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Microplastics are an emerging anthropogenic pollutant risk with a significant body of research dedicated to understanding the implications further. To generate the databases required to characterize the impact of microplastics on our environment, and improve recovery and recycling of current plastic materials, we need rapid, in-line characterization that can distinguish individual polymer types. Here, autofluorescence spectroscopy was investigated as an alternative characterization method to the current leading techniques based on vibrational spectroscopy. It was confirmed that the autofluorescence of seven common textile polymers (acrylic, polyester, nylon, polyethylene, polypropylene, cellulose/cotton, wool) arose due to the cluster-triggered emission phenomenon. Both simulated polymer aging via photooxidation and dyeing of the polymers were found to affect the resultant autofluorescence spectra. A total of 1485 spectra from 39 unique sample groups (polymer type, colour, and degree of photooxidation) were analysed via machine learning (k-means cluster analysis). Correct identification of the polymer type was achieved in 71% of the cases from only eight input values (normalized intensity values at three autofluorescence emission wavelengths, the total autofluorescence emission intensity, the sample RGB colour values, and the sample shape). This represents a significant step towards automated polymer identification at the sub-second time scales required for the in-line characterization of microplastics. [ABSTRACT FROM AUTHOR]

Pyrolysis of waste plastics can produce a product mixture with a high concentration of olefins (>50 wt%). The olefins, as building blocks in the petroleum industry, are potential precursors for valuable commodity chemicals with higher values (>$2000 per ton). In this work, we produce aldehydes by hydroformylation of the olefins present in pyrolysis oil from colored post-consumer recycled high-density polyethylene (PCR-HDPE). The obtained aldehydes in the oil are then converted into aliphatic amines via reductive amination with a Ru/C catalyst. The aminated oil was characterized by multiple analytical chemistry techniques including elemental analysis, nuclear magnetic resonance spectroscopy, high-resolution liquid chromatography-mass spectrometry, and gas chromatography-mass spectrometry with a Polyarc flame ionization detector. The concentration of metals in the PCR-HDPE and oil changes during the tandem processes, showing limited effects of these elements (e.g., Al, Ca, Fe, Mg, Ti, Zn) on hydroformylation and reductive amination. Additionally, we demonstrated that reductive amination of aldehydes with varied carbon numbers and branching properties can be achieved in the presence of a complex mixture, including paraffins and aromatics. The results indicate that waste plastics have the potential to serve as a renewable source for mono and di aliphatic amines, thereby diminishing reliance on fossil feedstocks as the current primary amine source. [ABSTRACT FROM AUTHOR]

Oxidative degradation is a powerful method to degrade plastics into oligomers and small oxidized products. While thermal energy has been conventionally employed as an external stimulus, recent advances in photochemistry have enabled photocatalytic oxidative degradation of polymers under mild conditions. This tutorial review presents an overview of oxidative degradation, from its earliest examples to emerging strategies. This review briefly discusses the motivation and the development of thermal oxidative degradation of polymers with a focus on underlying mechanisms. Then, we will examine modern studies primarily relevant to catalytic thermal oxidative degradation and photocatalytic oxidative degradation. Lastly, we highlight some unique studies using unconventional approaches for oxidative polymer degradation, such as electrochemistry. [ABSTRACT FROM AUTHOR]

Sustainable production of 1,4-pentanediol (1,4-PDO) from biomass is of great importance because 1,4-PDO is a monomer of degradable polyesters and plastics. This paper reviews the conversion of biomass-derived levulinic acid (LA) and furfural as well as their derivatives alkyl levulinate, γ-valerolactone (GVL) and furfuryl alcohol (FAL) into 1,4-PDO. MoOx or ReOx modified noble metal catalysts and non-noble metal catalysts with core–shell and alloy structures show a high 1,4-PDO yield and stability in LA hydrogenation under severe hydrothermal conditions. The conversion of furfural to 1,4-PDO involves the initial C＝O bond hydrogenation to form FAL, the consecutive acid-catalyzed ring-opening and the final hydrogenation. Therefore, it needs a bifunctional catalyst composed of metallic species and acid sites to improve the 1,4-PDO yield. Efforts are made here to highlight the employed catalysts, structure–performance relationship, reaction pathway and reaction mechanism in detail. The current challenges for large-scale applications of conversion of LA and furfural to 1,4-PDO have been proposed, including process development, catalyst cost, solvent and active site distribution. We believe that this review will provide new opportunities and expand the options for the production of 1,4-PDO via biorefining processes. [ABSTRACT FROM AUTHOR]

The accumulation of plastic packaging wastes in the natural environment highlights the significance of sustainable alternatives. Paper is widely used as a biodegradable packaging material, but poor mechanical strength, barrier properties, and water resistance limit its utility. Typical paper coating materials applied to overcome such drawbacks, such as polyethylene (PE) and ethylene vinyl alcohol (EVOH), are not desirable for sustainability due to environmental persistence. Here, we report a biodegradable, biocompatible, robust, and high-barrier paper coating strategy using boric acid-crosslinked poly(vinyl alcohol) (PVA). Various crosslinked-PVA solutions were prepared using boric acid (BA) and hydrochloric acid (HCl) as a crosslinker and an acid catalyst, respectively. The solutions were coated onto the Kraft paper (KP) through facile bar coating with epichlorohydrin (ECH) as a binder (henceforth referred to as coated papers). The coated papers (KP-P, KP-PB, KP-PBH) show remarkably improved oxygen (∼0.89 cc m−2 d−1) and water vapor (∼5.17 g m−2 d−1) barrier properties as well as tensile strength (∼53.0 MPa) that is retained in moist conditions. The coated papers were significantly mineralized into CO2 (59.2–81.6% over 111 d) in the simulated marine environment biodegradation test. Depolymerization of polymer chains and surface degradation of coated papers are evidenced via FT-IR and SEM, respectively. The microcosm test revealed that the intensive disintegration of the coated papers is synergistically driven by both biotic and abiotic factors (i.e., mechanical stress). Moreover, the in vitro biocompatibility tests employing human embryonic kidney and mouse embryonic fibroblast cells, and in vivo biocompatibility test with mice suggest that the coated papers are highly biocompatible. This work provides a promising strategy for paper packaging that enhances packaging performance without compromising environmental sustainability. [ABSTRACT FROM AUTHOR]

The development of an efficient and environmentally sustainable chemical hydrolysis process for recycling waste plastics, based on green chemistry principles, is a key challenge. In this work, we investigated the role of subcritical CO2 on the hydrolysis of polyethylene terephthalate (PET) into terephthalic acid (TPA) at 180–200 °C for 10–100 min. The addition of CO2 into the reaction mixture led to the in situ formation of carbonic acid that helps to catalyze PET hydrolysis relative to hot compressed H2O (i.e. N2– H2O). The highest TPA yield of 85.0 ± 1.3% was obtained at 200 °C, PET loading of 2.5 g PET in 20 mL H2O for 100 min, and 208 psi of initial CO2 pressure. In addition, the subcritical CO2–H2O system demonstrated high selectivity toward hydrolyzing PET in a mixture with polyethylene (PE) at 200 °C for 100 min, thus providing “molecular sorting” capabilities to the recycling process. The robustness of the process was also demonstrated by the ability to hydrolyze both colored Canada Dry and transparent Pure Life® waste PET bottles into high yields of TPA (>86%) at 200 °C. In addition, subcritical CO2–H2O hydrolysis of colored PET bottles resulted in a white TPA product similar to that generated from transparent PET bottles. Overall, this work shows that, under optimized reaction conditions, subcritical CO2 can provide acid tunability to the reaction medium to favor waste PET hydrolysis for subsequent recycling. [ABSTRACT FROM AUTHOR]

Plastic pollution has been a topic of grave concern worldwide due to major environmental, economic, health, and social impacts. Nevertheless, our society is far from casting plastics aside since they are essential for several applications (e.g. food packaging, automotive, electronics, building, and construction). Poly(terephtalate ethylene) (PET), an important synthetic polyester derived from petroleum, is extensively used in plastic packaging (mainly bottles and trays). Unfortunately, no greener polymer alternative has large-scale production to meet global demand. Consequently, plastic recycling is the most sustainable approach to manage the massive amounts of post-consumed PET materials, by recovering its monomeric units: terephthalic acid and ethylene glycol. However, current recycling methods are still costly, leading to more expensive reclaimed PET monomers than virgin ones obtained from fossil sources. Recently, PET upcycling emerged as a profitable strategy to value the reclaimed monomers by converting them into molecules with higher added value, enhancing the recycling process viability. In this review, we addressed all valuable commodities produced from the conversion of PET monomers catalyzed by microorganisms, as an eco-friendly process known as biological upcycling or bio-upcycling. We provided an outlook regarding potential markets and highlighted the benefits of the PET bio-upcycling route over the actual industrial production of each commodity. Moreover, we discussed different PET recycling methods employed to recover monomers prior to the bio-upcycling step, highlighting the pros and cons. Additionally, we addressed critical considerations about the major challenges regarding this novel recycling strategy, particularly in upscaling from lab-scale stage to real-world implementation. [ABSTRACT FROM AUTHOR]

Polylactic acid (PLA), a biomass material, has garnered increasing interest as a biodegradable alternative for the production of eco-friendly plastics. Accordingly, the sustainable synthesis of lactic acid (LA) and its derivatives from biomass sources is emerging as a viable approach. In this work, an In-TS-1 zeolite with exceptional catalytic activity and stability was successfully synthesized using a hydrothermal method and applied for the efficient one-pot conversion of fructose into methyl lactate (MLA). Characterization of the resulting catalysts, including pyridine-adsorbed Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, ultraviolet-visible diffuse reflectance spectroscopy, and energy dispersive X-ray spectroscopy for elemental mapping, confirmed that the uniform dispersion of indium (In) species contributed to its favorable acidity and significantly boosted the reaction efficiency. Under optimized reaction conditions, a remarkable MLA yield of 71.9% was achieved upon the complete conversion of fructose. The selectivity of MLA remained consistent over 14 cycles, underscoring its extraordinary stability under hydrothermal conditions attributed to the confinement of In species within the zeolite framework. This research technique establishes a potential strategy for the large-scale manufacture of LA and its esters, offering a sustainable and efficient path for the development of biodegradable plastics. [ABSTRACT FROM AUTHOR]

This review article provides a thorough overview of barrier coating materials that have been used in food packaging with a focus on biodegradable (bio-based or petroleum-based) materials, such as lipids, proteins, polysaccharides, agriculture waste and polyesters. The goal is to provide an opportunity to acknowledge progress made in this field, focusing on modifications made to coatings. These modifications aim to address the shortcomings of biodegradable substrates (either plastic or paper) and improve their performance, enabling them to compete with traditional petroleum-based food packaging materials. This includes their barrier against water vapor and oxygen, mechanical and surface characteristics (sealability and adhesion), as well as antimicrobial properties. The barrier of most biodegradable polymers underperforms in comparison with petroleum-based non-biodegradable polymers, which possess either high water vapor barrier or high oxygen barrier. Coating technology is a promising solution particularly in barrier improvement of biodegradable polymers. Currently, there are only metallized, or inorganic nanosheet coatings available for biodegradable films that meet food packaging requirements. There are some challenges in this field, for example, being able to retain the coating's biodegradability despite applied modifications to improve it's performance, the large-scale fabrication of biodegradable coatings, the coating's delamination and heat-sealability during service time, and the migration of the coating into the packaged food. Moreover, green chemistry and its sustainability needs in biodegradable polymeric coatings are also discussed regarding new ideas and possible directions for widespread application of coatings in food packaging. This is the first review that specifically summarizes biodegradable coatings on plastic and paper substrates with a focus on coating modifications to improve the performance of the base substrate to meet the required properties for food packaging applications. [ABSTRACT FROM AUTHOR]

Biodegradable plastics, represented by polylactic acid (PLA), are considered suitable alternatives to nondegradable commodity plastics; however, their degradation through microbial decomposition is seen as a waste of carbon resources and inevitably brings about CO2 emission. Alternatively, waste PLA plastics can be utilized as feedstocks for the sustainable production of value-added chemicals, which not only avoids a carbon footprint but also realizes upcycling of plastic waste. Here, we show a cascade system that combines alkali-induced depolymerization, pulsed electrooxidation, and electrochemical reductive amination to produce alanine with an overall yield of 69% under near ambient conditions. Specifically, we first implement an alkali catalyst in an aqueous solution to depolymerize PLA into lactate. The obtained PLA hydrolysate is directly utilized as both feedstock and electrolyte for pyruvate production over a nickel hydroxide-supported Pd electrocatalyst (Pd/Ni(OH)2) via a pulsed potential, which is followed by the transformation of pyruvate into alanine using a TiO2 catalyst. This cascade process for alanine production benefits from high efficiencies maintained in three consecutive processes, mild operation conditions, and the use of cost-effective feedstocks (plastic wastes), without suffering harsh conditions and expensive feedstock consumption required by conventional biological and chemical approaches for alanine synthesis, respectively. [ABSTRACT FROM AUTHOR]

To reduce global CO2 emissions in line with EU targets, it is essential that we replace fossil-derived plastics with renewable alternatives. This provides an opportunity to develop novel plastics with improved design features, such as better reusability, recyclability, and environmental biodegradability. Although recycling and reuse of plastics is favoured, this relies heavily on the infrastructure of waste management, which is not consistently advanced on a worldwide scale. Furthermore, today's bulk polyolefin plastics are inherently unsuitable for closed-loop recycling, but the introduction of plastics with enhanced biodegradability could help to combat issues with plastic accumulation, especially for packaging applications. It is also important to recognise that plastics enter the environment through littering, even where the best waste-collection infrastructure is in place. This causes endless environmental accumulation when the plastics are non-(bio)degradable. Biodegradability depends heavily on circumstances; some biodegradable polymers degrade rapidly under tropical conditions in soil, but they may not also degrade at the bottom of the sea. Biodegradable polyesters are theoretically recyclable, and even if mechanical recycling is difficult, they can be broken down to their monomers by hydrolysis for subsequent purification and re-polymerisation. Additionally, both the physical properties and the biodegradability of polyesters are tuneable by varying their building blocks. The relationship between the (chemical) structures/compositions (aromatic, branched, linear, polar/apolar monomers; monomer chain length) and biodegradation/hydrolysis of polyesters is discussed here in the context of the design of biodegradable polyesters. [ABSTRACT FROM AUTHOR]

Biodegradable plastics are considered as an alternative to commodity non-biodegradable plastics, but they still degrade slowly in the environment. Current strategies to promote their degradation rates often compromise their utility. Here, we enhance the degradation properties of poly(butylene terephthalate/adipate) (PBAT) by embedding an esterase mimic inside the polyester without compromising its processing and mechanical properties. This esterase mimic contains a binuclear zinc site and catalyzes the depolymerization of PBAT with a turnover frequency (TOF) an order of magnitude higher than that of conventional additives (ZnO). With 1 wt% of this enzyme mimic embedded, PBAT exhibits a 3.7-fold enhancement of the degradation rate under composting conditions. Mechanistic investigation indicates that the binuclear zinc binding center polarizes the ester carbonyl group and increases hydroxide uptake, thus leading to faster degradation. This work provides a possible approach to designing polymers that meet requirements of stability during use and fast degradation after use. [ABSTRACT FROM AUTHOR]

Consumers, companies, and governments are becoming more interested in compostable materials as the amount of waste generated from single-use petrochemical-based and non-biodegradable plastics has grown exponentially since 1960. A drawback to compostable flexible option films is the lack of equivalent moisture barrier performance to maintain a comparable shelf life of food products compared with traditional petrochemical-based versions. Stereocomplex PLA (SC-PLA), a combination of the stereoisomers L -PLA (PLLA) and D -PLA (PDLA), offers a potential solution to this problem. This study presents a viable and novel method to cast extrude SC-PLA films without using a masterbatch. For comparison, several blend compositions were produced, including 85/15, 70/30, 50/50, and 30/70 PLLA/PDLA and homocomplex PLLA and PDLA films. The samples were then annealed at 160 °C for 5, 15, and 30 min to understand the effect on the crystallinity (Xc), moisture vapor permeability coefficient (MVPC), and functional and mechanical performance. As expected, the Xc increased for all the samples upon annealing. We observed increased crystallization kinetics in the blended samples, which crystallized in 5 minutes, which can be ascribed to the nucleation effect, while the PLLA and PDLA started crystallizing between 15 and 30 minutes. PDLA acted as a nucleating agent at levels as low as 15% to induce crystallization in ≤5 minutes in the blended samples. We observed a correlation between the crystallization trend of various compositions and MVPC, with the blended annealed films having a significantly better moisture barrier than all the non-annealed films. The increased Xc reduces the strength properties due to higher brittleness associated with the higher Xc. Further optimization is needed to produce fully viable films for commercial applications; however, this work shows pathways to unlock the creation of PLA films with high barriers to water. [ABSTRACT FROM AUTHOR]

Plastic waste is globally ubiquitous and ecologically harmful, but it can be recycled as an abundant carbon source to alleviate worldwide heavy dependence on fossil resources and reduce CO2 emissions. Therefore, research into the chemical recycling of plastic waste has become a critical and pressing area. Compared with polyolefins, polyesters, as represented by PET and PLA, can easily achieve selective depolymerization to their corresponding monomers due to the presence of weaker ester bonds, thus favoring their closed-loop recycling and upcycling. However, comprehensive reviews on this important topic remain scarce, especially from the standpoint of re/upcycling. In this review, we present significant progress in the catalytic depolymerization of different polyesters, including biodegradable polyesters and nonbiodegradable polyesters, and discuss the key factors that limit the efficacies of the different methods and formidable challenges towards closed-loop recycling and upcycling. Such insightful discussion may benefit the further development of advanced strategies to address the problems with the increasing polyester plastic wastes and stimulate their efficient recycling to value-added chemicals and materials. [ABSTRACT FROM AUTHOR]

The environmental issues and health problems of waste plastics have attracted remarkable attention. It is quite important to convert waste plastics into high value-added electrochemical materials. Herein, four kinds of Co-based metal–organic frameworks (CoMOFs) were synthesized from poly(ethylene terephthalate) plastic, and their electrochemical applications were examined. A mixture of N,N-dimethylformamide (DMF) and H2O was used as the solvent, and hydrothermal reaction was employed. It is found that the surface area and porous structure of CoMOFs are closely related to the volume ratio of DMF/H2O. As a result, the prepared CoMOFs exhibit different catalytic enhancement activities toward the oxidation of p-phenylenediamine (PPD). Based on the solvent-controlled sensing performance of CoMOFs, a highly sensitive and rapid detection method has been developed for PPD, with a linear range from 0.05 to 8.0 μM. The detection limit was 45 nM, and the practical application in hair dye samples was successfully demonstrated. [ABSTRACT FROM AUTHOR]

Hydrogel-based materials with a capacity to absorb harmful electromagnetic waves have become increasingly popular. This paper outlines the preparation of an eco-friendly and biodegradable hydrogel-type electromagnetic shielding material through the use of table salt, which induces the self-assembly of sodium alginate. Poly(vinyl alcohol) (PVA) and poly(ethylene glycol) (PEG) were incorporated to create a rigid support structure, while multi-walled carbon nanotubes (MWCNTs) nanotubes served a synergistic function in constructing the conductive network. The compressive strength of PPSM-180 is 37.95 MPa, and its electrical conductivity level is 15.6 ms mm−1, translating to a 193.3% increase compared to PPSM-0. Additionally, its EMI shielding efficiency was 51.9 dB at a depth of only 2 mm. [ABSTRACT FROM AUTHOR]

The development and widespread adoption of commodity polymers changed societal landscapes on a global scale. Without the everyday materials used in packaging, textiles, construction and medicine, our lives would be unrecognisable. Through decades of use, however, the environmental impact of waste plastics has become grimly apparent, leading to sustained pressure from environmentalists, consumers and scientists to deliver replacement materials. The need to reduce the environmental impact of commodity polymers is beyond question, yet the reality of replacing these ubiquitous materials with sustainable alternatives is complex. In this tutorial review, we will explore the concepts of sustainable design and biodegradability, as applied to the design of synthetic polymers intended for use at scale. We will provide an overview of the potential biodegradation pathways available to polymers in different environments, and highlight the importance of considering these pathways when designing new materials. We will identify gaps in our collective understanding of the production, use and fate of biodegradable polymers: from identifying appropriate feedstock materials, to considering changes needed to production and recycling practices, and to improving our understanding of the environmental fate of the materials we produce. We will discuss the current standard methods for the determination of biodegradability, where lengthy experimental timescales often frustrate the development of new materials, and highlight the need to develop better tools and models to assess the degradation rate of polymers in different environments. [ABSTRACT FROM AUTHOR]

Bioplastic bags mixed with food waste seem inevitable with the growth of waste classification and the banning of non-biodegradable polymers in China. To solve the asynchronous degradation of both food waste (FW) and bioplastics in the anaerobic digestion process, we investigated to determine the most effective pretreatment method. Among the three treatment options—physical, chemical, and biological—we found that biological pretreatment holds the most promise, primarily due to the efficient catalytic hydrolysis capacity of enzymes. We utilized three types of enzymes—amylases, lipases, and proteinase K—at a concentration of 0.075 g L−1 for pretreatment. The pretreatment process involved subjecting the FW/bioplastics mixture to enzymatic action for a duration of 48 h, at temperatures of 35 °C and 55 °C. We observed that the methane production from anaerobic digestion increased by 22.72%, 32.51%, and 60.95%, respectively, at the temperature of 55 °C when treated with the mentioned enzymes. Additionally, the degradation time of the bioplastic bags decreased from 30 to 24 days. Scanning electron microscopy (SEM) analysis revealed noticeable physical degradation, with the emergence of holes on the surface of the bioplastic following the enzymatic pretreatments and the effect of proteinase K was the most obvious. Further analysis using Fourier-transform infrared spectroscopy (FTIR) indicated that the peak observed at 1700 cm−1 is a characteristic peak of proteinase K depolymerization and the peak sign was significantly weakened after the experiment. This discovery suggests that proteinase K possesses a unique ability to break certain chemical bonds within bioplastics. Furthermore, novel bacterial species were identified in the substrate microbiome after proteinase K pretreatment. Notably, temperature was also a significant factor influencing material degradation. The enzymatic pretreatment enhanced biodegradation, resulting in enhanced methane yield during anaerobic digestion. These findings demonstrated the efficacy of biological pretreatment in effectively addressing the asynchronous degradation issue between food waste and bioplastics. [ABSTRACT FROM AUTHOR]

The emergence of biodegradable polymers has brought hope for solving the problem of plastic pollution. Chemical recovery of biodegradable polymers not only avoids CO2 emissions from polyester degradation, but also enables sustainable utilization of feedstocks. In this study, biodegradable PGA-PBC-PGA triblock copolymers with chemical recovery characteristics were synthesized using ring-opening polymerization (ROP) of glycolide (GL). The Tonset of the triblock copolymers was higher than 315 °C. Mechanical tests showed that the tensile strengths of the copolymers were in the range of 27.5–98.2 MPa, and the elongations at break were in the range of 9.2–409%. The gas permeation test showed that the triblock copolymers had excellent O2 and CO2 barrier performance, which was better than PBS, PBAT and PLA. Besides, the triblock copolymers have excellent degradation properties under both enzymatic and non-enzymatic conditions. What's more, the triblock copolymers were allowed to recover GL by thermal depolymerization. Among them, PGA-PBC-PGA60 could recover GL in 82% yield at 240 °C in 3 hours. The recovered GL could be reused for the next polymerization after recrystallization and purification. The performances of the copolymers after re-polymerization were comparable to that of the original copolymer, successfully completing the closed-loop process from a monomer to a polymer and then to a monomer. [ABSTRACT FROM AUTHOR]

While modern research into biodegradable and renewable plastics has expanded to cover a wide variety of applications, some characteristics, such as desirable elastic properties, are still difficult to achieve without the use of petroleum-based monomers. In addition, 100% biomass-based polymers are in high demand as environmental regulations increasingly require the use of biomass-based monomers. In this study, biomass-derived monomers, such as adipic acid (AA), 2,5-furandicarboxylic acid (FDCA), and 1,3-propanediol (PDO), were used to synthesize terpolyesters with elastic properties. The unsymmetrical structure of FDCA led to a spiral motif that biodegrades efficiently, and its ring structure also plays an important role as a hard elastomer domain. Applying the "odd–even effect" of PDO resulted in very high biodegradation rates, low melting points, and low degrees of crystallinity. An FDCA : AA ratio of 7 : 3 led to an elongation of around 600% and a recovery rate of 89% (to the original state) at a fixed PDO concentration. [ABSTRACT FROM AUTHOR]

Fast pyrolysis of lignocellulosic biomass is a promising approach for producing biofuels and renewable chemicals, but the resultant bio-oil quality and diverse product distributions limit its widespread adaptation. Concurrently, the accumulation of waste plastics in the environment, particularly polyolefin thermoplastics, is becoming a growing threat. Co-pyrolysis of biomass with hydrogen-rich thermoplastics has shown promise for producing high-quality bio-oils, presenting an attractive solution to waste management. However, a molecular-level understanding of the synergy of the two components in the molten phase during co-pyrolysis is still lacking. In this work, we report the discovery of catalytic and inhibitory effects on cellulose fast pyrolysis caused by noncovalent interactions (NCIs) induced by molten plastics. Our microreactor experiments demonstrated that selectivity toward cellulose-derived anhydrosugars, small oxygenates, or furans increased due to the presence of polyketone, polyethylene glycol, or polystyrene, respectively, which are three thermoplastics with distinct functional groups. Density functional theory calculations reveal that key cellulose pyrolysis pathways leading to major products are catalyzed or inhibited due to perturbations of transition state geometries and partial charges caused by the NCIs induced by plastic functional groups. This discovery offers insights and opportunities for tuning cellulose fast pyrolysis via NCIs using a new family of unconventional molten plastic catalysts or inhibitors. [ABSTRACT FROM AUTHOR]

Due to the severe waste plastics pollution issues, fabricating biodegradable films as substitutes for plastic has been a pursuit of modern scientists for the past few years. UV (ultraviolet) shielding is essential for the application of biodegradable films in packaging materials, agricultural mulch, plastic greenhouses, and window films. Identified as a natural UV-absorber, lignin can be a safe additive to biodegradable film, endowing the film with urgently needed UV-resistance properties while ensuring the overall sustainability of the films. The present paper comprehensively reviews the research status on the preparation and application of lignin-containing biodegradable UV-blocking films. Additionally, the effect of lignin on the mechanical and optical properties of films is revealed. In general, this review provides some theoretical guidance for manufacturing lignin-containing biodegradable UV-blocking films with outstanding mechanical properties and optical transmittance, thus broadening their application in packaging, agriculture, and green building materials. [ABSTRACT FROM AUTHOR]

Polystyrene plastic is a widely used artificial material, but there is still no efficient, economic or environmentally friendly recycling method for waste polystyrene plastic, which has caused serious environmental pollution and a waste of resources. Herein, the method of nitric acid oxidative upgrade is used to convert polystyrene plastic into a high-value chemical raw material, benzoic acid. The yield can reach nearly 90% at 180 °C within 3 h, and the purity of the product is more than 95%. In this process, nitric acid is decomposed by heat to generate nitrogen dioxide and oxygen, which react with the carbon-centered radicals formed at weak sites on the long chain of polystyrene and further generate peroxy radicals and hydroxyl radicals. The formation of oxygen-containing functional groups promoted the fracture of the C–C bond and eventually formed benzoic acid. In addition, this method also has good treatment effects on real-life polystyrene plastic products. This research provides a new method for the recycling and high-value utilization of waste polystyrene plastics. The intrinsic material value of polymers can be maintained by recycling functional chemicals through oxidative upgrade. [ABSTRACT FROM AUTHOR]

For much of the Caribbean region, plastic pollution and the persistence of the great Atlantic Sargassum belt lead to significant regional loss in biodiversity, employment and tourism. Yet, seaweeds such as Sargassum possess all the characteristics for bioplastic production. This study presents a new process on the production of biodegradable calcium alginate (Ca(Alg)2) composite bioplastic, and evaluates its economic feasibility and environmental impact in the Caribbean, compared to bio-based polylactic acid (PLA) and synthetic plastics (PET). Our cradle-to-gate life cycle impact assessment (LCIA) shows normalized (kg CO2eq per kg plastic) greenhouse gas (GHG) impacts 3 to 7 times higher for the baseline alginate composite process over those of PLA and PET films – linked mainly to chemical consumption. However, through the integration of abundant bioenergy from the local paper industry and the nascent E-methanol (E-MeOH) supply chains, GHG impact reduces by 79% – illustrating a pathway to a sustainable bioplastic production flowsheet. More attractively, the alginate bioplastic outperforms in providing ultra-low oxygen barrier packaging properties – with a required mass of plastic material producing a total carbon footprint (kg CO2eq) 64–978 times lower than PLA and PET respectively, and overall packaging costs 280 times less than current synthetic plastic. Techno-economics illustrate that a total annualized cost (TAC) for alginate bioplastic of $US 4.56 per kg is possible, ensuring high economic feasibility, comparable to current commercial bio-based alternatives. Moreover, sensitivity analysis highlights that variability in TAC was mainly associated with sodium alginate utilization in the manufacture process – contributing up to 67% to the overall cost. In light of this, the integration of sound policies aligned to improved consumer awareness and reduced plastic waste can help to drive greater economic feasibility of the alginate bioplastic industry. Ultimately, our study illustrates a viable and sustainable alginate bioplastic alternative, promoting and informing on packaging innovation while achieving low carbon operations within the Caribbean plastic sector. [ABSTRACT FROM AUTHOR]

It is highly desirable but challenging to realize efficient photoreforming of plastic waste over metal-free semiconductors. Here, we synthesized metal-free carbon nitride porous microtube (CNxPM) photocatalysts by carrying out a pyrolysis of the supramolecular assembly formed by the self-assembly of L -arginine (L -Arg) and melamine, the modification of L -Arg rationally engineering the microstructure and electronic structure of the CNxPM system for efficient visible-light-driven photoreforming of poly(ethylene terephthalate) (PET) to hydrogen (H2) and high-value chemicals. In particular, the amount of formate converted from PET substrate under visible light was highest in metal-free semiconductors without any co-catalyst reported so far, presenting the first example of visible-light-driven photoreforming of PET over a completely metal-free single-component semiconductor without any co-catalyst. [ABSTRACT FROM AUTHOR]

(Co)poly-γ-butyrolactone (pGBL) is a thermoplastic material of high interest to replace common plastics with a more sustainable alternative due to its biodegradability, re-monomerizability and opportunity to be obtained from renewable feedstocks. Mild methods to produce pGBL by ring-opening polymerization (ROP) have only been developed in the last decade. Unfortunately, these methods involve the use of sophisticated catalysts, very low temperatures or relatively diluted mixtures. To develop a more environmentally, economically and industrially relevant pGBL synthesis process, the aim was to increase the ROP temperature to be applicable for large scale reaction and optimize the base/alcohol system to circumvent the use of sophisticated organic or rare earth metal catalysts. To that end, the strong base potassium tert-butoxide in combination with benzyl alcohol or with polyols such as 1,4-benzenedimethanol or glycerol was used for the ROP. This simple system gives access to high GBL conversions and medium to high molecular weight (co)polymers. [ABSTRACT FROM AUTHOR]

Global sustainable development has intensified the demand for switching to a renewable economy with a reduced carbon footprint. Here, we report a hybrid system, coupling a chemical process for CO2 reduction with hydrogen, and a biological process for polyhydroxybutyrate (PHB) synthesis, capable of converting CO2 into bioplastics with a theoretical carbon yield of 100%. The synthetic pathway from CO2 to PHB was modularly optimized by improving the catalytic efficiency of key enzymes, avoiding the kinetic trap of metabolic flux and optimizing the whole catalytic process, resulting in 5.96 g L−1 PHB with a productivity of 1.19 g L−1 h−1 and a molar CO2 utilization efficiency of 71.8%. These results represent a promising closed-loop production process from CO2 to biodegradable plastics. [ABSTRACT FROM AUTHOR]

Blending lignin with industrial degradable polyester is a sustainable and economically competitive strategy for biodegradable plastic production, but the miscibility of the composite remains a great challenge. In this study, the screened lignin with low molecular weight, uniform structure and rich hydroxyl groups was completely miscible with poly(butylene adipate-co-terephthalate) (PBAT). The low molecular weight of ethyl acetate dissolved lignin (EL) was critical for decreasing its glass transition temperature and steric hindrance, and the abundance of functional groups offered plenty of sites for forming strong intermolecular interactions between EL and PBAT. The intermolecular hydrogen bonds and π–π interactions of EL and PBAT promoted the dissociation of the lignin complex, thereby enhancing the plasticizing effect of PBAT on lignin. The PBAT/EL composite film with 50 wt% EL loading (P/EL50) displayed high tensile strength (24.7 MPa) and elongation at break (494.7%), being ahead of the currently reported PBAT composite films with high lignin addition. The yield strength increased threefold due to the rigid lignin structure and the intrinsic multiple noncovalent interactions. Moreover, compared to pure PBAT films, P/EL50 films exhibited a higher sensitivity of the mechanical performance to temperature and had a 22.9% cost reduction. [ABSTRACT FROM AUTHOR]

Stringent climate change mitigation scenarios rely on large-scale drawdown of carbon dioxide from the atmosphere. Amongst drawdown technologies, bioenergy with carbon capture and sequestration (BECCS) has received considerable attention in the climate mitigation literature. Recently, attention has shifted further from a relatively narrow focus on BECCS to a broader focus on Biomass Carbon Removal and Storage (BiCRS). The concept of BiCRS has the potential to enable a future where the climate mitigation value of biomass resources is more valuable than the energy value, due to the potential to remove and sequester large quantities atmospheric CO2. This article provides a qualitative overview of prominent BiCRS technologies from which a set of the most promising technologies are assessed quantitively through life cycle assessment. There are numerous opportunities to incorporate carbon removal and management within the bioeconomy, but the majority of immediate carbon removal potential exists in four bioproducts: bioenergy, bioplastics, biochar, and wood products. We analyze the life cycle greenhouse gas emissions and disposition of sequestered carbon over 10 000 years for four bioproducts representative of each broader category: an advanced BECCS pathway, biopolyethylene, oriented strand board, and biochar soil amendment. We find that the BECCS pathway has the greatest magnitude and durability of CO2 storage over all time horizons. However, non-BECCS pathways achieve 34–64% of the drawdown magnitude relative to BECCS and retain 55–67% of their initial drawdown over 100 years (central estimate). We identify three engineering strategies for enhancing carbon drawdown: reducing biomass supply chain emissions, maximizing carbon stored in long-lived products, and extending the term of carbon storage. Finally, we highlight the need to characterize both the magnitude and permanence of carbon drawdown as a means for policymakers and technology developers to deploy limited biomass resources to maximize mitigation benefits. [ABSTRACT FROM AUTHOR]

Methyl glycolate (MG) is an important biodegradable PGA plastic monomer. Herein, a green approach to synthesize MG by methanolysis of glucose is proposed, in which the subcritical methanol and phenol/quinone redox system were combined to promote the reversible C–C cleavage and oxidation during the cascade reaction of glucose to MG. [ABSTRACT FROM AUTHOR]

The pernicious impact of plastic originating from petroleum-based sources has been an increasing threat to our environment. Amongst several strategies tested and implied to manage these plastic wastes, one promising alternative is switching to biodegradable polymers. Polyhydroxyalkanoates (PHAs) are a class of microbial polyesters that are biodegradable, biocompatible and an attractive alternative for future packaging applications. They offer an approach to carbon neutrality and support a more sustainable industrialization. However, as these microbial polymers are stored intracellularly, development of downstream processes for extraction and purification are essential and are the most cost-intensive steps. A major drawback in most of the existing state-of-the-art is the use of harsh organic solvents which contributes to the non-eco-friendliness of the processes. This work proposes an alternative, sustainable PHA downstream process comprising the use of a green solvent. Biomass with an intracellular PHA content of ca. 49% (gPHA/gVSS) produced by mixed cultures was used in this study. A new hydrophobic natural deep eutectic solvent (hydrophobic NADES), Thymol : Vanillin (8 : 2 molar ratio) was synthesised and used as the extraction solvent while 1-heptanol was used as the purification solvent. Also, different intensities of sonication were applied to assist the cell wall rupture for the efficient release of PHAs. The optimised process yielded ∼99% polymer purity and recovery of ∼42% and did not alter the polymer composition. Furthermore, after successful extraction and purification of PHA, the organic solvents (hydrophobic NADES and 1-heptanol) used can be recycled or reused as per end-user requirements. [ABSTRACT FROM AUTHOR]

Sustainability concerns have led to the gradual expansion of the bio-derived 1,4-butanediol (BDO) monomer market, for the replacement of traditional plastics with biodegradable plastics. Herein, we report a new environmentally friendly route for the synthesis of bio-derived BDO from succinic acid (SA), including the first step of esterification of SA with methanol to yield 100% dimethyl succinate (DMS) over phosphotungstic acid, and the second step of one-pot chemoselective hydrogenation of DMS to BDO with a 91.2% yield over Cu1Fe1Al0.5 in a segmented temperature-controlled manner. The method showed excellent long-term stability without deactivation in activity or BDO selectivity during a 500 h time-on-stream test in a fixed-bed reactor. The as-obtained BDO yield with the Cu1Fe1Al0.5 catalyst in this case is one of the best results reported so far to the best of our knowledge. It was demonstrated that highly dispersed Cu nanoparticles and relatively higher metallic Cu area, optimal surface Cu0/(Cu0 + Cu+) molar ratio, and lower surface acidity of the Cu1Fe1Al0.5 catalyst were beneficial for the high activities towards the consecutive hydrogenation of DMS to BDO, and moreover, the strong interaction between Cu and Fe or Al species led to the stable performances during the long-term stability test. [ABSTRACT FROM AUTHOR]

Plastics have become an integral part of many areas of life. Their high chemical resistance has opened a huge range of applications. At the same time, this creates major challenges for the environment, so those plastic residues can now be found even in the remotest corners of the earth. The goal of the circular economy is to address this challenge by utilizing residual and waste streams as valuable raw materials. With suitable recycling strategies into the original or even added-value applications, driving forces for properly closed carbon cycles become available. In recent years, bioplastics possess tremendous growth rates. Biomass-based, they theoretically enable closed carbon cycles as their carbon atoms are harvested from CO2 by photosynthesis. Despite this advantage, their increasing market penetration must be accompanied by appropriate recycling technologies enabling sustainable and economic utilization of the chemically synthesized building blocks. This minireview addresses current knowledge on the (bio)chemical and thermal recycling of chemically novel bioplastics, that is biomass-based plastics not resembling the chemical structure of well-established fossil-derived plastics; major emphasis is on maintaining chemical functionality of the bioplastic building blocks. Available methodologies for thermal (gasification, pyrolysis), chemo-catalytic (homogeneous and heterogeneous catalysis) and bio-catalytic (enzymatic and whole-cell catalysis) recycling are summarized together with the available insights of LCA studies on recycling strategies for chemically novel biomass-based plastics. The literature review shows that although mechanical recycling presents currently the most attractive technology, LCA studies emphasize the potentially lower environmental impact of chemical recycling compared with other End-of-Life (EoL) solutions. Therefore, early development of viable technologies for chemical recycling in the growing field of biomass-based plastics is of utmost importance. [ABSTRACT FROM AUTHOR]

Single-use plastic packaging has become an inevitable part of every aspect of human life. In fact, the increase in the consumption of petroleum-based single-use plastics has resulted in the accumulation of municipal solid wastes which are a leading source of plastic pollution worldwide. Biobased materials are a virtuous replacement for single-use petroleum-based packaging products, when recycling is difficult or not practical, to fulfil environmental and economic demands. Starch is an abundant biobased polymeric material that is sustainable and biodegradable. However, the inefficiency of starch in processability due to the existence of hydrogen bonding interactions and intermolecular forces impedes its applications. An effective solution is plasticization of starch in the presence of heat and shear, and is termed plasticized starch (PS). Although different sources may refer to plasticized starch (PS) as thermoplastic starch (TPS), the plasticization process does not make the starch a thermoplastic material until it is blended with toughened polymer, making the nomenclature counterintuitive. TPS is procured through the process of plasticization of starch with water and plasticizers followed by blending with tougher polymers/biopolymers. This could enhance the flexibility and processability of the blend materials, which are an effective replacement for petroleum-based single-use plastic packaging. In this review the main focus is on analysing the effect of multiple plasticizers and compatibility enhancers such as compatibilizers, coupling agents and essential oils in TPS blends, and starch-based composites' preparation and their effective use in single-use packaging applications. Global production and market analysis of thermoplastic starches and their challenges in real-life packaging applications are also discussed. [ABSTRACT FROM AUTHOR]

Aerobic oxidation of 5-hydroxymethylfurfural (HMF) to 2,5-furandicarboxylic acid (FDCA) is a promising alternative route to produce renewable biodegradable plastics, which has stimulated intense interest in recent years. Supported gold catalysts have shown great potential for this reaction, but the selectivity and stability need to be improved. In addition, the requirement for base additives makes the process less effective and sustainable. Herein, highly active and selective Au–Ag bimetallic nanoclusters supported on MgAl-hydrotalcite (HT) were developed for HMF oxidation to FDCA under base-free reaction conditions using molecular oxygen as the oxidant. The presence of small amounts of Ag (0.034–0.065 wt%) in Au25 clusters greatly enhanced the catalytic reaction rates and selectivity for HMF tandem oxidative steps, leading to both high conversion of HMF (>97%) and high yield of FDCA (>95%). Besides, the catalyst stability was also enhanced by the addition of Ag. The characterization results suggested that the substitution of Ag atoms modified the electronic structure of Au while likely maintaining the primary geometry. Thus, a significant synergistic effect could be observed over trace Ag modified Au–Ag bimetallic nanoclusters. The present work provides new insight into the alloying effect, and helps understand highly efficient Au-based catalysts for aerobic oxidation of biomass derived molecules under base-free conditions. [ABSTRACT FROM AUTHOR]

As the demand for PLA increases, post-consumer disposal strategies must be carefully considered. While we would love to embrace a bioplastic future, we also need to tread carefully. Though PLA is widely claimed to be biodegradable, full degradation often requires conditions not typically found in landfills or industrial composting. Therefore, it will negatively impact the environment if treated carelessly. In this work, we report a simple PLA upcycling path to turn existing PLA wastes into new 3D printable materials within 48 hours. The ester bonds of PLA can be cleaved efficiently via aminolysis. The obtained monomeric compound was derivatized with methacrylic anhydride, which introduces double bonds and thus a cross-linkable monomer is obtained. In combination with a comonomer and initiator, a photocurable resin is produced. The resin can be fed into any commercially available photocuring 3D printer. The 3D printed parts derived from PLA wastes exhibit impressive performances with a tensile strength of 58.6 MPa, Young's modulus of 2.8 GPa, and glass transition at ∼180 °C. Our work demonstrates a new route to active upcycling of PLA while minimizing the need for disposal. [ABSTRACT FROM AUTHOR]

In this contribution, three redistributed arylgermanium-bearing mono-, bis- and tris-triethoxysilyl arms were designed through metal-free radical-initiated hydrogermylation. Their cooperative assembly using amphiphilic Pluronic P123 afforded novel functionalized SBA-15-type materials with embedded arylgermanium in the silica walls. The formation of an ordered mesostructure depended to some extent on the bulkiness of the precursors and the experimental conditions. A nicely distributed germanium pattern was observed through elemental mapping along the siloxane framework, thereby providing a new rational design for stabilizing single atoms in a confined network. When introduced in an aqueous colloidal solution of polyglucosaminated chitosan, evaporative-induced co-assembly of the mixture enables the entrapment of arylgermanium-containing siloxane within the polysaccharide network with the simultaneous formation of transparent bioplastics. The occurrence of phase-separation resulted in texturally engineered polysaccharide–siloxane hybrid nanostructures. [ABSTRACT FROM AUTHOR]

Biodegradable polylactide (PLA) is a promising alternative to conventional plastics. Although the material is degradable, a process for converting its post-consumer products to other value-added products is of interest. In this work, PLA-based nanofibers with a super-hydrophobic property are developed by using the chemical recycling products of PLA as an additive. An alcoholysis with glycerol was employed to generate glycerolized PLA (gPLA), i.e., hydroxyl-capped lactate oligomers with tunable structures. The materials were then used as OH-templates for reacting with a hydrophobic agent, alkyl ketene dimer (AKD). The PLA/gPLA blends were fabricated by electrospinning, whose surfaces were modified by directly adding AKD or dipping them into an AKD solution to enhance their surface hydrophobicity. The resulting super-hydrophobic and oleophilic nanofibers exhibited a high oil absorption rate and capacity (lubricant, diesel, and cooking oil), with the reusability of more than 10 cycles. The materials also showed high oil/water separation performance for practical use in the oil decontamination process. After application, the materials are designed to be re-utilized by a similar chemical recycling process to achieve the circularity of materials. [ABSTRACT FROM AUTHOR]

Plastic pollution caused by non-biodegradable plastics is one of the most widely discussed and notable challenges of the 21st century. Developing biodegradable plastics, such as polylactic acid (PLA), is broadly accepted as the ultimate way of alleviating this problem. However, current PLA production technology relies heavily on food-producible materials such as corn, which leads to competition for resources between material production and food supply. Carbon dioxide whose excessive emission aggravates global warming is an abundant underexplored carbon resource. Herein, we developed a cyanobacterial cell factory for the de novo biosynthesis of PLA directly from CO2, using combinational strategies of metabolic engineering and high-density cultivation (HDC). The heterologous pathway for PLA production, which involves engineered D -lactic dehydrogenase, propionate CoA-transferase, and polyhydroxyalkanoate synthase, was introduced into Synechococcus elongatus PCC7942. Subsequently, various metabolic engineering strategies, including promoter optimization, acetyl–CoA self-circulation, and carbon-flux redirection, were systematically applied, resulting in an approximately 19-fold increase of PLA to 15.0 mg g−1 dry cell weight (DCW) compared to the control. Finally, the PLA titer of 108.0 mg L−1 was obtained after using the HDC strategy, approximately 270 times higher than that obtained from the initially constructed strain. Surprisingly, the molecular weight (Mw, 62.5 kDa; Mn, 32.8 kDa) of our cyanobacterial PLA is among the highest reported levels, which is superior for commercialization. This study sheds light on the prospects of autotrophic plastic production from CO2 using cyanobacterial cell factories. [ABSTRACT FROM AUTHOR]

Correction for 'Characterization of polymer properties and identification of additives in commercially available research plastics' by Amy A. Cuthbertson et al., Green Chem., 2024, https://doi.org/10.1039/d4gc00659c. [ABSTRACT FROM AUTHOR]

It has been reported that microplastics exist ubiquitously in aquatic and terrestrial environments. Microplastic surveys on diverse daily foods with high consumption possibly containing microplastics have essential implications in clarifying the contamination routes, health risk assessment, and thereby preventing food pollution. Given the dependence of microplastic pollution on the regional environment, production and transportation, it further remains an open question on the number, size distribution and type of microplastics in foods from different countries worldwide. Here, we show that daily drinks produced worldwide, including beer, mineral water and tea, are all polluted with microplastics without exception. The number of microplastics investigated in this work lies in the range of 20–80 mL−1 for the beers, 10 mL−1 for the bottled mineral water, and 200–500 g−1 for the tea leaves. Quasi-spherical particles and irregular fragments dominate the shape of microplastics in beer and mineral water, whereas tea leaves carry numerous microplastic fibers. By identification through Raman spectroscopy, we observed the presence of polystyrene (PS) and polypropylene (PP) microplastics in beers, PP in bottled mineral water, and polyethylene (PE) and polyethylene terephthalate (PET) in tea leaves. Possible contamination sources include raw materials, atmosphere, and tools and containers that release microplastics. Given the facile adsorption of heavy metals and antibiotics to microplastics in beverages, public concern may arise regarding the accumulation of microplastics through the food chain and their synergetic harmful effect. Thus, our results should inspire further efforts that may contribute to the elimination and removal of microplastics from foods. [ABSTRACT FROM AUTHOR]

Polysaccharide esters with a low degree of substitution (DS) are expected to be biomass-derived biodegradable plastics with tunable properties that will replace conventional petroleum-derived plastics. However, they have difficulties in moulding and complex multistep synthesis is required to control their DS, thereby limiting their application as plastics. In this study, we demonstrate a continuous process of homogeneous acetylation of curdlan (β-1,3-glucan) and direct wet spinning of the reactant solution by consistently using an ionic liquid, and achieve both facile and green synthesis and fabrication of curdlan acetate fibres with the DS ranging from 0.1–1.0. The partial acetylation of curdlan improved the thermal stability and fiber properties: thermal degradation temperature (Td-5%) from 293 to 342 °C, Young's modulus (dry) from 2.9 to 4.0 GPa, and wet tenacity from 0.34 to 2.8 cN tex−1. Originally, a regenerated curdlan fibre was ductile with a high water absorbency of 85 wt% causing a considerable decrease in wet tenacity. In contrast, curdlan acetate fibres stiffened and the water absorbency was suppressed to 15 wt% at DS = 0.8 owing to the substitution of the C4-OH group (which contributed to the incorporation of water into the curdlan molecules). Consequently, the wet-to-dry tenacity ratio of the curdlan acetate fibres significantly improved from 0.03 to 0.5. Such enhanced properties were attributed to the change in the crystalline structure by acetylation at the DS exceeding 0.4 with preventing the formation of hydrogen bonding via the C2-OH group (which stabilised the original triple helical structure). [ABSTRACT FROM AUTHOR]

Multi-enzymatic cascade reaction systems were designed to generate biopolymer monomers using Escherichia coli-based cell modules, capable of carrying out one-pot reactions. Three cell-based modules, including a ω-hydroxylation module (Cell-Hm) to convert fatty acid methyl esters (FAMEs) to ω-hydroxy fatty acids (ω-HFAs), an amination module (Cell-Am) to convert terminal alcohol groups of the substrate to amine groups, and a reduction module (Cell-Rm) to convert the carboxyl groups of fatty acids to alcohol groups, were constructed. The product-oriented assembly of these cell modules involving multi-enzymatic cascade reactions generated ω-ADAs (up to 46 mM), α,ω-diols (up to 29 mM), ω-amino alcohols (up to 29 mM) and α,ω-diamines (up to 21 mM) from 100 mM corresponding FAME substrates with varying carbon chain length (C8, C10, and C12). Finally 12-ADA and 1,12-diol were purified with isolated yields of 66.5% and 52.5%, respectively. The multi-enzymatic cascade reactions reported herein present an elegant 'greener' alternative for the biosynthesis of various biopolymer monomers from renewable saturated fatty acids. [ABSTRACT FROM AUTHOR]

With approximately 250 000 marine species, the ocean is a vast reservoir of biodiversity and an abundant biological resource of natural polymers. The wide variety, renewable nature, tunable physicochemical and structural behavior and appealing biological properties make these marine biopolymers particularly attractive to the scientific community and numerous industrial sectors. As raw materials, they offer novel opportunities for the development of bio-based materials in response to recent demands for biodegradable plastic materials to lower plastic pollution in marine ecosystems. The biodegradation of marine biopolymers and biopolymer-based materials depends on marine environmental conditions such as temperature, pH and in particular microbial population. Marine microorganisms producing biopolymer-degrading enzymes (i.e., hydrolases, lyases, oxidoreductases) are well studied, nonetheless the biodegradation processes of marine biopolymers-based materials in the marine/aquatic environment need further investigation. This review describes various biodegradation parameters and mechanisms of the degradation of marine biopolymers in the marine environment. It also puts emphasis on the marine microorganisms and the corresponding enzymes that catalyze the degradation of different marine biopolymers. Finally, it focuses on the few studies on biodegradation of emerging bio-based materials in aquatic ecosystems. [ABSTRACT FROM AUTHOR]

This review highlights recent developments in the field of biodegradable polymeric materials intended to replace non-degradable conventional plastics, focusing on studies from the last ten years involving the stereoselective ring-opening polymerization of cyclic esters. This encompasses exciting advances in both catalyst design and monomer scope. Notably, the last decade has seen the emergence of metalfree stereocontrolled ROP for instance, as well as the synthesis and stereocontrolled polymerization of new types of chiral monomers. This study will emphasize recent stereoselective polymerization catalysts and chiral monomers and will focus on stereocontrol quantification, the mechanisms of stereocontrol and their differentiation if reported and studied for a specific catalyst system. [ABSTRACT FROM AUTHOR]

Levulinic acid (LA) is a biomass-derived feedstock that can be converted to a wide array of value-added products; several of these can be accessed efficiently by electrochemical conversion. Herein, we present a study of factors governing LA conversion in electrochemical environments. Most notably, we identify an unprecedentedly efficient pathway forming 4-hydroxyvaleric acid (HVA), a valuable monomer that can be used for production of bio-polyesters—specifically, poly(hydroxy acids)—as well as γ-valerolactone (GVL) (a green fuel/solvent) and other fine chemicals. This method shows >99.9% selectivity and >80% faradaic efficiency for conversion above 80%. Production rates higher than 40 g L−1 h−1 (or 200 kg L−1 mgeom.−2 h−1) were achieved; these are substantially higher than reports for compatible biochemical methods. We further identify mechanistic insights regarding the steering of selectivity toward this new pathway in comparison to known electrochemical routes toward valeric acid (VA) or to GVL. Finally, we provide a fast, sequential one-pot synthesis route to transform electrochemically-produced HVA to GVL with higher overall selectivity and faradaic efficiency than can be achieved by direct aqueous electrochemical conversion of LA to GVL (96% conversion and >99.9% selectivity, giving a total yield of 93% from LA). [ABSTRACT FROM AUTHOR]

UV-Vis spectroscopy is a versatile analytical tool used to examine the nature of various synthetic, biological and clinical molecules for pharmaceutical and environmental applications. The analysis is typically performed in a "cuvette or microplate" that is made of either high-priced quartz or eco-unfriendly plastic materials. Besides, cuvettes and microplates require a plethora of analyte volumes between 100 μL–5 mL that is unfeasible for expensive, rare and high-risk analytes. Herein, we have developed a low-cost sustainable biotemplate derived from fish scales for analysing the absorbance of various sub-10 μL analytes. Naturally acquired transparency enabled optical transmittance above ∼80% in the broad visible and near IR spectrum of 350–900 nm permitted accurate measurements. Most importantly, droplet retention over 30 minutes against gravity with the vertically aligned biotemplate supported such ultra-low volume measurements as well as monitoring of chemical reactions in situ. Moreover, the non-impregnated analyte droplets could be retrieved post-analysis due to the marginally porous hierarchically layered hydrophilic biotemplate with a contact angle of 79°. A customized reusable low-cost 3D-printed adapter was fabricated to position the biotemplate inside the cuvette slot. The biotemplate exhibited excellent compatibility to detect diverse chromophores such as organic dyes, bacteria, nanoparticles, quantum dots, proteins and metallic suspensions by revealing their corresponding absorbances. As a proof-of-concept, we demonstrated the on-biotemplate catalytic dye degradation analysis with an R2 value of 0.98, and the BSA standard assay to quantify as low as 50 μg mL−1 proteins with comparable sensitivities to that of microplate and quartz cuvettes. Finally, large-scale production has been demonstrated by generating ∼3000 biotemplates at an economical price of only Rs. 106 ($1.44). This ultralow-cost, plastic-free, use-and-throw biodegradable transparent biotemplate prepared from food waste as a bioresource stratagem has huge potential in routine scientific and pharmaceutical UV-Vis analytics. [ABSTRACT FROM AUTHOR]

The global ban on plastic microbeads for personal care products has forced researchers to find sustainable alternatives. However, current biodegradable microbeads rarely offer competitive qualities such as those related to the mechanical properties, stability, and toxicity of their degraded products. Herein, we synthesized 'chito-beads', which can satisfy the aforementioned requirements, and evaluated their practical usage, biodegradability, and phytotoxicity. Chito-beads were made into uniform spherical microbeads with a diameter of 280 μm through the reacetylation of chitosan – a renewable polymer from crustacean waste via an inverse emulsion system. Chito-beads exhibit a higher cleansing efficiency than conventional polyethylene microbeads, with a hardness of 128 MPa. Furthermore, they can be used to remove potentially toxic elements and are stable and functional in commercial cleansing. The used chito-beads were fully degraded in soils without any toxicity to the model plants. Our alternative can be used as competitive and environmentally friendly microparticles in sustainable daily necessities. [ABSTRACT FROM AUTHOR]

Designing efficient plastic-digesting microorganisms is necessary to accelerate the decomposition of biodegradable plastics leaking into outer environments. However, screening of microorganisms for hydrophobic plastics is labor-intensive and time-consuming. Herein, a high-throughput, straightforward micro-spray-based screening system is presented; the whole process only takes 1–5 days using a minimal amount of polymers. Bioplastic microparticles sprayed on an agar plate share a large interface with microorganisms, and therefore their discovery is readily recognizable. This method inspires finding new microorganisms that digest conventional plastics known as non-degradable plastics. [ABSTRACT FROM AUTHOR]

Multiple studies on textiles have shown that significant numbers of microparticulate fibres are released daily during washing and are discharged to sewer and wastewater treatment plants (WWTPs). These fibres can enter the environment and potentially cause adverse impacts on ecosystems. The aim of the present study is to evaluate the biodegradability (mineralization) of microplastic fibres compared to natural (cellulose), regenerated (viscose), polyethylene terephthalate (PET)/cotton blend and oxo-degradable PET fibres under laboratory conditions using a 60-day ready biodegradability test and an inoculum from a WWTP. Moreover, the influence of different textile finishes on the biodegradability of fibres was investigated using viscose fibres treated with two different types of reactive dyes (two- and three-anchor compounds), a cationic silicone based softener and a cationic quaternary amonium compound based antimicrobial agent. High mineralization of cotton as well as viscose was observed (reaching 70%), while PET fibres were not degraded (approx. 1.6%). Viscose fibres impregnated with certain finishing agents exhibited a lower degradation level (around 75%) than untreated fibres (reaching up to 85%), which indicates that textile finishing might also prolong the environmental half-lives of shed fibres. The addition of softener to the dyed fibres affected slightly their biodegradability, while the addition of antimicrobial agent significantly reduced the biodegradation level to 3–5%. The recalcitrance of treated fibres against biodegradation might be dependent on the durability and type of the finish. This is an important fact when aiming and chemically designing for more sustainable textile products. [ABSTRACT FROM AUTHOR]