Non-biodegradable Plastics Research Articles

Review on Biodegradable Aliphatic Polyesters: Development and Challenges.

Biodegradable polymers are gaining attention as alternatives to non-biodegradable plastics to address environmental issues. With the rising global demand for plastic products, the development of non-toxic, biodegradable plastics is a significant topic of research. Aliphatic polyester, the most common biodegradable polyester, is notable for its semi-crystalline structure and can be synthesized from fossil fuels, microbial fermentation, and plants. Due to great properties like being lightweight, biodegradable, biocompatible, and non-toxic, aliphatic polyesters are used in packaging, medical, agricultural, wearable devices, sensors, and textile applications. The biodegradation rate, crucial for biodegradable polymers, is discussed in this review as it is influenced by their structural properties and environmental conditions. This review discusses currently available biodegradable polyesters, their emerging applications, and the challenges in their commercialization. As research in this area grows, this review emphasizes the innovation in biodegradable aliphatic polyesters and their role in advancing environmental sustainability.

Preparation and Performance of PBAT/PLA/CaCO3 Composites via Solid-State Shear Milling Technology

Replacing traditional disposable, non-biodegradable plastic packaging with biodegradable plastic packaging is one of the key approaches to address the issue of “white pollution”. PBAT/PLA/inorganic filler composites are widely utilized as a biodegradable material, commonly employed in the field of packaging films. However, the poor dispersion of inorganic fillers in the polymer matrix and the limited compatibility between PBAT and PLA have led to inferior mechanical properties and elevated costs. In this work, we propose a simple and effective strategy to improve the dispersion of nano-CaCO3 in a PBAT/PLA matrix through solid-state shear- milling (S3M) technology, combined with mechanochemical modification and in situ compatibilization to enhance the compatibility between PBAT and PLA. The impact of varying milling conditions on the structure and performance of the PBAT/PLA/CaCO3 composites was investigated. During the milling process, PBAT and PLA undergo partial molecular chain fragmentation, generating more active functional groups. In the presence of the chain extender ADR during melt blending, more branched PBAT-g-PLA is formed, thereby enhancing matrix compatibility. The results indicate that the choice of milling materials significantly affects the structure and properties of the composite. The film obtained by milling only PBAT and CaCO3 exhibited the best performance, with its longitudinal tensile strength and fracture elongation reaching 22 MPa and 437%, respectively. This film holds great potential for application in the field of green packaging.

Genome-Centric Metagenomics Insights into the Plastisphere-Driven Natural Degradation Characteristics and Mechanism of Biodegradable Plastics in Aquatic Environments.

Biodegradable plastics (BPs) are pervasively available as alternatives to traditional plastics, but their natural degradation characteristics and microbial-driven degradation mechanisms are poorly understood, especially in aquatic environments, the primary sink of plastic debris. Herein, the three-month dynamic degradation process of BPs (the copolymer of poly(butylene adipate-co-terephthalate) and polylactic acid (PLA) (PBAT/PLA) and single PLA) in a natural aquatic environment was investigated, with nonbiodegradable plastics polyvinyl chloride, polypropylene, and polystyrene as controls. PBAT/PLA showed the weight loss of 47.4% at 50 days and severe fragmentation within two months, but no significant decay for other plastics. The significant increase in the specific surface area and roughness and the weakening of hydrophobicity within the first month promoted microbial attachment to the PBAT/PLA surface. Then, a complete microbial succession occurred, including biofilm formation, maturation, and dispersion. Metagenomic analysis indicated that plastispheres selectively enriched degraders. Based on the functional genes involved in BPs degradation, a total of 16 high-quality metagenome-assembled genomes of degraders (mainly Burkholderiaceae) were recovered from the PBAT/PLA plastisphere. These microbes showed the greatest degrading potential at the biofilm maturation stage and executed the functions by PLA_depolymerase, polyesterase, hydrolase, and esterase. These findings will enhance understanding of BPs' environmental behavior and microbial roles on plastic degradation.

Bioplastic films from starch of Colocasia esculenta and its waste: A smart template for sensing applications

The over usage plastics have possessed serious threat to the ecological system. Thus progressive advancement in fabricating biodegradable and renewable bioplastics is persuasively required to furnish an effective alternative to non-biodegradable plastics. In this view, the current work highlights the production of starch based bioplastic films using waste Colocasia esculenta (taro herb) as a viable starting precursor. The functional ability of developed taro starch based film was further modified by incorporating carbon dots (CQDs) fillers generated from the waste slurry produced during starch extraction from taro herbs. The optimization of films production was achieved by varying the CQDs amount (0.4 %, 0.8 %, 2 % and 4 % w/w) on taro-based films using casting technology. The data illustrates that the addition of CQDs has the ability to enhance the fluorescence property, mechanical properties (Tensile Strength 0.332–4.635 MPa, Elongation at break 42.45–547.63 %) and water resistance ability of films (Moisture content 15–6.4 %, Water Solubility 50–30 % Water Vapour Transmission Rate 2.0012–1.0054 g−2 h−1 and Water Contact Angle 40.6–89.6°). The developed films are found to be thermally stable. The formed films possessed anti-oxidative abilities which safeguard the film from oxidative attacks and ultimately protect the film from the external environment. The fluorescence nanosensor probe has further been developed by utilizing CQDs embedded in a starch-based bioplastic nanocomposite. The developed sensor displayed selective sensing ability towards Fe2+ ion with high sensitivity and accuracy in aqueous medium. Thus, the proposed sensor in this work offers a portable, efficient, low-cost, disposable, non-lethal, and eco-friendly nanosensor for on-site monitoring of metal ion for the food, beverage, and pharmaceutical industries. This is one of the primary reports where metal ions sensing is reported for Taro@CQDs nanocomposites based films. Our outcomes of this work hold significant relevance to providing a smart sensory and biodegradable probe for metal ion sensing by using waste resources, thus offering a better and sustainable alternative for environmental remediation applications.

Effect of Polar Aprotic Solvents on the Physical, Chemical, and Mechanical Properties of Cellulose Acetate Bioplastic Films

Abstract There has been a growing interest in bioplastics as a solution to increasing greenhouse gases and the pile up of waste caused by fossil-based non-biodegradable plastics. However, the use of harmful solvents in their synthesis may continue to be detrimental to the environment. A novel bio-based solvent, CyreneTM, is seen as an alternative to toxic polar aprotic solvents. With this, the study aimed to compare the properties of cellulose acetate (CA) bioplastic films using acetone, dimethylformamide (DMF), and CyreneTM as solvents and glycerol as the plasticizer. The following tests were used to characterize the synthesized bioplastics: Fourier-Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM), density, moisture content, biodegradability, tensile strength, Young’s Modulus, and elongation at break. CyreneTM films were found to have significantly high moisture content and elongation at break. A weight loss of 29% in biodegradation was recorded for CyreneTM films without glycerol over the course of 23 days. The properties of the CyreneTM films show that it may be applicable for mulching films and seedling containers in agricultural applications due to their high affinity for water. It can be concluded that the study of CyreneTM solvent for the synthesis of CA films and its properties contributes to greener synthesis methods for bioplastics.

Alternative and Emerging Mulch Technologies for Organic and Sustainable Agriculture in the United States: A Review

Plastic mulches made from nonbiodegradable polymers (e.g., polyethylene) provide an essential service in commercial horticultural production systems by enhancing crop productivity through weed suppression, soil moisture conservation, and moderating soil and canopy temperature conditions. Plastic mulches are particularly important in organic agriculture because weed management options are limited. Nevertheless, there is increasing concern about addressing the negative environmental impacts of plastic mulch waste. Soil-biodegradable plastic mulch (BDM) films that are designed to biodegrade in soils after incorporation are promising alternatives to nonbiodegradable plastic mulch. However, although the US organic standards technically permit the use of BDM films, no commercially available products meet National Organic Program (NOP) requirements for 100% biobased content and 90% degradation after 2 years following soil incorporation (7 Code of Federal Regulations, section 205.2). Other concerns about biodegradable film mulches include high perceived cost, esthetics, and uncertainties regarding the impacts of soil incorporation. New mulch technologies have emerged to diversify sustainable mulch options and overcome barriers associated with BDM film use in organic production. The objective of this study was to provide an overview of alternative and emerging mulch technologies, with an emphasis on biodegradable mulches, including water-based sprayable mulches such as hydromulch and foam mulch, and biobased agrotextiles. Information about how these mulch technologies contribute to organic and sustainable agriculture is provided, along with definitions, opportunities, challenges, and recommended areas for future research.

Sustainable hydrophobic coating of paper utilizing silica nanoparticles

The preparation of hydrophobic paper involved applying thin layers of non-biodegradable plastics to the paper, which made recycling difficult and contributed to microplastic pollution. In this study, we present a new method for coating paper to enhance its hydrophobic properties and long-term effectiveness of the hydrophobic surface. We use sustainable materials such as polyvinyl alcohol (PVOH), chitosan, monoaminopropyl terminated polydimethylsiloxane (PDMS), and silica nanoparticles (SiNPs). We use hexamethylene diisocyanate isocyanurate trimer (HDIT) and (3-aminopropyl)triethoxysilane (APTES) to link the chemicals covalently and to modify surface of SiNPs with amino groups, respectively. We also integrate PVOH to reduce the cost of the coating solution without compromising its hydrophobicity. We confirmed the long-lasting hydrophobicity of the coated paper by measuring the water contact angle for 60 min. When the paper coated with a solution containing amino SiNPs dispersed in ethanol, the maximum contact angle at 10 s and at 1 h were 132.3° and 95.7°, respectively. Additionally, the hydrophobic coating solution can be removed for potential recycling by treating it with hydrochloric acid or acetic acid. Our developed coating solution provides an environmentally friendly option for various paper-based applications, promoting paper recycling and contributing to sustainable development and environmental protection efforts.

Application of Active Packaging Films for Extending the Shelf Life of Red Meats: A Review

Meat is known for its high perishability and short shelf life if not properly packaged or stored. Packaging materials play a crucial role in preserving food quality, and there is a growing demand from consumers, industry professionals, and researchers for natural packaging materials that incorporate health-beneficial extracts. Additionally, there is an increasing emphasis on avoiding non-biodegradable plastics in order to reduce environmental pollution. Currently used polymers in food packaging typically feature properties such as oxygen barriers, moisture resistance, and oxidation inhibition, helping to prevent undesirable aromas, flavors, and colors in food. Packaging not only serves as a container for transportation but also prevents physical damage, maintains quality, and ensures food safety. In the pursuit of more sustainable solutions, various compounds are being explored for food packaging, including those derived from proteins, lipids, waxes, and polysaccharides. These materials can be combined with bioactive compounds, such as natural plant extracts, which provide antioxidant, antimicrobial, anti-inflammatory, and anticancer benefits. Different techniques, such as electrohydrodynamic processes and casting methods, are employed in the preparation of these packaging materials. This review highlights the applications and properties of polymers used in meat packaging and promotes the use of biodegradable materials as a viable solution to reduce environmental pollution.

Law on environmental protection in tourist villages in the context of sustainable development of the tourism industry: A qualitative case study in Vietnam

After the Covid-19 pandemic, Vietnam's tourism industry welcomed 1.37 million international visitors. For the whole year 2023, the total number of international visitors will reach 12.6 million, nearly 3.5 times higher than in 2022, exceeding 57% of the original target (8 million) and reaching the adjusted target (12 -13 million views). In Vietnam, which a country which is undergoing economic development, this is a good sign for many workers and businesses, but it can create great pressure on environmental protection in many localities with tourist destinations. For example, as a destination attracting foreign tourists in Hoi A City, Quang Nam Province, Vietnam, the average amount of waste per day is nearly 100 tons; of which single-use plastic waste accounts for 15 - 23% (Thu Huong 2022). In order to prevent and minimize environmental pollution in tourist villages, the Goverment of Vietnam has issued many different documents such as: Decree No. 08/2022/ND-CP orienting no circulation after 2025 and using single-use plastic products and non-biodegradable plastic packaging in tourist areas and destinations; Decision No. 1316/QD-TTg Project to strengthen plastic waste management in Vietnam also points out that by 2025, 100% of tourist resorts and accommodation establishments will not use single-use plastic products and plastic bags which are so hard to decompose. In addition, the Government has also issued a set of criteria guiding environmental protection for tourism establishments and services in tourist areas and destinations, with instructions on minimizing plastic waste...However, around the issue of environmental protection in tourist villages in Vietnam, there are still problems that need to be solved. Through qualitative analysis method, the authors will analyze and propose solutions to remove regulations related to environmental protection mechanisms in tourist villages, aiming at sustainable development of the tourism industry towards a circular economy in the current period.

PLASTAMINATION: Outcomes on the Central Nervous System and Reproduction.

Environmental exposures to non-biodegradable and biodegradable plastics are unavoidable. Microplastics (MPs) and nanoplastics (NPs) from the manufacturing of plastics (primary sources) and the degradation of plastic waste (secondary sources) can enter the food chain directly or indirectly and, passing biological barriers, could target both the brain and the gonads. Hence, the worldwide diffusion of environmental plastic contamination (PLASTAMINATION) in daily life may represent a possible and potentially serious risk to human health. This review provides an overview of the effects of non-biodegradable and the more recently introduced biodegradable MPs and NPs on the brain and brain-dependent reproductive functions, summarizing the molecular mechanisms and outcomes on nervous and reproductive organs. Data from in vitro, ex vivo, non-mammalian and mammalian animal models and epidemiological studies have been reviewed and discussed. MPs and NPs from non-biodegradable plastics affect organs, tissues and cells from sensitive systems such as the brain and reproductive organs. Both MPs and NPs induce oxidative stress, chronic inflammation, energy metabolism disorders, mitochondrial dysfunction and cytotoxicity, which in turn are responsible for neuroinflammation, dysregulation of synaptic functions, metabolic dysbiosis, poor gamete quality, and neuronal and reproductive toxicity. In spite of this mechanistic knowledge gained from studies of non-biodegradable plastics, relatively little is known about the adverse effects or molecular mechanisms of MPs and NPs from biodegradable plastics. The neurological and reproductive health risks of MPs/NPs exposure warrant serious consideration, and further studies on biodegradable plastics are recommended.

Eco Friendly Pharmaceutical Packaging

Abstract: Concerns over environmental contamination have been raised by the use of nonbiodegradable and non-renewable materials such as glass, plastics, and metals in packaging applications. With the goal of lessening the environmental impact of petroleum-based packaging materials, an extensive amount of research has been conducted to find alternative packaging materials. Due to their biodegradability, studies have shown that using bio-polymer-based materials can reduce the amount of packaging waste produced, which could partially address the issue of trash disposal. This review article is mainly focused on eco-friendly biodegradable material that can replace nonbiodegradable pharmaceutical packaging material. These materials come from natural resources like proteins, carbohydrates, etc. that have negligible to no negative effects on the environment and organisms that depend on it. This article depicts how we can replace the existing non-biodegradable plastics with eco-friendly material as the use of pharmaceutical packaging material also plays a crucial role in the therapeutic performance of pharmaceutical products.

Gallic Acid Based Polymers for Food Preservation: A Review.

The extensive usage of nonbiodegradable plastic materials for food packaging is a major environmental concern. To address this, researchers focus on developing biocompatible and biodegradable food packaging from natural biopolymers, such as polysaccharides, proteins, and polyesters. These biopolymer-based packaging materials extend the shelf life of food due to their inherent antimicrobial and antioxidant properties. An important additive that enhances these beneficial effects is gallic acid (GA), a naturally occurring phenolic compound. GA exhibits potent antioxidant activity by scavenging free radicals and excellent antimicrobial activity against a wide range of bacteria by disrupting cell membranes. These gallic acid based active packaging solutions have demonstrated remarkable abilities to inhibit lipid oxidation, enzymatic browning, and microbial contamination and even retard the ripening processes in mushrooms, walnuts, strawberries, fresh-cut apples, bananas, fish, pork, and beef. This review focuses on the antioxidant, antibacterial, and food preservation capabilities of GA-incorporated biodegradable food packaging materials as an eco-friendly alternative to conventional plastic packaging.

High-altitude aquatic ecosystems offer faster aging rate of plastics

While research on the aging behavior of plastics in aquatic systems is extensive, studies focusing on high-altitude ecosystems, characterized by higher solar radiation and lower temperatures, remain limited. This study investigated the long-term aging behavior of non-biodegradable plastics (non-BPs), namely polyethylene terephthalate (PET) and polypropylene (PP) and biodegradable plastics (BPs), specifically polylactic acid plus polybutylene adipate-co-terephthalate (PLA + PBAT) and starch-based plastic (SBP), in a tributary of the Yarlung Zangbo River on the high-altitude Tibetan Plateau. Over 84 days of field aging, all four types of plastics exhibited initial rapid aging followed by deceleration. This aging process can be divided into two phases: rapid surface oxidation aging and an aging plateau phase. Notably, PP aged at a rate comparable to BPs, contrary to expectations of faster aging for BPs. Compared to low-altitude aquatic ecosystems, plastics in this study showed a faster aging rate. This was primarily due to intense ultraviolet radiation causing severe photoaging. Furthermore, the lower temperatures contributed to the formation of thinner biofilms. These thinner biofilms exhibited a reduced capacity to block light, further exacerbating the photoaging process of plastics. Statistical analysis results indicated that temperature, total nitrogen TN, and total phosphorus TP were likely the main water quality parameters influencing plastic aging. The varying effects of water properties and nutrients underscore the complex interaction of water quality parameters in high-altitude environments. Given the delicate nature of the high-altitude environment, the environmental impact of plastics, especially BPs, warrants careful consideration.

Preparation of PBAT microplastics and their potential toxicity to zebrafish embryos and juveniles

The extensive use of traditional non-biodegradable plastics results in the generation of microplastics (MPs), forming a new pollutant that can pose significant environmental risks. Biodegradable plastics (BP) possess degradation properties and can partially replace conventional plastics, thereby reducing pollution. However, further investigation is needed into the toxicity of biodegradable microplastics (BMPs) on aquatic organisms. This study explores the toxic effects of PBAT microplastics (PBAT-BMPs) and microplastics produced from degradable PBAT/TPS (thermoplastic starch) composite film (PBAT/TPS-BMPs) on zebrafish embryos. Our findings indicate that the presence of microplastics on the embryo's surface increases with higher BMPs concentration. Nonetheless, PBAT-BMPs tend to aggregate and are blocked by the embryonic membrane, thus diminishing their toxic effects on the embryo. Acute toxicity experiments revealed that 30 mg/L of PBAT-BMPs significantly reduced the survival rate of zebrafish embryos, whereas PBAT/TPS-BMPs had a lesser effect on survival. Both types of BMPs influenced the hatching rate of the embryos, leading to prolonged incubation periods. Additionally, both types of BMPs impacted the locomotor behavior of zebrafish larvae, causing an increase in larval locomotor speed. However, these BMPs had little impact on larval body development and heartbeat behavior. Fluorescent microplastic tracer experiments demonstrated that PBAT-BMPs persisted in juvenile fish for at least 144 h and were difficult to metabolize and excrete. Our study aims to gain a better understanding of the potential effects of BMPs on aquatic ecosystems and biological health, as well as to propose effective strategies for reducing environmental pollution and protecting organisms.

Microplastic-induced hepatic adverse effects evaluated in advanced quadruple cell human primary models following three weeks of repeated exposure

Nano and microplastics are defined as particles smaller than 100 nm and 5 mm respectively. The widespread production and use of plastics in everyday life has resulted in significant accumulation of plastic debris in the environment. Over the last two decades there are increased concerns regarding the potential entry and accumulation of plastics in the human body with ingestion being one of the most important routes of exposure. However, the magnitude and nature of potential toxic effects of plastic exposure to human health is not yet fully understood. The liver is the body's principal detoxification organ and critically to this study recognized as the main accumulation site for particulates. In this study as the first of its kind the health impacts of long term low repeated polystyrene microplastics (1 and 5 μm) exposure was investigated in a functionally active 3D liver microtissue model, composed of primary human hepatocytes, Kupffer cells, sinusoidal endothelial cells and hepatic stellate cells. The highlight from the data includes microplastic-induced dose (3.125–25 μg/ml) and time dependent (up to 504 h) increase in cell death and inflammation manifested by enhanced release of IL6, IL8 and TNF-α. The exposure to repeated dosing of the plastics also resulted in notable pathology manifested as aberrant tissue architecture, such as dilated bile canaliculi and large lipid droplets inside the hepatic cells. This toxicity matched extremely well to the accumulation of the materials with the cells of microtissue predominately in the organ macrophages. This study highlights the real issue and danger of microplastic exposure with potential for long-term accumulation and adverse effects of non-biodegradable plastics within the liver.

ADAPTABLE MATERIALS FOR SUSTAINABLE DEVELOPMENT: A FOCUS ON SANITARY PADS

Menstrual hygiene is a vital health issue affecting millions of women and girls globally, impacting their physical health, dignity, and participation in various social, educational, and economic activities (Sommer et. al., 2016). Traditional sanitary pads, predominantly composed of non-biodegradable plastics and synthetic fibres, pose severe environmental challenges, taking hundreds of years to decompose and contributing to significant waste (Garside & Sutherland, 2019). These conventional products lead to landfill overload, water pollution, air pollution from incineration, and related health hazards (Smith, 2020). Additionally, the economic and social barriers posed by the high cost of these products disrupt education, workplace participation, and perpetuate social stigmas (Kuhlmann, 2018). This paper examines the use of adaptable materials to create sustainable sanitary pads, focusing on innovative materials like biodegradable and reusable options (White & O'Neill, 2021). It highlights the potential for technological advancements to revolutionize menstrual hygiene management, aligning with the Sustainable Development Goals (SDGs) related to health, gender equality, responsible consumption, and climate action (United Nations, 2021). The paper also presents case studies of successful initiatives worldwide, addressing challenges and proposing solutions to promote widespread adoption of sustainable menstrual hygiene products (Chaudhary & Dhawan, 2022). Through collaborative efforts in education, policy-making, and community engagement, sustainable sanitary pads can contribute significantly to a healthier, more equitable, and environmentally friendly future (Jones, 2023).

Materials based on biodegradable polymers chitosan/gelatin: a review of potential applications.

Increased mass manufacturing and the pervasive use of plastics in many facets of daily life have had detrimental effects on the environment. As a result, these worries heighten the possibility of climate change due to the carbon dioxide emissions from burning conventional, non-biodegradable polymers. Accordingly, biodegradable gelatin and chitosan polymers are being created as a sustainable substitute for non-biodegradable polymeric materials in various applications. Chitosan is the only naturally occurring cationic alkaline polysaccharide, a well-known edible polymer derived from chitin. The biological activities of chitosan, such as its antioxidant, anticancer, and antimicrobial qualities, have recently piqued the interest of researchers. Similarly, gelatin is a naturally occurring polymer derived from the hydrolytic breakdown of collagen protein and offers various medicinal advantages owing to its unique amino acid composition. In this review, we present an overview of recent studies focusing on applying chitosan and gelatin polymers in various fields. These include using gelatin and chitosan as food packaging, antioxidants and antimicrobial properties, properties encapsulating biologically active substances, tissue engineering, microencapsulation technology, water treatment, and drug delivery. This review emphasizes the significance of investigating sustainable options for non-biodegradable plastics. It showcases the diverse uses of gelatin and chitosan polymers in tackling environmental issues and driving progress across different industries.

Cassava bagasse starch and oregano essential oil as a potential active food packaging material: A physicochemical, thermal, mechanical, antioxidant, and antimicrobial study

This research evaluates the use of cassava bagasse starch and oregano essential oil (OEO) in an active film. For comparison, films of cassava starch (CS) and cassava bagasse starch (BS) were prepared with OEO at 1, 2, and 3 %. Physical, thermal, mechanical, antioxidant, and antimicrobial properties were determined. BS films presented higher thickness, WVP, ΔE, modulus of elasticity, and maximum stress, but lower strain at break compared to CS films. Adding OEO into the films increased their thickness, moisture, solubility, WVP and strain at break. However, maximum stress, modulus of elasticity, and Tdmax decreased. The CS films added with 3 % of OEO showed higher WVP (6.32 × 10−14 kg m/m2.s.Pa), intermediate solubility of 39 % and low maximum stress (0.19 MPa) while the BS film with 3 % of OEO presented 5.73 × 10−14 kg m/m2.s.Pa, 30 % and 0.39 MPa, respectively. The increase from 1 % to 3 % of OEO increased the total phenolic compound content and antioxidant activity of the films by 1.3-fold and 3.7-fold, respectively. The incorporation of 3 % OEO in the films inhibited the growth of S. aureus and E. coli. Therefore, BS and OEO films offer a promising solution as biodegradable active food packaging, providing a more sustainable alternative to traditional non-biodegradable plastic packaging.

Investigation of the mechanical, microstructure, and durability properties of concrete with fine uniform and non-uniform polyethylene terephthalate (PET) aggregates

Concrete manufacturing is highly resource-intensive and is a major source of greenhouse gas emission. Accelerating depletion of natural resources such as sand, which is the primary material for aggregate in concrete manufacture is a growing problem. At the same time, the disposal of vast volumes of non-biodegradable plastic waste poses a global environmental challenge. The incorporation of aggregates derived from municipal plastic waste to substitute for sand has the potential to help address both issues, while at the same time mitigating greenhouse gas emission. This study examines the potential of municipal polyethylene terephthalate (PET) plastic waste as a fine aggregate in concrete manufacturing. The primary focus was on PET aggregates with non-uniform and uniform shapes ranging in size from 2.36 to 4.75 mm. In the concrete mixtures, 0 %, 30 %, and 50 % of the fine natural aggregate by volume were replaced with fine PET aggregate with a water to cement ratio of 0.40. The obtained results showed a reduction in compressive and splitting tensile strength when compared to control specimens. However, replacing 30 % of fine natural aggregate with PET (both uniform and non-uniform shapes) significantly improved chloride resistance by 13 % and 12 %, respectively, while also enhancing the bond between cement paste and PET particles. This study characterizes the material properties of PET concrete, which represents a promising method for reusing municipal plastic waste and mitigating environmental concerns in concrete production.

Photocatalytic Cracking of non-Biodegradable Plastics to Chemicals and Fuels.

Plastic pollution is worsening the living conditions on Earth, primarily due to the toxicity and stability of non-biodegradable plastics (NBPs). Photocatalytic cracking of NBPs is emerging as a promising way to cleave inert C-C bonds and abstract the carbon atoms from these wastes into valuable chemicals and fuels. However, controlling these processes is a huge challenge, ascribed to the complicated reactions of various NBPs. Herein, we summarize recent advances in the CO2 and carbon-radical-mediated photocatalytic cracking of NBPs, with an emphasis on the pivotal intermediates. The CO2-mediated cracking proceeded with indiscriminate C-H/C-C bond cleavage of NBPs and tandem photoreduction of CO2, while carbon-radical-mediated cracking was realized by the prior activation of C-H bonds for selective C-C bond cleavage of NBPs. Catalytic generation and conversion of different intermediates greatly depend on the kinds of active species and the structure of photocatalysts under irradiation. Meanwhile, the fate of a specific intermediate is compared with small molecule activation to reveal the key problems in the cracking of NBPs. Finally, the challenges and potential directions are discussed to improve the overall efficiency in the photocatalytic cracking of NBPs.