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

Feasibility of biomass-based flexible and transparent AuNPs-acetylcellulose membrane for multifarious surface-enhanced Raman spectroscopy detection

BACKGROUND

Lignocellulosic biomass-based derivatives coupled with surface-enhanced Raman spectroscopy (SERS) technology have emerged as an appealing and indispensable tool in food safety and environmental monitoring for rapidly detecting trace contaminants like pesticide residues. The membrane material, serving as a substrate, ensures both sampling flexibility and test accuracy by directing the diffusion-adsorption process of the molecules. However, the existing membrane substrates, critical for the practical application of SERS, suffer from issues such as costly, intricate fabrication procedures, or restricted detection capabilities.

RESULTS

Herein, we present a flexible, transparent, and biodegradable cellulose acetate membrane with gold nanoparticles (AuNPs) uniformly embedded, fabricated using a simple scraping method. This membrane achieved a limit of detection (LOD) of thiram pesticide in water at 10-8 g mL-1. The unique optical transparency of the substrates allowed for in-situ detection on surfaces, with an LOD of thiram reaching 30 ng cm-2.

SIGNIFICANCE

Furthermore, SERS substrates made from corn stover-derived cellulose acetate enable the detection of various contaminants, highlighting their cost-effectiveness and eco-friendliness because of the abundance and low environmental impact of the raw materials.

Preparation and insecticidal performance of 1,8-cineole/cellulose acetate electrospun fibrous membranes

Plant essential oils and their components have broad application prospects as substitutes for chemical pesticides. However, the burst release and persistence time need to be optimized. In this study, 1,8-cineole (1,8-CIN) was embedded in degradable cellulose acetate (CA) by electrospinning to achieve sustained release. The results showed that the sustained-release membrane had good morphology and thermal stability. The release test showed that the deficiency of the explosive release of 1,8-CIN improved after encapsulation, and 21.74 % of the drug remained after 42 days. In the application test, the fiber membrane could kill the test insects in a short period of time and affect the behavior choices of the test insects. It affected the growth and oviposition of the test insects and reduced adult longevity by 13.64 % and oviposition by 23.35 %. This study can improve the utilization rate of pesticides, alleviate environmental pressure, and provide new ideas for pest control.

Challenges and opportunities in managing biodegradable plastic waste: A review

Biodegradable plastics have certain challenges in a waste management perspective. The existing literature reviews fail to provide a consolidated overview of different process steps of biodegradable plastic waste management and to discuss the support provided by the existing legislation for the same. The present review provides a holistic overview of these process steps and a comprehensive relative summary of 13 existing European Union (EU) laws related to waste management and circular economy, and national legislations plus source separation guidelines of 13 countries, to ensure the optimal use of resources in the future. Following were the major findings: (i) numerous types and low volumes of biodegradable plastics pose a challenge to developing cost-effective waste management infrastructure; (ii) biodegradable plastics are promoted as food-waste collection aids, but consumers are often confused about their proper disposal and are prone to greenwashing from manufacturers; (iii) industry-level studies demonstrating mechanical recycling on a full scale are unavailable; (iv) the existing EU legislation dealt with general topics related to biodegradable plastics; however, only the new proposal on plastic packaging waste and the EU policy framework for bioplastics clearly mentioned their disposal and (v) clear disparities were observed between disposal methods suggested by national legislation and available source separation guidelines. Thus, to appropriately manage biodegradable plastic waste, it is necessary to develop waste processing and material utilization infrastructure as well as create consumer awareness. In the end, recommendations were provided for improved biodegradable plastic waste management from the perspective of systemic challenges identified from the literature review.

Multiscale Computational Study of Cellulose Acetate-Water Miscibility: Insights from Molecularly Informed Field-Theoretic Modeling

Cellulose acetate (CA), a prominent water-soluble derivative of cellulose, is a promising biodegradable ingredient that has applications in films, membranes, fibers, drug delivery, and more. In this work, we present a molecularly informed field-theoretic model for CA to explore its phase behavior in aqueous solutions. By integrating atomistic details into large-scale field-theoretic simulations via the relative entropy coarse-graining framework, our approach enables efficient calculations of CA's miscibility window as a function of the degree of substitution (DS) of cellulose hydroxyl groups with acetate side chains. This allows us to capture the intricate phase behavior of CA, particularly its unique miscibility at intermediate substitution, without relying on experimental input. Additionally, the model directly probes CA solution behavior specific to the relative DS at C2, C3, and C6 alcohol sites, providing insights for the rational design of water-soluble CA for diverse applications. This work demonstrates a promising integration of molecularly informed field theories, complementing wet-lab experimentation, for engineering the next-generation polymeric materials with precisely tailored properties.

Leaching of organic matter from cigarette butt filters as a potential disinfection by-products precursor

The study aimed to evaluate cigarette butt filters (CBFs) as a potential source of dissolved organic carbon (DOC) in water leading to the formation of disinfection by-products. Two different forms of CBFs - intact (I) and disintegrated (D), as they occur in the environment, were selected for leaching in chlorinated (CI, CD), non-chlorinated (NI, ND), and highly chlorinated (HCD) water samples. The UV absorbance profiles of the leachate samples showed that intact CBFs exhibited higher DOC leaching compared to the disintegrated ones, which was further accentuated in chlorinated samples (CI > CD > NI > ND). The Fourier Transform Infrared spectra of the leachates revealed the presence of characteristic functional groups of cellulose acetate and its chlorinated derivatives, indicating the potential degradation of the polymer. Moreover, trihalomethane (THM) formation in chlorinated samples was relatively higher in CI samples (2 - 11.5 times) compared to CD, consistent with the DOC leaching trends. Further, the speciation characteristics of different THMs in both CI and CD samples were similar. Although spectral and morphological analyzes of CI and CD samples revealed negligible variation, HCD samples depicted significant surface roughness characterized by the formation of pits and holes, along with the evolution of crystallinity. This suggested accelerated degradation of CBFs and disruption of acetyl groups as a factor of elevated chlorine concentrations.

Designing for Degradation: Transient Devices Enabled by (Nano)Cellulose

Transient technology involves materials and devices that undergo controlled degradation after a reliable operation period. This groundbreaking strategy offers significant advantages over conventional devices based on non-renewable materials by limiting environmental exposure to potentially hazardous components after disposal, and by increasing material circularity. As the most abundant naturally occurring polymer on Earth, cellulose is an attractive material for this purpose. Besides, (nano)celluloses are inherently biodegradable and have competitive mechanical, optical, thermal, and ionic conductivity properties that can be exploited to develop sustainable devices and avoid the end-of-life issues associated with conventional systems. Despite its potential, few efforts have been made to review current advances in cellulose-based transient technology. Therefore, this review catalogs the state-of-the-art developments in transient devices enabled by cellulosic materials. To provide a wide perspective, the various degradation mechanisms involved in cellulosic transient devices are introduced. The advanced capabilities of transient cellulosic systems in sensing, photonics, energy storage, electronics, and biomedicine are also highlighted. Current bottlenecks toward successful implementation are discussed, with material circularity and environmental impact metrics at the center. It is believed that this review will serve as a valuable resource for the proliferation of cellulose-based transient technology and its implementation into fully integrated, circular, and environmentally sustainable devices.

Characterization and Performance Evaluation of Liquid Biodegradable Mulch Films and Its Effects on Peanut Cultivation

With the development of material science and increasing awareness of ecological environmental protection, liquid biodegradable mulch films (LBDMs) have garnered significant public interest. In this research, new LBDMs were developed using hydrophobically modified polymer materials, surfactants, and photosensitive catalysts. Characterization by scanning electron microscopy (SEM) revealed good material compatibility. LBDMs exhibited excellent wettability and degradability, effectively covering soil surfaces and enhancing soil moisture conservation, with a degradation rate of 76.09% after 80 days of burial. The field performance experiment was conducted over two consecutive years, 2021 and 2022, to assess differences in soil temperature and moisture, peanut agronomic traits, pod traits, and yield under four treatments: non-mulching (CK), LBDMs, clear polyethylene mulch films (CPEMs), and black polyethylene mulch films (BPEMs). LBDMs increased soil temperature by 0.56 °C and soil moisture by 19.25%, accelerated the seedling stage by 4-to-6 days, and improved the average emergence rate by 15.91%. Furthermore, LBDMs significantly promoted peanut growth, and it increased yield by 14.34% compared to CK. LBDMs performed comparably to the two types of PE films in maintaining soil conditions and different crop phenotype traits, including plant height, branch number, yield, and quality, and they even outperformed PE films in productivity per plant and 100-kernel weight. These findings suggest that LBDMs are a promising eco-friendly alternative to traditional PE films.

Toward a Circular Bioeconomy: Designing Microbes and Polymers for Biodegradation

Polymer production is rapidly increasing, but there are no large-scale technologies available to effectively mitigate the massive accumulation of these recalcitrant materials. One potential solution is the development of a carbon-neutral polymer life cycle, where microorganisms convert plant biomass to chemicals, which are used to synthesize biodegradable materials that ultimately contribute to the growth of new plants. Realizing a circular carbon life cycle requires the integration of knowledge across microbiology, bioengineering, materials science, and organic chemistry, which itself has hindered large-scale industrial advances. This review addresses the biodegradation status of common synthetic polymers, identifying novel microbes and enzymes capable of metabolizing these recalcitrant materials and engineering approaches to enhance their biodegradation pathways. Design considerations for the next generation of biodegradable polymers are also reviewed, and finally, opportunities to apply findings from lignocellulosic biodegradation to the design and biodegradation of similarly recalcitrant synthetic polymers are discussed.

Tracing microplastic pollution in Mahi River estuary, Gulf of Khambhat, Gujarat, and their influence on functional traits of macrobenthos

Most maritime habitats contain microplastic (MPs) contamination. The quality of the benthic ecosystem's habitat is declining as MPs accumulate in marine system. The contamination of MPs must therefore be investigated. We studied MPs pollution in the Mahi River, estuary, and macrobenthos. In the present study, the abundance of MPs fragments gradually decreased from the high tide zone to the low tide zone and muddy sediment has high MPs concentrations due to sediment characteristics and particle size. The majority of sediment and biota MPs were fibrous and black. MPs in both silt and biota have identical chemical compositions (modified cellulose), shapes, and colors. A significant source of pollutants and MPs fluxing into the ocean is well within the river system. Perinereis aibuhitensis ingested the most MPs out of 11 species, whereas Amphipods did not show any presence of MPs. Our findings showed that functional characteristics are essential for macrobenthos MPs intake. MPs in macrobenthos are high due to biological functions such as feeding, ecological groups, feeding mechanisms, body size, and bioturbation. MPs in marine sediment and organisms are tracked down to the Mahi River exceeding 50 km. The present work has investigated the idea that the macrobenthos that live in the sediment are ingesting the MPs that are building up there and this ingestion relies on the macrobenthos' functional characteristics.

A review on recent advances of cellulose acetate membranes for gas separation

This review thoroughly investigates the wide-ranging applications of cellulose-based materials, with a particular focus on their utility in gas separation processes. By focusing on cellulose acetate (CA), the review underscores its cost-effectiveness, robust mechanical attributes, and noteworthy CO2 solubility, positioning it as a frontrunner among polymeric gas separation membranes. The synthesis techniques for CA membranes are meticulously examined, and the discourse extends to polymeric blend membranes, underscoring their distinct advantages in gas separation applications. The exploration of advancements in CA-based mixed matrix membranes, particularly the incorporation of nanomaterials, sheds light on the significant versatility and potential improvements offered by composite materials. Fabrication techniques demonstrate exceptional gas separation performance, with selectivity values reaching up to 70.9 for CO2/CH4 and 84.1 for CO2/N2. CA/PEG (polyethylene glycol) and CA/MOF (metal-organic frameworks) demonstrated exceptional selectivity in composite membranes with favorable permeability, surpassing other composite CA membranes. Their selectivity with good permeability lies well above all the synthesised cellulose. As challenges in experimental scale separation emerge, the review seamlessly transitions to molecular simulations, emphasizing their crucial role in understanding molecular interactions and overcoming scalability issues. The significance of the review lies in addressing environmental concerns, optimizing membrane compositions, understanding molecular interactions, and bridging knowledge gaps, offering guidance for the sustainable evolution of CA-based materials in gas separation technologies.

Analysis of environmental biodegradability of cellulose-based pharmaceutical excipients in aqueous media

Pharmaceutical cellulosic polymers will inevitably reach natural water systems if they are not removed after entering wastewater. Biodegradation of organic chemicals in sewage or in the aquatic environment is an important removal mechanism. In this study, we investigated the environmental biodegradation of 14 cellulose derivatives commonly utilized as pharmaceutical excipients using three different test systems that are based on the closed bottle test (OECD 301D) and the manometric respirometry test (OECD 301F). For the different cellulose derivatives tested, we observed varying degrees of biodegradation ranging from 0 to 20.4 % chemical oxygen demand (COD). However, none met the criteria for classification as 'readily biodegradable'. In addition, 10 out of 14 cellulose derivatives and/or their possible transformation products formed during the experiments, may exhibit possible toxic inhibitory effects on the inoculum. This includes one or several derivatives of hydroxy propyl methyl cellulose, hydroxy propyl cellulose, methyl cellulose, ethyl cellulose, and hydroxy ethyl cellulose. Based on the results obtained, we have developed a graded classification score ('traffic light system') for excipient biodegradation. This could help streamline the assessment and classification of cellulose derivatives concerning risk of persistence and potential adverse environmental effects, thereby assisting in the prioritization of more favorable compounds. In the long term, however, excipients should be designed from the very beginning to be biodegradable and mineralizable in the environment ('benign by design').

Distinct microbial communities degrade cellulose diacetate bioplastics in the coastal ocean

IMPORTANCE

Cellulose diacetate (CDA) is a promising alternative to conventional plastics due to its versatility in manufacturing and low environmental persistence. Previously, our group demonstrated that CDA is susceptible to biodegradation in the ocean on timescales of months. In this study, we report the composition of microorganisms driving CDA degradation in the coastal ocean. We found that the coastal ocean harbors distinct bacterial taxa implicated in CDA degradation and these taxa have not been previously identified in prior CDA degradation studies, indicating an unexplored diversity of CDA-degrading bacteria in the ocean. Moreover, the shape of the plastic article (e.g., a fabric, film, or foam) and plasticizer in the plastic matrix selected for different microbial communities. Our findings pave the way for future studies to identify the specific species and enzymes that drive CDA degradation in the marine environment, ultimately yielding a more predictive understanding of CDA biodegradation across space and time.

Degradation Characteristics of Cellulose Acetate in Different Aqueous Conditions

Cellulose acetate (CA) is widely used in cigarette filters and packaging films, but due to its acetylation, it is difficult to degrade in the natural environment, and the problem of pollution has become a serious challenge. Understanding the degradation behavior and performance of CA in different environments is the basis and prerequisite for achieving its comprehensive utilization and developing efficient degradation methods. In this study, we investigated the degradation performance of CA in different aqueous environments to evaluate the effects of pH, salinity and microorganisms on CA degradation. The CA tows and films were immersed in HCl, NaOH solution, river water, seawater or homemade seawater for 16 weeks and the degradation mechanism was investigated by the changes in weight loss rate, degree of substitution, hydrophilicity, molecular structure and surface morphology. The results showed that the degradation of CA tow and film were the fastest in NaOH solution; the weight loss rates after 16 weeks were 40.29% and 39.63%, respectively, followed by HCl solution, and the degradation performance of CA tow was better than that of film. After 16 weeks of degradation in river water, seawater and homemade seawater, all the weight loss rates were less than 3%. In summary, this study illustrated that the environmental acidity, basicity and high concentration of inorganic salts had a critical promotion effect on the non-enzymatic hydrolysis of CA, whereas the number and type of microorganisms were the key factors affecting the biodegradation of CA.

Reconstruction of Cellulose Intermolecular Interactions from Hydrogen Bonds to Dynamic Covalent Networks Enables a Thermo-processable Cellulosic Plastic with Tunable Strength and Toughness

Its excellent renewability and biodegradability make cellulose an attractive resource to prepare fossil-based plastic alternatives. However, cellulose itself exhibits strong intermolecular hydrogen bond (H-bond) interactions, significantly restricting the mobility of cellulose chains, thus leading to poor thermo-processing performance. Here, we reconstructed the intermolecular interactions of cellulose chains via replacing the original H-bonds with dynamic covalent bonds. By this, cellulose can be easily thermo-processed into a cellulosic plastic under mild conditions (70 °C). Through adjusting the chemical structure of dynamic covalent networks, the cellulosic plastic shows tunable mechanical strength (3.0-33.5 MPa) and toughness (43-321 kJ m-2). The cellulosic plastic also exhibits excellent resistance to water, organic solvent, acid solution, alkali solution, and high temperature (>400 °C). Moreover, it owns good chemical and biological degradability and recyclability. This work provides an effective method to develop high-performance cellulosic plastics for fossil-based plastic substitution.

UV Light Causes Structural Changes in Microplastics Exposed in Bio-Solids

Bio-solids (biological sludge) from wastewater treatment plants are a significant source of the emission of microplastics (MPs) into the environment. Weakening the structure of MPs before they enter the environment may accelerate their degradation and reduce the environmental exposure time. Therefore, we studied the effect of UV-A and UV-C, applied at 70 °C, on three types of MPs, polypropylene (PP), polyethylene (PE), and polyethylene terephthalate (PET), that are commonly found in sewage sludge, using three shapes (fibers, lines, granules). The MPs were exposed to UV radiation in bio-solid suspensions, and to air and water as control. The structural changes in and degradation of the MPs were investigated using Attenuated Total Reflectance-Fourier Transform Infrared Spectrometry (ATR-FTIR) and surface morphology was performed with SEM analysis. UV exposure led to the emergence of carbonyl and hydroxyl groups in all of the PP samples. In PE and PET, these groups were formed only in the bio-solid suspensions. The presence of carbonyl and hydroxyl groups increased with an increasing exposure time. Overall, UV radiation had the greatest impact on the MPs in the bio-solids suspension. Due to the surface-to-volume ratio of the tested samples, which influences the degradation rate, the fibers were more degraded than the other two plastic shapes. UV-A was slightly more effective at degrading the MPs than UV-C. These findings show that ultraviolet radiation in combination with an elevated temperature affects the structure of polymers in wastewater bio-solids, which can accelerate their degradation.

3D/4D printing of cellulose nanocrystals-based biomaterials: Additives for sustainable applications

Cellulose nanocrystals (CNCs) have gained significant attraction from both industrial and academic sectors, thanks to their biodegradability, non-toxicity, and renewability with remarkable mechanical characteristics. Desirable mechanical characteristics of CNCs include high stiffness, high strength, excellent flexibility, and large surface-to-volume ratio. Additionally, the mechanical properties of CNCs can be tailored through chemical modifications for high-end applications including tissue engineering, actuating, and biomedical. Modern manufacturing methods including 3D/4D printing are highly advantageous for developing sophisticated and intricate geometries. This review highlights the major developments of additive manufactured CNCs, which promote sustainable solutions across a wide range of applications. Additionally, this contribution also presents current challenges and future research directions of CNC-based composites developed through 3D/4D printing techniques for myriad engineering sectors including tissue engineering, wound healing, wearable electronics, robotics, and anti-counterfeiting applications. Overall, this review will greatly help research scientists from chemistry, materials, biomedicine, and other disciplines to comprehend the underlying principles, mechanical properties, and applications of additively manufactured CNC-based structures.

Degradation of starch-based bioplastic bags in the pelagic and benthic zones of the Gulf of Oman

The Gulf of Oman is becoming increasingly polluted with plastics, hence bioplastics have been considered 'a substitute', although their biodegradability in marine environments has not been well investigated. Most research has been performed on cellulose-based bioplastics, whereas starch-based bioplastics have proven to be a suitable, but less researched, alternative. This study is the first of its kind designed to investigate the degradability of two different types of starch-based bioplastic bags, available in the market and labeled as "biodegradable", in the pelagic and benthic zones of one of the warmest marine environment in the world. Fourier-Transform Infrared Spectroscopy (FTIR) showed a clear reduction in the presence of OH, CH, and CO in the bioplastic bags after 5 weeks of immersion. Thermo-Gravimetric Analysis (TGA) indicated degradation of glycerol, starch, and polyethylene. The biofouling bacterial communities on bioplastic surfaces showed distinct grouping based on the immersion zone. Candidaatus saccharibacteria, Verrucomicrobiae, Acidimicrobiia and Planctomycetia sequences were only detectable on bioplastics in the pelagic zone, whereas Actinomyces, Pseudomonas, Sphingobium and Acinetobacter related sequences were only found on bioplastics in the benthic layer. We conclude that starch-based bioplastics are more readily degradable in the Gulf of Oman than conventional plastics, hence could serve as a better environmentally friendly alternative.

A Programmable Actuator as Synthetic Earthworm

Natural earthworm with the ability to loosen soils that favors sustainable agriculture has inspired worldwide interest in the design of intelligent actuators. Given the inability to carry heavy loads and uncontrolled deformation, the vast majority of actuators can only perform simple tasks by bending, contraction, or elongation. Herein, a degradable actuator with the ability to deform in desired ways is presented, which successfully mimics the burrowing activities of earthworms to loosen soils with increased soil porosity by digging, grabbing, and lifting the soil when it receives rains. Such a scarifying actuator is made of degradable cellulose acetate and uncrosslinked polyacrylamide via the swelling-photopolymerizing method. The water absorption of polyacrylamide in moisture conditions causes rapid and remarkable bending. Such mechanical bending can be controlled in specific areas of the cellulose acetate film if polyacrylamide is polymerized in a patterned way, so as to generate complicated deformations of the whole cellulose acetate. Patterning polyacrylamide within cellulose acetate is achieved based on reversible surface protection by means of pen writing, rather than the traditional masking techniques. The water-induced deformation of programmable cellulose-based actuators is well preserved in soil, which is appropriate for promoting rain diffusion as well as root breath.

Hydrogel Bioinks of Alginate and Curcumin-Loaded Cellulose Ester-Based Particles for the Biofabrication of Drug-Releasing Living Tissue Analogs

3D bioprinting is a versatile technique that allows the fabrication of living tissue analogs through the layer-by-layer deposition of cell-laden biomaterials, viz. bioinks. In this work, composite alginate hydrogel-based bioinks reinforced with curcumin-loaded particles of cellulose esters (CEpCUR) and laden with human keratinocytes (HaCaT) are developed. The addition of the CEpCUR particles, with sizes of 740 ± 147 nm, improves the rheological properties of the inks, increasing their shear stress and viscosity, while preserving the recovery rate and the mechanical and viscoelastic properties of the resulting fully cross-linked hydrogels. Moreover, the presence of these particles reduces the degradation rate of the hydrogels from 26.3 ± 0.8% (ALG) to 18.7 ± 1.3% (ALG:CEpCUR_10%) after 3 days in the culture medium. The 3D structures printed with the ALG:CEpCUR inks reveal increased printing definition and the ability to release curcumin (with nearly 70% of cumulative release after 24 h in PBS). After being laden with HaCaT cells (1.2 × 106 cells mL-1), the ALG:CEpCUR bioinks can be successfully 3D bioprinted, and the obtained living constructs show good dimensional stability and high cell viabilities at 7 days post-bioprinting (nearly 90%), confirming their great potential for application in fields like wound healing.

Chitin nanofiber-coated biodegradable polymer microparticles via one-pot aqueous process

Tailoring the surface of biodegradable microparticles is important for various applications in the fields of cosmetics, biotechnology, and drug delivery. Chitin nanofibers (ChNFs) are one of the promising materials for surface tailoring owing to its functionality, such as biocompatibility and antibiotic properties. Here, we show biodegradable polymer microparticles densely coated with ChNFs. Cellulose acetate (CA) was used as the core material in this study, and ChNF coating was successfully carried out via a one-pot aqueous process. The average particle size of the ChNF-coated CA microparticles was approximately 6 μm, and the coating procedure had little effect on the size or shape of the original CA microparticles. The ChNF-coated CA microparticles comprised 0.2-0.4 wt% of the thin surface ChNF layers. Owing to the surface cationic ChNFs, the ζ-potential value of the ChNF-coated microparticles was +27.4 mV. The surface ChNF layer efficiently adsorbed anionic dye molecules, and repeatable adsorption/desorption behavior was exhibited owing to the coating stability of the surface ChNFs. The ChNF coating in this study was a facile aqueous process and was applicable to CA-based materials of various sizes and shapes. This versatility will open new possibilities for future biodegradable polymer materials that satisfy the increasing demand for sustainable development.

Effect of Cellulose-Based Bioplastics on Current LDPE Recycling

The increased use of bioplastics in the market has led to their presence in municipal solid waste streams alongside traditional fossil-based polymers, particularly low-density polyethylene (LDPE), which bioplastics often end up mixed with. This study aimed to assess the impact of cellulose acetate plasticized with triacetin (CAT) on the mechanical recycling of LDPE. LDPE-CAT blends with varying CAT content (0%, 1%, 5%, 7.5%, and 10% by weight) were prepared by melt extrusion and analyzed using scanning electron microscopy, Fourier-transform infrared spectroscopy, thermal analysis (thermogravimetric and differential scanning calorimetry), dynamic rheological measurements, and tensile tests. The results indicate that the presence of CAT does not significantly affect the chemical, thermal, and rheological properties of LDPE, and the addition of CAT at different levels does not promote LDPE degradation under typical processing conditions. However, the addition of CAT negatively impacts the processability and mechanical behavior of LDPE, resulting in the reduced quality of the recycled material. Thus, the presence of cellulose-based bioplastics in LDPE recycling streams should be avoided, and a specific sorting stream for bioplastics should be established.

Cellulose acetate from lignocellulosic residues: An eco-friendly approach based on a hydrothermal process

The objective of this study was to produce cellulose acetate (CA) from oat (OH) and soybean (SH) hulls through an eco-friendly solvent-and catalyst-free hydrothermal process, and also to compare the acetylation of cellulose by the conventional synthesis process, employing sulfuric acid as the catalyst, and acetic acid as solvent. Cellulose was extracted from OH and SH using a one-step chlorine-free process, resulting in materials with 86 and 81 % cellulose, respectively. CA samples obtained by hydrothermal process had degrees of substitution ranging from 0.95 to 1.47, and from 1.10 to 1.50, for OH and SH samples, respectively, being classified as monoacetates, while the conventional acetylation resulted in cellulose di- and triacetates. The acetylation by the hydrothermal process did not affect cellulose fibers morphology or crystallinity. CA samples obtained by the conventional process showed changes in their surface morphology, with decrease in crystallinity indexes. Viscosimetric average molar mass increased for all modified samples, with mass gain ranging from 16.26 to 519.70 %. The hydrothermal treatment proved to be a promising process for obtaining cellulose monoacetates with some advantages, including short reaction times, it is a one-step process, and lower effluents generation when compared to the conventional processes.

Electrospun nanofibers for medical face mask with protection capabilities against viruses: State of the art and perspective for industrial scale-up

Face masks have proven to be a useful protection from airborne viruses and bacteria, especially in the recent years pandemic outbreak when they effectively lowered the risk of infection from Coronavirus disease (COVID-19) or Omicron variants, being recognized as one of the main protective measures adopted by the World Health Organization (WHO). The need for improving the filtering efficiency performance to prevent penetration of fine particulate matter (PM), which can be potential bacteria or virus carriers, has led the research into developing new methods and techniques for face mask fabrication. In this perspective, Electrospinning has shown to be the most efficient technique to get either synthetic or natural polymers-based fibers with size down to the nanoscale providing remarkable performance in terms of both particle filtration and breathability. The aim of this Review is to give further insight into the implementation of electrospun nanofibers for the realization of the next generation of face masks, with functionalized membranes via addiction of active material to the polymer solutions that can give optimal features about antibacterial, antiviral, self-sterilization, and electrical energy storage capabilities. Furthermore, the recent advances regarding the use of renewable materials and green solvent strategies to improve the sustainability of electrospun membranes and to fabricate eco-friendly filters are here discussed, especially in view of the large-scale nanofiber production where traditional membrane manufacturing may result in a high environmental and health risk.

Melt Processible Biodegradable Blends of Polyethylene Glycol Plasticized Cellulose Diacetate with Polylactic Acid and Polybutylene Adipate-Co-Terephthalate

Enhancing the melt processability of cellulose is key to broadening its applications. This is done via derivatization of cellulose, and subsequent plasticization and/or blending with other biopolymers, such as polylactic acid (PLA) and polybutylene adipate terephthalate (PBAT). However, derivatization of cellulose tends to reduce its biodegradability. Moreover, traditional plasticizers are non-biodegradable. In this study, we report the influence of polyethylene glycol (PEG) plasticizer on the melt processibility and biodegradability of cellulose diacetate (CD) and its blends with PLA and PBAT. CD was first plasticized with PEG (PEG-200) at 35 wt%, and then blended with PLA and PBAT using a twin-screw extruder. Blends of the PEG plasticized CD with PLA at 40 wt% and with PBAT at 60 wt% were studied in detail. Dynamic mechanical analysis (DMA) showed that PEG reduced the glass transition of the CD from ca. 220 °C to less than 100 °C, indicating effective plasticization. Scanning electron microscopy revealed that the CD/PEG-PBAT blend had a smoother morphology implying some miscibility. The CD/PEG-PBAT blend at 60 wt% PBAT had an elongation-to-break of 734%, whereas the CD/PEG-PLA blend had a tensile strength of 20.6 MPa, comparable to that of the PEG plasticized CD. After a 108-day incubation period under simulated aerobic composting, the CD/PEG-PBAT blend at 60 wt% PBAT exhibited a biodegradation of 41%, whereas that of the CD/PEG-PLA at 40 wt% PLA was 107%. This study showed that melt processible, biodegradable CD blends can be synthesized through plasticization with PEG and blending with PBAT or PLA.

Life cycle assessment of end-of-life options for cellulose-based bioplastics when introduced into a municipal solid waste management system

The partial degradation of cellulose-based bioplastics in industrial treatment of organic fraction of Municipal Solid Waste (MSW) opened to the investigation of further disposal routes for bioplastics in the waste management system. For this purpose, the environmental footprint of three MSW management scenarios differing only for the bioplastics final destination (organic, plastic or mixed waste streams) was assessed through a Life Cycle Assessment (LCA) approach. Results revealed how the treatment of bioplastics with organic waste achieved the worst environmental performance (5.8 kg CO₂ eq/FU) for most impact categories. On the other hand, treatment with plastics and mixed waste achieved negative impact values (that mean avoided GHG emissions) of -9.8 and -7.7 kg CO₂ eq/FU respectively, showing comparable benefits from these scenarios. The key reason was the lower quality of compost obtained from the organic treatment route, which reduced the environmental credits achieved by the energy recovery during anaerobic digestion.

Fabrication of Advanced Cellulosic Triboelectric Materials via Dielectric Modulation

The rapid rise of triboelectric nanogenerators (TENGs), which are emerging energy conversion devices in advanced electronics and wearable sensing systems, has elevated the interest in high-performance and multifunctional triboelectric materials. Among them, cellulosic materials, affording high efficiency, biodegradability, and customizability, are becoming a new front-runner. The inherently low dielectric constant limits the increase in the surface charge density. However, owing to its unique structure and excellent processability, cellulose shows great potential for dielectric modulation, providing a strong impetus for its advanced applications in the era of Internet of Things and artificial intelligence. This review aims to provide comprehensive insights into the fabrication of dielectric-enhanced cellulosic triboelectric materials via dielectric modulation. The exceptional advantages and research progress in cellulosic materials are highlighted. The effects of the dielectric constant, polarization, and percolation threshold on the charge density are systematically investigated, providing a theoretical basis for cellulose dielectric modulation. Typical dielectric characterization methods are introduced, and their technical characteristics are analyzed. Furthermore, the performance enhancements of cellulosic triboelectric materials endowed by dielectric modulation, including more efficient energy harvesting, high-performance wearable electronics, and impedance matching via material strategies, are introduced. Finally, the challenges and future opportunities for cellulose dielectric modulation are summarized.

Schwanniomyces etchellsii, acid-thermotolerant yeasts from urban city soil

Acid-tolerant yeasts are one of the important keys to producing ethanol from acidic substrates, especially from molasses and agricultural waste. In this study, selected cultivars of yeasts isolated from a variety of locations such as botanical gardens in Thailand urban areas, which are often found highly polluted in the air such as carbon dioxide which is a cause of acid rain. There is limited information about how tolerant yeasts, are or their functional properties related to the environment. Yeast species were determined by using the 18S rDNA sequence guide. The level of acid tolerance was evaluated by adding to the culture medium lactic acid (300-900 mM), acetic acid (100-400 mM), and propionic acid (25-100 mM). 18S rDNA analysis has shown a %similarity of the nucleotide sequence higher than 98.65% compared to the database. Schwanniomyces etchellsii strains found in urban city soil were notable for their tolerance of lactic acid up to 100 mM. There are two main types of yeasts in overall acid tolerance: S. etchellsii, which is recognized as an osmotic pressure-resistant species that is highly resistant to fermentation inhibitors and produces ethanol; and Schizosaccharomyces pombe, which cell wall has been reported to be characterized by accumulation of α-(1,3)-glucan and malic acid can be used in metabolic pathways. The results show that S. pombe, isolated from rice paddy fields, can grow efficiently in acetic and propionic acid up to 400 mM and 100 mM, respectively. This species could be cultured in ethanol at a concentration of 12.5% (v/v). Moreover, it presented high ethanol and acetic acid production of 14.5-15.9 g/L and 7-10 g/L, respectively, with or without acidic conditions. In comparison, S. etchellsii, isolated from the botanical garden soil, which is grown in acetic, propionic, and lactic acid, was also indicated to be an organic acid-tolerant species.

Small Butt Harmful: Individual- and Population-Level Impacts of Cigarette Filter Particles on the Deposit-Feeding Polychaete Capitella teleta

In the marine environment, discarded cigarette filters (CFs) deteriorate and leach filter-associated chemicals. The study aim was to assess the effects of smoked CFs (SCFs) and non-smoked CFs (NCFs) particles on individual life-history traits in the deposit-feeding polychaete Capitella teleta and extrapolate these to possible population-level effects. C. teleta was exposed to sediment-spiked particles of NCFs and SCFs at an environmentally realistic concentration (0.1 mg particles g^-1 dw sed) and a 100-fold higher (10 mg particles g^-1 dw sed) concentration. Experimental setup incorporated 11 individual endpoints and lasted approximately 6 months. There were significant effects on all endpoints, except from adult body volume and egestion rate, in worms exposed to 10 mg SCF particles g^-1 dw sed. Although not statistically significant, there was ≥50% impact on time between reproductive events and number of eggs per female at 0.1 mg SCF particles g^-1 dw sed. None of the endpoints was significantly affected by NCFs. Results suggest that SCFs are likely to affect individual life-history traits of C. teleta, whereas the population model suggests that these effects might not transform into population-level effects. The results further indicate that chemicals associated with CFs are the main driver causing the effects rather than the CF particles.

Discussion about suitable applications for biodegradable plastics regarding their sources, uses and end of life

This opinion paper offers a scientific view on the current debate of the place of biodegradable plastics as part of the solution to deal with the growing plastic pollution in the world's soil, aquatic, and marine compartments. Based on the current scientific literature, we focus on the current limits to prove plastic biodegradability and to assess the toxicity of commercially used biobased and biodegradable plastics in natural environments. We also discuss the relevance of biodegradable plastics for selected applications with respect to their use and end of life. In particular, we underlined that there is no universal biodegradability of plastics in any ecosystem, that considering the environment as a waste treatment system is not acceptable, and that the use of compostable plastics requires adaptation of existing organic waste collection and treatment channels.

Co-digestion of food waste and cellulose-based bioplastic: From batch to semi-continuous scale investigation

Only few studies on the behaviour of bioplastics in anaerobic co-digestion could be found in literature and most of them are conducted in batch mode. Despite the fact that continuous experiments confirm or add new insight to the findings acquired from batch ones, there is still lack of such studies. This work aims to cover this gap, carrying out a semi-continuous anaerobic co-digestion of food waste and cellulose acetate (which its behaviour under anaerobic environment is also quite unexplored). After a first evaluation of the potential methane production from each substrate at batch scale, the semi-continuous co-digestion of food waste and cellulose acetate was carried out in three configurations. During the semi-continuous process, a methane yield of 331 NmlCH₄/gVS was generated from the co-digestion of food waste and cellulose acetate while bioplastics specimens achieved a weight loss of about 45 %. The results were both lower than the one obtained from batch co-digestion, although methane production rates were comparable regardless of being fed with or without bioplastics. An increase was registered after 65 days of semi-continuous process, due to the accumulation of CA specimens. This confirms the different degradation trends between bioplastics and food waste.

Modified Cellulose Proton-Exchange Membranes for Direct Methanol Fuel Cells

A direct methanol fuel cell (DMFC) is an excellent energy device in which direct conversion of methanol to energy occurs, resulting in a high energy conversion rate. For DMFCs, fluoropolymer copolymers are considered excellent proton-exchange membranes (PEMs). However, the high cost and high methanol permeability of commercial membranes are major obstacles to overcome in achieving higher performance in DMFCs. Novel developments have focused on various reliable materials to decrease costs and enhance DMFC performance. From this perspective, cellulose-based materials have been effectively considered as polymers and additives with multiple concepts to develop PEMs for DMFCs. In this review, we have extensively discussed the advances and utilization of cost-effective cellulose materials (microcrystalline cellulose, nanocrystalline cellulose, cellulose whiskers, cellulose nanofibers, and cellulose acetate) as PEMs for DMFCs. By adding cellulose or cellulose derivatives alone or into the PEM matrix, the performance of DMFCs is attained progressively. To understand the impact of different structures and compositions of cellulose-containing PEMs, they have been classified as functionalized cellulose, grafted cellulose, acid-doped cellulose, cellulose blended with different polymers, and composites with inorganic additives.

Vitamin C-Induced Enhanced Performance of PEDOT:PSS Thin Films for Eco-Friendly Transient Thermoelectrics

Conjugated polymer-based energy-harvesting devices hold distinctive advantages in terms of low toxicity, high flexibility, and capability of large-area integration at low cost for sustainable development. An organic thermoelectric (OTE) device has been considered one of the promising energy-harvesting candidates in recent years because it can efficiently convert low-temperature waste heat into electricity over its inorganic counterparts. However, a cruel irony is that environmentally toxic solvents and acids are utilized for fabrication and performance improvement of the OTE devices, retarding the development and use of genuinely green energy-harvesting. Here, we present eco-friendly, non-toxic strategies for a poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS)-based high-performance OTE device by incorporating a nature-abundant material, vitamin C (VC), as an additive. We found that the intrinsic polar nature and reducing ability of VC induce synergy effects of microstructure alignment with PSS removal and dedoping of PEDOT, leading to simultaneous enhancement of the electrical conductivity (>400 S cm^-1) and the Seebeck coefficient (>30 μV K^-1) and a resultant high thermoelectric power factor of 51.8 μW m^-1 K^-2. In addition, inspired by the eco-friendly fabrication process, we further demonstrated a transient OTE device, which can be fully degraded with naturally occurring substances, by fabricating it on a bio-based cellulose acetate substrate. We believe that our eco-friendly strategies from fabrication to disposal of the OTE can be applied to the development of high-performance, wearable, and bio-compatible OTE devices with minimal waste and further trigger the research on genuinely green thermal energy harvesting.

Facile fabrication of flexible AuNPs@CDA SERS substrate for enrichment and detection of thiram pesticide in water

Pesticide residues in water is one of the most serious problems in developing countries. Surface enhanced Raman spectroscopy (SERS) is widely used in the detection and monitoring of pesticide and other trace compounds because of its low limits of detection (LODs). However, different SERS substrate synthesis methods have different economic benefits and environmental impacts. In this paper, a flexible AuNPs@CDA SERS substrate was fabricated by the gold nanoparticles (AuNPs) and the biomass-based cellulose diacetate (CDA), which had stable test performance and considerable LODs. The substrates were economically viable and environment friendly. The characterization analysis of the substrate allows us to flexibly select different test methods (drop-test or enrichment-test) as coping strategy in different situation. The results showed that the LODs of thiram pesticide in water by enrichment-test could reach 10^-7 g/mL, and had a good linear relationship in the concentration range of 10^-7-10^-6 g/mL. This strategy can realize the rapid and effective detection and monitoring of thiram pesticide in water.

Cellulose-Acetate-Based Films Modified with Ag2O and ZnS as Nanocomposites for Highly Controlling Biological Behavior for Wound Healing Applications

For wound healing, functional films with certain physicochemical and biological properties are needed. Thus, the current work aimed to fabricate multifunctional materials comprising metal oxide nanoparticles loaded with an efficient polymer to be used as dressing material. A composite containing polymeric phases of cellulose acetate (CA) blended with zinc sulfide (ZnS), silver oxide (Ag₂O), and graphene oxide (GO) was successfully synthesized. The prepared composite crystallinity was studied using the X-ray diffraction technique (XRD). Further, the functional groups and the elemental analysis were investigated using Fourier-transform infrared spectroscopy (FTIR) and energy-dispersive X-ray spectroscopy (EDX). Furthermore, the surface morphology was studied using scanning electron microscopy (SEM) to obtain the shape and size of particles. SEM showed that the particles were formed in wide distribution in the range of 18-915 nm with an average size of 235 nm for Ag₂O/ZnS/GO/CA. The particle size of Ag₂O in the CA film was in the range between 19 and 648 nm with an average size of 216 nm, while the particle size of ZnS in CA was in the range of 12-991 nm with an average age particle size of 158 mm. In addition, EDX, based on SEM investigation, detected high carbon and oxygen quantities at around 94.21% of the composite. The contact angle decreased and reached 26.28° ± 2.12° in Ag₂O/ZnS/CA. Furthermore, thermogravimetric analysis (TGA) was used to investigate the thermal stability, and the composition was thermally stable until 300 °C. Moreover, the cell viability of "normal lung cells" reached 102.66% in vitro at a concentration of 1250 µg/mL. The antibacterial activity of Ag₂O/ZnS/GO/CA was also detected against E. coli with a zone of inhibition reaching 17.7 ± 0.5 mm. Therefore, the composite can be used in biomedical applications due to its biocompatibility and antibacterial activity.

Remediation of Water Using a Nanofabricated Cellulose Membrane Embedded with Silver Nanoparticles

The removal of pesticide pollution is imperative, because of their high environmental load and persistence, and their potential for bioaccumulation in, and toxicity to the environment. Most pesticides are found to be toxic even at trace levels. AgNPs can be effectively used for the adsorption of pesticides, and the incorporation of the AgNPs onto a support polymeric membrane enhances their effectiveness and reduces the potential unwanted consequences of intentionally adding free nanoparticles to the environment. Here, silver nanoparticles (AgNPs) were synthesized using a reliable, eco-friendly, and one-step "green" method, by reacting Mentha Piperita (mint) extract with AgNO₃ aqueous solution at 60 °C in a microwave. The resulting high surface area nanoparticles are both economic and effective environmental remediation agents, playing a promising role in the elimination of aquatic pesticide pollution. Embedding the nanoparticles into a cellulose membrane at a low concentration (0.1 g) of AgNPs was shown to result in effectively adsorption of representative pesticides (Cypermethrin, Paraquat, and Cartap) within 60 min, while increasing the concentration of nanoparticles incorporated into the membrane further enhanced the removal of the exemplar pesticides from water. The high adsorption capacity makes the cellulose-AgNPs membrane an excellent substrate for the remediation of pesticide-polluted water.

Functional analysis of the N-terminal region of acetylxylan esterase from Caldanaerobacter subterraneus subsp. tengcongensis

Acetylxylan esterase from Caldanaerobacter subterraneus subsp. tengcongensis (TTE0866) has an N-terminal region (NTR; residues 23-135) between the signal sequence (residues 1-22) and the catalytic domain (residues 136-324), which is of unknown function. Our previous study revealed the crystal structure of the wild-type (WT) enzyme containing the NTR and the catalytic domain. Although the structure of the catalytic domain was successfully determined, that of the NTR was undetermined, as its electron density was unclear. In this study, we investigated the role of the NTR through functional and structural analyses of NTR truncation mutants. Based on sequence and secondary structure analyses, NTR was confirmed to be an intrinsically disordered region. The truncation of NTR significantly decreased the solubility of the proteins at low salt concentrations compared with that of the WT. The NTR-truncated mutant easily crystallized in a conventional buffer solution. The crystal exhibited crystallographic properties comparable with those of the WT crystals suitable for structural determination. These results suggest that NTR plays a role in maintaining the solubility and inhibiting the crystallization of the catalytic domain.

Effects of cellulose-based bio-plastics on the aerobic biological stabilization treatment of mixed municipal solid waste: A lab-scale assessment

The aim of this work is to assess how the presence of cellulose-based bio-plastics influence the biological stabilization of mixed Municipal Solid Waste (MSW). For the scope, two cellulose acetate bio-plastics have been mixed with a synthetic mixed waste to create samples with and without bio-plastics. A self-induced biostabilization has been carried out for 7 and 14 days where temperature and off-gas have been monitored continuously. Results about temperature evolution, O₂ consumption, CO₂ production and respiratory quotient did not show a substantial difference regarding both the duration of the process and the presence of cellulose-based bio-plastics on the mixture. On the average, the temperature peak and the maximum daily O₂ consumption and CO₂ production were 52.2 °C, 35.81 g O₂/kg DM *d and 48.95 g CO₂/kg DM *d respectively. Disintegration of bio-plastics samples after 7 and 14 days were comparable (on the average 23.13%). The self-induced biostabilization gave its main contribution after 4 days and resulted almost finished at the end of the day 7 of the process. Results showed that cellulose-based bio-plastics did not give a negative effect on mixed MSW biological stabilization and suggest a possible management, aiming at energy recovery of the outputs.

Levels of microplastics and their characteristics in molluscs from North-West Mediterranean Sea: Human intake

Microplastics (MPs) are accessible for organisms with active filter feeding strategies, as are many marine molluscs, which live attached or semi-buried in sediments. In the present study, MPs (from 0.02 to 5 mm) concentration, morphology, and composition were determined in consumed mollusc species of the Catalan coast (NW Mediterranean Sea). Microplastic concentrations, morphologic characteristics and composition were studied according to species, catchment zones and depuration condition. Finally, human intake of MPs through molluscs' consumption was determined. >2300 individuals were analysed, being 1460 MPs extracted and their size, and polymeric composition registered. Big oysters and mussels showed the highest MPs concentration by individual, with levels of 22.8 ± 14.4 and 18.6 ± 23.0 MPs/individual, respectively. Mean annual MPs (≥20 μm) consumption for adult population was estimated in 8103 MPs/year, with a 95th percentile of 19,418 MPs/year. It suggests that the consumption of molluscs is an important route of MPs exposure for the Catalan population.

Highly regioselective surface acetylation of cellulose and shaped cellulose constructs in the gas-phase

Gas-phase acylation is an attractive and sustainable method for modifying the surface properties of cellulosics. However, little is known concerning the regioselectivity of the chemistry, i.e., which cellulose hydroxyls are preferentially acylated and if acylation can be restricted to the surface, preserving crystallinities/morphologies. Consequently, we reexplore simple gas-phase acetylation of modern-day cellulosic building blocks - cellulose nanocrystals, pulps, dry-jet wet spun (regenerated cellulose) fibres and a nanocellulose-based aerogel. Using advanced analytics, we show that the gas-phase acetylation is highly regioselective for the C6-OH, a finding also supported by DFT-based transition-state modelling on a crystalloid surface. This contrasts with acid- and base-catalysed liquid-phase acetylation methods, highlighting that gas-phase chemistry is much more controllable, yet with similar kinetics, to the uncatalyzed liquid-phase reactions. Furthermore, this method preserves both the native (or regenerated) crystalline structure of the cellulose and the supramolecular morphology of even delicate cellulosic constructs (nanocellulose aerogel exhibiting chiral cholesteric liquid crystalline phases). Due to the soft nature of this chemistry and an ability to finely control the kinetics, yielding highly regioselective low degree of substitution products, we are convinced this method will facilitate the rapid adoption of precisely tailored and biodegradable cellulosic materials.

Attitudes, Beliefs, and Behaviors about Cigarette-Butt Littering among College-Aged Adults in the United States

This study reports attitudes, beliefs, and littering behaviors of 7532 college-aged cigarette smokers from across the United States. Four behavioral variables were measured: littering of last cigarette butt, number of butts littered in past 24 h, littering in past month, and ever having littered. Questions about beliefs centered on whether cigarette butts are biodegradable, if butts were harmful to the environment, and if butts are considered to be litter. One attitudinal question focused on whether seeing butts on the ground was bothersome. Littering was most likely among people who believed butts were biodegradable, believed they are not harmful to the environment, do not believe butts are litter, and among those with the attitude that littered butts are not bothersome. Logistic regression analyses found that the strongest influence on littering behavior was the attitude that seeing butts was bothersome. The second-strongest driver was the belief that butts are litter.

Degradation of Cellulose Derivatives in Laboratory, Man-Made, and Natural Environments

Biodegradable polymers complement recyclable materials in battling plastic waste because some products are difficult to recycle and some will end up in the environment either because of their application or due to wear of the products. Natural biopolymers, such as cellulose, are inherently biodegradable, but chemical modification typically required for the obtainment of thermoplastic properties, solubility, or other desired material properties can hinder or even prevent the biodegradation process. This Review summarizes current knowledge on the degradation of common cellulose derivatives in different laboratory, natural, and man-made environments. Depending on the environment, the degradation can be solely biodegradation or a combination of several processes, such as chemical and enzymatic hydrolysis, photodegradation, and oxidation. It is clear that the type of modification and especially the degree of substitution are important factors controlling the degradation process of cellulose derivatives in combination with the degradation environment. The big variation of conditions in different environments is also briefly considered as well as the importance of the proper testing environment, characterization of the degradation process, and confirmation of biodegradability. To ensure full sustainability of the new cellulose derivatives under development, the expected end-of-life scenario, whether material recycling or "biological" recycling, should be included as an important design parameter.

Closing the Carbon Loop in the Circular Plastics Economy

Today, plastics are ubiquitous in everyday life, problem solvers of modern technologies, and crucial for sustainable development. Yet the surge in global demand for plastics of the growing world population has triggered a tidal wave of plastic debris in the environment. Moving from a linear to a zero-waste and carbon-neutral circular plastic economy is vital for the future of the planet. Taming the plastic waste flood requires closing the carbon loop through plastic reuse, mechanical and molecular recycling, carbon capture, and use of the greenhouse gas carbon dioxide. In the quest for eco-friendly products, plastics do not need to be reinvented but tuned for reuse and recycling. Their full potential must be exploited regarding energy, resource, and eco efficiency, waste prevention, circular economy, climate change mitigation, and lowering environmental pollution. Biodegradation holds promise for composting and bio-feedstock recovery, but it is neither the Holy Grail of circular plastics economy nor a panacea for plastic littering. As an alternative to mechanical downcycling, molecular recycling enables both closed-loop recovery of virgin plastics and open-loop valorization, producing hydrogen, fuels, refinery feeds, lubricants, chemicals, and carbonaceous materials. Closing the carbon loop does not create a Perpetuum Mobile and requires renewable energy to achieve sustainability. This article is protected by copyright. All rights reserved.

The influence of bio-plastics for food packaging on combined anaerobic digestion and composting treatment of organic municipal waste

The use of bio-plastic-based packaging as an alternative to conventional plastic packaging is increasing. Among the plethora of different bio-based plastics, the most relevant ones are those that, at the end of their life, can be treated with the organic fraction of municipal solid waste. Even in these cases, their impact on the waste processing and recycling is not always positive. This study aim to assess on a laboratory scale the influence on combined anaerobic digestion and composting industrial processes of a bio-based plastic film, namely cellulose acetate (CA), in pure and modified (additions of additive) forms. CA films were mixed with organic waste and subjected to: (i) anaerobic digestion; (ii) active composting and (iii) two stages of curing composting. Anaerobic digestion and composting were monitored through methane yield and oxygen uptake respectively; additionally, the bio-plastics degree of disintegration was assessed during all the processes. The final disintegration of pure and modified CA was 73.82% and 54.66%, respectively. Anaerobic digestion contributes to the disintegration of the material, while aerobic treatment appears to be nearly ineffective, especially for modified CA. The presence of cellulose acetate during anaerobic digestion of food waste increased the methane yield by about 4.5%. Bioassay confirmed the absence of possible toxic effects on the final compost from the bio-plastic treatment. Although bio-based materials are not the only solution to plastic pollution, the findings confirm the need to upgrade the organic waste treatment plants and the necessity to revise the requirements for the use of compost in agriculture.

Cellulose acetate in fabrication of polymeric membranes: A review

Developing biodegradable polymers to fabricate filtration membranes is one of the main challenges of membrane science and technology. Cellulose acetate (CA) membranes, due to their excellent film-forming property, high chemical and mechanical stability, high hydrophilicity, eco-friendly, and suitable cost, are extensively used in water and wastewater treatment, gas separation, and energy generation purposes. The CA is one of the first materials used to fabricate filtration membranes. However, in the last decade, the possibility of modification of CA to improve permeability and stability has attracted the researcher's attention again. This review is focused on the properties of cellulose derivatives and especially CA membranes in the fabrication of polymeric separation membranes in various applications such as filtration, gas separation, adsorption, and ion exchange membranes. Firstly, a brief introduction of CA properties and used molecular weights in the fabrication of membranes will be presented. After that, different configurations of CA membranes will be outlined, and the performance of CA membranes in several applications and configurations as the main polymer and as an additive in the fabrication of other polymer-based membranes will be discussed.

High-Sensitivity Metal Oxide Sensors Duplex for On-the-Field Detection of Acetic Acid Arising from the Degradation of Cellulose Acetate-Based Cinematographic and Photographic Films

In this work, a system consisting of two resistive sensors working in tandem to detect and quantify the acetic acid released during the degradation of cellulose acetate-based ancient cinematographic and photographic films is presented. Acetic acid must be constantly monitored to prevent reaching concentrations at which autocatalytic degradation processes begin. The sensors are constituted by a thin layer of metal oxide (tungsten oxide and tin oxide) deposited over an interdigitated electrode capable of being heated, chosen to maximize the array response towards acetic acid vapors. The signals obtained from the sensor array are mathematically processed to reduce the background signal due to interferent gases produced during degradation of ancient cinematographic films. The sensor array reported a LOD of 30 ppb for acetic acid, with a linearity range up to 30 ppm. Finally, the sensor array was tested with different cinematographic and photographic film samples made of cellulose acetate, whose degradation state and acetic acid production was validated using the conventional technique (A-D strips). The presented array is suitable for remote monitoring large number of films in collections since, compared to the official technique, it has a lower detection limit (30 ppb vs. 500 ppb) and is much quicker in providing accurate acetic acid concentration in the film boxes (15 min vs. 24 h).