Plastic Decomposition Research Articles

Microplastic Pollution in Riparian Soils of the Rapidly Growing City of Thimphu, Bhutan

Plastic has become a vitally important material for humans; however, the large amount of plastic waste generated annually pollutes the environment. Plastic decomposition generates microplastics (MPs), which have emerged as a concerning global environmental pollutant because of their potential to be more harmful to the environment than their larger counterparts. This study examined the occurrence and abundance of MPs in riparian soils (RS) of a rapidly growing city in Thimphu, Bhutan. Additionally, the study investigated the relationships between the abundance of MP and several variables, such as the physicochemical properties of the soil, land use, the distance to impervious cover (IC), the plot IC%, surface plastic, textile waste, and the distance to upstream drainage outlets within the riparian zone (RZ). A density separation technique was used to extract MPs. The results showed that RS in urban sites had higher concentrations of MPs (93.3%) than in other land use (7.7%, p = 0.04). Blue MPs (46.2%) were the most common plastic colour. In urban RS, MPs ranged from 0 to 500 particles/kg. MP concentration showed a positive correlation with available phosphorus (p = 0.01) and the distance to the upstream drainage outlets (p = 0.01). Our findings highlight the nature and pathways of MP pollution in rapidly growing cities, where economic growth often overshadows environmental management. We also identify opportunities for these cities to mitigate MP pollution by reclaiming surface plastic and textile waste, stepping up recycling initiatives, and disposing of plastic-ridden waste in low-impact landfills.

Characteristics of low-temperature plasma for activation of plastic-degrading microorganisms

Plastic pollution is a problem that threatens the future of humanity, and various methods are being researched to solve it. Plastic biodegradation using microorganisms is one of these methods, and a recent study reported that plastic-degrading microorganisms activated by plasma increase the plastic decomposition rate. In contrast to microbial sterilization using low-temperature plasma, microbial activation requires a stable plasma discharge with a low electrode temperature suitable for biological samples and precise control over a narrow operating range. In this study, various plasma characteristics were evaluated using SDBD (Surface Dielectric Barrier Discharge) to establish the optimal conditions of plasma that can activate plastic-degrading microorganisms. The SDBD electrode was manufactured using low-temperature co-fired ceramic (LTCC) technology to ensure chemical resistance, minimize impurities, improve heat conduction, and consider freedom in designing the electrode metal part. Plasma stability, which is important for microbial activation, was investigated by changing the frequency and pulse width of the voltage applied to the electrode, and the degree of activation of plastic-degrading microorganisms was evaluated under each condition. The results of this study are expected to be used as basic data for research on the activation of useful microorganisms using low-temperature plasma.

Simulation investigation on heating characteristics of catalysts under microwave irradiation for decomposition of waste plastic

Microwave heating is a promising technique for heterogeneous catalytic reactions in plastic decomposition. The microwave-insensitive plastic material requires microwave-absorbing catalysts to facilitate catalytic-assisted decomposition and synergistic heating. However, the heating characteristics of catalyst particles within the microwave system is still unclear. In this study, the effects of particle size, particle arrangement direction, and particle shape on the microwave heating behavior of particles was investigated, and the model was experimentally validated and analyzed using infrared temperature data. The simulation results indicated that the heating rate increased as the particle size enlarged, with an average heating rate of 5.56 °C/s for the particle with a radius of 5 mm in comparison to 4.29 °C/s for that of 1 mm. Additionally, when particles were aligned parallel to the applied electric field, the electric field was intensely focused at the interparticle area, with a maximum electric field strength difference of 2.2 × 104 V/m in the samples. In contrast, the horizontal placement resulted in reduced electric field intensity (4.7 × 103 V/m) and lower temperatures (62 °C) near the areas adjacent to the particles compared to the maximum values in the particles. With respect to particle shape, cylindrical particles possessing larger aspect ratios exhibited superior heating performance due to the extended span of intraparticle microwave transmission aligned with the electric field direction but also resulted in increased thermal field distribution inhomogeneity. The research offers theoretical guidance to prevent catalyst sintering and promote microwave-assisted catalytic plastic decomposition.

Developing a circular economy from plastic waste and identifying microplastics in domestic water supplies in Ho Chi Minh City and the Southeastern provinces

Abstract While humans are struggling to deal with plastic waste, the plastic decomposition products, namely microplastics, have silently infiltrated almost all environmental states. This study examines the feasibility of a circular economy approach for addressing plastic waste and reducing microplastics in source water in Southeastern provinces. Of the 400 households surveyed, there were 200 households in Ho Chi Minh, 50 households in Dong-naiand 150 households in Binh Duong, only 10% of household plastic waste is recycled, 33% of them are sold as scrap and 57% of them are completely processed. Out of the remaining 57% of waste, it can be the starting material to produce later stage products and create income opportunities of hundreds of billions of VND per month for Ho Chi Minh and Binh Duong province. The process of breaking down plastic waste into microplastics in the Sai Gon River and Dong Nai River has resulted in the emergence of microplastic polymers such as Polypropylene (27.1%), Polyethylene (51.2%), Polyvinyl Chloride (13.4%), and 8.3% of other plastics. These microplastics pose a significant threat to human health. The SWOT analysis identifies opportunities and challenges for implementing a circular economy approach to minimize plastic waste and microplastics in the study area.

A Valuable Source of Promising Extremophiles in Microbial Plastic Degradation.

Plastics have accumulated in open environments, such as oceans, rivers, and land, for centuries, but their effect has been of concern for only decades. Plastic pollution is a global challenge at the forefront of public awareness worldwide due to its negative effects on ecological systems, animals, human health, and national economies. Therefore, interest has increased regarding specific circular economies for the development of plastic production and the investigation of green technologies for plastic degradation after use on an appropriate timescale. Moreover, biodegradable plastics have been found to contain potential new hazards compared with conventional plastics due to the physicochemical properties of the polymers involved. Recently, plastic biodegradation was defined as microbial conversion using functional microorganisms and their enzymatic systems. This is a promising strategy for depolymerizing organic components into carbon dioxide, methane, water, new biomass, and other higher value bioproducts under both oxic and anoxic conditions. This study reviews microplastic pollution, the negative consequences of plastic use, and the current technologies used for plastic degradation and biodegradation mediated by microorganisms with their drawbacks; in particular, the important and questionable role of extremophilic multi-enzyme-producing bacteria in synergistic systems of plastic decomposition is discussed. This study emphasizes the key points for enhancing the plastic degradation process using extremophiles, such as cell hydrophobicity, amyloid protein, and other relevant factors. Bioprospecting for novel mechanisms with unknown information about the bioproducts produced during the plastic degradation process is also mentioned in this review with the significant goals of CO2 evolution and increasing H2/CH4 production in the future. Based on the potential factors that were analyzed, there may be new ideas for in vitro isolation techniques for unculturable/multiple-enzyme-producing bacteria and extremophiles from various polluted environments.

Enzyme_Metal-Organic Framework Composites as Novel Approach for Microplastic Degradation.

Plastic pollution is one of the main worldwide environmental concerns. Our lifestyle involves persistent plastic consumption, aggravating the low efficiency of wastewater treatment plants in its removal. Nano/microplastics are accumulated in living beings, pushing to identify new water remediation strategies to avoid their harmful effects. Enzymes (e. g., Candida rugosa-CrL) are known natural plastic degraders as catalysts in depolymerization reactions. However, their practical use is limited by their stability, recyclability, and economical concerns. Here, enzyme immobilization in metal-organic frameworks (CrL_MOFs) is originally presented as a new plastic degradation approach to achieve a boosted plastic decomposition in aqueous systems while allowing the catalyst cyclability. Bis-(hydroxyethyl)terephthalate (BHET) was selected as model substrate for decontamination experiments for being the main polyethylene terephthalate (PET) degradation product. Once in contaminated water, CrL_MOFs can eliminate BHET (37 %, 24 h), following two complementary mechanisms: enzymatic degradation (CrL action) and byproducts adsorption (MOF effect). As a proof-of-concept, the capacity of a selected CrL_MOF composite to eliminate the BHET degradation products and its reusability are also investigated. The potential of these systems is envisioned in terms of improving enzyme cyclability, reducing costs along with feasible co-adsorption of plastic byproducts and other harmful contaminants, to successfully remove them in a single step.

Folding of a growing hyperelastic sheet in a viscous fluid

Understanding the growth-induced deformation of soft materials in viscous environments is important for a variety of problems in nature and engineering. Here, we focus on the fluid–structure interaction of a hyperelastic sheet growing in an incompressible Newtonian fluid in the Stokes flow regime. We develop a computational framework for simulating this problem, where the isogeometric boundary integral method is used with the Kirchhoff–Love shell formulation and elastic–plastic decomposition of the deformation gradient tensor. We quantify the relative effects of the growth rate, the sheet bending rigidity, and the fluid viscosity on the fold formation and development of the growing sheet. Our results suggest that the viscous resistance to in-plane deformation promotes fold formation, whereas the viscous resistance to out-of-plane deformation suppresses fold development. We also investigate the effects of the thickness and aspect ratio of the rectangular sheet. Finally, we compare the growth- and prestrain-induced deformations to find a common behavior of sheets under viscous environments.

Effect of Waste Plastic Decomposition Oil fuel Property on Exhaust Characteristics for small 2-stroke Engine

Effect of Waste Plastic Decomposition Oil fuel Property on Exhaust Characteristics for small 2-stroke Engine

Integrating experimental and computational approaches for deep eutectic solvent-catalyzed glycolysis of post-consumer polyethylene terephthalate

To achieve a sustainable and circular economy, developing effective plastic recycling methods is essential. Despite advances in the chemical recycling of plastic waste, modern industries require highly efficient and sustainable solutions to address environmental problems. In this study, we propose an efficient glycolysis strategy for post-consumer polyethylene terephthalate (PET) using deep eutectic solvents (DESs) to produce bis(2-hydroxyethyl) terephthalate (BHET) with high selectivity. Choline chloride (ChCl)- and urea-based DESs were synthesized using various metal salts and were tested for the glycolysis of PET waste; ChCl–Zn(OAc)2 exhibited the best performance. The DES-containing solvent system afforded a complete PET conversion, producing BHET at a high yield (91.6%) under optimal reaction conditions. The degradation mechanism of PET and its interaction with DESs were systematically investigated using density functional theory-based calculations. Furthermore, an intuitive machine learning model was developed to predict the PET conversion and BHET selectivity for different DES compositions. Our findings demonstrate that the DES-catalyzed glycolysis of post-consumer PET could enable the development of a sustainable chemical recycling process, providing insights to identify the new design of DESs for plastic decomposition.

Continuum kinematics with incompatible-compatible decomposition.

We present a framework for the kinematics of a material body undergoing anelastic deformation. For such processes, the material structure of the body, as reflected by the geometric structure given to the set of body points, changes. The setting we propose may be relevant to phenomena such as plasticity, fracture, discontinuities and non-injectivity of the deformations. In this framework, we construct an unambiguous decomposition into incompatible and compatible factors that includes the standard elastic-plastic decomposition in plasticity. This article is part of the theme issue 'Foundational issues, analysis and geometry in continuum mechanics'.

Effect of Sorbitol and Chitosan Addition on Tensile Strength and Degradation Rate of Biodegradable Plastic from Rice Bran Starch

The increasing use of plastic can cause enviromental pollution because plastic takes a very long time to decompose in the soil. Solutions that can be used to accelerate the process of plastic decomposition in the soil by replacing plastic making materials with natural polymer materials. Natural polymers are polymers produced from organic monomers, one of which is starch. Starch is one of the natural polymer materials used in the manufacture of biodegradable plastics, one of the natural materials containing starch is rice bran waste. From rice bran waste starch, bioderadable plastic can be made by adding chitosan and sorbitol by varying then succesively, namely 5:2:8, 5:3:7, 5:5:5, 5:7:3, 5:10:0, then making samples, then the samples are printed and tensile strength testing and degradation testing are carried out. From the tensile strength test results, the values obtained were 0.69 Mpa, 0.74 Mpa, 1.50 Mpa, 1.98 Mpa and 2.28 Mpa, respectively. The finel weight of the sampel after degradation is 0 gram, 0 gram, 0.0189 gram, 0.0226 gram, 0.1017 gram. It is concluded that biodegardable plastic with good tensile strength is in the variation of starch 5 grams, without sorbitol and chitosan 10 grams and for good degradation test in the variation of starch 5 grams, sorbitol 8 ml, chitosan 2 grams and variation of starch 5 grams, sorbitol 7 ml, chitosan 3 grams.

Pyrolysis and combustion kinetics of refuse derived fuel having different plastic ratio

This study reports the effect of plastic variation on the decomposition kinetics, and thermodynamic parameters of refuse-derived fuel (RDF) in the N2 and O2 atmospheres. Two simulated RDF compositions were analyzed: RDF-1 with 35 %-plastics, and RDF-2 with 5 %-plastics. Thermo-gravimetric analysis was conducted at multiple heating rates. The activation energy (E) and the pre-exponential factor (A) were determined using both Kissinger-Akahira-Sunnose, Flynn–Wall–Ozawa methods and the compensation factor method, respectively. In N2-atmosphere, increasing plastic fraction from 5 % to 35 %, increased both E, and A values from 169 to 259 kJ mol−1 and 1.6 × 1010 to 1.2 × 1023 s−1, respectively, due to higher energy requirement for plastic decomposition. However, an increase in plastic fraction reduces the fixed‑carbon content of RDF, which leads to a decrease in E and A values in the O2-atmosphere from 126 to 105 kJ mol−1 and 3.5 × 1016 to 1.6 × 106 s−1, respectively.

H-ZSM-5 Catalysts for the catalytic upcycling of polypropylene glycol

Without effective management, the steady increase of waste plastics threatens environmental well-being and ecological balance. Plastic up/recycling is a promising solution but has many challenges. In this work, catalytic cracking of polypropylene glycol (PPG) was investigated at varying reaction temperatures of 350–550 °C under nitrogen and steam, using H-ZSM-5 zeolites with different silica-to-alumina (SiO2/Al2O3) ratios of 23:1 and 50:1. The catalysts were assessed through physisorption, chemisorption, solid-state magic-angle spinning nuclear magnetic resonance spectrometry, thermogravimetry, electron microscopy, and positron annihilation lifetime spectroscopy. Extra framework aluminum and Lewis-to-Bronsted acid site ratios were found to play a significant role in the selectivity towards propionaldehyde, where values ∼ 80 % could be reached. In addition, a possible pathway for the PPG cracking reaction was proposed, which may lead to a better understanding of PPG and waste plastic decomposition via zeolite-based catalysts.

Degradation of Bio-Based and Biodegradable Plastic and Its Contribution to Soil Organic Carbon Stock.

Expanding the use of environmentally friendly materials to protect the environment is one of the key factors in maintaining a sustainable ecological balance. Poly(butylene succinate-co-adipate) (PBSA) is considered among the most promising bio-based and biodegradable plastics for the future with a high number of applications in soil and agriculture. Therefore, the decomposition process of PBSA and its consequences for the carbon stored in soil require careful monitoring. For the first time, the stable isotope technique was applied in the current study to partitioning plastic- and soil-originated C in the CO2 released during 80 days of PBSA decomposition in a Haplic Chernozem soil as dependent on nitrogen availability. The decomposition of the plastic was accompanied by the C loss from soil organic matter (SOM) through priming, which in turn was dependent on added N. Nitrogen facilitated PBSA decomposition and reduced the priming effect during the first 6 weeks of the experiment. During the 80 days of plastic decomposition, 30% and 49% of the released CO2 were PBSA-derived, while the amount of SOM-derived CO2 exceeded the corresponding controls by 100.2 and 132.3% in PBSA-amended soil without and with N fertilization, respectively. Finally, only 4.1% and 5.4% of the PBSA added into the soil was mineralized to CO2, in the treatments without and with N amendment, respectively.

Partial differential equations to determine elasto-plastic stress–strain behavior from measured kinematic fields

A system of partial differential equations (PDEs) is derived to compute the full-field stress from an observed kinematic field when the flow rule governing the plastic deformation is unknown. These equations generalize previously proposed equations that assume pure plastic behavior without elasticity. A method to numerically solve these equations is also presented. In addition to force balance, the equations are derived from the elastic–plastic decomposition of the deformation gradient, the assumption of isotropy, and the assumption that the function mapping the elastic strain to stress is known. The system of equations can be directly applied to complex geometries, finite deformation, non-linear elasticity and plasticity, compressible materials, rate dependent materials, and a variety of hardening laws. This system of PDEs is non-linear and time dependent. Furthermore, it overcomes an important prior limitation: it can be directly applied to cases where some regions of a body are elastically deforming while others are elasto-plastically deforming. A two-dimensional case study of necking in a uniaxial tensile specimen is investigated to illustrate and validate the method. The governing equations are numerically solved using strain fields output from a finite element simulation and validated against this same simulation showing accurate results.

Remediation technology towards zero plastic pollution: Recent advance and perspectives

The rapid growth of plastic wastes exceeds efforts to eliminate plastic pollution owing to the outbreak of COVID-19 in 2020 and then aggravates inherent environmental threats to the ecosystem. The paper provided a short introduction relating to the hazards of plastic wastes on environment and a detailed statement about plastic toxicity on human. The article stated on plastic how to enter the body and cause harm for us step by step. Given the toxicity and harm of plastic wastes on human, the degradation of plastic wastes via the physical, chemical and biotic methodologies is looked back. The advanced physical techniques are introduced briefly at firstly. Additionally, evaluate on chemical method for plastic decomposition and review on biotic degradation of plastic. The reactive oxygen species and the enzymes play a crucial role in chemical and biotic degradation processes, respectively. The reactive oxygen species are derived from the activated state of oxides, and the enzymes that aid the microorganism to ingest plastic through its metabolic mechanism are secreted by the microorganism. Subsequently, the potential possibility of upcycling plastic is analyzed from two aspects of the technology and application. The innovative technology utilizes sunlight as driver-power of plastic upcycling. And the carbon capture, utilization and sequestration and the growth substrate provided the novel guided directions for plastic recycle. Lastly, the three suggestions on plastic waste management are expected to establish an economy and efficient plastic sorting system, and two engineering solutions on plastic recycle are to make a contribution for sustainable upcycling of plastic.

Di-(2-ethyl hexyl) phthalate induced oxidative stress promotes microplastics mediated apoptosis and necroptosis in mice skeletal muscle by inhibiting PI3K/AKT/mTOR pathway

The plastic decomposition product microplastics (MPs) and the plastic additive Di (2-ethylhexyl) phthalate (DEHP) in the environment can damage various organs of the organism by inducing oxidative stress. The PI3K/AKT/mTOR signaling pathway participate in toxin-induced apoptosis and necroptosis. However, the effects of DEHP/MPs alone and combined exposure on skeletal muscle cell injury in mice and the role of PI3K/AKT/mTOR axis remain unclear. To investigate the effect of DEHP or/and MPs on skeletal muscle in mice and its possible toxicological mechanism, 60 mice were randomly divided into control group, DEHP group (DEHP 200 mg/kg dissolved in 50 mL corn oil mixed with 2.5 kg diet), MPs group (10 mg/L MPs in drinking water) and combined exposure group. In vitro, C2C12 cells were exposed to DEHP 600 μM/MPs 800 μM alone or in combination for 24 h. The results showed that DEHP/MPs exposure alone or in combination increased MDA content, decreased activities of CAT, T-AOC, SOD and GSH-Px, increased mRNA and protein expressions of Caspase-3, BAX, RIPK1, RIPK3 and MLKL, and decreased BCL-2 expression. The expression of PI3K/AKT/mTOR signaling pathway was significantly down-regulated. All the above results showed that the combined exposure group was more toxic, and similar experimental results were obtained by DEHP/MPs exposure test of C2C12 cells in vitro. It is suggested that DEHP/MPs can induce apoptosis and necroptosis by activating oxidative stress and down-regulating PI3K/AKT/mTOR pathway. This study provides new evidence for clarifying the possible mechanism of toxicity of DEHP and MPs to skeletal muscle of mice.

Microalgae as a Source of Biopolymer - A Comprehensive Review

The growth in overall demand for plastic materials has given rise to the manufacture and utilization of plastic articles throughout the world. This has led to extreme waste production, negatively influencing terrestrial and marine life. Microplastics lead to the endangerment of health. Therefore, plastic decomposition is a difficult task. Chemical treatments, recycling, carbonizing, and landfills aren’t ideal solutions for lowering plastic pollution. As a result of this, there is a need to

A constitutive model for elastic–plastic materials using scalar conjugate stress/strain base pairs

A constitutive model for elastic–plastic materials is developed using scalar, conjugate, stress–strain, base pairs in a finite deformation setting. These conjugate base pairs arise from an alternative QR decomposition of the deformation gradient that decomposes its matrix into an orthogonal rotation and an upper-triangular matrix, called the Laplace stretch. This decomposition is particularly useful from an experimental standpoint, as it enables one to directly measure the components of Laplace stretch and its plastic contributions in a specific coordinate system. Moreover, from an experimental standpoint, it is difficult to parameterize current material models due to a covariance between their tensor invariants, traditionally used in their constructions. The use of scalar, conjugate, base pairs are also helpful from that point of view. Interestingly, the multiplicative elastic–plastic decomposition of Laplace stretch leads to an additive decomposition of the total strain attributes into their corresponding elastic and plastic components. Although an additive strain decomposition is commonly used in small-strain theory, here such a decomposition is possible even for finite deformations. An additive decomposition of the strain attributes has a deeper consequence in the construction of our constitutive model. A maximum rate of dissipation criterion has been used in deriving our constitutive equations, as this criterion is valid for a wider class of materials. Two constitutive assumptions – one for a Helmholtz potential, and one for the rate of dissipation function – are required for our constitutive construction. This model does not presuppose the existence of a yield surface. In fact, it is shown that whether a material exhibits a yielding or a creep-like behavior depends upon the differentiability of the rate of dissipation function. Two cases of plastic deformation – volume-preserving and dilatant-pressure dependent deformations – have been considered. To illustrate the proposed model, finite strain versions of classical J2 plasticity and a Drucker–Prager model are derived.

Lensless digital holographic microscopy as an efficient method to monitor enzymatic plastic degradation

A big challenge of the 21st century is to cope with the huge amounts of plastic waste on Earth. Especially the oceans are heavily polluted with plastics. To counteract this issue, biological (enzymatic) plastic decomposition is increasingly gaining attention. Recently it was shown that polyethylene terephthalate (PET) can be degraded in a saltwater-based environment using bacterial PETase produced by a marine diatom. At moderate temperatures, plastic biodegradation is slow and requires sensitive methods for detection, at least at initial stages. However, conventional methods for verifying the plastic degradation are either complex, expensive, time-consuming or they interfere with the degradation process. Here, we adapt lensless digital holographic microscopy (LDHM) as a new application for efficiently monitoring enzymatic degradation of a PET glycol copolymer (PETG). LDHM is a cost-effective, compact and sensitive optical method. We demonstrate enzymatic PETG degradation over a time course of 43 days employing numerical analysis of LDHM images.