可降解塑料特征分析与快速鉴别方法研究进展

塑料污染是一个重大的全球环境问题。可降解塑料替代传统塑料制品成为缓解塑料污染的重要手段,但市场中可降解塑料虚假宣传等现象频发。综述了近年来塑料分析的几种常见方法以及它们的优点和局限性,旨在为可降解塑料的特征分析和快速鉴别提供一定的理论依据和技术支持,为市场监管提供有力的帮助。随着可降解塑料的快速发展和普及,其检测分析技术需要向更快速、更准确的方向不断发展进步。     

可降解塑料特征分析与快速鉴别方法研究进展

塑料污染是一个重大的全球环境问题。可降解塑料替代传统塑料制品成为缓解塑料污染的重要手段,但市场中可降解塑料虚假宣传等现象频发。综述了近年来塑料分析的几种常见方法以及它们的优点和局限性,旨在为可降解塑料的特征分析和快速鉴别提供一定的理论依据和技术支持,为市场监管提供有力的帮助。随着可降解塑料的快速发展和普及,其检测分析技术需要向更快速、更准确的方向不断发展进步。     

Converting Waste Plastic to Liquid Organic Hydrogen Carriers

The accumulation of waste plastics in landfills and the environment, as well as the contribution of plastics manufacturing to global warming, call for the development of new technologies that would enable circularity for synthetic polymers. Thus far, emerging approaches for chemical recycling of plastics have largely focused on producing fuels, lubricants, and/or monomers. In a recent study, Junde Wei and colleagues demonstrated a new catalytic system capable of converting oxygen-containing aromatic plastic waste into liquid organic hydrogen carriers (LOHCs), which can be used for hydrogen storage. The authors utilized Ru−ReO_x/SiO₂ materials with zeolite HZSM-5 as a co-catalyst for the direct hydrodeoxygenation (HDO) of oxygen-containing aromatic plastic wastes that yield cycloalkanes as LOHCs with a theoretical hydrogen capacity of ≈5.74 wt % under mild reaction conditions. Subsequent efficiency and stability tests of cycloalkane dehydrogenation over Pt/Al₂O₃ validated that the HDO products can serve as LOHCs to generate H₂ gas. Overall, their approach not only opens doors to alleviating the severe burden of plastic waste globally, but also offers a way to generate clean energy and ease the challenges associated with hydrogen storage and transportation.     

Study on pyrolysis behavior and kinetics of waste plastics with spent FCC catalyst

Pyrolysis is the most promising method for treating plastic waste since it can convert waste plastics into high value-added products, which have significant application potential. In this study, kinetic and thermodynamic analyses of spent fluid catalytic cracking (FCC) catalysts were performed for testing their applicability in catalytic cracking of mixed plastics. Thermogravimetric analysis data were obtained at different heating rates under an inert atmosphere, and the synergistic effect between the mixed plastics and activation energy reduction before and after pretreatment of the spent FCC catalysts was discussed. Through a variety of model-free methods (Flynn-Wall-Ozawa, Kissinger-Akahira-Sunose, Starink, and Kissinger methods), it is proved that the spent FCC catalyst facilitates the reduction in activation energy required for the pyrolysis of plastics, which is reduced by approximately 13% from 278 to 242 kJ/mol. The catalytic performance of spent FCC catalyst was improved after pretreatment, while its activation energy decreased by approximately 21% from 278 to 220 kJ/mol. The Friedman-Reich-Levi method was used to fit the curve, and the number of mechanism functions in plastic pyrolysis was determined according to the slope of the fitting curve. The C-R method was used in combination with the Malek method to determine the optimal mechanism function. Moreover, kinetic parameters of the spent FCC catalyst for catalytic cracking of plastics were obtained via kinetic studies on the pyrolysis of mixed plastics, which provided theoretical guidance for industrialization of plastic pyrolysis.     

Reducing Environmental Plastic Pollution by Designing Polymer Materials for Managed End-of-Life

Plastics are widely used synthetic materials in various industries worldwide. The abundance of plastics, which are mainly carbon-based polymers, has led to a significant accumulation of plastic waste in landfills and the environment due to their durability and affordability. Although plastic pollution of the oceans has been known for many years, there is still limited knowledge about the composition, distribution, impact, and fate of plastic waste in the environment. In this review, the focus is on environmental pollution by plastics, highlighting the source (feedstock) and degradation behavior of these materials. The goal is to provide insights for material design strategies that address the management of plastic waste at the end of its life cycle. The authors argue that the development of materials labeled marine biodegradable or universally biodegradable is not a sufficient solution on its own to address plastic pollution. Instead, it is critical to incorporate practical plans for recovery and treatment into material and product design principles. These plans should be based on existing systems or possibly developed in parallel. In summary, this article highlights the widespread pollution of the environment by plastics and emphasizes the need for comprehensive material design strategies that include not only biodegradability but also practical recovery and treatment methods. By considering the entire lifecycle of plastics, we can work to reduce the harmful impact of plastic waste on our planet.     

聚氨酯泡沫塑料吸附-电感耦合等离子体质谱(ICP-MS)法测定地球化学样品中的痕量金

探讨了聚氨酯泡沫塑料的预处理、样品浓度、水洗条件、基体元素对金吸附率的影响等因素。结果表明,用泡沫塑料吸附含金量为5 ng~500μg的溶液,吸附率均在90%以上。影响聚氨酯泡沫塑料吸附率的重要条件是振荡前要用水充分浸透,水洗基体元素,矿渣宜在酸性环境下进行。铁、钛等离子可以提高吸附率,钠、钙、锌、矿渣等影响不显著,铝离子有微弱的抑制作用。ICP-MS的灵敏度与介质的雾化率有一定的相关性,应当使用硫脲介质的工作溶液作工作曲线,内标元素可用103Rh或185Re,但是对于高含量W样品,只能使用103Rh作内标。用金矿石国家标准物质做精密度与准确度验证,测定值与标准值无显著差异,相对标准偏差(RSD)均小于10%,精密度能满足地球化学样品中痕量金的分析要求。     

How will additives shape the future of plastics?

Additives are essential components of plastic formulations providing maintenance and/or modification of polymer properties, performance and long-term use. The extension of polymer properties by additives has played a substantial role in the growth of plastics. At the beginning of the plastics age additives were used mainly to maintain polymer properties and to help plastics to survive heat treatment during transforming processes. The next generation of additives provided extension of service life as well as modification of mechanical and physical properties. These well-established additives - antioxidants, heat stabilizers, light stabilizers and others - cover the requirements of standard plastics and today's mass applications. The more recent developments of high-performance additives address more stringent or new requirements, more severe processing and use conditions and/or environmental concerns, but still with the main target of maintaining plastic properties. The future will introduce more and more new effects and functionalities through additives in plastic applications tailoring the properties of polymers and offering a vast potential of innovation in the plastics area. Recent examples of emerging technologies show that additives will not only modify the polymer itself and add new properties, but can also, when incorporated into the plastic, beneficially impact properties, which are of high value for the user. The paper shows the role of additives used in plastics from the past to the present with the focus on stabilization and performance of additives incorporated during melt processing, and outlines future trends.     

Quantification of heavy metals for the recycling of waste plastics from electrotechnical applications

Analytical data on element concentrations in plastics is an important prerequisite for the recycling of technical waste plastics. The chemical resistance and high additive contents of such materials place a high demand on analytical methods for quantifying elements in thermoplastics from electrotechnical applications. The applicability of three common independent analytical methods (EDXRF, AAS, ICP-AES) for the quantification of heavy metals in such technical waste plastics of varying composition was studied. Following specific sample pre-treatments, such as closed vessel microwave assisted digestion and wet ashing with H(2)SO(4), three hazardous metals (Pb, Cd, Sb) were determined. Conditions were investigated to minimize matrix effects for all analytical techniques employed. The trueness for the quantification of Cd was checked by using the certified reference material VDA 001-004 (40-400 mug g(-1) Cd in polyethylene), and no significant differences to certified values were found. The best detection limits were found to be 2, 1.3 and 7.9 mug g(-1) for Cd, Pb and Sb, respectively. In technical waste polymers, Sb was detected to be in the range 1-7%, Cd in the range 80-12 000 mug g(-1) and Pb in the range 90-700 mug g(-1). The precision reached for the analysis of this complex material, is comparable for all methods, and can be expressed by a relative standard deviation smaller than 8%. Application of multivariate analysis of variances (MANOVA) showed no differences between the mean results, except for the ICP-AES analysis following wet ashing with H(2)SO(4).     

Development of irradiation conditions for neutron activation analysis of inorganic trace impurities in plastics for microelectronic applications

The difficulties of analyzing plastics of high purity by chemical analysis methods have led to the application of neutron activation analysis. Because literature quotes pressure build-up in the irradiation containers as the reason for limited activation intensity the behavior of the six plastics PVI, PMMA, PVDF, PE, FEP and Silicone had to be investigated. The investigations showed, that pressure build-up was not the limiting factor. Furthermore hydrogen generation under irradiation seems to be the reason for explosions of ampoules by an oxyhydrogen reaction. The question of the ignition source could not be answered yet. To prevent oxyhydrogen reaction, the ampoules have to be filled with nitrogen. The experiments have shown, that if suitable sample masses and ampoule volumes are selected, even high neutron fluences can be applicated. After determining the permissible irradiation conditions, the impurity content of 30 elements in the six plastics were determined using destructive and nondestructive NAA.     

An accurate and sensitive analysis of trace and ultratrace metallic impurities in plastics by NAA

Neutron activation analysis (NAA) has been studied to improve the accuracy and sensitivity of the analysis of trace and ultratrace metallic impurities in plastic materials. There are two main problems in the analysis of plastics by NAA. First the contamination during sample preparation, especially sample crushing procedure is very serious for ultratrace analysis. Another problem is the destruction of the sample capsule due to the pressure build-up by the gases formed during neutron irradiation. A simple preparation technique of the sample crushing method using liquid nitrogen and reducing the capsule pressure by a pin hole was developed to solve the above problems. Two different irradiation and seven cooling conditions were also investigated to optimize the experimental conditions. A SRM from NIST (1632b coal) has been used to investigate the accuracy of the analysis. More than thirty elements could be analyzed in the range of sub-ppb to percent. Samples analyzed in this work were polyethylene and polypropylene which were made by different manufacturing procedure, and pigments. Two kinds of plastic products used for food and drug containers were also analyzed. It was found that NAA could be a powerful technique for the analysis of metallic impurities in plastics even though their concentrations were at ultratrace levels.     

Plastics waste management in Europe

Environmental concern about waste problems and regulatory measures from the governments have increased during the last decade. Plastics waste management has become a major strategic issue for the European plastics industry. A statistical study provides data on plastics consumption, post-users plastics waste arisings based on a life-time analysis and plastics recovery in the year 1989. An end-use sectorial split-up into sectors like municipal solid waste, automotive waste, agricultural waste, construction, as well as large distribution waste, will serve as a base for an integrated plastics waste management concept including recycling of mono-material and co-mingled waste, chemical recycling, energy recovery and landfill. An overview gives examples for ongoing plastics recycling activities in Western Europe and an outlook to the year 2000 is presented.     

Biodegradability of conventional and bio-based plastics and natural fiber composites during composting,anaerobic digestion and long-term soil incubation

Plastics are a major constituent of municipal solid waste that pose a growing disposal and environmental pollution problem due to their recalcitrant nature. To reduce their environmental impacts and allow them to be transformed during organic waste recycling processes, various materials have recently been introduced to improve the biodegradability of plastics. These include conventional plastics amended with additives that are meant to enhance their biodegradability, bio-based plastics and natural fiber composites. In this study, the rate and extent of mineralization of a wide range of commercially available plastic alternative materials were determined during composting, anaerobic digestion and soil incubation. The biodegradability was assessed by measuring the amount of carbon mineralized from these materials during incubation under conditions that simulate these three environments and by examination of the materials by scanning electron micrography (SEM). The results showed that during a 660 day soil incubation, substantial mineralization was observed for polyhydroxyalkanoate plastics, starch-based plastics and for materials made from compost. However, only a polyhydroxyalkanoate-based plastic biodegraded at a rate similar to the positive control (cellulose). No significant degradation was observed for polyethylene or polypropylene plastics or the same plastics amended with commercial additives meant to confer biodegradability. During anaerobic digestion for 50 days, 20–25% of the bio-based materials but less than 2% of the additive containing plastics were converted to biogas (CH₄ + CO₂). After 115 days of composting, 0.6% of an additive amended polypropylene, 50% of a plastarch material and 12% of a soy wax permeated paper pulp was converted to carbon dioxide. SEM analysis showed substantial disintegration of polyhydroxyalkanoate-based plastic, some surface changes for other bio-based plastics and coconut coir materials but no evidence of degradation of polypropylene or polypropylene containing additives. Although certain bio-based plastics and natural fibers biodegraded to an appreciable extent in the three environments, only a polyhydroxyalkanoate-based resin biodegraded to significant extents during the time scale of composting and anaerobic digestion processes used for solid waste management.     

Katalysatoren für die Produktion von Biokunststoffen

Bioplastics represent an important possibility to reduce environmental pollution by non‐degradable plastics and open up new resources for plastics production. To promote wide application of bioplastics, new catalysts are urgently needed. This article summarises recent developments of robust lactide polymerisation catalysts as well as the embedding of the produced PLA into the life cycle of bioplastics.     

Determination of Dihydroxybenzenes in Plastic Food Packaging Materials and in Food Simulating Liquids Using Capillary Electrophoresis

A capillary electrophoresis method has been developed to determine 1,2-dihydroxybenzene and 1,3-dihydroxybenzene in the food simulants distilled water, 3% acetic acid, 15% ethanol, and olive oil. Both substances, used as monomers and additives to make food packaging plastics, could be analyzed within 15 min. The 1,4-dihydroxybenzene isomer was unretained and eluted with the electroosmotic flow, and so the CE method can give only a semi-quantitative estimate of this isomer if it is present as a migrant. The analytical recovery for the 1,2- and 1,3-isomers from spiked simulants was good at 87% to 98% except for 1,2-dihydroxybenzene which could only be recovered to the extent of 58% from olive oil. Calibration graphs were linear and the limit of detection for each substance was 0.6 mg/kg, which is well below migration limits for these substances. It is concluded that CE offers a rapid and reliable analysis for the control of migration from plastics intended for food contact which employ 1,2-dihydroxybenzene or 1,3-dihydroxybenzene during manufacture, and offers a screening method for 1,4-dihydroxybenzene migration.     

PHB (poly‐β‐hydroxybutyrate) and its enzymatic degradation

Our daily life needs depend on plastics, as they are cheap and durable, so they become the most commonly used synthetic chemical products. But from an environmentalist's point of view, a major concern related to these plastics is their non‐biodegradable nature. Driven by growing demand to search for sustainable solutions to dispose off generating huge volume of synthetic plastic wastes, shifted the mind of researcher towards the use of biodegradable plastics which can be completely disposed‐off by microbial enzymatic degradation. These biodegradable plastics or “bioplastics” are also synthesized by microbes under certain stressed environmental conditions out of which poly(R‐3‐hydroxybutyrate) (PHB) is the most ubiquitous and best known representatives of polyhydroxyalkanoate family. The PHB is most intensively used for the innovative biomedical applications owing to suitable combination of biocompatibility, transport characteristics, and mechanical properties. These challenging aspects of PHB can be used for designing of novel medical devices, in tissue engineering, and for systematic sustained drug delivery. Lots of research reports on PHB degrading enzymes and their producing microorganisms including biochemical aspects are available but in scattered form. So this review highlighted all the relevant information of PHB and PHB‐degrading enzymes starting with basic classification, synthesis, mechanism, and applications that are environment friendly and are of public interest.     

Cellular and foamed plastics as separation media A new geometrical form of the solid phase in analytical liquid-solid contact

There has been considerable interest during the last few years in using cellular (foamed) plastics (mainly polyurethanes) either unloaded or as a means of immobilizing hydrophobic organic reagents, powdered ion-exchangers or finely divided precipitates, for the collection and separation of inorganic or organic species from aqueous solution. Foamed plastics with anchored (bonded) functional groups have also been used for the same purpose. It has been realized that the application of cellular plastics is often advantageous not only for quantitative work but also for qualitative and semiquantitative analysis. Methods available on the application of cellular and foamed plastics for the collection, separation and recovery of various inorganic and organic components from aqueous solution are reviewed.     

An uninflammable film adhesive and an adhesive prepreg based on it

The properties of a composition that can be used as a film adhesive and a binding agent for glass-reinforced plastics are presented. The composition is developed based on brominated epoxy resins and is selfextinguishing. It is shown that the use of adhesives and binding agents based on brominated epoxy resins makes it possible to obtain glass-reinforced plastics with hot-performance capabilities coming close to the properties of structural inflammable materials.     

Conversion of food industrial wastes into bioplastics

The usage of plastics in packaging and disposable products, and the generation of plastic waste, have been increasing drastically. Broader usage of biodegradable plastics in packaging and disposable products as a solution to environmental problems would heavily depend on further reduction of costs and the discovery of novel biodegradable plastics with improved properties. In the authors’ laboratories, various carbohydrates in the growth media, including sucrose, lactic acid, butyric acid, valeric acid, and various combinations of butyric and valeric acids, were utilized as the carbon (c) sources for the production of bioplastics byAlcaligenes eutrophus. As the first step in pursuit of eventual usage of industrial food wastewater as nutrients for microorganisms to synthesize bioplastics, the authors investigated the usage of malt wastes from a beer brewery plant as the C sources for the production of bioplastics by microorganisms. Specific polymer production yield by A. Latus DSM 1124 increased to 70% polymer/cell (g/g) and 32g/L cell dry wt, using malt wastes as the C source. The results of these experiments indicated that, with the use of different types of food wastes as the C source, different polyhydroxyal-kanoate copolymers could be produced with distinct polymer properties.     

利用焦化工艺处理废塑料技术研究 Ⅱ. 200 kg焦炉中试试验

利用200 kg焦炉考察两种废塑料(PS和WMP)与首钢炼焦配煤按不同比例均匀混合共焦化所得焦炭的质量变化规律，以期能为焦化工艺处理废塑料技术的工业应用提供基础数据。研究表明：废塑料与煤共焦化所得焦炭冶金焦率和焦炭质量降低明显，且随着废塑料添加比例增加，所得焦炭质量劣化程度整体加大；与添加同比例的PS相比，添加WMP虽得到较差的冶金焦率，但所得焦炭的转鼓强度（M40和M10）和反应后强度（CSR）均优于添加PS的情形；废塑料与炼焦配煤简单混合共焦化，严重影响焦炭质量，不能应用于工业实践。     

Chemical Upcycling of Waste Plastics to High Value-Added Products via Pyrolysis: Current Trends,Future Perspectives,and Techno-Feasibility Analysis

Chemical upcycling of waste plastics into high-value-added products is one of the most effective, cost-efficient, and environmentally beneficial solutions. Many studies have been published over the past few years on the topic of recycling plastics into usable materials through a process called catalytic pyrolysis. There is a significant research gap that must be bridged in order to use catalytic pyrolysis of waste plastics to produce high-value products. This review focuses on the enhanced catalytic pyrolysis of waste plastics to produce jet fuel, diesel oil, lubricants, aromatic compounds, syngas, and other gases. Moreover, the reaction mechanism, a brief and critical comparison of different catalytic pyrolysis studies, as well as the techno-feasibility analysis of waste plastic pyrolysis and the proposed catalytic plastic pyrolysis setup for commercialization is also covered.