An overview on PET waste recycling for application in packaging

Toxic effects of fragmented polyethylene terephthalate particles on the marine rotifer Brachionus koreanus: Based on ingestion and egestion assay, in vivo toxicity test, and multi-omics analysis

Microplastics (MPs) are a major concern in marine ecosystem because MPs are persistent and ubiquitous in oceans and are easily consumed by marine biota. Although many studies have reported the toxicity of MPs to marine biota, the toxicity of environmentally relevant types of MPs is little understood. We investigated the toxic effects of fragmented polyethylene terephthalate (PET) MP, one of the most abundant MPs in the ocean, on the marine rotifer Brachionus koreanus at the individual and molecular level. No significant rotifer mortality was observed after exposure to PET MPs for 24 and 48 h. The ingestion and egestion assays showed that rotifers readily ingested PET MPs in the absence of food but not when food was supplied; thus, there were also no chronic effects of PET MPs. In contrast, intracellular reactive oxygen species levels and glutathione S-transferase activity in rotifers were significantly increased by PET MPs. Transcriptomic and metabolomic analyses revealed that genes and metabolites related to energy metabolism and immune processes were significantly affected by PET MPs in a concentration-dependent manner. Although acute toxicity of PET MPs was not observed, PET MPs are potentially toxic to the antioxidant system, immune system, and energy metabolism in rotifers.

Polyethylene Terephthalate (PET) Recycled by Catalytic Glycolysis: A Bridge toward Circular Economy Principles

Plastic pollution has escalated into a critical global issue, with production soaring from 2 million metric tons in 1950 to 400.3 million metric tons in 2022. The packaging industry alone accounts for nearly 44% of this production, predominantly utilizing polyethylene terephthalate (PET). Alarmingly, over 90% of the approximately 1 million PET bottles sold every minute end up in landfills or oceans, where they can persist for centuries. This highlights the urgent need for sustainable management and recycling solutions to mitigate the environmental impact of PET waste. To better understand PET's behavior and promote its management within a circular economy, we examined its chemical and physical properties, current strategies in the circular economy, and the most effective recycling methods available today. Advancing PET management within a circular economy framework by closing industrial loops has demonstrated benefits such as reduced landfill waste, minimized energy consumption, and conserved raw resources. To this end, we identified and examined various strategies based on R-imperatives (ranging from 3R to 10R), focusing on the latest approaches aimed at significantly reducing PET waste by 2040. Additionally, a comparison of PET recycling methods (including primary, secondary, tertiary, and quaternary recycling, along with the concepts of "zero-order" and biological recycling techniques) was envisaged. Particular attention was paid to the heterogeneous catalytic glycolysis, which stands out for its rapid reaction time (20-60 min), high monomer yields (>90%), ease of catalyst recovery and reuse, lower costs, and enhanced durability. Accordingly, the use of highly efficient oxide-based catalysts for PET glycolytic degradation is underscored as a promising solution for large-scale industrial applications.

Microwave-Assisted Pyrolysis-A New Way for the Sustainable Recycling and Upgrading of Plastic and Biomass: A Review

The efficient utilization of organic solid waste resources can help reducing the consumption of conventional fossil fuels, mitigating environmental pollution, and achieving green sustainable development. Due to its dual nature of being both a resource and a source of pollution, it is crucial to implement suitable recycling technologies throughout the recycling and upgrading processes for plastics and biomass, which are organic solid wastes with complex mixture of components. The conventional pyrolysis and hydropyrolysis were summarized for recycling plastics and biomass into high-value fuels, chemicals, and materials. To enhance reaction efficiency and improve product selectivity, microwave-assisted pyrolysis was introduced to the upgrading of plastics and biomass through efficient energy supply especially with the aid of catalysts and microwave absorbers. This review provides a detail summary of microwave-assisted pyrolysis for plastics and biomass from the technical, applied, and mechanistic perspectives. Based on the recent technological advances, the future directions for the development of microwave-assisted pyrolysis technologies are predicted.

Does PET trays sorting affect the sustainability of plastic waste? An LCA and cost-revenue approach

Currently, the management of polyethylene terephthalate (PET) trays waste is still challenging since this packaging affects the consolidate recycling of PET bottles. It is important to separate PET trays from the PET bottle waste stream to avoid its contamination during recycling process and to recover a higher amount of PET. Hence, the present study aims to evaluate the environmental (by means of Life Cycle Assessment, LCA) and economic sustainability of sorting PET trays from the plastic waste streams selected by a Material Recovery Facility (MRF). For this scope, the case of a MRF in Molfetta (Southern Italy) was chosen as reference, and different scenarios have been evaluated by assuming different schemes of manual and/or automated PET trays sorting. The alternative scenarios did not achieve very pronounced environmental benefits over the reference case. Upgraded scenarios resulted in overall environmental impacts approx. 10 % lower as compared to the current scenario, with the exception of the climate and ozone depletion categories where differences in impacts were much higher. From an economic point of view, the upgraded scenarios achieved slightly lower costs (<2 %) than the current one. Electricity or labour costs were necessary in upgraded scenarios, but in this way fines for PET trays contamination in PET streams for recycling were avoided. Implementing any of the technology upgrade scenarios is then environmentally and economically viable, when the PET sorting scheme is performed in appropriate output streams through optical sorting.

Effects of Recycled Polymer on Melt Viscosity and Crystallization Temperature of Polyester Elastomer Blends

As the world is paying attention to the seriousness of environmental pollution, the need for a resource circulation economy is emerging due to the development of eco-friendly industrial groups. In particular, the recycling of thermoplastic elastomers without cross-link has been highlighted in the plastics field, which has rapidly developed the industry. Growing interests have been directed towards the advancement of thermoplastic polyether-ester elastomer (TPEE) as a material suitable for the circular economy owing to its remarkable recyclability, both in terms of mechanical and chemical processes. Due to its excellent processability, simple mechanical recycling is easy, which is a driving force towards achieving price competitiveness in the process. In molding TPEE resin, it is essential to check the thermal properties of the resin itself because the thermal properties, including the melting and crystallization temperatures of the resin, depend on the design of the polymer. In this study, the thermal and mechanical performances of TPEE blends were evaluated by manufacturing compounds by changing the amount of recycled resin and additives. When the recycled resin was added, the melt flow index (MFI) changed rapidly as the temperature of the melt flow index measurement increased. Rapid changes in MFI make the fiber spinning process uncontrollable and must be controlled by optimizing the addition of compatibilizers. Based on the thermal property results, compatibilizers such as Lotader and Elvaloy series exhibited minimal change in glass transition temperature, even with greater amounts added. This makes them well-suited as compatibilizers for fiber spinning.

Chemical Degradation of Waste PET and Its Application in Wood Reinforcement and Modification

In recent years, with the increasing scarcity of fossil resources and the worsening environmental pollution, the effective utilization of wood and plastic waste has become a critical issue. In this paper, propylene glycol (PG) was used as an alcoholysis agent to degrade waste poly(ethylene terephthalate) (PET), and unsaturated polyester (UPR) was synthesized by the polycondensation reaction. The Chinese fir was modified by chemical impregnation to obtain a new type of waste PET-based wood-plastic composites. It exhibits a compressive strength of about 107 MPa and a water absorption of less than 20%. These results highlight the outstanding modification effect on fir, demonstrating excellent mechanical properties and corrosion resistance. This study presents a green and efficient method for the preparation of wood-plastic composites and the recycling of waste PET, providing promising solutions for sustainable resource utilization and environmental protection.

Circular Production, Designing, and Mechanical Testing of Polypropylene-Based Reinforced Composite Materials: Statistical Analysis for Potential Automotive and Nuclear Applications

The circularity of polymer waste is an emerging field of research in Europe. In the present research, the thermal, surface, mechanical, and tribological properties of polypropylene (PP)-based composite produced by injection molding were studied. The pure PP matrix was reinforced with 10, 30, and 40% wt. of pure cotton, synthetic polyester, and polyethylene terephthalate post-consumer fibers using a combination of direct extrusion and injection molding techniques. Results indicate that PP-PCPESF-10% wt. exhibits the highest value of tensile strength (29 MPa). However, the values of tensile and flexural strain were lowered with an increase in fiber content due to the presence of micro-defects. Similarly, the values of modulus of elasticity, flexural modulus, flexural strength, and impact energy were enhanced due to an increase in the amount of fiber. The PP-PCCF-40% wt. shows the highest values of flexural constant (2780 MPa) and strength (57 MPa). Additionally, the increase in fiber loadings is directly proportional to the creation of micro-defects, surface roughness, abrasive wear, coefficient of friction, and erosive wear. The lowest average absolute arithmetic surface roughness value (Ra) of PP and PP-PCCF, 10% wt., were 0.19 µm and 0.28 µm. The lowest abrasive wear value of 3.09 × 10-6 mm3/Nm was found for pure PP. The erosive wear value (35 mm3/kg) of PP-PCCF 40% wt. composite material was 2 to 17 times higher than all other composite materials. Finally, the single-step analysis of variance predicts reasonable results in terms of the p-values of each composite material for commercial applications.

Chemical Recycling Processes of Waste Polyethylene Terephthalate Using Solid Catalysts

Polyethylene terephthalate (PET) is a non-degradable single-use plastic and a major component of plastic waste in landfills. Chemical recycling is one of the most widely adopted methods to transform post-consumer PET into PET's building block chemicals. Non-catalytic depolymerization of PET is very slow and requires high temperatures and/or pressures. Recent advancements in the field of material science and catalysis have delivered several innovative strategies to promote PET depolymerization under mild reaction conditions. Particularly, heterogeneous catalysts assisted depolymerization of post-consumer PET to monomers and other value-added chemicals is the most industrially compatible method. This review includes current progresses on the heterogeneously catalyzed chemical recycling of PET. It describes four key pathways for PET depolymerization including, glycolysis, pyrolysis, alcoholysis, and reductive depolymerization. The catalyst function, active sites and structure-activity correlations are briefly outlined in each section. An outlook for future development is also presented.

Progress and perspective for conversion of plastic wastes into valuable chemicals

Today, discarded plastics in nature have caused serious "white pollution", however these plastic wastes contain abundant carbon resources that could serve as the feedstock to produce commodities. Because of this, it is requisite to convert these plastic wastes into valuable chemicals. Herein, the state-of-the-art techniques for plastic conversion are divided into two categories, those performed under violent conditions and mild conditions, in which the conversion mechanisms are discussed. The strategies under violent conditions are closer to practical application thanks to their excellent conversion efficiencies, while the strategies under mild conditions are more environmentally friendly, showing enormous development potential in the future. We summarize in detail the pyrolysis, hydropyrolysis, solvolysis and microwave-initiated catalysis for bond cleavage in plastic wastes at temperatures ranging from 448 to 973 K. Also, we overview the photocatalysis, electrocatalysis and biocatalysis for bond cleavage in plastic wastes at near and even normal temperature and pressure. Finally, we present some suggestions and outlooks concerning the improvement of current techniques and in-depth mechanisms of investigation for conversion of plastics into valuable chemicals.

Chemical Recycling of Used PET by Glycolysis Using Niobia-Based Catalysts

Plastic production has steadily increased worldwide at a staggering pace. The polymer industry is, unfortunately, C-intensive, and accumulation of plastics in the environment has become a major issue. Plastic waste valorization into fresh monomers for production of virgin plastics can reduce both the consumption of fossil feedstocks and the environmental pollution, making the plastic economy more sustainable. Recently, the chemical recycling of plastics has been studied as an innovative solution to achieve a fully sustainable cycle. In this way, plastics are depolymerized to their monomers or/and oligomers appropriate for repolymerization, closing the loop. In this work, PET was depolymerized to its bis(2-hydroxyethyl) terephthalate (BHET) monomer via glycolysis, using ethylene glycol (EG) in the presence of niobia-based catalysts. Using a sulfated niobia catalyst treated at 573 K, we obtained 100% conversion of PET and 85% yield toward BHET at 195 °C in 220 min. This approach allows recycling of the PET at reasonable conditions using an inexpensive and nontoxic material as a catalyst.

Catalytic Chemical Recycling of Post-Consumer Polyethylene

Among commercial plastics, polyolefins are the most widely produced worldwide but have limited recyclability. Here, we report a chemical recycling route for the conversion of post-consumer high-density polyethylene (HDPE) into telechelic macromonomers suitable for circular reprocessing. Unsaturation was introduced into HDPE by catalytic dehydrogenation using an Ir-POCOP catalyst without an alkene acceptor. Cross-metathesis with 2-hydroxyethyl acrylate followed by hydrogenation transformed the partially unsaturated HDPE into telechelic macromonomers. The direct repolymerization of the macromonomers gave a brittle material due to the low overall weight-average molecular weight. Aminolysis of telechelic macromonomers with a small amount of diethanolamine increased the overall functionality. The resulting macromonomers were repolymerized through transesterification to generate a polymer with comparable mechanical properties to the starting post-consumer HDPE waste. Depolymerization of the repolymerized material catalyzed by an organic base regenerated the telechelic macromonomers, thereby allowing waste polyethylene materials to enter a chemical recycling pathway.

Closing the Carbon Loop in the Circular Plastics Economy

Today, plastics are ubiquitous in everyday life, problem solvers of modern technologies, and crucial for sustainable development. Yet the surge in global demand for plastics of the growing world population has triggered a tidal wave of plastic debris in the environment. Moving from a linear to a zero-waste and carbon-neutral circular plastic economy is vital for the future of the planet. Taming the plastic waste flood requires closing the carbon loop through plastic reuse, mechanical and molecular recycling, carbon capture, and use of the greenhouse gas carbon dioxide. In the quest for eco-friendly products, plastics do not need to be reinvented but tuned for reuse and recycling. Their full potential must be exploited regarding energy, resource, and eco efficiency, waste prevention, circular economy, climate change mitigation, and lowering environmental pollution. Biodegradation holds promise for composting and bio-feedstock recovery, but it is neither the Holy Grail of circular plastics economy nor a panacea for plastic littering. As an alternative to mechanical downcycling, molecular recycling enables both closed-loop recovery of virgin plastics and open-loop valorization, producing hydrogen, fuels, refinery feeds, lubricants, chemicals, and carbonaceous materials. Closing the carbon loop does not create a Perpetuum Mobile and requires renewable energy to achieve sustainability. This article is protected by copyright. All rights reserved.

Environmental impact of increased soap consumption during COVID-19 pandemic: Biodegradable soap production and sustainable packaging

A year into the coronavirus disease 2019 pandemic, the role of washing hands with soap and hand disinfectants is unavoidable as a primary way to control the infection spread in communities and healthcare facilities. The extraordinary surge in demand for handwashing products has led to environmental concerns. Since soaps are complex mixtures of toxic and persistent active ingredients, the prudent option is to promote eco-friendly replacements for the current products. On the other hand, with the increase in soap packaging waste production, soap packaging waste management and recycling become essential to reduce environmental impact. This systematic review aimed to collect some recent methods for identifying biodegradable and sustainable raw materials to produce and package cleaning agents, especially soap.

Polyolefins and Polyethylene Terephthalate Package Wastes: Recycling and Use in Composites

Plastics are versatile materials used in a variety of sectors that have seen a rapid increase in their global production. Millions of tonnes of plastic wastes are generated each year, which puts pressure on plastic waste management methods to prevent their accumulation within the environment. Recycling is an attractive disposal method and aids the initiative of a circular plastic economy, but recycling still has challenges to overcome. This review starts with an overview of the current European recycling strategies for solid plastic waste and the challenges faced. Emphasis lies on the recycling of polyolefins (POs) and polyethylene terephthalate (PET) which are found in plastic packaging, as packaging contributes a signification proportion to solid plastic wastes. Both sections, the recycling of POs and PET, discuss the sources of wastes, chemical and mechanical recycling, effects of recycling on the material properties, strategies to improve the performance of recycled POs and PET, and finally the applications of recycled POs and PET. The review concludes with a discussion of the future potential and opportunities of recycled POs and PET.

An improved multi-variable grey model for forecasting China's finished products from comprehensive waste utilization

A reasonable prediction of the finished products from waste recycling and reprocessing is of great significance to the sustainable use of limited resources, the reduced pollution caused by waste, and the reflected comprehensive waste utilization (CWU) creativity. To this end, an improved multi-variable grey model was employed to forecast the finished products in China's CWU. Firstly, the degree of grey incidence was applied to select explanatory variables and eliminate multicollinearity between them. Then, compared with the traditional GM(1,N) model, the linear correction term and grey action quantity were added in the proposed improved model, and the response function and parameter estimation method of the improved model were deduced and proved. Thirdly, the finished products from CWU was simulated and predicted by the proposed model. The mean relative simulation percentage error of the improved model was only 0.0001%, in comparison with the ones obtained from the traditional GM(1,N) and the classical GM(1,1), which were 12.1232 and 8.8402%, respectively. Lastly, the results show that the finished products from CWU are mainly affected by the comprehensive utilization of general industrial solid waste and the number of industrial enterprises in CWU, and the future trends from 2020 to 2025 are unstable.

Immobilization of PETase enzymes on magnetic iron oxide nanoparticles for the decomposition of microplastic PET

Polyethylene terephthalate (PET) is responsible for a large amount of environmental contamination with microplastics. Based on its high affinity, the PET degrading enzyme PETase can be immobilized on superparamagnetic iron oxide nanoparticles through a His-tag. The His-tag increases enzyme stability, and allows magnetic separation for recovery. Multiple recycling steps are possible and microplastic particles can be decomposed depending on the PET's crystallinity. The separation or decomposition of PET allows for a sustainable way to remove microplastic from water.

Synthesis and characterization of polyethylene terephthalate (PET) precursors and potential degradation products: Toxicity study and application in discovery of novel PETases

Polyethylene terephthalate (PET) is widely used material and as such became highly enriched in nature. It is generally considered inert and safe plastic, but due to the recent increased efforts to break-down PET using biotechnological approaches, we realized the scarcity of information about structural analysis of possible degradation products and their ecotoxicological assessment. Therefore, in this study, 11 compounds belonging to the group of PET precursors and possible degradation products have been comprehensively characterized. Seven of these compounds including 1-(2-hydroxyethyl)-4-methylterephthalate, ethylene glycol bis(methyl terephthalate), methyl bis(2-hydroxyethyl terephtahalate), 1,4-benzenedicarboxylic acid, 1,4-bis[2-[[4-(methoxycarbonyl)benzoyl]oxy]ethyl] ester and methyl tris(2-hydroxyethyl terephthalate) corresponding to mono-, 1.5-, di-, 2,5- and trimer of PET were synthetized and structurally characterized for the first time. In-silico druglikeness and physico-chemical properties of these compounds were predicted using variety of platforms. No antimicrobial properties were detected even at 1000 μg/mL. Ecotoxicological impact of the compounds against marine bacteria Allivibrio fischeri proved that the 6 out of 11 tested PET-associated compounds may be classified as harmful to aquatic microorganisms, with PET trimer being one of the most toxic. In comparison, most of the compounds were not toxic on human lung fibroblasts (MRC-5) at 200 μg/mL with inhibiting concentration (IC50) values of 30 μg/mL and 50 μg/mL determined for PET dimer and trimer. Only three of these compounds including PET monomer were toxic to nematode Caenorhabditis elegans at high concentration of 500 μg/mL. In terms of the applicative potential, PET dimer can be used as suitable substrate for the screening, identification and characterization of novel PET-depolymerizing enzymes.

Evaluation and optimization of blanket production from recycled polyethylene terephthalate based on the coordination of environment, economy, and society

The recycling of waste polyethylene terephthalate (PET) is widely regarded as an eco-friendly and cost-effective technology and has been gradually developed into an important direction for the utilization of solid waste resources. However, the integrated evaluation research on this technology from the environmental, economic, and social aspects are still not in place. Based on the theory of collaborative entropy, this study constructs an integrated evaluation and optimization methodology system for the environmental, economic, and social impacts of blanket production from recycled PET, using environmental life cycle assessment, life cycle cost assessment, social life cycle assessment, and sensitivity analysis. The study assessed the environmental load, economic cost, and social impact of blanket production from recycled PET, and then identified the key processes through sensitivity analysis. In addition, the graphical method and the principle of collaborative entropy model are applied to evaluate two of the environmental load, economic cost, and social impact in the blanket production from recycled PET. The results of the two methods are consistent, which indicates that to carry out multi-objective integrated evaluation with collaborative entropy model have good reliability. Moreover, the quantified results of collaborative entropy showed that the key processes that affected the coordinated development of the environment, economy, and society were organic chemicals usage process, electricity generation process, and direct air emission process. Based on the "Reduce-Reuse-Recycle" theory and the position of key processes in the system, feasible optimization suggestions were proposed. The establishment of this methodology system could provide theoretical and practical references for other waste utilization industry.

Determination of the composition and properties of PET bottles: Evidence of the empirical approach from Perm, Russia

Efficient collection systems and information about the characteristics and quality of collected secondary plastic waste flows are of fundamental importance for the development of circular economies. In order to assess the effectiveness of the implementation of separate collection systems for plastic packaging, especially polyethylene terephthalate (PET) bottles, characteristic of the collected PET bottles in street mesh containers were studied in the city of Perm, Russia. The share of extraneous fractions was assessed and differentiation was carried out by volume, type of product, label presence, shape, content of solid and liquid impurities and colour. These results indicate that PET composition in different seasons is very similar, despite the assumption that the consumption of PET bottles in the spring and autumn seasons varies. In the mesh containers, up to 34% of the items were foreign objects, considering that only PET bottles should be collected. In each dimensional flow of PET bottles, the proportion of transparent bottles prevailed; it ranged from 31% to 70%. Based on the results of the experiment, almost all PET bottle categories had a standard shape, except packaging for food products and household chemicals, in which 26-27% of PET bottles had a non-standard shape. The results about charactersitic of source-separated PET bottles are fundamental for goal-oriented design and implementation of collection, recycling technologies, secondary separation facilities, the economics of recycling intitatives and reverse vending machines for collecting materials.

Enhanced Impact Strength of Recycled PET/Glass Fiber Composites

In this paper, we report a study on the effects of different ethylene copolymers in improving the impact strength of a fiber-reinforced composite based on a recycled poly(ethylene terephthalate) (rPET) from post-consumer bottles. Different ethylene copolymers have been selected in order to evaluate the effects of the polar co-monomer chemical structure and content. The composite mixtures were prepared via melt extrusion, and the samples were manufactured by injection molding. Impact strength was evaluated using Izod tests, and a morphological study (FESEM) was performed. As a result, a composite with substantially improved impact properties was designed. This study demonstrates that a post-consumer PET from the municipal waste collection of plastic bottles can be successfully used as a matrix of high-performance, injection-molded composites, suitable for use in the automotive sector, among others, with no compromise in terms of mechanical requirements or thermal stability.

Catalytic methods for chemical recycling or upcycling of commercial polymers

Polymers (plastics) have transformed our lives by providing access to inexpensive and versatile materials with a variety of useful properties. While polymers have improved our lives in many ways, their longevity has created some unintended consequences. The extreme stability and durability of most commercial polymers, combined with the lack of equivalent degradable alternatives and ineffective collection and recycling policies, have led to an accumulation of polymers in landfills and oceans. This problem is reaching a critical threat to the environment, creating a demand for immediate action. Chemical recycling and upcycling involve the conversion of polymer materials into their original monomers, fuels or chemical precursors for value-added products. These approaches are the most promising for value-recovery of post-consumer polymer products; however, they are often cost-prohibitive in comparison to current recycling and disposal methods. Catalysts can be used to accelerate and improve product selectivity for chemical recycling and upcycling of polymers. This review aims to not only highlight and describe the tremendous efforts towards the development of improved catalysts for well-known chemical recycling processes, but also identify new promising methods for catalytic recycling or upcycling of the most abundant commercial polymers.

An Overview of Plastic Waste Generation and Management in Food Packaging Industries

Over the years, the world was not paying strict attention to the impact of rapid growth in plastic use. This has led to unprecedented amounts of mixed types of plastic waste entering the environment unmanaged. Packaging plastics account for half of the global total plastic waste. This paper seeks to give an overview of the use, disposal, and regulation of food packaging plastics. Demand for food packaging is on the rise as a result of increasing global demand for food due to population growth. Most of the food packaging are used on-the-go and are single use plastics that are disposed of within a short space of time. The bulk of this plastic waste has found its way into the environment contaminating land, water and the food chain. The food industry is encouraged to reduce, reuse and recycle packaging materials. A wholistic approach to waste management will need to involve all stakeholders working to achieve a circular economy. A robust approach to prevent pollution today rather than handling the waste in the future should be adopted especially in Africa where there is high population growth.

Functionalized PET Waste Based Low-Cost Adsorbents for Adsorptive Removal of Cu(II) Ions from Aqueous Media

The widespread use of polyethylene terephthalate (PET) in the packaging industry has led to the discharge of huge amounts of such waste into the environment and is an important source of pollution. Moreover, because the degradation of PET waste requires a very long time (over 180 years), the recycling of this waste is the only solution to reduce environmental pollution in this case. The solution proposed in this study, is the transformation of PET waste into granular adsorbent materials by functionalization with different phenolic compounds (phenol, p-chlor-phenol, and hydroxyquinone), and then their use as adsorbent materials for removing metal ions (ex. Cu(II) ions) from aqueous solutions. The functionalization of PET waste was done with different amounts (2–8 g) of each phenolic compound. The adsorption capacity of obtained materials was tested at different initial Cu(II) ions concentrations, in batch systems, at room temperature (20 ± 1 °C). The experimental results have shown that the adsorbent material obtained by the functionalization of PET waste with 8 g of phenol has the best adsorptive performances (q = 12.80 mg g−1) at low initial concentrations of Cu(II) ions, while the adsorbent material obtained by the functionalization of PET waste with 2 g of hydroxyquinone is more efficient in removal of high concentrations of Cu(II) ions (q = 61.73 mg g−1). The experimental isotherms were modeled using Langmuir and Freundlich isotherm models, to highlight the adsorptive performances of these new adsorbents and their potential applicability in environmental decontamination processes.

A Door-to-Door Waste Collection System Case Study: A Survey on its Sustainability and Effectiveness

Municipal waste management is a relevant topic these days, in its relation to sustainable and environmental concerns. Sorting waste fractions at home for a door-to-door collection system proves to positively affect the environmental impacts of waste management strategies both by reducing the amounts of the waste landfilled and by originating new circular economies. However, the environmental impact caused by both waste collection and transport, together with waste quality, should be carefully evaluated to assess the sustainability of such a collection system. In order to evaluate the logistic and environmental effectiveness of a newly implemented door-to-door collection system in Altamura, a mid-sized town in Southern Italy, a survey was designed and submitted to a sample of citizens. The results obtained from the 385 completed surveys show that the door-to-door collection of glass waste is inefficient since most of the designated bins remain partially filled and less frequently delivered; citizens are more motivated to adequately collect sorted waste fractions upon receiving information about the subsequent environmental benefits and outcomes of the fractions collected; a high percentage of people still use disposable items in their daily life. Possible changes to the weekly bins collection schedule have been proposed in order to have a more proficient and environmentally sustainable waste collection service in the town. The survey is part of a project aiming at developing a smart device to support users in home waste management.

Multilayer packaging: Advances in preparation techniques and emerging food applications

In recent years, with advantages of versatility, functionality, and convenience, multilayer food packaging has gained significant interest. As a single entity, multilayer packaging combines the benefits of each monolayer in terms of enhanced barrier properties, mechanical integrity, and functional properties. Of late, apart from conventional approaches such as coextrusion and lamination, concepts of nanotechnology have been used in the preparation of composite multilayer films with improved physical, chemical, and functional characteristics. Further, emerging techniques such as ultraviolet and cold plasma treatments have been used in manufacturing films with enhanced performance through surface modifications. This work provides an up-to-date review on advancements in the preparation of multilayer films for food packaging applications. This includes critical considerations in design, risk of interaction between the package and the food, mathematical modeling and simulation, potential for scale-up, and costs involved. The impact of in-package processing is also explained considering cases of nonthermal processing and advanced thermal processing. Importantly, challenges associated with degradability and recycling multilayer packages and associated implications on sustainability have been discussed.

PET bottles recycling in China: An LCA coupled with LCC case study of blanket production made of waste PET bottles

A large number of polyethylene terephthalate (PET) bottles are discarded daily after usage. Thus, plastic bottle recycling has elicited considerable attention in recent years. In this context, this study aims to quantify the environmental and economic impacts of blanket production from 100% recycled waste plastic bottles in China through a life cycle assessment coupled with life cycle costing method. In addition, the environmental impact of replacing coal with natural gas and solar energy was evaluated. Results show that impact categories of global warming and fossil depletion have significant influence on the overall environment. Carbon dioxide, water, iron, coal and chromium (VI) to water are the main contributors to the overall environmental burden. The internal and external costs are $6433/metric ton and $370/metric ton, respectively. Analysis results indicate that the optimization of organic chemicals, recycled polyester filament and steam production processes can reduce environmental and economic burdens substantially. Energy substitutions with natural gas and the use of solar photovoltaic in steam production and electricity generation are effective measures for decreasing environmental impacts. Finally, suggestions based on research results and the current status of waste plastic bottle recycling in China are proposed.

Biobased Poly(ethylene terephthalate)/Poly(lactic acid) Blends Tailored with Epoxide Compatibilizers

To increase the biobased content of poly(ethylene terephthalate) (PET), up to 30 wt % poly(lactic acid) (PLA) was blended with PET using twin-screw compounding and injection molding processes. Multifunctional epoxide compatibilizers including a chain extender and an impact toughening agent were used as blend modifiers to improve the poor mechanical properties of PET/PLA blends. The mechanical and thermodynamic performances were investigated along with the morphological features through scanning electron microscopy, atomic force microscopy, and interfacial tension determination. From rheological and differential scanning calorimetry results, it was observed that the molecular weight of both PET and PLA increased with compatibilizers because of epoxide reactions. The toughening agent, poly(ethylene-n-butylene-acrylate-co-glycidyl methacrylate) (EBA-GMA), provided a 292% increase in impact strength over the blend but reduced modulus by 25%. In contrast, 0.7 phr addition of the chain extender, poly(styrene-acrylic-co-glycidyl methacrylate) (SA-GMA), yielded comparable performance to that of neat PET without sacrificing the tensile and flexural properties. When both compatibilizers were present in the blend, the mechanical properties remained relatively unaltered or decreased with increasing EBA-GMA content. The differences in mechanical performance observed were considered in relation to the strengthening mechanism of the two differing compatibilizers and their effects on the miscibility of the blend.