Article

Biodegradability of Plastics: Challenges and Misconceptions

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Abstract

Plastics are one of the most widely used materials and, in most cases, they are designed to have long life times. Thus, plastics contain a complex blend of stabilizers that prevent them from degrading too quickly. Unfortunately, many of the most advantageous properties of plastics such as their chemical, physical and biological inertness and durability present challenges when plastic is released into the environment. Common plastics such as polyethylene (PE), polypropylene (PP), polystyrene (PS), and polyethylene terephthalate (PET) are extremely persistent in the environment, where they undergo very slow fragmentation (projected to take centuries) into small particles through photo-, physical, and biological degradation processes1. The fragmentation of the material into increasingly smaller pieces is an unavoidable stage of the degradation process. Ultimately, plastic materials degrade to micron-sized particles (microplastics), which are persistent in the environment and present a potential source of harm for organisms.

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... (Bio)degradable plastics waste minimally constitute the total packaging waste collected from households. Generally, (bio)degradable plastics wastes can be collected with other plastics, organic or residual waste (Hottle et al., 2017) but there is no global data available on the amount of (bio)degradable plastics in each waste streams (Kubowicz and Booth, 2017). ...
... Thus, if consumers must separate (bio)degradable plastics from conventional petrochemical ones, extra labeling is necessary although this could generate more confusion for the customers. So, it is crucial to sort out (bio)degradable plastics from selected conventional petrochemical plastics (commonly with optical or spectral sensor) to avoid affecting the recycling of the latter (yield and quality) and to recover single streams of (bio)degradable plastics to recycle them (Kubowicz and Booth, 2017). ...
... In different cases, the biodegradation of natural materials eco-designed plastics reaches 90%, giving the definition "compostable" to these materials according to EN 13432. A solution for the non-complete (bio) degradable plastics degradation after anaerobic digestion could be the application of a combined anaerobic digestion process and digestate, which allows a further recovering energy and nutrients and/or removing the non-degraded (bio)degradable plastics through sieving, together with other non-compostable items, after the process is complete (Kubowicz and Booth, 2017). The latter topic also challenges the existing national and European regulations concerning compost quality. ...
Article
In order to mitigate the social and ecological impacts of post-consumer plastic made of conventional petrochemical polymers, the market of (bio)degradable plastics have recently become more widespread. Although (bio)degradable plastics could be an environmentally friendly substitute of petrochemical ones, the consequences of their presence in the waste management system and in the environment (if not correctly disposed) are not always positive and plastic pollution is not automatically solved. Consequently, this work aims to review how plastic (bio)degradability affects the municipal solid waste management cycle. To this end, the state-of-the-art of the intrinsic (bio)degradability of conventional and unconventional petrochemical and bio-based polymers has been discussed, focusing on the environment related to the waste management system. Then, the focus was on strategies to improve polymer (bio)degradability: different types of eco-design and pre-treatment approach for plastics has been investigated, differently from other works that focused only on specific topics. The information gathered was used to discuss three typical disposal/treatment routes for plastic waste. Despite many of the proposed materials in eco-design have increased the plastics (bio)degradability and pre-treatments have showed interesting results, these achievements are not always positive in the current MSW management system. The effect on mechanical recycling is negative in several cases but the enhanced (bio)degradability can help the treatment with organic waste. On the other hand, the current waste treatment facility is not capable to manage this waste, leading to the incineration the most promising options. In this way, the consumption of raw materials will persist even by using (bio)degradable plastics, which strength the doubt if the solution of plastic pollution leads really on these materials. The review also highlighted the need for further research on this topic that is currently limited by the still scarce amount of (bio)degradable plastics in input to full-scale waste treatment plants.
... Other than this, lack of stable waste supply, suitable reactor technology, and presence of inorganics in the waste stream possess challenges in the chemical recycling of the plastics (Payne et al. 2019). Lack of investments, production of by-products and metal-based catalysts systems contribute to other significant difficulties in the chemical valorization of waste plastics (Cabanes et al. 2020;Kubowicz and Booth 2017). ...
... Fig. S3 of supplementary data shows an overview of the biodegradation of plastics. Oxo-degradable plastics which is one of the major classes of bioplastics that possess challenges due to rapid breakage into microplastics when conditions (sunlight and oxygen) are favorable (Kubowicz and Booth 2017). The behavior of specific polymers interrupts their degradation into monomers due to which the microbial activity is ineffective for non-hydrolyzable manufactured polymers as the activity of the microorganisms responsible for the degradation differs concerning the environmental conditions (Ali et al. 2021). ...
... The behavior of specific polymers interrupts their degradation into monomers due to which the microbial activity is ineffective for non-hydrolyzable manufactured polymers as the activity of the microorganisms responsible for the degradation differs concerning the environmental conditions (Ali et al. 2021). Other challenges include the consumption of energy for recycling and time for degradation of the generated microplastics along with socioeconomic challenges such as more time and capital investment and lack of resources (Kubowicz and Booth 2017). Collection and separation of bio-PW and a lack of effective policy contribute to some other barriers related to bio-based polymers and recycling. ...
Article
This review article aims to suggest recycling technological options in India and illustrates plastic recycling clusters and reprocessing infrastructure for plastic waste (PW) recycling in India. The study shows that a majority of states in India are engaged in recycling, road construction, and co-processing in cement kilns while reprocessing capabilities among the reprocessors are highest for polypropylene (PP) and polyethylene (PE) polymer materials. This review suggests that there are key opportunities for mechanical recycling, chemical recycling, waste-to-energy approaches, and bio-based polymers as an alternative to deliver impact to India's PW problem. On the other hand, overall, polyurethane, nylon, and polyethylene terephthalate appear most competitive for chemical recycling. Compared to conventional fossil fuel energy sources, polyethylene (PE), polypropylene (PP), and polystyrene are the three main polymers with higher calorific values suitable for energy production. Also, multi-sensor-based artificial intelligence and blockchain technology and digitization for PW recycling can prove to be the future for India in the waste flow chain and its management. Overall, for a circular plastic economy in India, there is a necessity for a technology-enabled accountable quality-assured collaborative supply chain of virgin and recycled material. Supplementary information: The online version contains supplementary material available at 10.1007/s13762-022-04079-x.
... The most common commodity polymers currently utilized are nonbiodegradable or have a prolonged biodegradation rate [3]. Different methods have been used for developing and industrializing biodegradable plastics [88]. One of these methods is adding some additives, so-called prodegradant or pro-oxidant, to the conventional nonbiodegradable plastics, e.g., polyethylene, polypropylene, and polyethylene terephthalate, to enhance the oxidation process [88]. ...
... Different methods have been used for developing and industrializing biodegradable plastics [88]. One of these methods is adding some additives, so-called prodegradant or pro-oxidant, to the conventional nonbiodegradable plastics, e.g., polyethylene, polypropylene, and polyethylene terephthalate, to enhance the oxidation process [88]. These pro-oxidants are transition metal ion complexes catalyzing plastics oxidation [135]. ...
... Additionally, oxodegradable plastics containing additives for accelerating the oxidation process and facilitating biodegradation are considered biodegradable, and literally don't degrade rapidly. Due to accelerated oxidation under outdoor conditions, oxo-degradable plastics' fragmentation creates tiny fragmented plastics that take a very long time for complete biodegradation [88]. ...
Chapter
Plastics’ unique physical and chemical properties made them indispensable parts of our everyday life and technology. Due to the mismanagement of plastic wastes, 10% of global plastic production annually entering the ocean accounts for 60–80% of marine debris.With the current plastic production rate, more plastics will exist in the oceans than fish by 2050. Plastic waste does not decompose in nature, or its decomposition takes a long time. Among plastic contaminants, microplastics, which are plastic pieces less than 5 mm in size, have attracted much attention because of their potential risks to organisms’ lives. This chapter discusses plastic polymers, their types, and their features that affect plastics’ degradation. Here, we present the interaction between organisms and microplastics and their hazardous effects on living organisms. Bioremediation and biodegradation are explained. Also, new approaches in biodegradation, such as enzyme engineering, are introduced. Plastic polymers’ chemical and physical features such as molecular weight, molecular backbone’s atoms, chemical bonds, crystallinity, hydrophobicity, and additives presence are important factors in vulnerability to decomposing agents. Aging and weathering by abiotic factors including sunlight, heat,moisture, and oxygen decrease the microplastics’ surface hydrophobicity and facilitate microorganism attachments and biofilm formation. Microplastics, because of releasing toxic additives, metallic and organic toxic compounds’ adsorption on their surfaces, threaten organisms’lives. Microplastics’ harmful effects on marine organisms, especially the primary producers’ food chains such as microalgae, can directly or indirectly influence food web consumers such as fish, aquatic birds, and even humans. Antibiotic adsorption on microplastics and, therefore, enrichment of potentially pathogenic and antibiotic resistant bacteria and antibiotic-resistance genes through horizontal gene transfer are other microplastics-related concerns. Following the biofilm formation, microorganisms’ activity and their secreted enzymes and agents deteriorate the microplastics and lead to molecular fragmentation and depolymerization. Assimilation and mineralization of the fragmented molecules are the last biodegradation steps that give rise to CO2, H2O, CH4, and biomass production. Some genus and species of fungi and bacteria and their powerful enzymes such as oxidoreductases and hydrolases are key players in bioremediation by microorganisms. Electron microscopy, spectroscopy techniques, weight loss measurements, mechanical properties, molar mass changes, CO2 evolution/O2 consumption, radiolabeling, clear-zone formation, enzymatic degradation, and controlled composting test are employed for biodegradation evaluation. Since more than 99% of prokaryotes and some eukaryotic microbes are unculturable, hence, to select plastic-decomposing microorganisms, culture independent methods, i.e., metagenomic analysis, are utilized. The metagenome analysis and in silico mining lead to a deeper investigation of the explored and unexplored nature to find efficient enzymes and microorganisms for microplastics’ bioremediation. Using microbial consortia and engineered microorganisms and their enzymes are other promising approaches for plastics bioremediation. Keywords : Microplastics · Bioremediation · Biodegradation · Biodegradable plastics · Aquatic environment · Bacteria · Fungi · Antibiotic resistance · Enzyme engineering · In silico and metagenomics analysis
... Recycling has to be consistent with the high volume production of biodegradable materials. Thus, the shift toward using biodegradable plastics as a more environmentally friendly alternative should be stopped [80,81]. ...
... Besides, plastic products labeled with "biodegradable" may mislead or encourage consumers to use more plastics. Even biodegradable plastics can decompose in aquatic environments, it fails to meet the goals for a circular economy [80]. ...
Article
The ubiquitous appearance of microplastics (MPs) in aquatic environments brings about a growing concern for plastic pollution. Although the MPs occurrence, transportation, fate, and impacts have been summarized thoroughly, it calls for a better understanding of the control and removal strategies for aquatic MPs. Herein, we emphasized the positive effect of source control for MPs removal. Besides, we systematically reviewed the published removal technologies, including filtration, membrane technology, density separation, coagulation, agglomeration, adsorption removal, magnetic separation, oil film separation, froth flotation, and advanced oxidation processes. We also put forward potential challenges and possible improvement protocols for removal strategies and treatment processes of MPs. Exploring MPs characteristics may facilitate the removal technologies of MPs. A specific removal technology contributes to the high removal efficiency under experimental conditions, but in aquatic environments, a desirable extraction requires large-scale experiments. At last, the removal strategies of MPs can borrow separation methods with high-performance from other fields.
... An example is oxo-degradable plastic, which is essentially conventional plastic (e.g., PE, PP, PET) with additives (prodegradants) that accelerate the oxidation process. The problem is only partially solved since the oxo-degradable plastic used in mulching quickly deteriorates to fragments, while their complete biodegradation takes a long time [91]. Second, the fragments of plastic mulch can adsorb pesticides and fertilizers from the soil, resulting in deeper soil and water pollution. ...
... Portillo et al. and Feuilloley et al. found that the degradation rate of photo-degradable PE and oxo-degradable PE film does not reach the requirements of current international standards [80]. The biodegradability of biodegradable plastics, such as PLA, PCL, and PBAT, depends on the polymer properties, additives incorporated into the final product, as well as the environmental conditions in which the material ends up [91]. ...
Article
Full-text available
As society becomes more aware of environmental pollution, global warming, and environmental disasters, people are increasingly turning to sustainable materials and products. This includes agrotextiles in a wide range of products, including nonwoven agrotextiles for mulching. This review provides insight into relevant available data and information on the condition, possibilities, and trends of nonwoven mulches from natural fibres, biopolymers, and recycled sources. The basic definitions and differences between biodegradation and composting processes are explained, and the current standards related to biodegradation are presented. In addition, an insight into the biodegradation of various nonwoven mulches and films, including their advantages and disadvantages, is provided, to predict the future directions of nonwoven mulches development.
... 28,47-51 "Oxodegradable" plastics, also called "oxo-biodegradable" plastics, are a type of plastic material that is commonly promoted due to their improved biodegradation potential. 52 However, European Bioplastics (EUBP) differentiated oxo-degradable plastics from biodegradable plastics (i.e., plastics produced from fossil materials) and bioplastics (i.e., plastics synthesized from biomass or renewable resources) 28 and defined them as conventional plastics made of petroleum-based polymers combined with special additives that promote the oxidative degradation of the product. 53 This process is usually accelerated by light (ultraviolet irradiation), heat exposure and/or mechanical stress. ...
... 51 However, the major problem with oxodegradable plastics is the environmental concerns linked to their rapid fragmentation and the accelerated formation of MPs released in the environment, with potential adverse effects on ecosystems and organisms. 52,57 For this reason, the European Chemical Agency (ECHA) has restricted the oxodegradable plastics since 2019. 58 In addition, chemical additives are often used in the apparel industry to endow the produced garments with desirable features. ...
Article
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...
... However, owing to its durability, a high proportion of the remaining 70% continues to exist in some form. This is often in the form of waste, with some of it eventually reaching the marine space (OSPAR, 2009;Geyer et al., 2017;Kubowicz and Booth, 2017;Booth et al., 2018). In fact, plastic waste has become a critical environmental challenge for ocean biodiversity (Derraik, 2002;Pawar et al., 2016;Phelan et al., 2020), as well as its cultural value in terms of litter on beaches. ...
... We suggest the lack of action to date, from states, due to a number of factors, including lack of suitable and cost-effective alternative materials, consumerism and the 'throw away culture'. While bioplastics and biodegradable plastics have been proposed as solutions, both represent their own challenges (Kubowicz and Booth, 2017;Booth et al., 2018). Bioplastics, for example, are derived from crops that compete with food crops for available land and are typically comprised of the exact same polymers made from fossil fuels (e.g. ...
Article
The effectiveness of a legally binding treaty to manage plastic pollution will depend on how people perceive the risk of the problem in terms of both whether and how much they fear it. Plastic pollution caught the attention of the global public owing to uncertainty surrounding potential human health impacts. Despite an initial concern about human exposure, especially to microplastics, scientific evidence started emerging that the risks of ingesting and even inhaling microplastic was relatively small, suggesting low levels of personal risk. Still, at UNEA5 in Nairobi in 2022, a resolution was passed to start negotiations towards a legally binding agreement for the governance of plastics throughout its life cycle. We compare the trajectory of marine plastics as an environmental governance issue with other global challenges and do a comparative analysis using culture theory to assess how individual risk perception and worldviews inform collective attitudes on governance. We conclude by considering how different risk perceptions may have changed when even more knowledge became available concerning the implications of microplastics breaking down further into nanoplastics and being registered in human blood samples. We argue that this may have contributed to shifting public perception about personal risk and given the requisite push for coordinated global governance of this material.
... The emergence of different plastics in daily products is directly related to the growth of life's quality since the 1950s, presenting new opportunities and more social benefits for all mankind [1]. Considering its exceptional intrinsic properties [2], versatility [3], reduced cost [4], and ease of processing [5], it was effortless to achieve the status of most handled material by distinct industries. Among the industries that introduce plastic in their products, the packaging sector stands out globally, with many millions of tons being produced annually, accounting for almost 50% of the total weight. ...
... The fragmentation emerges quicker in an industrial composter because thermophilic temperatures are most easily achieved on a large scale and constitute less risk of microplastics exhibition to the environment as the degradation occurs within a sealed and controlled system. In opposition, it is much more difficult to achieve these temperatures in small-scale residential composting units, often referred to as "backyard" or "home" composting, and the toxicological effects on the environment are by far distinct [3]. Until now, no international standards have been presented concerning specifications for domestic compostability. ...
Article
Full-text available
Our society lives in a time of transition where traditional petroleum-based polymers/plastics are being replaced by more sustainable alternative materials. To consider these bioproducts as more viable options than the actual ones, it is demanded to ensure that they are fully biodegradable or compostable and that there is no release of hazardous compounds to the environment with their degradation. It is then essential to adapt the legislation to support novel specific guidelines to test the biodegradability of each biopolymer in varied environments, and consequently, establish consistent data to design a coherent labeling system. This review work aims to point out the current standards that can serve as a basis for the characterization of biopolymers’ biodegradation profile in different environments (soil, compost, and aquatic systems) and identify other laboratory methodologies that have been adopted for the same purpose. With the information gathered in this work, it was possible to identify remaining gaps in existing national and international standards to help establish new validation criteria to be introduced in future research and policies related to bioplastics to boost the sustainable progress of this rising industry.
... 137 However, it is stated that the decomposition of biodegradable plastics in natural water is similar to that of conventional plastics, and hence they produce similar amounts of MPs. 138 In addition, some eco-toxicological studies also argued that biodegradable and conventional MPs had a similar toxic impact on marine organisms. 137 Therefore, it is reasonable to be concerned about the adsorption of different contaminants on biodegradable MPs as much as non-biodegradable MPs. ...
Article
Hundreds of review studies have been published focusing on microplastics (MPs) and their environmental impacts. With the microbiota colonization of MPs being firmly established, MPs became an important carrier for contaminants to step inside the food web all the way up to humans. Thus, the continuous feed of MPs into the ecosystem has sparked a multitude of scientific concerns about their toxicity, characterization, and interactions with microorganisms and other contaminants. The reports of common subthemes have agreed about many findings and research gaps but also showed contradictions about others. To unravel these equivocal conflicts, we herein compile all the major findings and analyze the paramount discrepancies among these review papers. Furthermore, we systematically reviewed all the highlights, research gaps, concerns, and future needs. The covered focus areas of MPs' literature include the sources, occurrence, fate, existence, and removal in wastewater treatment plants (WWTPs), toxicity, interaction with microbiota, sampling, characterization, data quality, and interaction with other co-contaminants. This study reveals that many mechanisms of MPs' behavior in aquatic environments like degradation and interaction with microbiota are yet to be comprehended. Furthermore, we emphasize the critical need to standardize methods and parameters for MP characterization to improve the comparability and reproducibility of the incoming research.
... It involves a combination of physical, chemical, and physicochemical processes [26]. During physical biodegradation, microorganisms degraded the polymers by attacking their surface [67]. In chemical biodegradation, microbes depolymerized the polymer chains by direct action on polymers [63]. ...
Article
Full-text available
The globe is facing the ever-increasing challenge of plastic pollution due to the single-use of plastic-based packaging material. The plastic material is being continuously dumped into the natural environment which causes serious harm to the entire ecosystem. Polymer degradation in nature is very difficult, so the use of biodegradable polymers instead of conventional polymers can mitigate this issue. In recent years, keeping plastic hazards in mind the production and implication of biodegradable plastics have significantly increased. This review focus on the use of poly (butylene adipate terephthalate) (PBAT), which is one of the most prospective and prevalent biodegradable polymers instead of non-biodegradable polymers. PBAT can be degraded by biological (actinomycetes, bacteria, fungus, and physical agents (biochemical processes) in aerobic as well as anaerobic environments defined by ASTM standards. Due to the advancement in molecular biology, many studies have reported specific microbes that can effectively degrade PBAT. Aliphatic polyesters undergo hydrolytic cleavage of ester groups, so they can be easily degraded by microorganisms. Microorganisms utilize polymer as their nutrient source, using this approach microorganisms can be isolated. Due to the good mechanical properties and biodegradability, aliphatic–aromatic polymers are being widely commercialized. Feed ratios and curing conditions of monomers are very important for controlling mechanical properties, degradation rates, crystallinity, hydrophilicity, and biocompatibility of polymers. By considering published and current studies, we focused on synthesis, biodegradation mechanism, factors affecting the rate of biodegradation, application of biodegradable polymers especially emphasizing the synthesis, mechanical properties degradation mechanism of PBAT (Polybutylene adipate terephthalate) (biodegradable polymer). Graphical abstract
... The evolutionary history was inferred by using the maximum likelihood method and the Poisson correction model [46]. The bootstrap consensus tree inferred from 1000 replicates was taken to represent the evolutionary history of the taxa analyzed [47]. Branches corresponding to partitions reproduced in less than 50% bootstrap replicates were collapsed. ...
Article
Full-text available
The use of poly (butylene adipate-co-terephthalate) (PBAT) has increased widely but PBAT-degrading bacteria have rarely been studied. During this study, we used farm soil (Shaanxi (yuan Jia cun)) to isolate and identify PBAT-degrading bacteria (Bacillus strains). We then accessed the effect of growth factors on PBAT degradation as well as the lipase activity of PBAT-degrading bacteria. Most active strains (SUST B1, SUST B2, and SUST B3) were selected for degradation study. The lipase activity under different pH, temperature, degradation products, and carbon sources was studied. The degradation mechanism was investigated using attenuated total reflection Fourier transform infrared spectroscopy, scanning electron microscopy, X-ray diffraction, and thermogravimetric analysis. The results showed that each strain had a significant degrading effect on PBAT. Under certain conditions, the lipase activity of strain SUST B2 was 10.42 U/mL and degraded 10.5% of PBAT films. Results of the study displayed a significant change in PBAT properties throughout the experiment. The pH of the degradation solution also displayed significant reduction throughout the experiment and reached a minimum value at the end of the experiment. The secreted lipase enzyme catalyzed the degradation of ester bonds present in the PBAT structure. Terephthalic acid, 1, 4-butanediol, and adipic acid were the by-products of this reaction. Strains utilize these products as carbon sources hence completely degrading PBAT. The bioremediation of PBAT in the environment can be achieved using these strains. Graphical abstract
... Bioplastics have attracted considerable interest due to their properties which are comparable to synthetic polymers and can potentially replace conventional synthetic plastics. Although the term 'biodegradable' has become appealing to the mass market and consumers, yet, in the natural environment, complete degradation will take years or decades, and potentially destructive small particles are generated in the process (Kubowicz & Booth, 2017). Biodegradation involves a combined action of abiotic and biotic factors (Lucas et al., 2008;Sivan et al., 2011). ...
... Degradation rates of plastics can vary from hundreds to thousands of years and are dependent on the environmental conditions [6,7]. During degradation, plastics release toxic, harmful chemicals such as bisphenol A and heavy metals, which can leach into the natural environment, causing ecological harm along with potential detrimental effects to human health [8][9][10][11][12]. A growing concern is the increasing accumulation of plastic wastes in the marine environment, contributing 50-80% of all marine debris, and its detrimental effect on marine life [12][13][14]. ...
Article
Full-text available
Plastics are versatile materials used in a variety of sectors that have seen a rapid increase in their global production. Millions of tonnes of plastic wastes are generated each year, which puts pressure on plastic waste management methods to prevent their accumulation within the environment. Recycling is an attractive disposal method and aids the initiative of a circular plastic economy, but recycling still has challenges to overcome. This review starts with an overview of the current European recycling strategies for solid plastic waste and the challenges faced. Emphasis lies on the recycling of polyolefins (POs) and polyethylene terephthalate (PET) which are found in plastic packaging, as packaging contributes a signification proportion to solid plastic wastes. Both sections, the recycling of POs and PET, discuss the sources of wastes, chemical and mechanical recycling, effects of recycling on the material properties, strategies to improve the performance of recycled POs and PET, and finally the applications of recycled POs and PET. The review concludes with a discussion of the future potential and opportunities of recycled POs and PET.
... Plastics had been originally developed and adopted worldwide owing to their striking characteristics such as resilience, lightness, flexibility, non-reactivity, durability, waterproof nature and cheap price (Ellen MacArthur Foundation 2016;Geyer et al. 2017;Dauvergne 2018). However, the resilience and durability of this particular polymer consist of one major drawback which is its persistence in the environment and thus, rendering it immune to biodegradation (Kubowicz and Booth 2017;Geyer et al. 2017). This particular resistance gives rise to a phenomenon which is the white pollution problem and poses a major threat to the sustainable management of waste. ...
Article
Currently, major focus in the biopolymer field is being drawn on the exploitation of plant-based resources grounded on holistic sustainability trends to produce novel, affordable, biocompatible and environmentally safe polyhydroxyalkanoate biopolymers. The global PHA market, estimated at USD 62 Million in 2020, is predicted to grow by 11.2 and 14.2% between 2020–2024 and 2020–2025 correspondingly based on market research reports. The market is primarily driven by the growing demand for PHA products by the food packaging, biomedical, pharmaceutical, biofuel and agricultural sectors. One of the key limitations in the growth of the PHA market is the significantly higher production costs associated with pure carbon raw materials as compared to traditional polymers. Nonetheless, considerations such as consumer awareness on the toxicity of petroleum-based plastics and strict government regulations towards the prohibition of the use and trade of synthetic plastics are expected to boost the market growth rate. This study throws light on the production of polyhydroxybutyrate from lignocellulosic biomass using environmentally benign techniques via enzyme and microbial activities to assess its feasibility as a green substitute to conventional plastics. The novelty of the present study is to highlight the recent advances, pretreatment techniques to reduce the recalcitrance of lignocellulosic biomass such as dilute and concentrated acidic pretreatment, alkaline pretreatment, steam explosion, ammonia fibre explosion (AFEX), ball milling, biological pretreatment as well as novel emerging pretreatment techniques notably, high-pressure homogenizer, electron beam, high hydrostatic pressure, co-solvent enhanced lignocellulosic fractionation (CELF) pulsed-electric field, low temperature steep delignification (LTSD), microwave and ultrasound technologies. Additionally, inhibitory compounds and detoxification routes, fermentation downstream processes, life cycle and environmental impacts of recovered natural biopolymers, review green procurement policies in various countries, PHA strategies in line with the United Nations Sustainable Development Goals (SDGs) along with the fate of the spent polyhydroxybutyrate are outlined.
... 5 Among the particulate MPs in indoor dust, PP and PE had the highest abundance. They are widely used plastics with numerous consumer applications 41 and were frequently detected in indoor dust in previous studies. 5 Degradable plastic polymers, including PLA and poly(vinyl alcohol), were also detected, though only in a small proportion ( Figure 1A). ...
... According to Kubowicz and Booth (2017), the current problem regarding plastic pollution is the stabilisers present in the plastics. The stabilisers cause plastic substances to be more durable and last longer. ...
... Nearly 80% of plastic debris from land-based sources ends up in the ocean as a result of mismanagement of the plastic waste throughout the plastic supply-chain life cycle, starting from production until post-consumer disposal [119]. The non-biodegradable nature of most commercially used plastics lead to their landfill accumulations for many years, hence resulting in direct plastic contamination [120]. On the other hand, the incomplete disintegration of durable plastics result in the formation of microplastic polymer particles of various morphologies that invade the environments and food chains. ...
Article
Full-text available
In parallel to the rapid growth in economic and social activities, there has been an undesirable increase in environmental degradation due to the massively produced and disposed waste. The need to manage waste in a more innovative manner has become an urgent matter. In response to the call for circular economy, some solid wastes can offer plenty of opportunities to be reutilized as raw materials for the fabrication of functional, high-value products. In the context of solid waste-derived polymeric membrane development, this strategy can pave a way to reduce the consumption of conventional feedstock for the production of synthetic polymers and simultaneously to dampen the negative environmental impacts resulting from the improper management of these solid wastes. The review aims to offer a platform for overviewing the potentials of reutilizing solid waste in liquid separation membrane fabrication by covering the important aspects, including waste pretreatment and raw material extraction, membrane fabrication and characterizations, as well as the separation performance evaluation of the resultant membranes. Three major types of waste-derived polymeric raw materials, namely keratin, cellulose, and plastics, are discussed based on the waste origins, limitations in the waste processing, and their conversion into polymeric membranes. With the promising material properties and viability of processing facilities, recycling and reutilization of waste resources for membrane fabrication are deemed to be a promising strategy that can bring about huge benefits in multiple ways, especially to make a step closer to sustainable and green membrane production.
... Plastics have been important components of disposable bottles and synthetic bres; however, the highly stable microplastics 333 that result from the discharge of plastic waste into the environment and outow out from rivers to oceans has led to a worldwide problem of pollution affecting the marine exposome (Fig. 11a). [334][335][336][337] The degradation process of plastics can be investigated by in vitro experiments conducted in the ocean. Biodegradable plastics, which can decompose in the environment, are a promising solution for the environmental problems caused by disposal of plastics. ...
Article
Full-text available
The environment, from microbial ecosystems to recycled resources, fluctuates dynamically due to many physical, chemical and biological factors, the profile of which reflects changes in overall state, such as environmental illness caused by a collapse of homeostasis. To evaluate and predict environmental health in terms of systemic homeostasis and resource balance, a comprehensive understanding of these factors requires an approach based on the "exposome paradigm", namely the totality of exposure to all substances. Furthermore, in considering sustainable development to meet global population growth, it is important to gain an understanding of both the circulation of biological resources and waste recycling in human society. From this perspective, natural environment, agriculture, aquaculture, wastewater treatment in industry, biomass degradation and biodegradable materials design are at the forefront of current research. In this respect, nuclear magnetic resonance (NMR) offers tremendous advantages in the analysis of samples of molecular complexity, such as crude bio-extracts, intact cells and tissues, fibres, foods, feeds, fertilizers and environmental samples. Here we outline examples to promote an understanding of recent applications of solution-state, solid-state, time-domain NMR and magnetic resonance imaging (MRI) to the complex evaluation of organisms, materials and the environment. We also describe useful databases and informatics tools, as well as machine learning techniques for NMR analysis, demonstrating that NMR data science can be used to evaluate the exposome in both the natural environment and human society towards a sustainable future.
... Conventional plastics which are generally derived from fossil fuel-based petrochemicals such as polypropylene (PP), polystyrene (PS), poly(ethylene terephthalate) (PET) are difficult to degrade in nature. The degradation of conventional plastics into small particles is estimated will take place over the centuries through photographic, physical, and biological degradation [2]. Plastic waste that is not degraded may cause all kinds of environmental and health problems. ...
Conference Paper
Bioplastic as an alternative to conventional plastic was synthesized through a crosslinking method by adding maleic acid to reduce the mobility of the structure and to increase the mechanical strength of plastic. The plastic was then reinforced with two different fillers, pure cellulose and cellulose palmitate, which is useful to reduce the level of water intake and increase the strength of the crosslinked PVA/starch. The plastics were then characterized and tested in the level of tensile strength, and swelling ability.
... An assessment of such practice in various countries in Africa as carried by some workers showed numerous benefits of recycling plastic waste, and it's more environmentally friendly than the other methods of waste disposal [1]. Other workers contended that recycling of plastic waste lead to material and energy recovery, and therefore value will be derived from the waste instead of regarding it as garbage [5]. ...
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This study seeks to understand waste handling and disposal practices, including hindering segregation and recycling plastic bottles and tin cans in Zanzibar. Focusing specifically on the household, schools, collectors, pickers, key informants, and recycling agencies in Zanzibar, the study uncovered the factors that influence the separation and selling of empty plastic bottles and tin cans from households to recycling agencies in Zanzibar. Therefore, this study was done to understand the current practices on waste recycling, agencies involved, and barriers to market penetration from households to recycling agencies. Data were collected from 60 household surveys, focus group discussions with secondary school students and NGOs, in-depth interviews with key informants, and systematic observations in the households, recycling agencies, and collectors. The findings show that waste is generally not separated in households, among collectors and Zanzibar Municipality Council. The study identifies a lack of proper education, poor knowledge of law and policy enforcement, insufficient capital, limited storage warehouses, and an unstable recycling market among the major challenges to sustainable plastic bottle handling and tin can waste. To encourage tin can and plastic bottle users to separate their waste and hand in their plastic bottles and tin cans for recycling, the study recommends some suggestions to improve the situation such as the provision of proper education and loan, law enforcement, promotion of environmental clubs, as well as the creation of a more stable market for the recycling agents.
... The market for bioplastics, including BPs, was 2.1 million tons in 2020, which accounts for only 0.5% of the total plastic market. Nevertheless, growing concerns over microplastics and global warming encourage the widespread use of biodegradable plastics, which are not just fragmented to smaller sizes, but truly degradable, e.g., polylactic acid (PLA), polycaprolactone (PCL), polybutylene succinate (PBS), and polyhydroxyalkanoate (PHA) [10,11]. ...
Article
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Polyhydroxyalkanoate (PHA) is a biodegradable plastic with great potential for tackling plastic waste and marine pollution issues, but its commercial applications have been limited due to its poor processability. In this study, surface-modified cellulose nanocrystals were used to improve the mechanical properties of PHA composites produced via a melt-extrusion process. Double silanization was conducted to obtain hydrophobically treated CNC-based fillers, using tetraethyl orthosilicate (TEOS) and methyltrimethoxysilane (MTMS). The morphology, particle size distributions, and surface characteristics of the silanized CNCs and their compatibility with a PHA polymer matrix differed by the organosiloxane treatment and drying method. It was confirmed that the double silanized CNCs had hydrophobic surface characteristics and narrow particle size distributions, and thereby showed excellent dispersibility in a PHA matrix. Adding hydrophobically treated CNCs to form a PHA composite, the elongation at break of the PHA composites was improved up to 301%, with little reduction of Young’s modulus, compared to pure PHA. Seemingly, the double silanized CNCs added played a similar role to a nucleation agent in the PHA composite. It is expected that such high ductility can improve the mechanical properties of PHA composites, making them more suitable for commercial applications.
... It is claimed that BPs can be converted to CO 2 and H 2 O as final products by naturally-occurring microorganism mineralization, providing new pathways for end-of-life treatment for plastic wastes like anaerobic digestion and composting (Lambert and Wagner, 2017;Tabone et al., 2010). Problematically, 100% degradation of biodegradable materials cannot be achieved under natural environments (Kubowicz and Booth, 2017;Viera et al., 2020). Evidences showed that BPs in natural environments also led to generation of biodegradable microplastics (BMPs) like conventional oil-based MPs did (Bagheri et al., 2017;Shruti and Kutralam-Muniasamy, 2019). ...
Article
Biodegradable plastics attract public attention as promising substitute for non-degradable plastics that trigger serious plastic pollution, and they are claimed to be environmentally harmless and biodegradable by microorganisms. However, not all biodegradable plastics are completely degradable under natural conditions. Some of them may be disintegrated into microplastics more rapidly than conventional plastics, emerging as another threat to soil environments. As a part of microplastics, biodegradable microplastics may pose stronger negative effects on several soil species than oil-based microplastics under some conditions. Currently, there is a fiercely increasing trend to replace nondegradable plastic commodities with biodegradable ones. Therefore, to discuss the ecological safety of biodegradable plastics is essential before promoting wide application of them during commercial use. This review provided a brief introduction on biodegradable plastics and summarized their deterioration behaviors in terrestrial environments, together with evidences on releases of additives and biodegradable microplastics. Then, potential adverse effects of biodegradable microplastics in soil ecosystems, including responses on soil properties, microbial communities, and several soil species were discussed, suggesting biodegradable microplastics as a potential threat to ecological safety of soil ecosystems. By this token, biodegradable plastics might not be a panacea to the existing “white pollution” and need further exploring.
... It involves a combination of physical, chemical, and physicochemical processes [26]. During physical biodegradation, microorganisms degraded the polymers by attacking their surface [67]. In chemical biodegradation, microbes depolymerized the polymer chains by direct action on polymers [63]. ...
Article
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The globe is facing the ever-increasing challenge of plastic pollution due to the single-use of plastic-based packaging material. The plastic material is being continuously dumped into the natural environment which causes serious harm to the entire ecosystem. Polymer degradation in nature is very difficult, so the use of biodegradable polymers instead of conventional polymers can mitigate this issue. In recent years, keeping plastic hazards in mind the production and implication of biodegradable plastics have significantly increased. This review focus on the use of poly (butylene adipate terephthalate) (PBAT), which is one of the most prospective and prevalent biodegradable polymers instead of non-biodegradable polymers. PBAT can be degraded by biological (actinomycetes, bacteria, fungus, and physical agents (biochemical processes) in aerobic as well as anaerobic environments defined by ASTM standards. Due to the advancement in molecular biology, many studies have reported specific microbes that can effectively degrade PBAT. Aliphatic polyesters undergo hydrolytic cleavage of ester groups, so they can be easily degraded by microorganisms. Microorganisms utilize polymer as their nutrient source, using this approach microorganisms can be isolated. Due to the good mechanical properties and biodegradability, aliphatic-aromatic polymers are being widely commercialized. Feed ratios and curing conditions of monomers are very important for controlling mechanical properties, degradation rates, crystallinity, hydrophilicity, and biocompatibility of polymers. By considering published and current studies, we focused on synthesis, biodegradation mechanism, factors affecting the rate of biodegradation, application of biodegradable polymers especially emphasizing the synthesis, mechanical properties degradation mechanism of PBAT (Polybutylene adipate terephthalate) (biodegradable polymer).
... The evolutionary history was inferred by using the maximum likelihood method and the Poisson correction model [46]. The bootstrap consensus tree inferred from 1000 replicates was taken to represent the evolutionary history of the taxa analyzed [47]. Branches corresponding to partitions reproduced in less than 50% bootstrap replicates were collapsed. ...
Article
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The use of poly (butylene adipate-co-terephthalate) (PBAT) has increased widely but PBAT-degrading bacteria have rarely been studied. During this study, we used farm soil (Shaanxi (yuan Jia cun)) to isolate and identify PBAT-degrading bacteria (Bacillus strains). We then accessed the effect of growth factors on PBAT degradation as well as the lipase activity of PBAT-degrading bacteria. Most active strains (SUST B 1 , SUST B 2, and SUST B 3) were selected for degradation study. The lipase activity under different pH, temperature, degradation products, and carbon sources was studied. The degradation mechanism was investigated using attenuated total reflection Fourier transform infrared spectroscopy, scanning electron microscopy, X-ray diffraction, and thermogravimetric analysis. The results showed that each strain had a significant degrading effect on PBAT. Under certain conditions , the lipase activity of strain SUST B 2 was 10.42 U/mL and degraded 10.5% of PBAT films. Results of the study displayed a significant change in PBAT properties throughout the experiment. The pH of the degradation solution also displayed significant reduction throughout the experiment and reached a minimum value at the end of the experiment. The secreted lipase enzyme catalyzed the degradation of ester bonds present in the PBAT structure. Terephthalic acid, 1, 4-butanediol, and adipic acid were the by-products of this reaction. Strains utilize these products as carbon sources hence completely degrading PBAT. The bioremediation of PBAT in the environment can be achieved using these strains.
... The enzymatic hydrolysis of biodegradable polyesters has been studied extensively in the aspects of enzyme activities, hydrolysis conditions (temperature and pH), hydrolysis rate/products, effects of polymer characteristics (crystallinity and molecular weight), etc. (Castilla-Cortázar et al., 2012;Fukushima et al., 2013;Gan et al., 1997;Khatiwala et al., 2008;Laycock et al., 2017;Li et al., 2003;Ma et al., 2020;Nishida and Tokiwa, 1993;Shi et al., 2020). However, these studies primarily focus on bulk polymer samples, and little attention has been paid to the potential release of microplastics into the surroundings during the biodegradation process in different environments (composting sites, soil, landfill sites, freshwater, and seawater) (Agarwal, 2020;Gaillard et al., 2019;Kubowicz and Booth, 2017;Qin et al., 2021;Wang et al., 2021;Yu et al., 2021). ...
Article
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In this article, we show that enzymatic hydrolysis of a biodegradable polyester (poly(ε-caprolactone)) by Amano Lipase PS in an aqueous (buffer) environment yielded rapidly an excessive number of microplastic particles; merely 0.1 g of poly(ε-caprolactone) film was demonstrated to yield millions of particles. There were also indications of non-enzymatic hydrolysis at the same conditions, but this did not yield any particles within the time frame of the experiment (up to 6 days). Most microplastic particles formed had an irregular branch shape with an average size of around 10 µm, with only a few reaching 60 µm. The formation of microplastic particles resulted from the uneven hydrolysis/erosion rate across the polymer film surface, which led to a rough and undulating surface with ridge, branch, and rod-shaped micro-protruding structures. The consequent detachment and fragmentation of these micro-sized protruding structures resulted in the release of microplastics to the surroundings. Together with microplastics, hydrolysis products such as acidic monomers and oligomers, were also released during the enzymatic hydrolysis process, causing a pH decrease in the surrounding liquid. The results suggest that the risk of microplastic pollution from biodegradable plastics is notable despite their biodegradation. Special attention needs to be paid when using and disposing of biodegradable plastics, considering the enormous impact of the paradigm shift towards more biodegradable products on the environment.
... The preparation of the film for biodegradable food packaging is mainly from two perspectives. The first is that the film material is made from renewable raw materials, increasing soil fertility, reducing greenhouse gas emissions, and saving waste management costs (Kubowicz and Booth 2017;Veliz et al. 2019). The second is to add different additives to polyolefin materials such as carbonyl synthetics, organic acids, and starch to make them biodegradable in the environment (Eyheraguibel et al. 2018;Nilsen-Nygaard et al. 2021). ...
Article
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Non-degradable plastic places a serious burden on the environment, so consumers and researchers are working to develop biodegradable, safe, and sustainable food packaging materials. The starch-based film has become emerging material for food packaging. Not only does it shows excellent physicochemical properties, but also provides the desired degradation characteristics after use or the digestive properties after consumption, thus needing to comprehensively evaluate the quality of starch-based food packaging materials. This review summarizes the degradation behavior of the starch-based film in different degradation environments, and compares the suitability of degradation environments. Besides, the physicochemical properties of the composite or blend film during the degradation process were further discussed. The factors affecting the digestibility of starch-based edible film were reviewed and analyzed. Finally, the application and the future trend of the biodegradable starch-based film in the food packaging field were proposed. Future studies should combine and evaluate the physical properties and biodegradability of the composite/blend film, to develop food packaging materials with good characteristics and biodegradability.
... In the next decade, millions of tons of waste will be generated every day, among them the disposable e-waste are estimated to grow exponentially [1][2][3]. The energy storage system (ESS) in these e-wastes, such as lithium-ion batteries and supercapacitors, contain high levels of heavy metals electrode and toxic and highly corrosive electrolytes, posing a serious threat to our living environment [4,5]. ...
Article
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Pollution of the discarded batteries to the environment has become a challenge that needs to be solved urgently. The innovation of energy storage devices with degradable materials are essential to this mission. Here, an environmentally friendly PVA-gelatin hydrogel-based water-in-salt electrolytes (HiSE) was developed for the high-performance Zn dual-ion battery (ZDIB) with transient degradation advantage. Specifically, PVA and gelatin collectively constrain the water coordinated with ZnCl2 inside the polymer network, which enhances battery reaction dynamics due to the reduced radius of Zn hydrate ion. Several advantages are combined into a single platform in this battery, including not only fast degradation in water, high ionic conductivity, dendrite suppression and high operating voltage, but also easy replication and expansion. The HiSE-based ZDIB exhibits operating voltage of 2.0 V, excellent rate performance and good stability with a capacity retention of 96.2% after 8,000 cycles. Our work paves a way towards sustainable and high-performance energy storage systems.
... When exposed to sunlight and oxygen (O 2 ), oxo-degradable polymers rapidly break down into vast quantities of MPs (Meereboer et al., 2020). Despite advances in the technologies, MPs produced from oxo-degradable polymers takes longer time to disintegrate completely in the natural environmental settings, presenting a threat to the environment (Kubowicz and Booth, 2017). ...
Article
Recent years have seen upsurge in plastic manufacturing and its utilization in various fields, such as, packaging, household goods, medical applications, and beauty products. Due to various adverse impacts imposed by synthetic plastics on the health of living well-being and the environment, the biopolymers have been emerged out an alternative. Although, the biopolymers such as polyhydroxyalkanoates (PHA) are entirely degradable. However, the other polymers, such as poly (lactic acid) (PLA) are only partially degradable and often not biosynthesized. Biodegradation of the polymers using microorganisms is considered an effective bioremediation approach. Biodegradation can be performed in aerobic and anaerobic environments. In this context, the present review discusses the biopolymer production, their persistence in the environment, aerobic biodegradation, anaerobic biodegradation, challenges associated with biodegradation and future perspectives. In addition, this review discusses the advancement in the technologies associated with biopolymer production, biodegradation, and their biodegradation standard in different environmental settings. Furthermore, differences in the degradation condition in the laboratory as well as on-site are discussed.
... Biodegradation is also achieved by oxo-biodegradation, where materials are broken down in the presence of oxygen and light to a smaller size, fit to be consumed by microorganisms and fungi. However, this process also leads to the production of micro-plastics which can be very harmful, if they reach water bodies [53], [54]. Hence, various industrial bodies have come out against the use of oxo-biodegradable additives in plastics [55], [56]. ...
Article
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With the increasing global attention on sustainability, biocomposites have been touted as a solution to deal with the issues of unsustainable raw material production, product manufacture and disposal that are common with typical plastic and composite materials. However, after decades of research, the tangible outcomes in terms of impactful raw materials are few and far. It has been observed that though people are more aware of sustainability, this rarely translates into purchasing behaviour favouring biocomposites. In this review, the history of biocomposite development is considered, including their classification, raw materials, commercial aspects and notable products. This review reveals that the presence of a wide range of bio-degradation standards and inconsistent use of ‘eco’ terms creates confusion amongst consumers and, while many natural materials are valued for their visual aspects, most biocomposites are not. The lack of widespread acceptance for biocomposites could be driven by their lack of desirability and distinguishability. To create favourable perceptual attributes for biocomposites, various mechanisms behind material perception, ‘good’ experiences and ‘natural’ perception are reviewed. We propose that biocomposites could be made desirable and distinguishable by modifying the physical characteristics and the perceptual attributes associated with them.
... The fragmented particles of polyethylene (PE), polystyrene (PS), and polyethylene terephthalate (PET) polymers sinking in water bodies are a serious concern to marine life [6]. These fragmented plastic particles known as microplastics end up disturbing the marine ecosystem and recycling of microplastics and their derivatives are tedious than the plastics themselves [7]. Moreover, dissolved organic carbon leaching, trace gases leaching from plastics have hazardous effects on the environment. ...
Article
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The extensive and uncontrolled usage of plastic has led to the generation of millions of tons of plastic waste resulting in its amassment in the marine and terrestrial environments. Continuous disposal of plastic waste in open environments such as water bodies and landfills have a severe impact on the ecosystem which results in environmental pollution. This untreated disposal of low and high molecular weight plastics is a major environmental concern. These polymers are highly recalcitrant; hence, this global problem of plastic pollution needs urgent attention. This further warrants the exploration of an efficient, eco-friendly, and cost-effective approach to plastic degradation. In the past few years, some of the findings have explored the idea of the degradation of plastics using diverse microbial groups viz., fungi, bacteria, and algae. However, it was found that previously identified microbial agents and their secreted enzymes showed low efficiencies in plastic degradation. So far, in most of the studies, microbial species were isolated from the soil samples collected from plastic dumpsites but there might be several unexplored microbial species that can have greater efficiency to degrade plastics. Such microbial species are still unexplored because of their uncultivable nature in the lab conditions. However, advancements in bioinformatics and sequencing techniques allow rapid metagenomic screening of microbial communities along with the mining of related enzymes and genes involved in biodegradation. Therefore, exploring uncultivable microbial communities through metagenomics could serve as a great tool to find efficient plastic degrading genes and enzymes.
... Moreover, the temperatures used for both processes are often higher than 200 o C, indicating high energy input and inhibitory cost. The relatively low cost of virgin PET stimulates the demand of PET production capacity and makes the recycling processes not economically competitive (Kubowicz and Booth 2017). ...
Article
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The polyethylene terephthalate (PET) is one of the major plastics with a huge annual production. Alongside with its mass production and wide applications, PET pollution is threatening and damaging the environment and human health. Although mechanical or chemical methods can deal with PET, the process suffers from high cost and the hydrolyzed monomers will cause secondary pollution. Discovery of plastic-degrading microbes and the corresponding enzymes emerges new hope to cope with this issue. Combined with synthetic biology and metabolic engineering, microbial cell factories not only provide a promising approach to degrade PET, but also enable the conversion of its monomers, ethylene glycol (EG) and terephthalic acid (TPA), into value-added compounds. In this way, PET wastes can be handled in environment-friendly and more potentially cost-effective processes. While PET hydrolases have been extensively reviewed, this review focuses on the microbes and metabolic pathways for the degradation of PET monomers. In addition, recent advances in the biotransformation of TPA and EG into value-added compounds are discussed in detail.
... In fact, the fragmentation and aging of plastics can be also achieved through photo-and physical degradation processes (Kubowicz and Booth, 2017;ter Halle et al., 2016). Ultraviolet (UV) oxidation is introduced as a fundamental and important way to form aged MPs in natural environment via photolytic, photo-oxidative and thermo-oxidative reactions (Feldman, 2002;Wu et al., 2021;Duan et al., 2021;Sun et al., 2020;Zhao et al., 2021;Zhu et al., 2019). ...
Article
Biodegradable plastic (BPs) bags are introduced and widely used as alternatives to conventional commercial plastic bags in an effort to mitigate the adverse impacts of nondegradable (conventional) plastics. However, being used as packaging, the stability and safeness of the BPs and even the conventional plastics with photo irradiation in short duration remain unknown. In this study, we systematically explored the photo aging of commercial BPs bags and conventional plastic bags in film forms in both outdoor and laboratory experiments in short duration (~ one month) under the scenario of ordinary daily use. Conventional plastic bags (polyethylene (PE)) and BPs bags (hybrids of polylatic acid (PLA) and poly(butylene adipate-co-terephthalate) (PBAT) with additives (Magadiite or Starch)) were investigated. In contrast with the visually negligible surface change of PE films in both outdoor and laboratory environments, obvious surface alteration as surface deterioration with cracks and holes was obtained for BPs from SEM images in direct irradiation by both natural and simulated sunlight. Consistently, AFM results also indicated that the surface of BPs had the tendency to be rougher after photo aging process. Further FTIR and XPS results demonstrated that though the visual surface alteration of conventional and biodegradable plastics are distinct, the mechanisms dominating the change of C-H/C-C bonds to carbon‑oxygen functional groups (i.e., C-O/C=O/O-C=O) for both conventional plastics and BPs during the photo aging process are similar. Moreover, tensile strength tests demonstrated that BPs bags being easily broken compared with the conventional PE bags might attribute to the difference in their mechanical properties. The findings of this study suggest that the potential risk of MPs and NPs released from the BPs bags via photo aging process are great new threats to natural environment and even human health.
... The production of plastics is rapidly growing each year, whereas, the policies of recycling, repurposing, and reusing are not effectively implemented in a few developing countries (Wang et al., 2019) (Avio et al., 2017). From the 1950s to 2015, almost 6.3 billion tons of plastic waste have been calculated to be generated globally (Geyer et al., 2017) (Kubowicz et al., 2017). This number might increase to 26 billion tons by 2050 if this continues (Guglielmi, 2017). ...
Chapter
The spreading and abundance of micro and nano plastics into the world are so wide that many researchers used them as main pointers of the modern and contemporary period defining a new historical era. However, the inferences of microplastics are not yet systematically understood. There is the significant difficulty involved to know their impact due to dissimilar physical-chemical characteristics that make micro-plastics complex stressors. Micro-plastics carry toxic chemicals in the ecosystems, therefore serving as vectors of transport, and, on the other hand, a combination of dangerous chemicals that are further voluntarily during their manufacture as additives to increase polymer properties and extend their life. In this chapter, the authors prominently discuss the different kinds of literature on micro and nano-plastic exposure pathways and their probable risk to human health to encapsulate present information with the target of enhanced attention, upcoming study in this area, and information gaps.
... PLA is the most commercially developed and widespread polymer among biodegradable plastics ( Gere and Czigany, 2020 ). Biodegradability is considered to be ecofriendly in nature due to its decomposition to natural building blocks and reduction of waste generation ( Kubowicz and Booth, 2017 ). However, the thermal, mechanical, and rheological properties of the PLA and other biodegradable plastics are not as on par as fossil-based plastics. ...
Article
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The upward trend of global demand for fossil-fuel energy for non-energy purposes especially for the production of plastics, and non-renewable energy use (NREU) and global warming potential of the plastics life cycle is poorly understood. Alternatives to petrochemical plastics have been researched intensely, but they have not been developed to replace current plastic products at a commercially viable scale. Here, we identify challenges facing to energy intensiveness of plastic production, land use crisis for biomass production, and non-renewable energy use and global warming potential on the life cycle of plastics, and we propose a material lifecycle perspective for bioplastics. Our estimate shows that an average of about 13.8 exajoule (EJ), ranging from 10.9 to 16.7 EJ, of fossil-fuel energy consumed in 2019 was diverted to fossil-fuel feedstock for the production of plastics worldwide, this translates between 2.8 and 4.1% share of the total consumed fossil-fuel energy globally. The life cycle analysis estimate shows that bioplastics produced from 2nd generation feedstock have 25% less NREU than that of 1st generation, while the bioplastics from 1st generation feedstock required about 86% less NREU than that of petrochemical plastics. Similarly, the estimates of the greenhouse gas (GHG) emissions show that the reduction of GHG emission was about 187% more in biomass feedstock than that of petrochemical plastics. We conclude by presenting strategies for improving the recyclability of biological plastics through polymer design, application biotechnology, and by adopting a circular bio-based economy.
Article
In this study, chitosan(CS), nano-silicon aerogels(nSA) and tea polyphenols(TP) were used as film-forming materials and processed with ultrasonication to form films using the tape-casting method. The effects of ultrasonication time, temperature and frequency on the properties of CS/nSA/TP film were explored via material property testing. The results of response surface showed that the maximum tensile strength of the film was 4.036 MPa at ultrasonication time(57.97 min), temperature(37.26 ℃) and frequency(30 kHz). The maximum elongation at break of the film was 279.42 % at ultrasonication time(60.88 min), temperature(39.93 ℃) and frequency(30 kHz). Due to cavitation and super-mixing effects, ultrasonication may make the surface of the film smoother and easier to degrade. After ultrasonication, TPs were protected by the 3D network structure composed of CS and nSA. Ultrasonication improved the antioxidant and antibacterial properties of the film. These results show that ultrasonication is an effective method to improve the properties of films.
Article
Plastics are ubiquitously used by societies, but most of the plastic waste is deposited in landfills and in the natural environment. Their degradation into submillimetre fragments, called microplastics, is a growing concern due to potential adverse effects on the environment and human health. Microplastics are present in the air and may be inhaled by humans, but whether they have deleterious effects on the respiratory system remain unknown. In this study, we determined the presence of microplastics in human lung tissues obtained at autopsies. Polymeric particles (n =33) and fibres (n=4) were observed in 13 of 20 tissue samples. All polymeric particles were smaller than 5.5 µm in size, and fibres ranged from 8.12 to 16.8 µm. The most frequently determined polymers were polyethylene and polypropylene. Deleterious health outcomes may be related to the heterogeneous characteristics of these contaminants in the respiratory system following inhalation.
Article
Due to the increasing evidence of widespread plastic pollution in the air, the impact on plants of airborne particles of polycarbonate (PC), polyethyleneterephthalate (PET), polyethylene (PE), and polyvinylchloride (PVC) was tested by administering pristine and aged airborne micro-nanoplastics (MNPs) to Tillandsia usneoides for two weeks. Here we showed that exposure to pristine MNPs, significantly reduced plant growth with respect to controls. Particularly, PVC almost halved plant development at the end of the treatment, while the other plastics exerted negative effects on growth only at the beginning of the exposure, with final stages comparable to those of controls. Plants exposed to aged MNPs showed significantly decreased growth at early stages with PC, later in the growth with PE, and even later with PET. Aged PVC did not exert a toxic effect on plants. When present, the plastic-mediated reduction in plant growth was coupled with a decrease in photosynthetic activity and alterations in the plant concentration of macro- and micronutrients. The plastic particles were showed to adhere to the plant surface and, preferentially, on the trichome wings. Our results reported, for the first time, evidence of negative effects of airborne plastic pollution on plant health, thus raising concerns for related environmental risks.
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Since plastic waste pollution is a severe environmental concern in modern life, the demand for recycling poly(ethylene terephthalate) (PET) has increased due to its versatile applications. Taking advantage of plastic recycling methods creates the chances of minimizing overall crude oil-based materials consumption, and as a result, greenhouse gasses, specifically CO2, will be decreased. Although many review articles have been published on plastic recycling methods from different aspects, a few review articles exist to investigate the organic reaction mechanism in plastic recycling. This review aims to describe other processes for recycling bottle waste of PET, considering the reaction mechanism. Understanding the reaction mechanism offers practical solutions toward protecting the environment against disadvantageous outgrowths rising from PET wastes. PET recycling aims to transform into a monomer/oligomer to produce new materials from plastic wastes. It is an application in various fields, including the food and beverage industry, packaging, and textile applications, to protect the environment from contamination and introduce a green demand for the near future. In this review, the chemical glycolysis process as an outstanding recycling technique for PET is also discussed, emphasizing the catalysts' performance, reaction conditions and methods, degradation agents, the kinetics of reactions, and reprocessing products. In general, a correct understanding of the PET recycling reaction mechanism leads to making the right decisions in waste management.
Article
Microplastic research constitutes nowadays a very interesting and challenging research field since more and more studies are showing that plastic particles are present in every environmental compartment (water, air, soil and biota) in which they are causing important effects that still need to be fully understood. The study of their presence, behaviour and fate in the environment is extremely necessary to solve such puzzle. In this context, chromatography is currently playing a very important role, since it is being used to determine the composition of microplastics (in particular those with an extremely low size), to study their sorption behaviour as well as to analyse the organic contaminants that they retain during their travel through the environment, among other issues. This review article pretends to provide an overview of such relevant applications, in particular, focusing on works published in the last ten years, as well as to highlight the potential of chromatography as part of this relevant research field.
Chapter
The use of traditional petrochemical-based plastics has led to increased fossil fuel utilization, CO2 emissions, and plastic waste generation. Sustainable, renewable, biocompatible, and largely biodegradable bioplastics especially aliphatic biopolymers such as polyhydroxyalkanoates and polylactides show high potential as environment-friendly, green alternatives to traditional plastics. Bioplastics have a relatively shorter residence time and unfavorable impact on environment. Often, these biopolymers negate the long-term environmental effects and negative carbon footprint caused through landfill and incineration of petrochemical-based plastics. Copolymer blends of these biopolymers serve to relieve many obstacles encountered during product development, sustainability, and degradation in research and industry. The demand of the day is to highlight types, process development challenges, production statistics, sustainability, degradation, and applications of such biopolymers. The present chapter focuses on the nature, material characteristics, productivity, and potential of aliphatic biobased and bioderived polymers along with their current or emerging applications.
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Microplastics (MPs) are among the contaminants that have been of considerable concern in the last decade. One of the most significant contributors to MPs pollution in the environment is the effluent from wastewater treatment plants (WWTP). Previous studies showed that high MPs removal could be achieved in WWTPs. However, the parameters affecting MPs removal performances have not yet been analyzed for actual WWTPs. This review critically evaluates the physical, chemical, and biological treatment processes implemented in the actual WWTPs to remove MPs and summarizes the parameters affecting the removal. This work shows that applying physical, chemical and biological methods is promising: each can be implemented in WWTPs separately, and when combined, higher MPs removal rates are possible. The main parameters that affect the MPs removal are the initial MPs load to the WWTPs and the retention time of MPs in the operational units. MP removal is mainly observed via the physical sedimentation process, which leads MPs to accumulate in wastewater sludge; hence treatment parameters and possibilities of extracting MPs from sludge should be considered to prevent release of MPs from the WWTPs to the environment. The main limitation of MP dissapearance estimation in WWTPs is the lack of a standard MP analysis procedure, which prevents a clear comparison between MP species identification, characterization, and separation. More parameters could be linked to the MPs removal if more consistent and standardized data were obtained from the WWTPs.
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As a significant contributor of plastic waste to the marine environment, Indonesia is striving to construct a national strategy for reducing plastic debris. Hence, the primary aim of this study is to create a model for plastic waste quantity originating from the mainland, accumulated in estuaries. This was achieved by compiling baseline data of marine plastic disposal from the mainland via comprehensive contextualisation of data generated by remote sensing technology and spatial analysis. The parameters used in this study cover plastic waste generation, land cover, population distribution, and human activity identification. These parameters were then used to generate the plastic waste disposal index; that is, the distribution of waste from the mainland, flowing through the river, and ultimately accumulating in the estuary. The plastic waste distribution is calculated based on the weighting method and overlap analysis between land and coastal areas. The results indicate that 0.6% of Indonesia, including metropolitan cities, account for the highest generation of plastic waste. Indicating of plastic releases to the ocean applied by of developing three different scenarios with the highest estimation 11.94 tonnes on a daily basis in an urban area, intended as the baseline study for setting priority zone for plastic waste management.
Article
The current trend towards the use of biodegradable polymers is considered as a sustainable solution to plastic pollution. However, microplastics (MPs) generation due to harsh degradation conditions may impose higher environmental risks on organisms in the aquatic environment, especially when coexisted with various complicated pollutants. This study aimed at investigating the significance of microbial colonization and degradation in the Cu(II) adsorption by poly(lactic acid) (PLA) MPs. The PLA MPs covered with biofilms showed higher monolayer Cu(II) adsorption capacity than the pristine PLA (151.802 ug·g⁻¹ versus 1045.670 ug·g⁻¹), which was attributed to the surface complexation between Cu(II) and functional groups contained in biofilms. The adsorption kinetics of the sewage-incubated PLA was limited by film diffusion and intraparticle diffusion, whereas film diffusion dominated the Cu(II) adsorption by the pristine PLA. Degradation of PLA MPs was detected by Fourier transform infrared spectroscopy (FTIR) with the breakdown of ester bonds, and the biofilm-mediated alterations were further enhanced with the extension of incubation. In addition, removal of biofilms increased the Cu(II) adsorption on PLA MPs by 32.36% due to the higher surface area with more adsorption sites and the pore-filling mechanism. Cu(II) adsorption capacity of PLA MPs was pH-dependent and the biofilm-removed PLA exhibited the lowest adsorption ability at the pH ranging from 4.5 to 6.0. Fulvic acid (FA) inhibited the Cu(II) adsorption due to the complexation of Cu(II) with FA. Our results filled the knowledge gap concerning the influence of microbial colonization and degradation on the adsorption behavior of biodegradable PLA MPs, which can further serve as the cornerstone to understand the environmental interaction between poly(α-hydroxy acid)-type polyesters and heavy metal pollutants.
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Micro- and nanoplastics are inevitably generated from biodegradable plastics during weathering and degradation. In this perspective article, we discuss whether micro- and nanoplastics generated from biodegradable plastics, especially soil-biodegradable plastic mulches, are of environmental concern. The environmental risk of micro- and nanoplastics generated from soil-biodegradable plastic mulches depends on size, concentration, time of exposure, and polymer characteristics (e.g., surface charge and hydrophobicity), similar to that of micro- and nanoplastics from conventional plastics. We argue that micro- and nanoplastics generated from soil-biodegradable plastic mulches will likely not cause environmental harm if soil-biodegradable plastic mulches are disposed of appropriately into soil or compost, because soil-biodegradable plastic mulches can degrade in a relatively short time, limiting the accumulation and exposure of generated micro- and nanoplastics in the terrestrial environment. However, micro- and nanoplastics from soil-biodegradable plastic mulches can be of concern when inappropriate disposal or off-site transport to atmospheric and aquatic environments happens. In such cases, the micro- and nanoplastics can no longer degrade readily and have environmental impacts.
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Polymers are an important class of materials that are providing unparalleled benefits in our daily life. Over the past decade, there is a rapid increase in demand for ecofriendly materials to counter various problems, such as environmental issues, biodegradability, sustainability, and biocompatibility. Thus, sustainable polymers derived from renewable resources is fast growing and evolving research field for energy and environmental applications. The sustainable polymers can be derived from natural sources or synthesized from renewable resources. However, in order to design ecofriendly materials, there is a need for a basic knowledge of sustainable polymers. Therefore, the present book chapter provides discussion on the classification of sustainable polymers and their structures, physical and chemical properties. Further, polymeric materials which exhibit high performance for energy storage and environmental applications are briefly discussed.
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Environmental pollution of microplastics (MPs) is known to be anthropogenically mediated menace to biosphere and becoming a debatable concern globally. Large quantities of plastic fragments are left behind after crop cultivation and like sewage sludge application to soil. The leftover plastic debris, gradually degrade into minute fragments with a diameter of less than 5 mm, known as MPs. MPs are responsible for many changes in the soil physicochemical characteristics, including porosity, enzymatic activities, microbial activities, plant growth, and yield. Because of their ubiquitous nature, high specific surface area and strong hydrophobicity, MPs play an important role in the transportation of toxic chemicals such as plasticisers, polycyclic aromatic hydrocarbons (PAHs), antibiotics, and potentially toxic elements (PTEs). MPs may be transported deep into the soil and can pollute underground water. This review paper investigates the deleterious effects of MPs on the soil environment, enzymatic activities, soil microbes, flora, fauna and crop production, and highlights the general concept of MPs contamination as well as its possible environmental consequences. The review also converses some of the key areas for future research and for key stakeholders concerned with policymaking
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Plastics are widely used by society, and their degradation into millimetre fragments, called microplastics (MPs), has become a global environmental threat to ecosystems and human health. However, airborne MPs' presence and fallout fluxes from the atmosphere are poorly understood and can vary significantly by different conditions, especially in megacities of low- and middle-income countries, where high levels of vehicular air pollution, a high-density population, high plastic use, and inadequate disposal are environmental threats related to airborne MPs. In this study, we investigate the amount, chemical composition, and morphological characteristics of outdoor and indoor airborne MPs fallout in the megacity of São Paulo and assess the influence of weather and seasons on airborne MPs fallout. The results were as follows: MPs were found in all samples with an average fallout rate of 309.40 ± 214.71 MPs/m²/day in the indoor environment, and 123.20 ± 47.09 MPs/m²/day in the outdoor environment; MPs concentrations were higher in the indoor environment than the outdoor environment, with more fibres than particles; polyester fibres (100%), polyethylene (59%) and polypropylene (26%) particles were the dominant polymers indoors, while in outdoors, polyester fibres (76%) and polyethylene (67%) and polyethylene terephthalate (25%) particles were dominant. Fragment was the dominant morphology of particles found in indoor and outdoor samples (64% and 74%, respectively). Outdoor MPs fallout correlated positively with rainfall, wind velocity, and relative humidity. This evidence is the first on airborne MPs in a Latin America megacity and highlights the relevant role that this source plays in different environments.
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In the development of polymer materials, it is an important issue to explore the complex relationships between domain structure and physical properties. In the domain structure analysis of polymer materials, ¹H-static solid-state NMR (ssNMR) spectra can provide information on mobile, rigid, and intermediate domains. But estimation of domain structure from its analysis is difficult due to the wide overlap of spectra from multiple domains. Therefore, we have developed a materials informatics approach that combines the domain modeling (http://dmar.riken.jp/matrigica/) and the integrated analysis of meta-information (the elements, functional groups, additives, and physical properties) in polymer materials. Firstly, the ¹H-static ssNMR data of 120 polymer materials were subjected to a short-time Fourier transform to obtain frequency, intensity, and T2 relaxation time for domains with different mobility. The average T2 relaxation time of each domain is 0.96 ms for Mobile, 0.55 ms for Intermediate (Mobile), 0.32 ms for Intermediate (Rigid), and 0.11 ms for Rigid. Secondly, the estimated domain proportions were integrated with meta-information such as elements, functional group and thermophysical properties and was analyzed using a self-organization map and market basket analysis. This proposed method can contribute to explore structure–property relationships of polymer materials with multiple domains.
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In this technology report, three test methods were developed to characterize the degradation of plastic in marine environment. The aim was to outline a test methodology to measure the physical and biological degradation in different habitats where plastic waste can deposit when littered in the sea. Previously, research has focused mainly on the conditions encountered by plastic items when floating in the sea water (pelagic domain). However, this is just one of the possible habitats that plastic waste can be exposed to. Waves and tides tend to wash up plastic waste on the shoreline, which is also a relevant habitat to be studied. Therefore, the degradation of plastic items buried under sand kept wet with sea water has been followed by verifying the disintegration (visual disappearing) as a simulation of the tidal zone. Most biodegradable plastics have higher densities than water and also as a consequence of fouling, they tend to sink and lay on the sea floor. Therefore, the fate of plastic items lying on the sediment has been followed by monitoring the oxygen consumption (biodegradation). Also the effect of a prolonged exposure to the sea water, to simulate the pelagic domain, has been tested by measuring the decay of mechanical properties. The test material (Mater-Bi) was shown to degrade (total disintegration achieved in less than 9 months) when buried in wet sand (simulation test of the tidal zone), to lose mechanical properties but still maintain integrity (tensile strength at break = -66% in 2 years) when exposed to sea water in an aquarium (simulation of pelagic domain), and substantially biodegrade (69% in 236 days; biodegradation relative to paper: 88%) when located at the sediment/sea water interface (simulation of benthic domain). This study is not conclusive as the methodological approach must be completed by also determining degradation occurring in the supralittoral zone, on the deep sea floor, and in the anoxic sediment.
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This paper provides an introduction to some of the fundamental principles and approaches in environmental economics which are of significance to achieving an integrated sustainability science. The concept of a circular economy, introduced by the late David Pearce in 1990, addresses the interlinkages of the four economic functions of the environment. The environment not only provides amenity values, in addition to being a resource base and a sink for economic activities, it is also a fundamental life-support system. Environmental economists have suggested that, taking these four functions as an analytical starting point, unpriced or underpriced services should be internalised in the economy. In Europe significant advances have been achieved in the pricing of externalities by means of truly interdisciplinary analysis which accounts in detail for the environmental consequences. The monetary estimates reached as a result of such interdisciplinary research are gradually being applied to the economic analysis of environmental policy priorities. Although such figures provide only a partial and incomplete picture of the environmental costs at stake, they support and inform the analysis of the virtues of a circular economy for individual resources as well as for sustainability as a future trajectory. http://pure.au.dk/portal/da/persons/mikael-skou-andersen(d6eb07fd-3020-4801-9beb-04c0cc0f0914)/publications/an-introductory-note-on-the-environmental-economics-of-the-circular-economy(3ff4e710-7e9e-11dd-a5a8-000ea68e967b).html
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Some polymer materials are produced wholly or partly from renewable (the term renewable here is very limited, as was previously explained) raw materials. Some examples are listed below. Braskem - green polyethylene: is the traditional polyethylene, but derived from ethylene produced with ethanol from sugar cane. DuPont - PTT - poly(trimethylene terephthalate): one of its monomers, 1,3-propanediol, is obtained from corn or sugar beets. Coca-Cola Co: PlantBottle: PET bottle made from ethylene glycol obtained from alcohol derived from sugar cane and molasses. In addition, the PP cap is slightly smaller. The proportion of raw materials obtained from fossil fuels (oil, coal and gas) and obtained from plants can be found through analysis of the proportion of carbon-12 to carbon-14 present in the polymer, since fossil fuels contain virtually no carbon-14 whose half-life is about 5730 years (see ASTM D6866-11).
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Polypropylene (PP) is a widely used plastic with consumer applications ranging from food packaging to automotive parts, including car battery casings. To differentiate it from other recyclable plastics, it is designated as #5. Here, the factors contributing to PP recycling rates are briefly reviewed. Considerations include collection and separation efficiency, processing chemistry, and market dynamics for the products derived from recyclates.
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Biodegradable polymers are by definition those that degrade as a result of the action of microorganisms and/or enzymes. The rate of this biodegradation may vary from hours to years depending on the molecular architecture of the polymer in question. Biopolymers like lignin take years to degrade while many proteins and polysaccharides degrade within hours to days. The same is true for the synthetic biodegradable polymers where polyethylene is sometimes regarded as inert to biodegradation while polyanhydrides are rapidly biodegradable. The influence of structure, morphology, and surface area on the biodegradability are discussed, with polyesters and degradable polyethylene (with pro-oxidant and/or biodegradable additives) as examples. The rate of biodegradation is controllable by choosing the appropriate molecular architecture. In addition to this the environmental interaction of these polymers should be determined. The degradation product pattern of biodegradable polymers should be compatible with the natural degradation mechanisms (i.e., catabolisms).
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The use of engineering plastics, especially polyolefins has increased significantly in recent decades largely due to their low cost, good mechanical properties and light weight. However, this increase in usage has also created many challenges associated with disposal and their impact on the environment. This is because polyolefins do not easily degrade in the natural environment and hence the need for degradable polyolefins has become a major topic of research. Degradable polyolefins are designed to retain functionality as a commodity plastic for the required service life but degrade to non-toxic end products in a disposal environment. They are typically designed to oxo-degrade while undergoing changes in chemical structure as a result of oxidation in air, thus causing the breakdown of the molecules into small fragments that are then bioassimilated. This article presents (i) a comprehensive review of the chemistry of additives for the degradation of polyolefins, (ii) a patent and scientific literature summary of technologies including commercially available systems, (iii) the mechanisms of degradation and biodegradation, (iv) testing methods and (v) toxicity.
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Plastic waste disposal is one of the serious environmental issues being tackled by our society today. Polyethylene, particularly in packaging films, has received criticism as it tends to accumulate over a period of time, leaving behind an undesirable visual footprint. Degradable polyethylene, which would enter the eco-cycle harmlessly through biodegradation would be a desirable solution to this problem. However, the "degradable polyethylene" which is presently being promoted as an environmentally friendly alternative to the nondegradable counterpart, does not seem to meet this criterion. This article reviews the state of the art on the aspect of degradability of polyethylene containing pro-oxidants, and more importantly the effect these polymers could have on the environment in the long run. On exposure to heat, light, and oxygen, these polymers disintegrate into small fragments, thereby reducing or increasing the visual presence. However, these fragments can remain in the environment for prolonged time periods. This article also outlines important questions, particularly in terms of time scale of complete degradation, environmental fate of the polymer residues, and possible accumulation of toxins, the answers to which need to be established prior to accepting these polymers as environmentally benign alternatives to their nondegradable equivalents. It appears from the existing literature that our search for biodegradable polyethylene has not yet been realized.
Polymers and the Environment
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Biodegradable polymers and environmental interaction Biodegradability of Polymers: Regulations and Methods for Testing The influence of biotic and abiotic factors on the rate of degradation of poly(lactic) acid (PLA) coupons buried in compost and soil
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