Non-biodegradable Plastics Research Articles

Scalable fabrication of biodegradable, thermally insulating, fire-proof bioplastic foams via rapid magnetic force assisted squeezing and ambient drying

Foam materials are in great demand in modern society, which are widely used in shock absorption, packaging, heat preservation, and building insulation. However, the severe contamination of non-biodegradable plastic foam waste accumulated in the environment has increased the demand and interest in the development of degradable and multifunctional bio-sourced materials. Manufacturing of biomass foam, however, often requires long-term operation of specialized equipment under extreme conditions, making it not as environmentally friendly as claimed. Here we present an energy-efficient freeze-drying-free approach for bioplastic foam production from marine biomass waste via freeze-thawing of shear-flow-induced micro-/nano-fibrous hydrogels and rapid magnetic force-assisted squeezing and ambient drying, which differs substantially from existing inefficient and energy-consuming drying processes. The magnetic force-assisted pre-dehydration strategy prevents the collapse of the 3D network structure under capillary action during solvent evaporation, enabling a low density of 25.5–37.5 mg cm−3 and ultralow shrinkage of 9.3%-12.2%. These ambient-dried chitosan foams exhibit a high compressive modulus (366–732 kPa, supporting ∼ 4600 times its own weight), favorable thermal insulation performance (0.038 W m−1 K−1), competitive thermal stability, and fire resistance (smokeless combustion and self-extinguishing). Moreover, this bioplastic foam has been demonstrated to be recyclable and biodegradable with a substantially reduced environmental impact, as evidenced by life-cycle assessment analysis, representing a promising alternative to petroleum-based plastic foam.

Metagenomic insights into the potential risks of representative bio/non-degradable plastic and non-plastic debris in the upper and lower reaches of Haihe Estuary, China

As vectors for microorganisms and genetic elements, vast amounts of solid wastes, including plastics and non-plastics, enter oceans through estuaries globally. The heterogeneity of microbiomes developed on different types of plastic and non-plastic matrices and their potential environmental risks in field estuarine regions have not been fully explored. Here, microbial communities, antibiotic resistance genes (ARGs), virulence factors (VFs), and mobile genetic elements (MGEs) on substrate debris (SD) covering non-biodegradable plastics, biodegradable plastics, and non-plastics were first comprehensively characterized based on metagenomic analyzes (substrate identity). These selected substrates were field-exposed at both ends of the Haihe Estuary, China (geographic location). For substrate identity: conspicuously diverse functional gene profiles on different substrates were obtained; the relative gene copies of ARGs, VFs, and MGEs on non-biodegradable plastics were highest at both locations; non-biodegradable plastic matrices recruited the most abundant unique ARGs from ambient waters; the relative abundance of potential bacterial hosts carrying multiple ARGs and VFs (BH-AV) was much higher on non-biodegradable plastic surfaces than on the other two substrates, especially in the coastal water environment. For geographic locations: more abundant specific ARGs, VFs, and MGEs were significantly enriched on SD from the upper estuary; the average relative abundance of identified BH-AV on SD from the upper estuary was 1.99–7.14 folds from the lower estuary. Finally, the results of the Projection Pursuit Regression model verified the higher comprehensive potential risks arising from non-biodegradable plastics (substrate identity) and SD from the upstream of the estuary (geographic location). Based on comparative analysis, our results alert us to pay particular attention to ecological risks triggered by conventional non-biodegradable plastics in rivers and coastal environments and highlight the microbiological risk from terrestrial solid waste to the downstream marine environment.

Waste plastic-derived aerogel modified with graphene oxide for hygroscopic material and oil spill treatment

Plastic bags, also known as nylon bags, plastic packaging, latex bags, and bubble bags, are one of the most harmful segments of plastic waste to the ecosystem. Researchers estimate that plastic bags in natural surroundings take between 500 and 1000 years to fully decompose. Therefore, the recycling of non-biodegradable plastic products such as plastic bags is always a prime topic. In this study, plastic bags were used as raw materials for the synthesis of aerogel (PBA) and modified with graphene oxide (GO/PBA) to increase mechanical strength. Young's module results show that GO/PBA can withstand a maximum compression of about 55 N while PBA has a compressive force of only about 10 N. GO/PBA has a porous 3D structure, low density (0.026 g/cm3), and the major elements are C, O with the existence of C − O, which are suitable as hygroscopic materials. GO/PBA are able to absorb moisture up to 17 g/g compared to that of PBA with 10 g/g. Besides, GO/PBA is hydrophobically modified with PDMS (PDMS/GO/PBA) to increase selectivity in oil/water systems, oil spill treatment application with high oil adsorption capacity reaching 27 g/g, about 10 times the mass of the material. Thus, GO/PBA and PBMS/GO/PBA were successfully synthesized for the application of desiccant and oil adsorbent, respectively. The kinetics of the two adsorption processes are shown by pseudo-order first and second models.

Physicochemical, mechanical and barrier properties of semi‐refined carrageenan packaging films incorporated with germinated fenugreek seed extract

This work investigates the physicochemical, mechanical and barrier properties of edible packaging films based on semi‐refined κ‐carrageenan (SRC) plasticized with sorbitol and enriched with a water extract of germinated fenugreek seeds (W‐GeFS). The results showed that the incorporation of W‐GeFS into SRC films did not change their water solubility, but their moisture content increased when W‐GeFS was added at 1525 %. The incorporation of 120 % W‐GeFS increased significantly the tensile strength, reaching values comparable to or higher than those reported for conventional nonbiodegradable plastic films. A significant increase in the elongation at break was observed in SRC film containing 15 % W‐GeFS. Besides that, with the addition of 110 % W‐GeFS, Young’s modulus of SRC films significantly increased, indicating an increase in their stiffness. Significant enhancement on water vapor-barrier ability was achieved with the addition of 1 % W‐GeFS. Interestingly, light and oil barrier properties were remarkably improved after W‐GeFS incorporation. Microstructural studies of selected SRC films indicated that W‐GeFS is compatible with the SRC matrix and formed a compact film structure. In conclusion, SRC films containing W‐GeFS could be ideal candidates for sustainable food packaging.

Experimental examination of concrete using hazardous plasti-fiber and rub – fiber

The most typical building material is concrete. It is used by communities all over the world second only to water. On the other hand, an increasing environmental threat is caused by the accumulation of unmanaged or non-decomposable waste from industries, such as plastic, rubber, tin, and others. As a result, it is actively encouraged to prepare concrete using unmanaged materials. However, there are few studies on using plastic and rubber as fibers in cement concrete. The current study focuses on the mechanical properties of Plasti-Fiber Reinforced Concrete (PFRC) and Rub - Fiber Reinforced Concrete (RFRC) made from hand shredded plasti- fibers 10 mm × 50 mm consisting of 40-µm polyethylene (PE) plastic bags and polyethylene teraphthalite (PET) bottles in a 1:4 ratio and cycle tyre rubber. The shear behaviour of PFRC and RFRC beams have been studied. At ages of 7 and 28 days, the M25 grade PFRC and RFRC with 0.25% and 0.5% fibers were evaluated for mechanical properties compared to conventional concrete. It was discovered that increasing the dose of plasti-fiber enhanced the compressive, flexural, and split tensile strength of PFRC. Concrete's mechanical properties were increased by 4%, 14%, and 17% with additions of 0.25 and 0.5% plastic fiber, as well as by 1%, 6%, and 10%. While additions of 0.25 and 0.5% of rubber fiber enhanced each by 7%, 15%, and 21% and 9%, 18%, and 26%, respectively. As a result, the use of non-biodegradable plastics and rubber as concrete fibers allows for greater sustainability through more effective and better concrete.

Green preparation of 3D micronetwork eugenol-encapsuled porous starch for improving the performance of starch-based antibacterial film

In order to find a non-enzymatically treated alternative wall material with effective encapsulation properties, and to reduce the use of conventional non-biodegradable plastics, a novel 3D-micronetwork porous starch (3D-MPS) was created via a modified sacrificial template method to encapsulate eugenol (3D-EMPS) and used to incorporate with TiO2-starch film, for significantly improving the performance of starch-based antibacterial film. At the template SiO2 nanoparticles concentration of 0.1 %, the 3D-MPS exhibited anticipated alveolate structure with internal aperture of approximately 10 μm confirmed by SEM. With addition of 3D-EMPS, higher tensile strength (29.70 Mpa) and water barrier property (924 g/cm2·24 h) of the composite film was obtained. Moreover, molecular docking technique was used to model the intermolecular forces, which showed that the major forces maintaining the internal bonding of the composite film were hydrogen bonding and the interaction between eugenol and 3D-MPS skeleton in 3D-EMPS. Meanwhile, the composite film demonstrated the expected eugenol retardation and antimicrobial capacity against S. aureus, E. coli, and B. subtilis. Finally, the composite films were used for evaluating the feasibility in the actual food, which largely extended its shelf life compared to the negative control. This high-performance film revealed their potential for packaging materials application.

A study on the mechanical behavior of concrete made with partial replacement of fine aggregate with waste plastic (LDPE)

Waste plastic disposal is a worldwide environmental problem due to the health risks it poses and the difficulty it presents when trying to landfill it. Due to the high expense of disposal and the need for extensive landfill space, waste plastic is frequently dumped in an unauthorized and haphazard manner. Reusing waste is important from a variety of perspectives because it minimizes environmental pollution, sustain and conserves non-renewable natural resources, and helps not only to recycle but also to save energy during the production. Hence, there is an urgent need to explore alternative approaches for reusing plastic waste for other purposes, and concrete has been identified as one of the viable option. The construction industry has grown substantially as a result of population increase and urbanization, resulting in increased demand for natural materials like fine and coarse aggregate. Reusing non-biodegradable plastic waste materials allows for both lowering environmental danger and reducing the usage of natural resources for construction. This study investigated the effect of utilizing Low-Density Poly-Ethylene (LDPE) as partial replacement for fine aggregate in concrete. The impact of plastic material on the mechanical and physical properties was investigated. Five different mixes of M20 Grade concrete, one each with 0%, 5%, 10%, 15%, and 20% LDPE in replacement of sand, were prepared with a water-cement ratio of 0.5. Concrete specimens were cast to estimate the concrete strength. Replacing of fine aggregate by 5%-20% with plastic waste, the strength in compression of the plastic concrete is observed to reduce by about 35 to 50%. Depending on the mechanical properties obtained from experimental studies with different LDPE replacement levels, the obtained concrete can be utilized to non-structural components without a high compressive strength requirement.

Environmental evaluation of polyhydroxyalkanoates from animal slaughtering waste using Material Input Per Service Unit

The massive production and extensive use of fossil-based non-biodegradable plastics are leading to their environmental accumulation and ultimately cause health threats to animals, humans, and the biosphere in general. The problem can be overcome by developing eco-friendly ways for producing plastics-like biopolymers from waste residues such as of agricultural origin. This will solve two currently prevailing social issues: waste management and the efficient production of a biopolymer that is environmentally benign, polyhydroxyalkanoates (PHA). The current study assesses the environmental impact of biopolymer (PHA) manufacturing, starting from slaughterhouse waste as raw material. The Material Input Per Service Unit methodology (MIPS) is used to examine the sustainability of the PHA production process. In addition, the impact of shifting from business-as-usual energy provision (i.e., electricity from distribution grid network and heat provision from natural gas) to alternative renewable energy sources is also evaluated. As a major outcome, it is shown that the abiotic material contribution for PHA production process is almost double for using hard coal as an energy source than the petro-plastic low-density-poly(ethene) (LPDE), which PHA shall ultimately replace. Likewise, abiotic material contribution is 43 % and 7 % higher when using the electricity from the European electricity mix (EU-27 mix) and biogas, respectively, than in the case of LDPE production. However, PHA production based on wind power for energy provision has 12 % lower abiotic material input than LDPE. Furthermore, the water input decreases when moving from the EU-27 mix to wind power. The reduction in water consumption for various electricity provision resources amounts to 20 % for the EU-27 mix, 25 % for hard coal, 71 % for wind, and 70 % for biogas. As the main conclusion, it is demonstrated that using wind farm electricity to generate PHA is the most environmentally friendly choice. Biogas is the second-best choice, although it requires additional abiotic material input.

Mechanical degradation of sugar palm crystalline nanocellulose reinforced thermoplastic sugar palm starch (TPS)/poly (lactic acid) (PLA) blend bionanocomposites in aqueous environments

Abstract The concerning issue regarding petrochemical plastic wastes had prompted scientists and researchers to develop biodegradable plastic in effort to tackle environmental pollution. Alternative bioresources such as poly (lactic acid), sugar palm starch and nanocellulose fibre were utilized in producing cheap, biodegradable and sustainable plastic with satisfactory mechanical properties for food packaging application. In this study, sugar palm crystalline nanocellulose (SPCNC) was priorly dispersed in thermoplastic sugar palm starch (TPS) before melt blended with poly (lactic acid) (PLA) and later compress moulded into a sheet form. Initial biodegradation test of PLA100 and all PLA/TPS blends bionanocomposite samples indicated that PLA60TPS40 has the least variation in weight loss due to the good miscibility between TPS and PLA promoting the reinforcement of SPCNC. Greater weight losses in seawater (17.54%), river water (18.97%) and sewer water (22.27%) result in greater mechanical degradation as observed at the reduction of tensile strength from 12.11 MPa to 2.72 MPa in seawater, 1.48 MPa in river water and 0.40 MPa in sewer water. Similarly, higher weight losses in seawater (22.16%), river water (21.6%) and sewer water (23.09%) correlated with the reduction of flexural strength from 18.37 MPa to 3.5 MPa in seawater, 3.83 MPa in river water and 3.6 MPa in sewer water. The scanning electron microscope (SEM) images of tensile fracture morphology demonstrated clear porous structure due to the removal of starch particles by microbial activity. The homogenous structure of PLA60TPS40 had a steady and consistent degradation, which wholly diminished the interfacial adhesion that led to mechanical properties losses. The mechanical strength reduction clarified that the biodegradation rate within the media used might be able to resolve the excessive non-biodegradable plastic waste in open waters.

Murraya koenigii extract blended nanocellulose-polyethylene glycol thin films for the sustainable synthesis of antibacterial food packaging

Non-biodegradable plastics are a worldwide problem that have a negative impact on all living things, including humans. Nanocellulose, an excellent biopolymer is known for their increasing uses in food, healthcare, cosmetics, and various other fields. Nanocellulose is readily biodegradable, bioderived, and useful for creating innovative bioplastics that are employed in the production of food packaging and wound dressing. Curry leaves (Murraya koenigii) belongs to the rutaceae family and has many health benefits. Synthesis of Murraya koenigii incorporated nanocellulose thin films, and its characterisation using FT-IR, and XRD is discussed in detail. The source of nanocellulose in this study is sugar cane bagasse, an easily available agricultural residue in Kerala. Also, a biocompatible plasticizer is utilised to produce antibacterial packaging for food. The synthesised nanocomposites showed non-toxicity against THP1-derived macrophage cells and significant antibacterial activity against gram positive and gram-negative bacteria suggesting the possible application as a viable alternative for food packaging materials.

Biodegradable polymers – research and applications

Abstract The major concern in ecology we are facing in this era of modernization is environmental pollution due to non-biodegradable plastics. Because of its low cost, readily available nature, light weight, corrosion resistance, and added additives, it is adaptable and suitable for a wide range of applications. But the problem is that most of the petroleum-based plastics are not recyclable. Recycling and degradation of plastics are time-consuming and also release harmful chemicals, which pose a great threat to the environment. It is the need of the modern era to focus on the production of biodegradable and eco-friendly polymers as alternatives to these plastics. Nowadays, plant-based polymers are coming onto the market, which are easily degraded into soil with the help of microorganisms. However, commercialization is less due to its high production costs and the requirement for large agricultural lands for production, and their degradation also necessitated the use of special composting techniques. It is urgently needed to produce good quality and a high quantity of biodegradable polymers. The microorganisms are often searched for and screened from the carbon-rich and nutrient-deficient environment, but the commercial value of the polymers from microorganisms is very costly. Moreover, the currently explored microbes like Ralstonia eutropha, Aspergillus eutrophus, Cupriavidus necator, etc. are producing polymers naturally as a carbon reserve. But the quality as well as quantity of production are low, which means they cannot meet our requirements. So, the main aim of this chapter is to focus on the wide applications of different biodegradable polymers from plants, animals and even microbes and recent advancements in their production and improvement of biopolymers to increase their quality and quantity from natural sources, as well as their applications in packaging, the medical field, aquaculture, and other various fields for the commercialization of the product.

A State-of-the-Art Review on the Technological Advancements for the Sustainable Management of Plastic Waste in Consort with the Generation of Energy and Value-Added Chemicals

Plastic waste poses a serious threat to the environment and it has been increasing at an alarming rate. In 2022, global plastic waste generation was reported to be around 380 million tonnes as compared to 353 million tonnes in 2019. Production of liquid fuel from plastic waste is regarded as a viable method for disposing of the plastic and utilizing its energy. Currently, a wide range of technologies have been explored for turning plastic waste into fuel, including the conventional pyrolysis, incineration, gasification and advanced oxidation. However, a systematic summary and comparative analysis of various technologies has still not reported. Traditional non-biodegradable plastic waste (NPW) treatment methods include landfilling and incineration, but these methods encounter bottlenecks and are unable to adequately address NPW issues. This review attempts to present a thorough summary of treatment methods for plastic waste (both conventional and novel treatment technologies that have recently been reported), examine their mechanism and their current state of development. Furthermore, the superiority and drawbacks of each technology are analysed and the prospects of technology application are proposed. By tackling the problems of white pollution and energy scarcity, this review intends to inspire the use of solid waste as a source of energy.

From trash to treasure: Sourcing high-value, sustainable cellulosic materials from living bioreactor waste streams

The appreciation of how conventional and fossil-based materials could be harmful to our planet is growing, especially when considering single-use and non-biodegradable plastics manufactured from fossil fuels. Accordingly, tackling climate change and plastic waste pollution entails a more responsible approach to sourcing raw materials and the adoption of less destructive end-of-life pathways. Livestock animals, in particular ruminants, process plant matter using a suite of mechanical, chemical and biological mechanisms through the act of digestion. The manure from these “living bioreactors” is ubiquitous and offers a largely untapped source of lignocellulosic biomass for the development of bio-based and biodegradable materials. In this review, we assess recent studies made into manure-based cellulose materials in terms of their material characteristics and implications for sustainability. Despite the surprisingly diverse body of research, it is apparent that progress towards the commercialisation of manure-derived cellulose materials is hindered by a lack of truly sustainable options and robust data to assess the performance against conventional materials alternatives. Nanocellulose, a natural biopolymer, has been successfully produced by living bioreactors and is presented as a candidate for future developments. Life cycle assessments from non-wood sources are however minimal, but there are some initial indications that manure-derived nanocellulose would offer environmental benefits over traditional wood-derived sources.

Physicochemical characteristics of Pangasius sp. skin-gelatin-based-edible film enriched with silver nanoparticles

Background: Edible films intended for food packaging have been produced from hydrocolloids, lipids, resins, and composites, including gelatin. Gelatin is known to have a good filming ability and has been suggested as an alternative to non-biodegradable plastics. Naturally active compounds incorporated into film packaging may not only protect the food product from oxidation and microbial contamination, but they may also alter the physicochemical properties of the film. Silver nanoparticles have been used in food packaging as active agents due to their antibacterial and antifungal properties. The addition may affect the characteristics of the packaging. Therefore, this study aims to determine the effect of the addition of silver nanoparticles on the physicochemical characteristics of edible film from Pangasius sp. skin gelatin Methods: Mangrove extract of Bruguiera gymnorrhiza was used to synthesize silver into nanoparticle size. In this study, silver nanoparticles (AgNPs) with different concentrations (0, 2, 4 and 8%) were added into gelatin-based edible film. The edible films produced were observed for their physicochemical characteristics, including thickness, tensile strength, elongation, water vapour transmission, moisture content, pH, and colour. Results: AgNPs affected the colour of the fish-gelatin-based edible film, as an increased concentration of AgNPs resulted in a darker film. Nevertheless, the addition of AgNPs showed no significant effect on the thickness (145–216 µm), tensile strength (14.58–19.72 MPa), elongation (21.86–54.19%), water vapour transmission (30. 91–42.55 g/m2/day), moisture content (9.57–11.16%) or pH (5.92–6.01) of the fish-gelatin-based edible film. Conclusions: The addition of AgNPs has no significant effect on gelatin-based edible film physicochemical properties except colour. Therefore, the incorporated edible film has the potential to be developed further.

Water bottles or tap water? A descriptive-social-norm based intervention to increase a pro-environmental behavior in a restaurant

The impact of humanity's behavior on the ecological environment is a hot topic that has been widely studied over the past few years. The consumption of plastic bottled water has steadily increased, even in countries where the quality of tap water is considered excellent. This poses a problem for the environment for multiple reasons, for example: emissions due to transportation and non-biodegradable plastic waste. This paper addresses the issue of how policy-makers implement interventions aimed at increasing the consumption of tap water instead of bottled water. Specifically, it investigates how the use of a descriptive social norm in a restaurant might reduce the plastic bottled water consumption. Results show that the presence of the message “TWO IN THREE PEOPLE FROM THIS AREA DRINK TAP WATER” induced a significant impact on behavior because it decreased plastic bottled water sales by 12 percentage points, from 96% to 84%, considering only the 4055 water requests, bottled or tap, and not the overall number of drink orders. Behavioral public policy is discussed to discourage bottled water consumption.

Investigation of the use of non-biodegradable waste materials in concrete via experimental research

Plastic trash disposal is a big problem in current time, since the usage of plastics is rising all the time, and plastic material took 100 years to degrade. There are several practical solutions for recycling and repurposing plastics being developed. This research investigates the use of non-biodegradable plastic aggregate generated from high density polyethylene (HDPE) waste in place of natural fine aggregate in concrete. To determine the best replacement, substitute fine aggregate weight by 10 %, 20 %, 25 %, or 30 %. Compressive strength, split tensile strength, and flexural strength tests are performed on hardened concrete as well as basic tests on fresh concrete, such as the slump cone test and compaction factor test, to determine the characteristics and behavior of concrete utilizing plastic aggregate. The results of concrete generated strength in the hardened condition of concrete and basic tests on fresh concrete, such as the slump cone test and compaction factor test, were taken care of after the casted specimens were tested for various days, such as the 7th, 21st, and 28th days. After testing for 7, 14, and 28 days, the outcomes of concrete made with plastic aggregate are contrasted with those of conventional concrete.

Mechanical properties of tef starch based edible films: Development and process optimization

The non-biodegradable synthetic plastic is one of the greatest challenges facing the food packaging business since it seriously harms the environment. To solve this problem, non-biodegradable plastic may be disposed of more affordably and with less harm on the environment by using edible starch-based biodegradable film. Therefore, the present study was focused on the development and optimization of tef starch based edible films based on mechanical properties. In this study response surface methodology was employed by considering 3–5g of tef starch, 0.3–0.5% of agar and 0.3–0.5% of glycerol. The prepared film showed the tensile strength of 17.97–24.25 Mpa, elongation break of 1.21–2.03%, elastic modulus of 17.58–108.69 MPa, puncture force of 2.55–15.02 N, puncture formation of 9.59–14.95 mm. The findings showed that as glycerol concentrations in the film-forming solution increased, the prepared tef starch edible films' tensile strength, elastic modulus, and puncture force declined while their elongation at break and puncture deformation increased. Tef starch edible films' mechanical characteristics, including as tensile strength, elastic modulus, and puncture force, were increased by the increase of agar concentration. The optimized (from 5 gm tef starch, 0.4 g agar and 0.3% glycerol) tef starch edible film exhibited higher tensile strength, elastic modulus, and puncture force while lower elongation at break and puncture deformation. The composite edible film based tef starch with agar exhibited good mechanical properties and can be suggested for application in food industry as food packaging.

Polysaccharides for Biodegradable Packaging Materials: Past, Present, and Future (Brief Review).

The ecological problems emerging due to accumulation of non-biodegradable plastics are becoming more and more urgent. This problem can be solved by the development of biodegradable materials which will replace the non-biodegradable ones. Among numerous approaches in this field, there is one proposing the use of polysaccharide-based materials. These polymers are biodegradable, non-toxic, and obtained from renewable resources. This review opens discussion about the application of polysaccharides for the creation of biodegradable packaging materials. There are numerous investigations developing new formulations using cross-linking of polymers, mixing with inorganic (metals, metal oxides, clays) and organic (dyes, essential oils, extracts) compounds. The main emphasis in the present work is made on development of the polymer blends consisting of cellulose, starch, chitin, chitosan, pectin, alginate, carrageenan with some synthetic polymers, polymers of natural origin, and essential oils.

Formation of polyhydroxyalkanoates using agro and industrial waste as a substrate – a review

ABSTRACT In the present scenario, rising environmental concerns of non-biodegradable plastic pollution and depletion of petroleum based raw materials lead to the development of biopolymers. The biodegradability of biopolymers gives them a specific advantage for the environmental concerns. Polyhydroxyalkanoates (PHAs) are a type of biopolymers which are synthesized by microorganisms. Although there are different substrates available in pure forms which are currently used in the production of PHA, 40% of production cost depends on the expensive substrate which is a major disadvantage and make it far from many applications. The use of an inexpensive carbon source which is high in organic matter content such as waste streams of process industries can make this process viable and diminish PHA production cost. This study explores the current research initiatives on various agricultural and industrial waste feedstocks, formulations and processing conditions for producing PHA in a way that is both inexpensive and beneficial to the environment. The creation of fermentation conditions and metabolic engineering techniques for promoting microbial growth and PHA synthesis were also discussed in the review.

Effects of plastic-derived carbon dots on germination and growth of pea (Pisum sativum) via seed nano-priming

Seed nano-priming is a promising technology employed in the agronomic field to promote seed germination and plant growth. However, the effects of carbon dots (CDs) on plant development via seed nano-priming remain unclear. In the present study, CDs synthesized from non-biodegradable plastic wastes were adopted as a nano-priming agent for pea (Pisum sativum) seed treatment. The results demonstrated positive effects of seed priming at all CD concentrations (0.25–2 mg/mL), including accelerated seed germination rate, increased shoot and root elongation, biomass accumulation, and root moisture level compared to the control groups. Surface erosion of seed coat was observed after CD priming, which effectively promoted seed imbibition capability. CD penetration, internalization, and translocation were confirmed using transmission electron microscopy. Furthermore, the CD-plant interaction significantly enhanced seed antioxidant enzyme activity, as well as augmented root vigor, chlorophyll content, and carbohydrate content. These findings exhibit great potential of waste-derived CDs as nano-priming agents for seed germination and seedling development in a cost-effective and sustainable manner.