic performance of cellulose acetate coming from the used cigarette filters. The porous structure was studied through the measurement and the prediction (using an inverse methodology) of some non-acoustic properties (bulk density, fiber size, porosity or flow resistivity and tortuosity). The sound absorption performance was evaluated by comparing experimental measurements using an impedance tube according to ISO 10534-2 with the best-fit approach obtained using some empirical models (Delany and Bazley, Garai-Pompoli, Komatsu and Miki). The accuracy of empirical models to obtain the flow resistivity was relatively high showing differences lower than 8% in the case of the Miki model or lower than 12% in the case of Delany & Bazley model. Regarding the absorption spectra, the errors found were lower than 9% for all the empirical models used in this work. These results showed that using relatively simple models such as empirical models were able to predict accurately the acoustic behaviour of the cellulose acetate. Finally, the sound absorption spectra obtained for cellulose acetate were compared with those obtained for fibrous materials currently used in building sector, suggesting that this fibrous waste could act as a possible substitute to traditional ones, due to the similar relatively high NRC values obtained for both type of fibrous absorber (NRC = 0.65).

Water sorption and diffusion in cellulose acetate: The effect of plasticisers

The conservation of cellulose acetate plastics in museum collections presents a significant challenge, due to the material's instability. Several studies have led to an understanding of the role of relative humidity (RH) and temperature in the decay process. It is well established that a major decay mechanism in cellulose acetate museum objects is the loss of plasticiser, and that the main decay mechanism of the polymer chain involves hydrolysis reactions. This leads to the loss of sidechain groups and the breakdown of the main polymer backbone. However, interactions between these decay mechanisms, specifically the way in which the loss of plasticiser can modify the interaction between cellulose acetate and water, has not yet been investigated. This research addresses the role of RH, studying the sorption and diffusion of water in cellulose acetate and how this interaction can be affected by plasticiser concentration using Dynamic Vapour Sorption (DVS).

Cellulose acetate-polyvinyl alcohol blend hemodialysis membranes integrated with dialysis performance and high biocompatibility

Hemodialysis considered as therapy of end-stage renal disease (ESRD) for the separation of protein and uremic toxins based on their molecular weights using semi-permeable membranes. Cellulose Acetate (CA) hemodialysis membrane has been widely used in the biomedical field particularly for hemodialysis applications. The main issue of CA membrane is less selectivity and hemocompatibility. In this study, to enhance the filtration capability and biocompatibility of CA hemodialysis membrane modified by using Polyvinyl Alcohol (PVA) and Polyethylene Glycol (PEG) as additives. CA-PVA flat sheet membranes were cast by phase inversion method, and separation was done by dead-end filtration cell. The synthesized membranes were described in terms of chemical structure using Fourier Transform Infrared Spectroscopy (FTIR) and morphology by Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM), pure water flux, solute permeation, and protein retention. Biocompatibility of the membranes was tested by the platelet adherence, hemolysis ratio, thrombus formation, and plasma recalcification time. SEM images exposed that the CA-PVA membrane has a uniform porous structure. 42.484 L/m² h is the maximum pure water flux obtained. The CA-PVA rejected up to 95% of bovine serum albumin (BSA). A similar membrane separated 93% of urea and 89% of creatinine. Platelet adhesion and hemolysis ratio of casted membranes were less than the pure CA membrane. Increased clotting time and less thrombus formation on the membrane's surface showed that the fabricated membrane is biocompatible. CA-PVA hemodialysis membranes are more efficient than conventional reported hemodialysis membranes. It revealed that CA-PVA is high performing biocompatible hemodialysis membrane.

Idiosyncratic cellulose acetate nanocomposite membranes: synthesis and performance control study for desalination

In order to enhance the characteristic performance of cellulose acetate (CA) membranes, a novel nanofiller synergy is adopted herein for desalination purpose. Activated zinc oxide and aero-silica synergy in seven different ratio based combinations were introduced into CA matrix adopting solution mixing technique. The functionalized nanofillers loading impact on membranes surface texture, crystalline structural difference, functional groups presence, thermal decomposition and phase transition temperatures were scrutinized. The sole membranes were practically employed to determine salts (NaCl and MgCl₂) rejection tested by dead-end filtration system. Time dependent flux rate and fouling study were performed to decide the reuseability of nanocomposite membranes. The results validate a remarkable improvement by idiosyncratically synthesized nanocomposite membranes.

Effects of cigarette butts on marine keystone species (Ulva lactuca L. and Mytilus edulis L.) and sediment microphytobenthos

Outdoor mesocosms with constantly flowing natural seawater were used to test the effects of littered cigarette butts on the filter feeder Mytilus edulis (blue mussel), the macroalga, Ulva lactuca (sea lettuce) and sediment microphytobenthos in a semi-natural marine setting. Either conventional, cellulose acetate, or biodegradable, cellulose, smoked cigarette butts were added at densities of 0.25 or 1 butt L^-1. The clearance rates of mussels exposed to 1 butt L^-1 of cellulose acetate butts were three times less than the controls. The growth of U. lactuca was not measurably affected by cigarette butts, however the sediment chlorophyll content was significantly less in mesocosms exposed to 0.25 and 1 butt L^-1 of cellulose acetate butts. These effects occurred despite constant replacement of seawater indicating how hazardous conventional cigarette butts are to marine life. Biodegradable cellulose cigarette butts had minimal effects on the measured variables but should still not be discarded as litter.

Improved digestive stability of probiotics encapsulated within poly(vinyl alcohol)/cellulose acetate hybrid fibers

Novel cellulose acetate (CA) and poly(vinyl alcohol) (PVA) hybrid fibers, fabricated via angled dual-nozzle electrospinning, were used for the encapsulation of probiotics to enhance their gastrointestinal stability. In this study, Escherichia coli strain Nissle 1917 (EcN) cells were encapsulated within PVA/CA composite mats, where CA enhanced the bacterial stability under gastric conditions and PVA provided protection against the toxic solvent during the electrospinning process. Scanning electron microscopy images revealed that EcN was successfully encapsulated within the hybrid fibers. In the simulated digestive system, free cells lost their viability within 100 min, whereas PVA/CA-encapsulated cells survived with a final count of 3.9 log CFU/mL (from an initial count of 7.8 log CFU/mL), an increase of 1 log CFU/mL compared with those in PVA/PVA fibers. Considering the enhanced viability of the encapsulated cells in the gastrointestinal system, multi-nozzle electrospinning is a promising technique for the fabrication of novel matrices for probiotic encapsulation.

Vitamin D3-loaded electrospun cellulose acetate/polycaprolactone nanofibers: Characterization, in-vitro drug release and cytotoxicity studies

Vitamin D deficiency is now a global health problem; despite several drug delivery systems for carrying vitamin D due to low bioavailability and loss bioactivity. Developing a new drug delivery system to deliver vitamin D₃ is a strong incentive in the current study. Hence, an implantable drug delivery system (IDDS) was developed from the electrospun cellulose acetate (CA) and ε-polycaprolactone (PCL) nanofibrous membrane, in which the core of implants consists of vitamin D₃-loaded CA nanofiber (CAVD) and enclosed in a thin layer of the PCL membrane (CAVD/PCL). CA nanofibrous mat loaded with vitamin D₃ at the concentrations of 6, 12, and 20% (w/w) of vitamin D₃ were produced using electrospinning. The smooth and bead-free fibers with diameters ranged from 324 to 428 nm were obtained. The fiber diameters increased with an increase in vitamin D₃ content. The controlled drug release profile was observed over 30-days, which fit with the zero-order model (R² > 0.96) in the first stage. The mechanical properties of IDDS were improved. Young's modulus and tensile strength of CAVD/PCL (dry) were161 ± 14 and 13.07 ± 2.5 MPa, respectively. CA and PCL nanofibers are non-cytotoxic based on the results of the in-vitro cytotoxicity studies. This study can further broaden in-vivo study and provide a reference for developing a new IDDS to carry vitamin D₃ in the future.

Electrospinning cellulose acetate/silk fibroin/Au-Ag hybrid composite nanofiber for enhanced biocidal activity against MCF-7 breast cancer cell

The development of multifunctional nanomaterials with enhanced biocompatible potential is crucial for effective biomedical applications. Herein we propose electrospun silk fibroin/cellulose acetate/gold-silver nanoparticles (CA/SF/Au-Ag) composite nanofiber for anticancer applications. The silk fibroin and cellulose acetate serving as the reducing and stabilizing agent for Ag⁺ and Au⁺ ions with improved biocompatibility. The fabricated CA/SF/Au-Ag nanofiber was studied with different functional, surface and crystallographic techniques. The CA/SF polymer matrix was formed in the needle and rod-shaped morphology with the range of 86.02 ± 57.35 nm in diameter and the Au and Ag NPs were embedded on the fiber matrix with an average size of 17.32 nm and 53.21 nm respectively. Further, it strongly triggers the cytotoxic effects against MCF-7 and MDA-MB-231 human breast cancer cells with an effective IC₅₀ value. Our findings implied that CA/SF/Au-Ag composite nanofibers are an effective material for safer anticancer applications.

Physical and chemical aspects of the interaction of chitosan and cellulose acetate with ions Ca2+ and K+ using DFT methods

Motivated by the use of chitosan (Ch), and cellulose acetate (AC) as organic matrices in several therapeutic drugs, a theoretical study has been elaborated through the density functional theory method (DFT) to investigate the interaction mechanism between two essential ions for the human body Ca²⁺, K⁺ and two organic matrices chitosan (Ch), and cellulose acetate (AC). Many physical and chemical aspects have been carried out after the achievement of structural optimization. This involves structural parameters, molecular electrostatic potential (MEPs), interaction energy, reactivity indexes, frontier molecular orbitals (FMOs), quantum theory atoms in molecules (QTAIM) analysis, and non-covalent interaction (NCI) analysis. The results of FMOs, MEPs, and reactivity index studies have revealed that the site of interaction can be predicted. The calculation of electron interaction energies shows that those ions interact with the matrix of AC and Ch. Concretely, the Ca²⁺ ion interacted efficiently with the AC matrix. The structural analysis results show that the interaction of Ch and ions appear spontaneously (ΔG < 0) while the interaction of AC and ions (ΔG >0) requires more energy to occur. Finally, the QTAIM analysis data indicates that the interactions of AC-ions and Ch-ions are non-covalent presenting an electrostatic character.

Designing active mats based on cellulose acetate/polycaprolactone core/shell structures with different release kinetics

Core/shell electrospun mats based on cellulose acetate (CA) and polycaprolactone (PCL) were developed as novel active materials for releasing quercetin (Quer) and curcumin (Cur). The effect of polymeric uniaxial and coaxial electrospun systems and the chemical structures of Quer and Cur on the structural, thermal, and mass transfer properties of the developed mats were investigated. Release modelling indicated that the diffusion of the active agents from the uniaxial PCL fibers was highly dependent on the type of food simulant. Higher diffusion coefficients were obtained for both active agents in acid food simulant due to the higher swelling of the electrospun mats. In addition, CA/PCL coaxial structures slowed down the diffusion of both active agents into both food simulants. CA increased the retention of the active compounds in the polymer structure, resulting in partition coefficients values higher than the values obtained for uniaxial active PCL mats.

Simple conversion of 3D electrospun nanofibrous cellulose acetate into a mechanically robust nanocomposite cellulose/calcium scaffold

Cellulose and its derivatives are widely used as nanofibrous biomaterials, but obtaining 3D cellulose nanofibers is difficult and relevant research is scarce. In the present study, we propose a simple method for converting electrospun 3D cellulose acetate/lactic acid nanofibers via calcium hydroxide treatment into a 3D cellulose/calcium lactate nanocomposite matrix. The conversion resulted in producing a stronger nanofibrous matrix (1.382 MPa vs. 0.112 MPa) that is more hydrophilic and cell-friendly compared to the untreated cellulose acetate/lactic acid group. The successful conversion was verified via FTIR, XPS, TGA, DTG, and XRD. The ability of the scaffolds to provide a suitable environment for cell growth and infiltration was verified by CCK assay and confocal microscopy. The porous nature, mechanical strength, and presence of calcium make the 3D cellulose/calcium lactate matrix a promising material for bone tissue engineering.

Degradable or not? Cellulose acetate as a model for complicated interplay between structure, environment and degradation

Degradable and/or biobased plastics are advocated as possible solution to plastic waste problem. Although mechanical and chemical recycling or energy recovery are in many cases a preferred option to regain the material value, for some applications composting is ideal. However, to more generally ensure complete degradation of plastics within a relatively short time-frame in all-natural environments would be extremely challenging, if not impossible. It is also important to keep in mind that it is the chemical structure and composition in combination with degradation environment that determines whether the plastic will degrade and within what timeframe. Biobased materials can be as stable as the petroleum-based counterparts and face the same waste-management problems. One interesting group of biobased materials are the modified biopolymer-based plastics, such as cellulose acetate (CA). How different modifications affect the inherent degradability of biopolymers is still poorly understood, which is reflected in the contradictory literature. This mirrors the complex interplay between structure-environment-degradability, where structural changes such as degree of substitution in the case of CA and changes in selected degradation environment can lead to totally different end-results and conclusions. Understanding these interactions is a fascinating scientific question. The deposition of CA based products as common surface litter makes it also question of societal and environmental interest. The purpose of this review is to summarize the existing knowledge on degradation of CA and in larger perspective highlight the complicated nature of plastic and bioplastic degradation in natural environments and the interplay between different environmental parameters and material modifications on this process.

Fabrication and characterization of cellulose acetate-based nanofibers and nanofilms for H2S gas sensing application

Electrospun nanofibers and solution-casting nanofilms were produced from an environmentally friendly cellulose acetate (CA) blended with glycerol (as an ionic liquid (IL)), mixed with polypyrrole (PPy, a conducting polymer) and doped with tungsten oxide (WO₃) nanoparticles. The sensing membranes fabricated were used to detect H₂S gas at room temperature and shown to exhibit high performance. The results revealed that the lowest operating temperature of both nanofiber and nanofilm sensors was 20 °C, with a minimum gas detection limit of 1 ppm. Moreover, the sensor exhibits a reasonably fast response, with a minimum average response time of 22.8 and 31.7 s for the proposed nanofiber and nanofilm based sensors, respectively. Furthermore, the results obtained indicated an excellent reproducibility, long-term stability, and low humidity dependence. Such distinctive properties coupled with an easy fabrication technique provide a promising potential to achieve a precise monitoring of harmful H₂S gas in both indoor and outdoor atmospheres.

Comparison of the aerobic biodegradation of biopolymers and the corresponding bioplastics: A review

Biodegradable plastics made from biopolymers (made in nature) or from bio-based polymers (made in a factory) are becoming increasingly important in replacing the massive amounts of conventional, non-degradable fossil-based plastics that have been produced and disposed over the past decades. In this review we compare the biodegradation rates and mechanisms of the bioplastics thermoplastic starch, cellulose acetate and lignin based bioplastics with the biodegradation rates and mechanisms of starch, cellulose and lignin, which are the unmodified biopolymers from which these bioplastics are produced. With this comparison we aim to determine to what extent the extensive knowledge on unmodified biopolymer biodegradation can be applied to the biodegradation of bioplastics (modified biopolymers) in the terrestrial environment. This knowledge is important, since it can be of great help in giving direction to the future research and development of bioplastics and for the development of bioplastic waste assessments and policies. We found that the similarities and differences in biodegradation are dependent on the structural changes imposed on a biopolymer during the bioplastic production process. A change in higher level structure, as found in thermoplastic starch, only resulted in a limited number of differences in the biodegradation process. However, when the chemical structure of a polymer is changed, as for cellulose acetate, different microorganisms and enzymes are involved in the biodegradation. Based on the cellulose acetate biodegradation process, a conceptual model was proposed that can be used as a starting point in predicting biodegradation rates of other chemically modified biopolymers used as bioplastics. Future bioplastic biodegradation research should focus on conducting long-term field experiments, since most studies are conducted in a laboratory setting and do not capture all processes occurring in the field situation. This applies even more to lignin based bioplastics, since very little experimental data were available on modified lignin biopolymer biodegradation.