Investigation on the effect of several parameters involved in the biodegradation of polyethylene (PE) and low-density polyethylene (LDPE) under various seawater environments.

This work investigates the biodegradation of polyethylene (PE) and low-density polyethylene (LDPE) and the leaching of their harmful additives. Micro/macro-plastics of both types were subjected to different laboratory-controlled conditions for 3 months. Gas Chromatography-Mass Spectroscopy (GC-MS) results revealed that leachate concentrations ranged from 0.40 ± 0.07 µg/L to 96.36 ± 0.11 µg/L. It was concluded that the additives' leaching process was promoted by light. However, light was not the only factor examined; microorganisms, pH, salinity, aeration/mixing and temperature influenced the biodegradation process, too. GC-MS results showed a prodigious impact on the biodegradation process when Pseudomonas aeruginosa was added to the artificial seawater compared to plastics exposed to light/air only. Scanning Electron Microscopy (SEM) micrographs demonstrated a significant alteration in the plastics' morphologies. Similarly, Fourier-Transform Infrared Spectroscopy (FTIR) spectra showed obvious changes in plastics characteristic peaks, especially microplastics. Furthermore, it was shown that PE was more susceptible to degradation/biodegradation than LDPE. Inductively Coupled Plasma-Optical Emission Spectroscopy (ICP-OES) findings showed that some toxic metals were present in water samples after experiments, with concentrations above the permissible limits. For instance, bio-augmentation/bio-stimulation experiments showed that the concentrations of Pb, Sr, and Zn were 0.59 mg/L, 70.09 mg/L, and 0.17 mg/L, respectively; values above the permissible limits. It is crucial to emphasise that plastics must be meticulously engineered to avoid environmental and human impacts, originated from their degradation by-products. Furthermore, a holistic approach engaging stakeholders, researchers, policymakers, industries and consumers, is essential to effectively tackle the global challenge of marine plastic pollution.

New polyvinyl alcohol/gellan gum-based bioplastics with guava and chickpea extracts for food packaging.

Plastic is a fossil-based synthetic polymer that has become an essential material in our daily life. Plastic pollution resulting from the accumulation of plastic objects has become problematic for our environment. Bioplastic can be a biodegradable environmentally friendly alternative for the synthetic plastic. In this paper, bioplastics based on polyvinyl alcohol (PVA)/gellan gum (GG) blend have been produced in three different compositions and their chemical structure, mechanical, morphological and thermal properties have been studied. Glycerol has been used as a plasticizer. To add extra features to the PVA/GG bioplastic, Psidium guajava (guava) leaves, GL, and chickpea, CP, extracts have been added to the PVA/GG (30/70) blend. Water and aqueous ethanol have been used in the extraction of GL and CP, respectively. The addition of the plant's extracts enhanced the tensile properties of the PVA/GG bioplastic. Weathering acceleration tests have been carried out to examine the degradation of the prepared bioplastics. Cytotoxicity studies revealed that the prepared bioplastic is safe to be used in food packaging applications. Water and oxygen permeability for the new PVA/GG bioplastic have also been studied. The addition of the plant extracts (GL and CP extracts) increased the oxygen and water permeability to different extents. Bioplastic life cycle assessment (LCA) and CO2 emissions in comparison to fossil-based plastic have been investigated. From all the results, PVA/GG based bioplastic proved to be a degradable, safe and effective alternative for fossil-based plastics in food packaging applications.

A novel, robust mechanical strength, and naturally degradable double crosslinking starch-based bioplastics for practical applications.

The increasing number of petroleum-based plastics has caused severe environmental pollution, which has attracted great research interest in the development of low-cost, renewable, and degradable starch-based bioplastics. However, developing starch-based bioplastics with robust mechanical strength, excellent water resistance, and thermal resistance remains a great challenge. In this study, we presented a simple and efficient method for preparing high-performance novel starch-based bioplastics with chemical and physical double crosslinking network structures filled with 2,2,6,6-tetramethylpiperidine 1-oxy-oxidized cellulose nanofibers and zinc oxide nanoparticles. Compared with pure starch-based bioplastics, the tensile strength of the novel robust strength starch-based bioplastics increased by 431.2 %. The novel starch-based bioplastics exhibited excellent mechanical properties (tensile strength up to 24.54 MPa), water resistance, thermal resistance, and biodegradability. In addition, the novel starch-based bioplastics could be reused, crushed, dissolved, and re-poured after use. After recycling, the novel starch-based bioplastics could be discarded in the soil to achieve complete degradation within six weeks. Owing to these characteristics, the novel starch-based bioplastics are good alternatives used to replace traditional petroleum-based plastics and have great development prospects.

Plastic Interactions with Pollutants and Consequences to Aquatic Ecosystems: What We Know and What We Do Not Know.

Plastics are a group of synthetic materials made of organic polymers and some additives with special characteristics. Plastics have become part of our daily life due to their many applications and uses. However, inappropriately managed plastic waste has raised concern regarding their ecotoxicological and human health risks in the long term. Due to the non-biodegradable nature of plastics, their waste may take several thousands of years to partially degrade in natural environments. Plastic fragments/particles can be very minute in size and are mistaken easily for prey or food by aquatic organisms (e.g., invertebrates, fishes). The surface properties of plastic particles, including large surface area, functional groups, surface topography, point zero charge, influence the sorption of various contaminants, including heavy metals, oil spills, PAHs, PCBs and DDT. Despite the fact that the number of studies on the biological effects of plastic particles on biota and humans has been increasing in recent years, studies on mixtures of plastics and other chemical contaminants in the aquatic environment are still limited. This review aims to gather information about the main characteristics of plastic particles that allow different types of contaminants to adsorb on their surfaces, the consequences of this adsorption, and the interactions of plastic particles with aquatic biota. Additionally, some missing links and potential solutions are presented to boost more research on this topic and achieve a holistic view on the effects of micro- and nanoplastics to biological systems in aquatic environments. It is urgent to implement measures to deal with plastic pollution that include improving waste management, monitoring key plastic particles, their hotspots, and developing their assessment techniques, using alternative products, determining concentrations of micro- and nanoplastics and the contaminants in freshwater and marine food-species consumed by humans, applying clean-up and remediation strategies, and biodegradation strategies.

Maximizing olefin production via steam cracking of distilled pyrolysis oils from difficult-to-recycle municipal plastic waste and marine litter.

Plastic waste is steadily polluting oceans and environments. Even if collected, most waste is still predominantly incinerated for energy recovery at the cost of CO2. Chemical recycling can contribute to the transition towards a circular economy with pyrolysis combined with steam cracking being the favored recycling option for the time being. However, today, the high variety and contamination of real waste remains the biggest challenge. This is especially relevant for waste fractions which are difficult or even impossible to recycle mechanically such as highly mixed municipal plastic waste or marine litter. In this work, we studied the detailed composition and the steam cracking performance of distilled pyrolysis oil fractions in the naphtha-range of two highly relevant waste fractions: mixed municipal plastic waste (MPW) considered unsuitable for mechanical recycling and marine litter (ML) collected from the sea bottom. Advanced analytical techniques including comprehensive two-dimensional gas chromatography (GC × GC) coupled with various detectors and inductively coupled plasma - mass spectrometry (ICP-MS) were applied to characterize the feedstocks and to understand how their properties affect the steam cracking performance. Both waste-derived naphtha fractions were rich in olefins and aromatics (~70% in MPW naphtha and ~51% in ML naphtha) next to traces of nitrogen, oxygen, chlorine and metals. ICP-MS analyses showed that sodium, potassium, silicon and iron were the most crucial metals that should be removed in further upgrading steps. Steam cracking of the waste-derived naphtha fractions resulted in lower light olefin yields compared to fossil naphtha used as benchmark, due to secondary reactions of aromatics and olefins. Coke formation of ML naphtha was slightly increased compared to fossil naphtha (+ ~50%), while that of MPW naphtha was more than ~180% higher. It was concluded that mild upgrading of the waste-derived naphtha fractions or dilution with fossil feedstocks is sufficient to provide feedstocks suitable for industrial steam cracking.

Biodegradation of petroleum based and bio-based plastics: approaches to increase the rate of biodegradation.

Plastic production and consumption are on the rise due to their variety of uses. Plastics often accumulate in the environment and pose a risk due to the lack of a viable strategy for their safe disposal. Even prohibiting plastic covers does not solve the problems of plastic waste generation. Plastics are degraded by various microbes, although at a very slow rate. In addition, efforts to enhance plastic degradation efficiency by microbes are rarely addressed. This paper describes the biodegradation of both petroleum-based and bio-based plastics, as well as studies on plastic biodegradation in both the Indian and global scenarios. This paper also discusses the biochemical and molecular aspects of plastic biodegradation, which are essential since they disclose more about how bacteria break down plastics. We also shed light on initiatives to boost biodegradation rates using various strategies in this article. Understanding the enzymes and genes involved in biodegradation would also help researchers figure out how to use them to enhance microorganism's ability to degrade plastic.

Biopolymer Composites: Synthesis, Properties, and Applications.

Petroleum-based plastics can be found everywhere in our habitual life in diverse applications such as automobiles, aerospace, and medical science [...].

How blood met plastics, plant and animal extracts: Material encounters between medicine and industry in the twentieth century.

Twentieth-century medicine saw the remarkable rise of complex machines and infrastructures to process blood for medical purposes, such as transfusion, dialysis, and cardiac surgery. Instead of attributing these developments to technological ingenuity, this article argues for the primacy of material encounters as a promising focal point of medical historiography. In fact, blood's special properties consistently clashed with most materials used in medical practice, provoking a series of material exchanges. Drawing on a combination of epistemological and network approaches, three exemplary cases are presented to examine blood's encounters with plastics, plant and animal extracts: William M. Bayliss's (1860-1926) injections of dissolved gum acacia to expand diminished blood volume; Charles H. Best's (1899-1978) production of the anticoagulant heparin from animal organs; and the preservation of fragile blood cells by silicone coatings inside of John H. Gibbon Jr.'s (1903-1973) heart-lung machine. The case studies demonstrate how the complementarity of blood and these materials produced hybridizations between medicine and a range of industrial branches, from colonial forestry and meatpacking to commercial chemistry. In this light, the paper concludes by discussing the dependencies of today's healthcare environments on globally distributed, capitalistically appropriated resources in the face of crises like the COVID-19 pandemic.

Research and economic perspectives on an integrated biorefinery approach for the simultaneous production of polyhydroxyalkanoates and biohydrogen.

Alarming environmental impacts have been resulted across the globe due to the recovery and consumption of fossil fuels. The elevated global carbon footprint has paved the way to an alternative to combat the prevalent pollution. On the other hand, the fossil-based plastics produced from the byproducts of petroleum remain intact in the environment leading to pollution. Fossil abated bioproducts are in high demand due to the increase in pollution. This call to utilize feedstock for simultaneous production of biologically useful products through carbon capture utilisation where the leftover carbon-rich substrate is converted into usable chemicals like bioplastics, methanol, urea and various other industrially essential components. The present review extensively focuses on the research and economic perspectives of an integrated biorefinery and addresses technical breaches, bottlenecks, and efficient strategies for the simultaneous production of biohydrogen and polyhydroxyalkanoates.

Effect of an Antioxidant Based on Red Beetroot Extract on the Abiotic Stability of Polylactide and Polycaprolactone.

This study investigated the effect of natural antioxidants inherent to beetroot (Beta vulgaris var. Vulgaris) on the ageing of environmentally friendly plastics. Certain properties were examined in this context, comprising thermal, mechanical, and morphological properties. A visual evaluation of relevant changes in the given polymers (polylactide and polycaprolactone) was conducted during an ageing test in a UV chamber (45 °C, 70% humidity) for 720 h. The films were prepared by a casting process, in which samples with the extract of beetroot were additionally incorporated in a common filler (bentonite), this serving as a carrier for the extract. The results showed the effect of the incorporated antioxidant, which was added to stabilize the biodegradable films. Its efficiency during the ageing test in the polymers tended to exceed or be comparable to that of the reference sample.

Transparent Bioplastic Derived from CO2-Based Polymer Functionalized with Oregano Waste Extract toward Active Food Packaging.

Active packaging materials, biodegradable and from renewable resources, are the most promising substitutes of nonbiodegradable, petroleum-based plastics, toward green and sustainable packaging solutions. In this study, an innovative bioplastic system, composed of carbon dioxide-derived poly(propylene carbonate) (PPC) and nature-originated cellulose acetate (CA), was developed. The extract from oregano waste was incorporated into the bioplastics as a low-cost and effective antioxidant resource. Thin, freestanding, and flexible PPC.CA bioplastic films were obtained by a simple, easily scalable solvent casting technique. The pristine films, without the oregano extract, featured good transparency and high water vapor barrier ability, along with suitable mechanical and thermal properties that are comparable to commercial plastics used for packaging. Interestingly, the incorporation of oregano waste extract added to the bioplastics high UV protection and high antioxidant activity, suitable features for active food packaging applications, without compromising the intriguing properties of the pristine films. The biocomposite films were not only biocompatible but also started biodegrading after just 1 week in seawater. The reported biocomposites are foreseen as promising candidates for several packaging applications, but in particular for sustainable active food packaging.

Permanently Positively Charged Stable Isotope Labeling Agents and Its Application in the Accurate Quantitation of Alkylphenols Migrated from Plastics to Edible Oils.

A new permanently positively charged stable isotope labeling (SIL) agent pair, 4-(((2,5-dioxopyrrolidin-1-yl)oxy)carbonyl)-N,N,N-trimethylbenzenaminium iodide(DPTBA) and its deuterated counterpart d3-DPTBA, was designed and synthesized. The SIL agents were applied to the liquid chromatography-tandem mass spectrometry analysis of alkylphenols. Light labeled standards and heavy labeled samples were mixed and analyzed simultaneously. Matrix effect which mainly occurred during the ionization process was minimized because of the identical ionization processes between samples and standards. Meanwhile, derivatization made alkylphenols be positively charged, and thus the sensitivity was enhanced. The limits of detection were in the range of 1.5-1.8 ng/L, and the limits of quantitation were in the range of 4.8-6.1 ng/L. The developed method was applied to analyze alkylphenols migrated from plastics to edible oils. The recoveries for all analytes were in the range of 88.6-95.3%, while the matrix effects for all analytes were in the range of 96.2-99.6%.

Recycling of phosphorus-containing plastic based on the dual effects of switchable hydrophilicity solvents.

Plastic waste has caused severe environmental problems. Some additives in plastics, like organophosphates, enter the environment with plastic waste, causing significant harm to plants and creatures. However, the primary method of recycling phosphorus-containing plastic, especially polycarbonate and acrylonitrile-butadiene-styrene copolymer (PC/ABS), is a mechanical method, which not only does not effectively separate plastics and organophosphates but also tends to cause polymer degradation during recycling. In order to overcome these problems, we proposed an efficient and sustainable approach to recycle of phosphorus-containing plastic. In this method, N, N-dimethylcyclohexylamine (DMCHA), a switchable hydrophilicity solvent (SHS), was used to react with and extract organophosphates in plastic, achieving the goal of complete separation of plastic and organophosphates. PC/ABS can be recovered by precipitation. Dissolved organophosphates can also be easily recovered due to the switching characteristics of SHS. Both of recovered materials were of high purity and were close to virgin materials. This technique is an easy and efficient approach to separate plastic and organophosphates, which has excellent application prospects in recycling phosphorus-containing plastic.

Sorption behaviors of crude oil on polyethylene microplastics in seawater and digestive tract under simulated real-world conditions.

The role of plastic as a vector for bioaccumulation of hydrophobic organic pollutants has been widely studied. However, the interactions between microplastics (MPs) and crude oil, and the transfer kinetics of sorbed oil from ingested MPs into aquatic biota are largely unknown. In this study, interactions between MPs and crude oil in seawater and digestive tract mimic of aquatic biota have been examined. To mimic the living, transportation and cooking conditions of aquatic organisms, sorption and desorption behaviors were investigated under room temperature-bath (25 °C), ice-bath (0∼4 °C) and boiling water-bath (95∼100 °C), and pH was set as 4 and 7 for the simulated gut fluid. The results showed that sorption capacity of polyethylene (PE) MPs for crude oil in seawater was higher than that in intestinal tract, indicating more oil residue in aqueous phase of gut fluid in the present of organic particles. The sorption kinetics models were well fitted to the pseudo-order model, and isotherms models were well fitted to the Freundlich model. In addition, the results demonstrated that temperature played a significant effect on crude oil viscosity, and the sorption capacity under different temperatures was in the order of 25 °C > 95∼100 °C > 0∼4 °C, indicating that more oil was remained in aqueous phase at boiling water-bath and ice-bath. The increment of pH enhances the sorption capacities of PE MPs. Moreover, the desorption experiment has supplemented the current findings from the sorption experiments.

Microbial Transglutaminase as a Tool to Improve the Features of Hydrocolloid-Based Bioplastics.

Several proteins from animal and plant origin act as microbial transglutaminase substrate, a crosslinking enzyme capable of introducing isopeptide bonds into proteins between the aminoacids glutamines and lysines. This feature has been widely exploited to modify the biological properties of many proteins, such as emulsifying, gelling, viscosity, and foaming. Besides, microbial transglutaminase has been used to prepare bioplastics that, because made of renewable molecules, are able to replace the high polluting plastics of petrochemical origin. In fact, most of the time, it has been shown that the microbial enzyme strengthens the matrix of protein-based bioplastics, thus, influencing the technological characteristics of the derived materials. In this review, an overview of the ability of many proteins to behave as good substrates of the enzyme and their ability to give rise to bioplastics with improved properties is presented. Different applications of this enzyme confirm its important role as an additive to recover high value-added protein containing by-products with a double aim (i) to produce environmentally friendly materials and (ii) to find alternative uses of wastes as renewable, cheap, and non-polluting sources. Both principles are in line with the bio-economy paradigm.

Physical-Chemical Evaluation of Active Food Packaging Material Based on Thermoplastic Starch Loaded with Grape cane Extract.

The aim of this paper is to evaluate the physicochemical and microbiological properties of active thermoplastic starch-based materials. The extract obtained from grape cane waste was used as a source of stilbene bioactive components to enhance the functional properties of thermoplastic starch (TPS). The biomaterials were prepared by the compression molding technique and subjected to mechanical, thermal, antioxidant, and microbiological tests. The results showed that the addition of grape cane extract up to 15 wt% (TPS/WE15) did not significantly influence the thermal stability of obtained biomaterials, whereas mechanical resistance decreased. On the other side, among all tested pathogens, thermoplastic starch based materials showed antifungal activity toward Botrytis cinerea and antimicrobial activity toward Staphylococcus aureus, suggesting potential application in food packaging as an active biomaterial layer.

Ultrasensitive determination of organotin compounds in plastic food packaging and edible oils by sheathless capillary electrophoresis-electrospray ionization-mass spectrometry.

The determination of trace-amount organotins in plastic food packaging materials is of great significance in food safety. However, due to the complexity of organotins and sample treatment processes, it is still a challenging task. Here, we report a method for the sensitive and simultaneous determination of organotins in plastic food packaging materials and edible oils, by utilizing sheathless capillary electrophoresis-electrospray ionization-mass spectrometry. The method of sample pretreatment with ultrasonic extraction and solid phase extraction is used to eliminate interference. The results showed low limits of detection (LODs) of 2 pg mL-1-50 pg mL-1 and excellent inter/intra-day repeatability. Good average recoveries in the range of 80.27% to 108.52% were obtained at three spiked concentrations, with a relative standard deviation less than 8.71%. The successful simultaneous determination of the target analytes will pave the way for further assessment of contamination and migration behaviour of organotins from packaging materials to food, which is of great significance for evaluating and controlling food safety.

Selenium in buoyant marine debris biofilm.

Marine debris is widespread in all the world's oceans. Currently little is understood about how marine debris affects the chemistry of the surface oceans, particularly trace elements that can adsorb to the surface of marine debris, especially plastic debris, or be taken up by biofilms and algae growing on the surface of marine debris. Selenium (Se) is a micronutrient that is essential to all living organisms. Average seawater Se concentrations in the modern ocean are <1 nM. Here we measure the concentration of Se in surface water and one deep water sample and the concentration of Se found in algae/biofilms growing on the surface of macro-debris collected in October of 2012. Concentrations of Se in biofilm varied more according to the type of biofilm rather than the type of plastic. However, further Se measurements are needed for more conclusive results.

Preparation and characterization of coffee hull fiber for reinforcing application in thermoplastic composites.

Nowadays, there is an increasing concern toward substituting the scarce wood fibers with alternative lignocellulosic fibers that originate from crop residue to reinforce biocomposites. In this paper, the potential application of coffee hull (CH) of the reinforced polyethylene (PE) matrix composites was studied for the first time. Experiments of composite that enhanced with CH on mechanical properties, hydroscopicity, thermogravimetric analysis, fiber treatment, and microstructures were tested in this study. The PE matrix was reinforced with varying volume fractions of CH and was studied. The results show that incorporation of coffee hull markedly improved the mechanical properties of the reinforced high-density polyethylene (HDPE) matrix composites. Micrographs show a strong interfacial adhesion between the CH fiber particles. This property may be the main reason for the stability between composites. At the same time this work investigated the effect of different treatments on the mechanical properties and water absorption behavior of composites. The fiber surface treatments were done using active chemicals such as calcium hydroxide (Ca(OH)2), silane coupling agent (SCA), maleic anhydride grafted polypropylene (MA-g-PP), stearic acid (SA), ethylene bis stearamide (EBS) and the combination (MA-g-PP, SA, EBS). The results show that (Ca(OH)2)treatment is the best way to improve its properties. Probably because attributed to removal of surface active functional groups (-OH) from the CH fiber and induction of hydrophobicity that in turn improved the compatibility with the polymer matrix. As a result, the use of coffee hull in composites could have great significance for the industry.

Influence of aluminum oxide nanoparticle with different particle sizes on the working attributes of diesel engine fueled with blends of diesel and waste plastic oil.

In the present work, an experimental investigation was conducted to study the influence of adding aluminum oxide nanoparticles (Al2O3) with different average particle sizes as additive to blends of diesel and waste plastic oil (WPO) on performance, emission, and combustion attributes of single-cylinder diesel engine operated at a constant speed. Two samples of Al2O3 nanoparticle with average particle sizes of 20 and 100 nm were dispersed into a WPO20 blend containing 20% of WPO and 80% of diesel in the mass fractions of 10 and 20 ppm using ultrasonic stabilization. The experimental recordings revealed a decrease in engine performance and increase in all emission constituents while replacing diesel with WPO20. However, the addition of both 20- and 100-nm-sized Al2O3 nanoparticles into WPO20 was found to enhance the brake thermal efficiency (BTHE) by 12.2 and 8.9% respectively and decrease the brake-specific fuel consumption (BSFC) by 11 and 8% respectively. The emission constituents such as carbon monoxide (CO), hydrocarbons (HC), nitric oxide (NO), and smoke opacity were minimized by the addition of both 20- and 100-nm-sized nanoparticles into WPO20 blend. However, the reduction of emissions was better for 20-nm-sized particles compared with that of 100-nm-sized particles. The combustion attributes such as cylinder pressure, heat release rate (HRR), and rate of pressure rise (RPR) were raised with shortened ignition delay (ID) by the addition of both sized nanoparticles. Overall, the inclusion of 20-nm-sized nanoparticles performs better catalytic activity to enhance the engine output characteristics along with minimum exhaust emissions.