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With a growing population of about 7.8 billion, humans are generating tons of waste in the form of non-biodegradable plastics on a daily basis that ends up in landfills and oceans. The introduction of packaging has been a blessing to mankind by facilitating the ease of convenience in transportation, delivery and general usage. The downside, however, is that majority of the packaging currently available is harmful to the environment and takes thousands of years to decay. This paper discusses the use of chitosan from shrimp shells and other marine animals' exoskeleton waste in food packaging industries. Chitosan extracted from marine organisms is modulated in the form of packaging material. Compared to conventional packaging, chitosan films are 73.4% biodegradable in soil under laboratory conditions whereas 100% degraded in an open field. Chitosan with metal oxides, essential oils, natural extracts, proteins and other polymers show enhanced tensile strength, water vapor permeability, oxygen and ultraviolet barrier. Chitosan and composite film show antimicrobial activity against gram positive and negative bacteria. Comparative approaches on environmental impacts between conventional plastics and chitosan films are enlightened, thereby highlighting the importance of natural polymers as packaging films that are considered economic based on the addition of additives. [ABSTRACT FROM AUTHOR]

The exploitation of exciting features of plastics for diverse applications has resulted in significant plastic waste generation, which negatively impacts environmental compartments, metabolic processes, and the well-being of aquatic ecosystems biota. A shotgun metagenomic approach was deployed to investigate the microbial consortia, degradation pathways, and enzyme systems involved in the degradation of plastics in a tropical lentic pond sediment (APS). Functional annotation of the APS proteome (ORFs) using the PlasticDB database revealed annotation of 1015 proteins of enzymes such as depolymerase, esterase, lipase, hydrolase, nitrobenzylesterase, chitinase, carboxylesterase, polyesterase, oxidoreductase, polyamidase, PETase, MHETase, laccase, alkane monooxygenase, among others involved in the depolymerization of the plastic polymers. It also revealed that polyethylene glycol (PEG), polyhydroxyalkanoates (PHA), polyhydroxybutyrate (PHB), polylactic acid (PLA), polybutylene adipate terephthalate (PBAT), polyethylene terephthalate (PET), and nylon have the highest number of annotated enzymes. Further annotation using the KEGG GhostKOALA revealed that except for terephthalate, all the other degradation products of the plastic polymers depolymerization such as glyoxylate, adipate, succinate, 1,4-butanediol, ethylene glycol, lactate, and acetaldehyde were further metabolized to intermediates of the tricarboxylic acid cycle. Taxonomic characterization of the annotated proteins using the AAI Profiler and BLASTP revealed that Pseudomonadota members dominate most plastic types, followed by Actinomycetota and Acidobacteriota. The study reveals novel plastic degraders from diverse phyla hitherto not reported to be involved in plastic degradation. This suggests that plastic pollution in aquatic environments is prevalent with well-adapted degrading communities and could be the silver lining in mitigating the impacts of plastic pollution in aquatic environments. [ABSTRACT FROM AUTHOR]

Microplastics are micrometre-sized emerging pollutants produced by plastic fragmentation. They have been recently detected in most ecosystems, even in remote areas. Here, we review microplastics with emphasis on sources, occurrence, transport, detection methods, policies, toxicity, and management methods. In the transport section, we discuss sorption kinetics, layered microplastics, and influencing factors such as biofilm formation. Microplastic management can be done by adsorption, filtration, oxidation, and biodegradation. Microplastic interaction is influenced by temperature, pH, salinity, and dissolved organic matter. [ABSTRACT FROM AUTHOR]

Plastic pollution is becoming a major health issue due to the recent discovery of microplastics and nanoplastics in living organisms and the environment, calling for advanced technologies to remove plastic waste. Here we review enzymes that degrade plastics with focus on plastic properties, protein engineering and polymers such as poly(ethylene terephthalate), poly(butylene adipate-co-terephthalate), poly(lactic acid), polyamide and polyurethane. The mechanism of action of natural and engineered enzymes has been probed by experimental and computation approaches. The performance of polyester-degrading enzymes has been improved via directed evolution, structure-guided rational design and machine learning-aided strategies. The improved enzymes display higher stability at elevated temperatures, and tailored substrate-binding sites. [ABSTRACT FROM AUTHOR]

The global plastic production has steadily increased from 1.7 million tons in 1950 to over 400 million tons in 2022, with about 60% of plastic ultimately ending up in landfills and oceans. There is also growing evidence that microplastics exert negative effects on biota and ecosystems. Biodegradable plastics may represent a safe alternative, yet their potential adverse effects have not been comprehensively analyzed. Here, we reviewed biodegradable plastics, with focus on their conversion into microplastics, their interactions with pollutants, and their combined toxicity for aquatic biota. Biodegradable plastics include polylactic acid, polyhydroxyalkanoates, polybutylene succinate, poly(butylene adipate-co-terephthalate), and poly(ε-caprolactone). We found that some biobased plastics are hardly biodegradable. Some biobased plastics are compostable but require specific environmental conditions for their biodegradation. Biobased plastics can generate microplastics when released into the environment, which can impact biota. Contrary to the common public belief, biodegradable plastics may not only originate from biosources but can be synthesized from fossil fuels. Microplastics originating from biodegradable plastics can interact with pollutants, adsorbing and transporting these pollutants, resulting in synergistic or antagonistic effects on exposed organisms. Biofilm formation on microplastics impacts their degradation and pollutant interactions. [ABSTRACT FROM AUTHOR]

To improve the shortcomings of poly (3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV), such as brittleness, large grain size and high crystallinity, a kind of bio-based engineering polyester elastomer (BEPE) was incorporated into PHBV by melting blending method with benzoyl peroxide (BPO) as the initiator. With the addition of BPO, the interfacial adhesion between PHBV and BEPE was improved, and BPO hindered the crystallization and reduced the crystallinity of PHBV/BEPE blends. At the same time, the gel content, the dynamic complex viscosity and dynamic elastic modulus of blends were increased significantly in low-frequency region with 0.7-phr BPO. Compared to that of neat PHBV, the elongation at break and impact strength of PHBV/BEPE/BPO (0.7 phr) blends were increased by 373.6 and 158.7%, respectively. Compared to that of PHBV/BEPE blends, the elongation at break and impact strength of the PHBV/BEPE/BPO (0.7 phr) blends were increased by 44.3 and 122.7%, respectively. The above phenomena were resulted from the formation of chemical micro-crosslinking between PHBV and BEPE. The main mechanism can be explained, PHBV and BEPE polymer radicals were generated by BPO initiator, and then, PHBV and BEPE polymer radicals recombined to form carbon–carbon crosslinking. [ABSTRACT FROM AUTHOR]

The article describes a green and efficient synthesis method for pyrano[2,3-c]-pyrazoles, employing DL-alpha-tocopherol methoxypolyethylene glycol succinate solution (TPGS-750-M) as a green and biodegradable surfactant in water. The utilization of water as a reaction medium and TPGS-750-M as a surfactant obviates the necessity for organic solvents, thereby enhancing the environmental sustainability of the synthesis. The compounds synthesized using this novel method was characterized using various spectroscopic techniques, including 1H-NMR, 13C-NMR, and mass spectrometry. [ABSTRACT FROM AUTHOR]

The advancement of sustainable packaging technologies is crucial for environmental conservation and enhancing food shelf life. We advance sustainable packaging by developing cassava starch sheets functionalized with silver nanoparticles (AgNPs) via plasma-deposited 2-methyl-2-oxazoline thin film. This innovative method requires less precursors and generates no liquid waste, presenting a significant leap in eco-friendly packaging solutions. Uniquely, it deviates from traditional nanoparticle incorporation methods by emphasising surface functionalization over bulk integration, leveraging plasma polymerization for environmentally friendly and efficient AgNP immobilisation. This surface-centric approach offers distinct advantages in active packaging by enhancing the initial antimicrobial interaction at the packaging's surface. Surface morphology, characterised by SEM–EDX, and chemical composition, verified by XPS, indicated successful AgNP immobilisation after 5 and 25 h, albeit with some aggregation at prolonged immobilisation time. UV–Vis spectroscopy results confirmed the successful immobilisation of AgNPs and suggested enhanced light barrier properties of the treated sheets. AFM measurements revealed alterations in surface roughness post-treatment, correlating with changes in hydrophilicity and potentially impacting the moisture barrier properties of the packaging. The treated bioplastics showed improved mechanical properties, indicated by tensile strength and elongation at break. Antimicrobial testing revealed substantial efficacy against Gram-positive and Gram-negative bacteria, but not against fungi. All bioplastic samples demonstrated non-toxicity to fibroblast cells, irrespective of the treatments applied. This work paves the way for future developments targeted at improving the efficacy and scalability of plasma-nanoengineered bioplastics. [ABSTRACT FROM AUTHOR]

Detecting, separating, and characterizing airborne microplastics from other airborne particulates is currently challenging due to the various instrumental constraints and related sample preparation hurdles that must be overcome. The ability to measure these real-world environments is needed to better assess the risks associated with microplastics. To that end, the current study focused on developing a methodology for sampling and characterizing airborne microplastics. Particulate sampling was carried out at a municipal materials recovery facility near a conveyer belt containing sorted plastic materials to collect airborne environmental particles on filters. Nucleopore filters were mounted on Teflon support rings, coated with 100 nm aluminum to reduce the background signal for micro-Raman spectroscopy, and marked with a fiducial pattern using a laser engraver. The fiducial pattern was crucial in identifying samples, relocating particles, and efficiently enabling orthogonal measurements on the same samples. Optimum sampling conditions of 2 h at 25 L/min were determined using light microscopy to evaluate the particle loadings. The filters were then cut into slices which were attached to sections of thin beryllium-copper sheeting for easy transfer of the filter between microscopy platforms. Scanning electron microscopy was used to identify carbon-rich particles. Light microscopy was used to identify colored particles which were also carbon-rich which were then analyzed using micro-Raman spectroscopy to identify specific polymers. [ABSTRACT FROM AUTHOR]

Microbeads find widespread usage in personal care items and cosmetics, serving as exfoliants or scrubbing agents. Their micro-scale size poses challenges in effective drainage capture and given their origin from non-biodegradable oil-based plastics, this contributes substantially to marine pollution. In this study, microbeads were prepared by a simple yet scalable melt homogenization method using four types of polyhydroxyalkanoates (PHA), namely poly[(R)-3-hydroxybutyrate] (P(3HB)), poly[(R)-3-hydroxybutyrate-co-(R)-3-hydroxyvalerate] (P(3HB-co-3HV)), poly[(R)-3-hydroxybutyrate-co-(R)-3-hydroxyhexanoate] (P(3HB-co-3HHx)) and poly[(R)-3-hydroxybutyrate-co-(R)-4-hydroxyvalerate] (P(3HB-co-4HB)). Microbeads with different surface smoothness, compressive strength (6.2–13.3 MPa) and diameter (from 1 ~ 150 μm) could be produced. The microbeads were subjected to a comprehensive degradation analysis using three techniques: enzymatic, Biochemical Oxygen Demand (BOD) evaluations, and in situ degradation tests in the deep-sea off Misaki Port in the northern Pacific Ocean (depth of 757 m). Qualitatively, results from enzymatic and in situ degradation demonstrated significant degradation within one week and five months, respectively. Quantitatively, BOD findings indicated that all PHA microbeads degraded similarly to cellulose (~ 85% biodegradability in 25 days). In conclusion, PHA microbeads from this study exhibit promising potential as alternatives to conventional non-biodegradable microbeads. [ABSTRACT FROM AUTHOR]

In light of increasing apprehensions surrounding the environmental impact of non-biodegradable plastics, there has been a surge in the exploration of biodegradable films as a viable and sustainable alternative. This research has focused on developing Tara gum (TG)-based films incorporated with Lavender essential oil (LEO) at different concentrations (5–20% w/w) to improve the properties of the films. According to the results, GC-MS analysis confirmed the presence of linalool and linalyl acetate as the major compounds in LEO. Among the composite films, the sample containing 5% (w/w) LEO exhibited the highest homogeneity, as evidenced by SEM micrographs, and the CLSM image demonstrated the absence of any clustering or coalescence of LEO within this film. FTIR spectra demonstrated intermolecular interactions between TG and LEO, as evidenced by a new peak at 1458 cm−1 in the LEO-loaded films. The addition of LEO resulted in a significant decrease in the water content (WC) and water solubility (WS) of the films. Furthermore, LEO incorporation improved the contact angle (CA) of the films up to 1.5 times. The TG-LEO films exhibited good transparency, higher elongation at break (EB), and lower Young's modulus (YM). Additionally, LEO positively affected the antioxidant and antimicrobial properties of the films. Overall, the results authenticated the hypothesis of this study and indicated that TG-LEO films have great potential as biodegradable films with promising functionalities for food packaging applications. [ABSTRACT FROM AUTHOR]

The root cause of global pollution is the reflection of usage of non-degradable plastics. The solutions and methods to mitigate the plastic pollution are in high demand. The application of green technology in polymer science from the marine resource gives stability to the ecosystem. The bio-composite films were fabricated using gelatin of fish scale, agar of seaweed and chitosan of shrimp shell waste by a solvent casting technique. The plasticity and bioactivity enhanced using glycerol and clove essential oil. The physic-chemical and mechanical properties of the film were evaluated against the range of test of thickness, tensile strength, elongation at break, puncture resistance, water vapor permeability, Attenuated Total Reflection—Fourier Transform Infrared spectroscopy, X-ray diffraction and atomic force microscopy. The characteristics of active packaging mechanism assessed based on antimicrobial and antioxidative properties. A level of 1.5% clove essential oil ration was given desirable properties of active packaging material. The biodegradability was calculated in terms of percentage weight loss under the soil burial and water immersion test. The biodegradation process of composite film took 21 days in soil and 158 in water. Hence, the bio-composite film prepared from green technology is a promising alternative to the conventional plastic to mitigate plastic pollution. [ABSTRACT FROM AUTHOR]

Functional antibacterial textile materials are in great demand in the medical sector. In this paper, we propose a facile, eco-friendly approach to the design of antibacterial biodegradable cotton fabrics. Cotton fiber fabrics were enhanced with a chitosan coating loaded with plant extracts and essential oils. We employed Fourier-transform infrared (FTIR) and X-ray photoelectron spectroscopy (XPS), UV–Vis spectrophotometry, optical microscopy, scanning electron microscopy (SEM), and thermogravimetric analysis (TGA) to characterize the color, structure, and thermal properties of the modified fabrics. The fabrics were found to effectively induce growth inhibition of Gram-positive and Gram-negative bacteria, especially when a synergic system of aloe vera extract and cinnamon essential oil was applied in the coating formulation. Additionally, we observed significant color and weight changes after 5, 10, and 20 days in soil biodegradability tests. Given the straightforward modification process and the use of non-toxic natural materials, these innovative bio-based and biodegradable cotton fabrics show great promise as protective antimicrobial textiles for healthcare applications. [ABSTRACT FROM AUTHOR]

Plastic accumulation is a severe threat to the environment due to its resistivity to thermal, mechanical and biological processes. In recent years, microbial degradation of plastic waste disposal is of interest because of its eco-friendly nature. In this study, a total of 33 fungi were isolated from the plastisphere and out of which 28 fungal species showed halo zone of clearance in agarized LDPE media. The fungus showing highest zone of clearance was further used to evaluate its degradation potential. Based on morphological and molecular technique, the fungus was identified as Cladosporium sphaerospermum. The biodegradation of LDPE by C. sphaerospermum was evaluated by various methods. The exposure of LDPE with C. sphaerospermum resulted in weight loss (15.23%) in seven days, higher reduction rate (0.0224/day) and lower half-life (30.93 days). FTIR analysis showed changes in functional group and increased carbonyl index in LDPE treated with C. sphaerospermum. SEMimages evidenced the formation of pits, surface aberrations and grooves on the LDPE film treated with the fungus whereas the untreated control LDPE film showed no change. AFM analysis confirmed the surface changes and roughness in fungus treated LDPE film. This might be due to the extracellular lignolytic enzymes secreted by C. sphaerospermum grown on LDPE. The degradation of polyethylene by Short chain alkanes such as dodecane, hexasiloxane and silane were identified in the extract of fungus incubated with LDPE film through GC–MS analysis which might be due to the degradation of LDPE film by C. sphaerospermum. This was the first report on the LDPE degradation by C. sphaerospermum in very short duration which enables green scavenging of plastic wastes. [ABSTRACT FROM AUTHOR]

Cellulose is the most attractive renewable natural polymer, carrying off a 211 billion USD market size that entered the plastic world for industrial application. However, the extraction of cellulose forms (micro/nano) in an economical manner is still challenging for researchers who have been trying different cellulose-based sources and methods. Henceforth, the present study focused on extracting cellulose microfibers (CMFs) from agro biomass to mitigate the cost of satisfying industrial demands. The waste fallen dried leaves were used to extract micro cellulose through alkaline peroxide treatment and studied the essential characteristics like morphology, spectral and crystallinity, and CMFs having 45.8 µm size with rough morphology and the spectral peak of 3339 cm−1, and 2890 cm−1 corresponding to hydrogen bond O–H, and C–H of cellulose respectively. Further, the various % (5–15) of CMFs were reinforced to polyvinyl alcohol (PVA) to prepare CMFs/PVA composites through the solution casting method. The experimental results showed that the composites having chemical interaction bond at 3260 cm−1 and 2θ = 19.6◦ diffraction peak. The optimized % of CMFs showing tensile strength 80.37 MPa and 2.51 GPa and decreased 9.37% elongation at break. CMFs loading significantly enhanced biodegradation by about 21.44%. This improvement in biodegradation highlights the potential environmental benefits of utilizing CMFs in plastic film production. In conclusion, this study provides the idea of economically obtaining micro cellulose and designing biodegradable plastic for packaging application. [ABSTRACT FROM AUTHOR]

There are several physical and chemical methods for synthesizing nanomaterials, while the most appropriate techniques involve using green chemistry and eco-friendly material. Recently, green synthesized materials for different applications have gained attention as a result of their environmental friendliness and cost-effectiveness. Applying green synthesized nanoparticles (NPS) in food packaging has been extensively investigated. Biopolymers require filler to enhance the optical, barrier, thermal, antimicrobial, and mechanical properties of packaging. Biopolymer packaging incorporated with green synthesized NPs is expected to simultaneously enhance performance while reducing environmental damage. The current review article focuses on biopolymer films with bio (green)-synthesized nanomaterials and their effectiveness in reducing the negative environmental implications of synthetic packaging. It also covers the general concepts of green synthesis of NPs, their production methods, their performance, and characterization, and discusses the potential, performance and recent developments of bio-nanocomposite films/coatings in biodegradable food packaging. Recent reports and trends provide more insight into the impact of green synthesized nanomaterials on food packaging. [ABSTRACT FROM AUTHOR]

Polyethylene terephthalate (PET), the most abundantly produced polyester plastic, can be depolymerized by the Ideonella sakaiensis PETase enzyme. Based on multiple PETase crystal structures, the reaction has been proposed to proceed via a two-step serine hydrolase mechanism mediated by a serine-histidine-aspartate catalytic triad. To elucidate the multi-step PETase catalytic mechanism, we use transition path sampling and likelihood maximization to identify optimal reaction coordinates for the PETase enzyme. We predict that deacylation is likely rate-limiting, and the reaction coordinates for both steps include elements describing nucleophilic attack, ester bond cleavage, and the "moving-histidine" mechanism. We find that the flexibility of Trp185 promotes the reaction, providing an explanation for decreased activity observed in mutations that restrict Trp185 motion. Overall, this study uses unbiased computational approaches to reveal the detailed reaction mechanism necessary for further engineering of an important class of enzymes for plastics bioconversion. Polyethylene terephthalate (PET) can be depolymerized by the Ideonella sakaiensis PETase enzyme, however, questions remain about the precise catalytic mechanism. Here, the authors use unbiased QM/MM MD simulations to determine optimal mechanistic descriptions of the acylation and deacylation reactions, revealing the rate-limiting step and key interactions within the catalytic triad and Trp185 conformation. [ABSTRACT FROM AUTHOR]

The current growing environmental awareness has forced the use of biodegradable plasticizers, which are sustainable and abundant in plant resources. Rose petal plasticizers (RPP) act as an actual substitute for chemical plasticizers in this situation as they are biocompatible and biodegradable. Chemical procedures like amination, alkalization, and surface catalysis are used to extract the natural emollients from rose petals. XRD, FT-IR, and UV studies were used to understand the characteristics of the rose petal plasticizer. Based on the XRD data, the RPP's crystallinity size (CS) and crystallinity index (CI) values were determined to be 9.36 nm and 23.87%, respectively. The surface morphology of the isolated plasticizer is investigated using SEM, EDAX analysis and AFM. RPP surface pores with rough surfaces are visible in SEM images, which make them appropriate for plasticizing novel bioplastics with superior mechanical qualities. The plasticizer's heat degradation behaviour is investigated using thermogravimetric and differential thermogram analysis curves. Following the characterization of the synthesised molecules, the plasticization effect was examined using a biodegradable polymer matrix called poly (butylene adipate-co-terephthalate) (PBAT). The reinforcement interface was also examined using scanning electron microscopy analysis. RPP-reinforced films demonstrated greater flexibility and superior surface compatibility at a 5% loading compared to PBAT-only films. Based on a number of reported features, RPP could be a great plasticizer to address future environmental problems. [ABSTRACT FROM AUTHOR]

In the Anthropocene, plastic pollution has become a new environmental biotope, the so-called plastisphere. In the oceans, nano- and micro-sized plastics are omnipresent and found in huge quantities throughout the water column and sediment, and their large surface area-to-volume ratio offers an excellent surface to which hydrophobic chemical pollutants (e.g. petrochemicals and POPs) can readily sorb to. Our understanding of the microbial communities that breakdown plastic-sorbed chemical pollutants, however, remains poor. Here, we investigated the formation of 500 nm and 1000 nm polystyrene (PS) agglomerations in natural seawater from a coastal environment, and we applied DNA-based stable isotope probing (DNA-SIP) with the 500 nm PS sorbed with isotopically-labelled phenanthrene to identify the bacterial members in the seawater community capable of degrading the hydrocarbon. Whilst we observed no significant impact of nanoplastic size on the microbial communities associated with agglomerates that formed in these experiments, these communities were, however, significantly different to those in the surrounding seawater. By DNA-SIP, we identified Arcobacteraceae, Brevundimonas, Comamonas, uncultured Comamonadaceae, Delftia, Sphingomonas and Staphylococcus, as well as the first member of the genera Acidiphilum and Pelomonas to degrade phenanthrene, and of the genera Aquabacterium, Paracoccus and Polymorphobacter to degrade a hydrocarbon. This work provides new information that feeds into our growing understanding on the fate of co-pollutants associated with nano- and microplastics in the ocean. [ABSTRACT FROM AUTHOR]

In the Anthropocene, plastic pollution has become a new environmental biotope, the so-called plastisphere. In the oceans, nano- and micro-sized plastics are omnipresent and found in huge quantities throughout the water column and sediment, and their large surface area-to-volume ratio offers an excellent surface to which hydrophobic chemical pollutants (e.g. petrochemicals and POPs) can readily sorb to. Our understanding of the microbial communities that breakdown plastic-sorbed chemical pollutants, however, remains poor. Here, we investigated the formation of 500 nm and 1000 nm polystyrene (PS) agglomerations in natural seawater from a coastal environment, and we applied DNA-based stable isotope probing (DNA-SIP) with the 500 nm PS sorbed with isotopically-labelled phenanthrene to identify the bacterial members in the seawater community capable of degrading the hydrocarbon. Whilst we observed no significant impact of nanoplastic size on the microbial communities associated with agglomerates that formed in these experiments, these communities were, however, significantly different to those in the surrounding seawater. By DNA-SIP, we identified Arcobacteraceae, Brevundimonas, Comamonas, uncultured Comamonadaceae, Delftia, Sphingomonas and Staphylococcus, as well as the first member of the genera Acidiphilum and Pelomonas to degrade phenanthrene, and of the genera Aquabacterium, Paracoccus and Polymorphobacter to degrade a hydrocarbon. This work provides new information that feeds into our growing understanding on the fate of co-pollutants associated with nano- and microplastics in the ocean. [ABSTRACT FROM AUTHOR]

Fossil fuels are a major source of energy worldwide and serve as raw materials for the production of plastics. However, they have disadvantages such as uneven distribution, price instability, limited availability, and environmental impact. Consequently, there is a need to find alternatives to fossil fuels for both energy and polymer production in the short term. This review focuses on the synthesis of poly(hydroxyalkanoate)s (PHAs), a type of biopolymer, using different bioethanol stream wastes. PHAs exhibit properties comparable to petroleum-based plastics, making them promising replacements. There has been a significant increase in research studies exploring alternatives to fossil fuels and synthetic polymers, as evidenced by the growing number of publications. While biopolymers currently account for only 1% of global polymer production derived from petroleum, the PHA industry is experiencing rapid growth. The market value of PHAs was estimated at $ 168.9 million in 2020, and it is projected to reach $ 440 million by 2031, indicating a compound annual growth rate of 9.2%. The production of this biopolymer is already contributing to an expanding industrial value chain, which is expected to further growth with increased availability of commercial PHAs. [ABSTRACT FROM AUTHOR]

Plastic waste is being manufactured for the production of hydrogen. The amount of plastic waste collected annually is 189,953 tonnes from adjacent nations like Indonesia and Malaysia. Polyethylene (PE), Polypropylene (PP), Polyethylene Terephthalate (PET), Polyvinyl chloride (PVC), and Polystyrene (PS) are the five most prevalent forms of plastic found in most waste. Pyrolysis, water gas shift and steam reforming reaction, and pressure swing adsorption are the three main phases utilized and studied. In this research, authors examines the energy consumption on every stage. The plastic waste can be utilized to manufacture many hydrocarbons using the pyrolysis reaction. For this process, fast pyrolysis is being used at a temperature of 500 °C. A neutralization process is also needed due to the presence of Hydrochloric acid from the pyrolysis reaction, with the addition of sodium hydroxide. This is being carried to prevent any damage to the reactor during the process. Secondly, the steam reforming process continues after the water gas shift reaction has produced steam and carbon monoxide, followed by carbon dioxide and hydrogen formation. Lastly, pressure swing adsorption is designed to extract H2S and CO2 from the water gas shift and steam reforming reaction for greater purity of hydrogen. From the simulation study, it is observed that using various types of plastic waste procured (total input of 20,000 kg per hour of plastics) from, Brunei Darussalam, Malaysia and Indonesia, can produce about 340,000 tons of Hydrogen per year. Additionally, the annual profit of the Hydrogen production is estimated to be between $ 271,158,100 and $ 358,480,200. As per the economic analysis, it can be said that its a good to start hydrogen production plant in these regions. [ABSTRACT FROM AUTHOR]

The pervasive presence of microplastics within river ecosystems has a profound and often underestimated detrimental impact. These minuscule yet persistent particles have infiltrated diverse biological habitats, making their detrimental effects on aquatic life increasingly concerning worldwide. The ability of microplastics to accumulate within aquatic organisms further exacerbates this concern. Consequently, the monitoring of microplastic pollution in surface water environments has emerged as a crucial endeavour, offering invaluable insights into the extent of this ecological threat. This study delved into the contamination levels of microplastics within two bivalve species, Perna viridis and Villorita cyprinoides, along the Chandragiri River in Kerala and Karnataka, South-West India, spanning eight distinct locations. The investigation yielded a significant discovery, with a total of 667 microplastic particles extracted from 288 individuals. On average, each individual bivalve harboured approximately 2.31 ± 0.93 microplastic items. Notably, these microplastic particles exhibited a wide range of morphological characteristics, underscoring their diverse origins and pathways into the ecosystem. Furthermore, five polymer types of microplastics were unequivocally confirmed through FTIR-ATR analysis, shedding light on the types of plastics that pose a threat to the riverine ecosystem. The findings of this study contribute to a growing body of evidence highlighting the global threat of microplastic pollution, urging international collaboration and innovative solutions to prevent further contamination and remediate existing microplastic burdens in aquatic environments. Highlights: • Microplastic contamination is a major concern in river ecosystems. • Microplastic in two bivalve species were characterized at Chandragiri River India. • The microplastics had diverse shapes and were composed of five different polymers. • This study emphasizes the need to tackle river microplastic pollution. [ABSTRACT FROM AUTHOR]

Global growing concern on plastics disposal and their environmental impact has impulsed the development of lower impact biodegradable plastics, however their functional properties and processability are still limited. In this study, thermoplastic starch (TPS) was synthetized through reactive extrusion (REX) to obtain single oxidized thermoplastic (O-TPS) and single maleated thermoplastic (MA-TPS), as well as, dual (oxidized-maleated thermoplastic (O-MA-TPS) modified starches aiming to incorporate new functionalities, diminish the viscosity and improve TPS processability. Spectroscopic analysis showed different band intensities as a result of TPS modification. TPS presented B-type and V-type crystal structures. O-MA-TPS showed the lowest percentage of crystallinity and complex viscosity values compared to single modified TPS because the combination of modifications. The specific mechanical energy decreased with respect to chemical modifications of starch (TPS > O-TPS > MA-TPS > O-MA-TPS), which were associated with the diminishing of viscosity resulting from the modification and starch-glycerol interactions. These starches can be incorporated into mixtures with other plastic polymers, by allowing better mixing (minor viscosity difference) and the replacement of a greater amount of plastic with TPS or in applications where a TPS with lower viscosity and easier processability is required. [ABSTRACT FROM AUTHOR]

Plastic products are an indispensable part of life and are widely used in different fields. However, plastic products have the characteristics of short average service life and not easy to degrade naturally, which are prone to cause serious environmental pollution by long-term accumulation in the environment. The use of low-cost catalysts is the goal pursued by enterprises. In this paper, polypropylene (PP), low-density polyethylene (LDPE), polystyrene (PS), mixed waste plastics (WPs) and spent FCC catalyst (a solid waste produced by oil refining enterprises) were used as research objects to simulate the pyrolysis and catalytic pyrolysis of waste plastics in real life. The results showed that compared with the direct pyrolysis of plastics, the addition of spent FCC catalysts could significantly reduce the initial pyrolysis temperature of PP, LDPE and WPs, with the largest decrease in the initial pyrolysis temperature of PP (about 59 K). The average activation energy of PP, LDPE and WPs decreased with the participation of spent FCC catalyst compared with the direct pyrolysis. Among them, the activation energy of LDPE decreased most significantly (about 22 mass%), followed by PP, and WPs decreased the least. However, the results of thermogravimetric analysis and kinetic calculations showed that the spent FCC catalyst was not suitable for catalytic pyrolysis of PS. The purpose of this experiment is to promote "circular economy". The solid waste products produced by oil refining enterprises are applied to the catalytic pyrolysis of waste plastics, which provides theoretical support and data reference for reducing the energy consumption of plastic pyrolysis and realizing the diversified application of spent FCC catalysts. [ABSTRACT FROM AUTHOR]

Substantial quantities of discarded plastic have resulted in detrimental effects on the environment and ecosystems, calling for effective recycling of plastic wastes. Chemical methods for managing plastic wastes have been extensively studied, and selective recycling of products has grown in popularity. Pyrolysis, photocatalysis, and supercritical fluids were the main chemical methods reported for processing plastics. This article reviews reaction mechanisms and representative studies of pyrolysis, photocatalysis and supercritical fluid disposal of plastics. Three challenges are identified: first, high temperatures, above 400 °C, pose safety risks and potentially release harmful gases. Second, the photocatalytic decomposition of plastics is generally economical and environmentally friendly, however, reaction rates are uncontrollable. Third, the exceptional solubility and mass transfer properties exhibited by supercritical fluids have the potential to significantly augment the decomposition of plastics. Supercritical fluids can also serve as reactants that directly influence the thermal or kinetic mechanisms of the reaction. Whereas individual treatment methods are limited, coupled methods enable efficient plastic management and facilitate the selective acquisition of products. In particular, this review suggests that coupling photocatalysis and supercritical carbon dioxide should allow to dispose of plastics and convert carbon dioxide into valuable resources. [ABSTRACT FROM AUTHOR]

Escalating global population and expanding industrialisation have significantly contributed to an increased demand for plastics. Methods for plastic waste disposal predominantly involve landfilling, which consumes space and pollutes soil and water bodies, posing a substantial threat to the environment and public health. The critical challenge herein lies in efficiently managing the abundant biomass and plastics waste. Here we review gasification and pyrolysis, two prominent waste treatment processes. Co-pyrolysis of plastics and biomass exhibits a synergistic effect, significantly enhancing the yield and quality of bio-oil, biochar, and syngas. Integration of gasification and pyrolysis reduces activation energy, increases hydrogen production during co-gasification, and improves bio-oil calorific value. The gasification of polyethylene terephthalate with air in the presence of activated carbon limits tar formation with enhanced syngas production. Steam gasification enhances hydrogen generation by up to 40.0% compared to air gasification. Selective catalysts in the integrated pyrolysis–gasification process of biomass and plastics mixtures demonstrate optimisation of the production of high-purity carbon nanotubes and bio-oil. Application of innovative approaches such as microwaves, steam purging, and catalysts like zeolite or composite catalysts enhance heat transfer mechanism, tar cracking, and devolatilisation. [ABSTRACT FROM AUTHOR]

This work aims to statistically assess the biocompatibility and the biodegradability of hydrogels which synthesized to different conditions for the wound-dressing applications. The present work also focuses on providing information about the synthesis of chitosan and gelatine by using a cross-linker. Experiments were designed by using Box-Behnken experimental design method. Effects of chitosan amount, gelatin amount and glutaraldehyde amount on biocompatibility and biodegradability of hydrogels have been statistically investigated. This parameters optimized by the response surface methodology in order to maximize responses as swelling, porosity, in vitro degradation and in vitro enzymatic degradation. Structural analysis of hydrogels was performed by FTIR spectroscopy. Analysis of variance was performed to assess statistically significant differences between the parameters on the biocompatibility and the biodegradability of hydrogels by using the Design Expert 13 statistical program. Mathematical model was found for each response variable, and the optimum values of the parameters were determined. The maximum percentage swelling, porosity, in vitro degradation and in vitro enzymatic degradation were obtained 470%, 92%, 83% and 86%, respectively, under conditions that 0.2 g chitosan, 0.8 g gelatin and 0.5 mL cross-linker. The limitations due to the use of glutaraldehyde are related to its high cytotoxicity. 1-(3-Dimethylaminopropyl)-3-ethyl-carbodimide (EDC) does not form toxic aldehydes. Therefore, EDC was used in hydrogel synthesis in our study for comparison against glutaraldehyde. In this optimum conditions, the effect of the molecular weight of chitosan, cross-linker type (glutaraldehyde and EDC) and ambient pH on biocompatibility (swelling, porosity analysis) and biodegradability was determined. In this study, to improve wound healing, it is thought that the results of the statistical evaluation of the effect of the simultaneous changes of the parameters on the properties of the biomaterial in obtaining the optimum condition hydrogels will contribute to biomedical applications. [ABSTRACT FROM AUTHOR]

The presence of plastic and microplastic within the oceans as well as in marine flora and fauna have caused a multitude of problems that have been the topic of numerous investigations for many years. However, their impact on human health remains largely unknown. Such plastic and microplastic particles have been detected in blood and placenta, underlining their ability to enter the human body. Plastics also contain other compounds, such as plasticizers, antioxidants, or dyes, whose impact on human health is currently being studied. Critical enzymes within the metabolism of endogenous molecules, especially of xenobiotics, are the cytochrome P450 monooxygenases (CYPs). Although their importance in maintaining cellular balance has been confirmed, their interactions with plastics and related products are poorly understood. In this study, the possible relationship between different plastic-related compounds and CYP3A4 as one of the most important CYPs was analyzed using hepatic cells overexpressing this enzyme. Beginning with virtual compound screening and molecular docking of more than 1000 plastic-related compounds, several candidates were identified to interact with CYP3A4. In a second step, RNA-sequencing was used to study in detail the transcriptome-wide gene expression levels affected by the selected compounds. Three candidate molecules ((2,2′-methylenebis(6-tert-butyl-4-methylphenol), 1,1-bis(3,5-di-tert-butyl-2-hydroxyphenyl)ethane, and 2,2′-methylenebis(6-cyclohexyl-4-methylphenol)) had an excellent binding affinity to CYP3A4 in-silico as well as cytotoxic effects and interactions with several metabolic pathways in-vitro. We identified common pathways influenced by all three selected plastic-related compounds. In particular, the suppression of pathways related to mitosis and 'DNA-templated DNA replication' which were confirmed by cell cycle analysis and single-cell gel electrophoresis. Furthermore, several mis-regulated metabolic and inflammation-related pathways were identified, suggesting the induction of hepatotoxicity at different levels. These findings imply that these compounds may cause liver problems subsequently affecting the entire organism. [ABSTRACT FROM AUTHOR]

Polyhydroxybutyrate (PHB) is known for wide applications, biocompatibility, and degradability; however, it cannot be commercialized due to conventional recovery using solvents. The present study employed mechanical cell-disruption methods, such as Pestle and mortar, sonication, and glass bead vortexing, for solvent-free extraction of PHA from Bacillus sp. Different time intervals were set for grinding (5, 10, 15 min), sonicating (1, 3 and 5 min), and vortexing (2, 5 and 8 g glass beads with 5, 10 and 15 min each) hence studying their effect on cell lysis to release PHA. Tris buffer containing phenylmethyl sulfonyl fluoride (PMSF) (20 mM Tris–HCl, pH 8.0, 1 mM PMSF) was employed as a lysis buffer to study its action over Bacillus cells. Its presence was checked with the above methods in cell lysis. Sonicating cells for 5 min in the presence of lysis buffer achieved a maximum PHA yield of 45%. Cell lysis using lysis buffer yielded 35% PHA when vortexing with 5 g glass beads for 15 min. Grinding cells for 15 min showed a maximum yield of 34% but lacked a lysis buffer. The overall results indicated that the action of lysis buffer and physical extraction methods improved PHA yield by %. Therefore, the study sought to evaluate the feasibility of applying laboratory methods for cell disruption. These methods can showcase possible opportunities in large-scale applications. The polymer yield results were compared with standard sodium hypochlorite extraction. Confirmation of obtained polymers as polyhydroxy butyrate (PHB) was made through FTIR and 1HNMR characterization. [ABSTRACT FROM AUTHOR]

Research on the plastic contamination of organic fertilizer (compost) has largely concentrated on particles and fragments > 1 mm. Small, submillimeter microplastic particles may be more hazardous to the environment. However, research on their presence in composts has been impeded by the difficulty to univocally identify small plastic particles in such complex matrices. Here a method is proposed for the analysis of particles between 0.01 and 1.0 mm according to number, size, and polymer type in compost. As a first demonstration of its potential, the method is used to determine large and small microplastic in composts from eight municipal compost producing plants: three simple biowaste composters, four plants processing greenery and cuttings and one two-stage biowaste digester-composter. While polyethylene, PE, tends to dominate among fragments > 1 mm, the microplastic fraction contained more polypropylene, PP. Whereas the contamination with PE/PP microplastic was similar over the investigated composts, only composts prepared from biowaste contained microplastic with a signature of biodegradable plastic, namely poly(butylene adipate co-terephthalate), PBAT. Moreover, in these composts PBAT microplastic tended to form the largest fraction. When the bulk of residual PBAT in the composts was analyzed by chloroform extraction, an inverse correlation between the number of particles > 0.01 mm and the total extracted amount was seen, arguing for breakdown into smaller particles, but not necessarily a mass reduction. PBAT oligomers and monomers as possible substrates for subsequent biodegradation were not found. Remaining microplastic will enter the environment with the composts, where its subsequent degradability depends on the local conditions and is to date largely uninvestigated. [ABSTRACT FROM AUTHOR]

The microbial biotransformation using low-cost feedstock to produce biopolymers (degradable), an alternative to petrochemical-based synthesis plastics (non-degradable), can be a beneficial approach towards sustainable development. In this study, the dairy industry processes waste (whey) is used in polyhydroxyalkanoate (PHA) copolymer production. Initial screening suggested that Ralstonia eutropha produced higher PHA as compared to Bacillus megaterium. A central composite rotatable design-based optimization using two process variables (amino acid and tween-80) concentration remarkably influenced PHA co-polymer production under physiological conditions of pH (7), temperature (37 °C), and agitation rate of 150 rpm. High polyhydroxybutyrate (PHB) mass fraction yield of 69.3% was observed as compared to predicted yield of 62.8% from deproteinized whey as feed. The combination of tryptophan (50 mg L−1) and tween-80 (3 mL−1) enhanced R. eutropha mass gain to 6.80 g L−1 with PHB contents of 4.71 g L−1. Further, characterization of PHA and its copolymers was done by ESI–MS, FTIR, and TEM. On upscaling up to 3.0 L, the PHA contents and yields were noted as quite similar by R. eutropha. This study demonstrates that dairy waste processing waste can be potentially utilized as inexpensive feed for producing high content of biopolymers to develop a sustainable system of waste management. [ABSTRACT FROM AUTHOR]

While microplastics have been recently detected in human blood and the placenta, their impact on human health is not well understood. Using a mouse model of environmental exposure during pregnancy, our group has previously reported that exposure to polystyrene micro- and nanoplastics throughout gestation results in fetal growth restriction. While polystyrene is environmentally relevant, polyethylene is the most widely produced plastic and amongst the most commonly detected microplastic in drinking water and human blood. In this study, we investigated the effect of maternal exposure to polyethylene micro- and nanoplastics on fetal growth and placental function. Healthy, pregnant CD-1 dams were divided into three groups: 106 ng/L of 740–4990 nm polyethylene with surfactant in drinking water (n = 12), surfactant alone in drinking water (n = 12) or regular filtered drinking water (n = 11). At embryonic day 17.5, high-frequency ultrasound was used to investigate the placental and fetal hemodynamic responses following exposure. While maternal exposure to polyethylene did not impact fetal growth, there was a significant effect on placental function with a 43% increase in umbilical artery blood flow in the polyethylene group compared to controls (p < 0.01). These results suggest polyethylene has the potential to cause adverse pregnancy outcomes through abnormal placental function. [ABSTRACT FROM AUTHOR]

The flexibility and the low production costs offered by plastics have made them crucial to society. Unfortunately, due to their resistance to biological degradation, plastics remain in the environment for an extended period of time, posing a growing risk to life on earth. Synthetic treatments of plastic waste damage the environment and may cause damage to human health. Bacterial and fungal isolates have been reported to degrade plastic polymers in a logistic safe approach with the help of their microbial cell enzymes. Recently, the bacterial strain Ideonella sakaiensis (201-F6) was discovered to break down and assimilate polyethylene terephthalate (PET) plastic via metabolic processes at 30 °C to 37 °C. PETase and MHETase enzymes help the bacterium to accomplish such tremendous action at lower temperatures than previously discovered enzymes. In addition to functioning at low temperatures, the noble bacterium's enzymes have amazing qualities over pH and PET plastic degradation, including a shorter period of degradation. It has been proven that using the enzyme PETase, this bacterium hydrolyzes the ester linkages of PET plastic, resulting in production of terephthalic acid (TPA), nontoxic compound and mono-2-hydroxyethyl (MHET), along with further depolymerization of MHET to release ethylene glycogen (EG) and terephthalic acid (TPA) by the second enzyme MHETase. Enzymatic plastic degradation has been proposed as an environmentally friendly and long-term solution to plastic waste in the environment. As a result, this review focuses on the enzymes involved in hydrolyzing PET plastic polymers, as well as some of the other microorganisms involved in plastic degradation. [ABSTRACT FROM AUTHOR]

Poly-β-hydroxybutyrate (PHB) is a potential source of biodegradable plastics that are environmentally friendly due to their complete degradation to water and carbon dioxide. This study aimed to investigate PHB production in the cyanobacterium Synechocystis sp. PCC6714 MT_a24 in an outdoor bioreactor using urban wastewater as a sole nutrient source. The culture was grown in a thin-layer raceway pond with a working volume of 100 L, reaching a biomass density of up to 3.5 g L−1 of cell dry weight (CDW). The maximum PHB content was found under nutrient-limiting conditions in the late stationary phase, reaching 23.7 ± 2.2% PHB per CDW. These data are one of the highest reported for photosynthetic production of PHB by cyanobacteria, moreover using urban wastewater in pilot-scale cultivation which multiplies the potential of sustainable cultivation approaches. Contamination by grazers (Poterioochromonas malhamensis) was managed by culturing Synechocystis in a highly alkaline environment (pH about 10.5) which did not significantly affect the culture growth. Furthermore, the strain MT_a24 showed significant wastewater nutrient remediation removing about 72% of nitrogen and 67% of phosphorus. These trials demonstrate that the photosynthetic production of PHB by Synechocystis sp. PCC6714 MT_a24 in the outdoor thin-layer bioreactor using urban wastewater and ambient carbon dioxide. It shows a promising approach for the cost-effective and sustainable production of biodegradable carbon-negative plastics. Key points: • High PHB production by cyanobacteria in outdoor raceway pond • Urban wastewater used as a sole source of nutrients for phototrophic growth • Potential for cost-effective and sustainable production of biodegradable plastics [ABSTRACT FROM AUTHOR]

Aim: The pollution caused by agricultural plastic mulch film and the resulting microplastics has garnered significant attention. The partial application of biodegradable plastic mulch film (BPM) appears to be a promising method for reducing plastic pollution in agricultural soil. Methods: However, there is currently limited information available on the impact of BPM and the resulting microplastics on agricultural ecosystems. Many mechanisms and conclusions regarding this issue remain uncertain. Accordingly, a comprehensive understanding of the limitations of BPM applications is crucial for assessing the potential ecological risks and guiding future research. Results: Problematically, the actual environmental conditions of agricultural soil, climatic conditions, degradability, market price, and acceptance by farmers all significantly limit the implementation of BPM. Due to the faster and easier degradation of BPM compared to conventional plastic mulch film (CPM), a larger amount of microplastics may be generated within the same time frame. In addition, the implementation of BPM can result in significant alterations in soil microbial diversity, thereby affecting the emissions of CO2, N2O, and CH4. These changes can ultimately have unpredictable consequences on the carbon and nitrogen cycles. Conclusion: The price, uncertainty of degradation in soil, and potential negative impact on the soil environment also restrict the wide application of BPM. Overall, considering the existing knowledge gap and potential issues, further research is needed to determine whether BPM can effectively address the problem of residual mulch film and microplastic pollution in farmland. There is still a long way to go before BPM can completely replace CPM in agricultural production. [ABSTRACT FROM AUTHOR]

The microwave irradiation was successfully and firstly used to improve the solvent-free ring-opening polymerization (ROP) of ε-caprolactone (ε-CL) with different n-butyltin(IV) chloride (nBumSnCln; m and n = 1–3) initiators such as tri-n-butyltin(IV) chloride (nBu3SnCl), di-n-butyltin(IV) dichloride (nBu2SnCl2), n-butyltin(IV) trichloride (nBuSnCl3). The performance of these n-butyltin(IV) chloride initiators in the synthesis of poly(ε-caprolactone) (PCL) was benchmarked and compared to the conventional initiating system of tin(II) 2-ethylhexanoate (Sn(Oct)2). The ROP of ε-CL with all initiating systems was completed in a short time of 30 min by using microwave power of 450 W. The chlorine (Cl) atom presented in the nBumSnCln initiators played an important role in the molecular weight of PCL. The higher amount of Cl in nBumSnCln and the lower PCL molecular weight were obtained. Under the condition used in this work, the performance of initiating systems in the synthesis of PCL via microwave irradiation was in the following order: nBu3SnCl > nBu2SnCl2 > nBuSnCl3 ≈ Sn(Oct)2. Surprisingly, the slowest nBu3SnCl initiator produced the highest weight average molecular weight (Mw = 6.31 × 104 g/mol) of PCL under microwave irradiation and solvent-free condition. The dispersity (Đ) of the synthesized PCL became narrower (Đ = 1.39–1.90) when the nBu3SnCl initiator was used instead of other initiating systems (Đ = 1.62–2.34). The synthesized PCLs were characterized by the Fourier transform infrared spectroscopy (FTIR), proton and carbon-nuclear magnetic resonance spectroscopy (1H- and 13C-NMR), and gel permeation chromatography (GPC) techniques. The mechanism of the ROP of ε-CL with all initiating systems was also explained. The microwave irradiation by a commercial microwave oven could be considered as an effective route in terms of the cost-effective and short synthesis time for biodegradable polymer production. [ABSTRACT FROM AUTHOR]

Polyhydroxybutyrate (PHB), a sustainable biodegradable polymer with various industrial and medical applications, produced by microorganisms is a good replacement of conventional plastics, a major environmental contaminant. The aim of this study is to isolate and evaluate the PHB producing ability of the microorganisms isolated from various soil sources. By employing different staining methods such as Sudan black B, Nile red and Nile blue A, the primary screening of PHB producers was performed. Among the 104 soil isolates, four strains (SNA1, SNA2, SNA3 and SNA4) exhibited positive results for all the staining tests. On further studies, among these the strain SNA2 produced highest level of PHB (64%) from its whole cell dry weight, while glucose (20 g/L) and urea (2 g/L) were used as the carbon and nitrogen sources respectively at pH 7, 30 °C after 48 h of incubation. The Fourier transform infrared spectroscopy (FTIR) and Proton Nuclear Magnetic Resonance (1H NMR) results confirmed that the polymer produced was PHB. The 16S rRNA sequencing revealed results that the strain SNA2 was Klebsiella pneumonia. The production ability of the novel Klebsiella pneumonia SNA2 was further enhanced by optimizing various process parameters such as carbon and nitrogen sources, pH, temperature and incubation period. The process optimization resulted in enhanced PHB synthesis (up to 75%) with Xylose as carbon source and urea as the nitrogen source with pH 7.5 at 35 °C after 36 h. In addition, an attempt to produce a biofilm from the extracted polymer was also successful. Thus, the novel bacterial isolate Klebsiella pneumonia SNA2 was proved to be a challenging host for the synthesis of PHB and the scale up studies are under progress. Whole genome sequencing, identification of pathway genes and metabolic engineering strategies were believed to enhance the PHB synthesis further to the industrial scale. [ABSTRACT FROM AUTHOR]

The poly(L-lactic acid)/carbon nanotube/graphene nanoplate (PLLA/CNTs/GNPs) porous conductive composite materials were successfully prepared by nonsolvent-induced phase separation (NIPS). Combining the synergistic effect of nanomaterials with different geometries and the network structure constructed by polymer solution phase separation, an electrically conductive channel was successfully constructed and achieved 2.78 S/m at 5 wt% nanomaterial content. The relationship between the rate of phase separation of polymer solutions and the conductive network has been investigated and it has been found that perfect conductive channels can be constructed by rapid phase separation. According to the differential scanning calorimetry, the crystal growth can be limited by the lamellar structure of the GNP, and the distribution of carbon nanomaterials, influenced by phase separation rate, therefore can be inferred by crystallinity. Moreover, combined with the good ability of nanomaterials to induce nucleation of molecular chains and the successful shortening of crystal growth by rapid phase separation, the crystal size can be reduced to form the surface microstructure which increases the surface water contact angle to 140.2°. Furthermore, the distribution of nanomaterials significantly increased the thermal degradation temperature of PLLA. This work provides a facile method to fabricate a PLLA bioplastic foam and suggests excellent electrical conductivity, hydrophobicity, and high heat resistance. [ABSTRACT FROM AUTHOR]

Due to the serious environmental impacts of plastic pollution, some conventional plastics have been replaced with biodegradable alternatives. However, these biodegradable options can also fragment and form microplastics, which can be ingested by and harm various biota. The standard methods for quantifying ingested microplastics involve digestion of the gut or the whole organism using acidic, alkaline, or oxidative processes. However, these aggressive methods may destroy biodegradable microplastics, leading to erroneous results. Therefore, in this study, we employed thermal analysis methods, specifically differential scanning calorimetry (DSC) and thermogravimetry (TG), to quantify the ingestion of poly-3-hydroxybutyrate (P3HB), a biodegradable microplastic, by the freshwater crustacean, Daphnia magna. During chronic experiments, we analysed organisms exposed to P3HB with sizes smaller than 125 and 63 μm, at concentrations ranging from 1.56–25 mg L−1. DSC identified an endothermic peak associated with the melting of semicrystalline P3HB, and its enthalpies were utilised to compute the number/mass of P3HB ingested by D. magna. Notably, shifts in melting points suggested that higher concentrations induced particle agglomeration, and these agglomerates could not penetrate deeply into the organism. The TG approach involved subtracting the mass loss between 200 and 400 °C in D. magna specimens exposed to P3HB suspensions from controls without P3HB exposure. Both methods provided comparable data, revealing that, depending on particle size, individual D. magna ingested up to 10% of their body mass. Our findings indicate that both methods effectively detect P3HB (and potentially other plastic fragments), with DSC demonstrating better sensitivity. While the suggested approach did not enable us to calculate the level of determination or quantification, we were able to demonstrate that DSC can detect P3HB in only one specimen of D. magna exposed to the lowest suspension concentration. This indicates that D. magna exposed to the 63 μm fraction ingested approximately 3 μg of P3HB, whereas those exposed to the 125 μm P3HB ingested around 4 μg of P3HB. The introduced methods expand the possibilities for detecting ingested microplastics and probably also nanoplastics, in zooplankton and possibly also other species. [ABSTRACT FROM AUTHOR]