Monitoring the degradation of stabilization systems in polypropylene during accelerated aging tests by liquid chromatography combined with atmospheric pressure chemical ionization mass spectrometry

Recovering Valuable Chemicals from Polypropylene Waste via a Mild Catalyst-Free Hydrothermal Process

Waste polypropylene (PP) presents a significant environmental challenge, owing to its refractory nature and inert C-C backbone. In this study, we introduce a practical chemical recovery strategy from PP waste using a mild catalyst-free hydrothermal treatment (HT). The treatment converts 64.1% of the processed PP into dissolved organic products within 2 h in an air atmosphere at 160 °C. Higher temperatures increase the PP conversion efficiency. Distinct electron absorption and emission characteristics of the products are identified by spectral analysis. Fourier transform-ion cyclotron resonance-mass spectrometry (FT-ICR-MS) reveals the oxidative cracking of PP into shorter-chain homologues (10-50 carbon atoms) containing carboxylic and carbonyl groups. Density functional theory (DFT) calculations support a reaction pathway involving thermal C-H oxidation at the tertiary carbon sites in the polymer chain. The addition of 1% H2O2 further enhances the oxidation reaction to produce valuable short-chain acetic acids, enabling gram-scale recycling of both pure PP and disposable surgical masks from the real world. Techno-economic analysis (TEA) and environmental life cycle costing (E-LCC) analysis suggest that this hydrothermal oxidation recovery technology is financially viable, which shows significant potential in tackling the ongoing plastic pollution crisis and advancing plastic treatment methodologies toward a circular economy paradigm.

Leaching and transformation of chemical additives from weathered plastic deployed in the marine environment

Plastic pollution causes detrimental environmental impacts, which are increasingly attributed to chemical additives. However, the behaviour of plastic additives in the marine environment is poorly understood. We used a marine deployment experiment to examine the impact of weathering on the extractables profile, analysed by liquid chromatography-mass spectrometry, of four plastics at two locations over nine months in Aotearoa/New Zealand. The concentration of additives in polyethylene and oxo-degradable polyethylene were strongly influenced by artificial weathering, with deployment location and time less influential. By comparison, polyamide 6 and polyethylene terephthalate were comparatively inert with minimal change in response to artificial weathering or deployment time. Non-target analysis revealed extensive differentiation between non-aged and aged polyethylene after deployment, concordant with the targeted analysis. These observations highlight the need to consider the impact of leaching and weathering on plastic composition when quantifying the potential impact and risk of plastic pollution within receiving environments.

Sample transformation in online separations: how chemical conversion advances analytical technology

While the advent of modern analytical technology has allowed scientists to determine the complexity of mixtures, it also spurred the demand to understand these sophisticated mixtures better. Chemical transformation can be used to provide insights into properties of complex samples such as degradation pathways or molecular heterogeneity that are otherwise unaccessible. In this article, we explore how sample transformation is exploited across different application fields to empower analytical methods. Transformation mechanisms include molecular-weight reduction, controlled degradation, and derivatization. Both offline and online transformation methods have been explored. The covered studies show that sample transformation facilitates faster reactions (e.g. several hours to minutes), reduces sample complexity, unlocks new sample dimensions (e.g. functional groups), provides correlations between multiple sample dimensions, and improves detectability. The article highlights the state-of-the-art and future prospects, focusing in particular on the characterization of protein and nucleic-acid therapeutics, nanoparticles, synthetic polymers, and small molecules.

Quantification and stability assessment of 7,9-di‑tert‑butyl‑1-oxaspiro(4,5)deca-6,9-diene-2,8‑dione leaching from cross-linked polyethylene pipes using gas and liquid chromatography

This study assesses the formation and stability of the water contaminant 7,9-di‑tert‑butyl‑1-oxaspiro(4,5)deca-6,9-diene-2,8‑dione ([1]) which repeatedly occurs in the migration waters of cross-linked polyethylene (PE-X) pipes. In aqueous solution [1] is partially transformed to 3-(3,5-di‑tert‑butyl‑1‑hydroxy-4-oxo-2,5-cyclohexadien-1-yl)propionic acid ([2]). For a better understanding of the formation of [1] and its transformation into [2] an analytical method was established to allow the analysis of both species separately. Because of thermal instability [2] cannot be detected with GC-MS. Therefore, two methods were validated for a reliable and reproducible quantification: GC-MS for [1] and HPLC-MS/MS for both [1] and [2]. Comparative measurements of migration waters from PE-X pipes using GC-MS and HPLC-MS/MS methods showed that the concentrations of [1] detected with GC-MS corresponds to the sum of [1] and [2] measured with HPLC-MS/MS. In the migration waters [1] was detected in higher concentrations than [2]. The highest concentrations of [1], detected with GC-MS, were > 300 µg/L. The longer the materials are stored without contact with water, the more [1] is measured in the migration waters. Most of the previous values reported in the literature for [1] were based on semi-quantification. Hence, we compared results of the semi-quantitative determination according to EN 15768 with those of a quantitative method with a standard. The results gained with the semi-quantitative method represent less than 50% of the quantified values for the amount leaching from the pipes, which means that the semi-quantification method according to EN 15768 leads to a significant underestimation of [1]. Finally, stability assessment showed that [1] developed an equilibrium with [2] under acidic conditions, whereas it will completely be transferred to [2] at pH 10. At pH 7, it takes more than 50 days for [1] to reach an equilibrium with [2]. However, at increasing the temperature to 60 °C, [1] will be rapidly transformed into [2]. Besides [1] and [2], other currently unknown degradation products are formed. As there is no comprehensive toxicological assessment for both substances available today, our findings underline the need for regulatory consequences.

Combination of Structure Databases, In Silico Fragmentation, and MS/MS Libraries for Untargeted Screening of Non-Volatile Migrants from Recycled High-Density Polyethylene Milk Bottles

Chemical contamination is one of the major obstacles for mechanical recycling of plastics. In this article, we built and open-sourced an in-house MS/MS library containing more than 500 plastic-related chemicals and developed mspcompiler, an R package, for the compilation of various libraries. We then proposed a workflow to process untargeted screening data acquired by liquid chromatography high-resolution mass spectrometry. These tools were subsequently employed to data originating from recycled high-density polyethylene (rHDPE) obtained from milk bottles. A total of 83 compounds were identified, with 66 easily annotated by making use of our in-house MS/MS libraries and the mspcompiler R package. In silico fragmentation combined with data obtained from gas chromatography-mass spectrometry and lists of chemicals related to plastics were used to identify those remaining unknown. A pseudo-multiple reaction monitoring method was also applied to sensitively target and screen the identified chemicals in the samples. Quantification results demonstrated that a good sorting of postconsumer materials and a better recycling technology may be necessary for food contact applications. Removal or reduction of non-volatile substances, such as octocrylene and 2-ethylhexyl-4-methoxycinnamate, is still challenging but vital for the safe use of rHDPE as food contact materials.

Deep Generative Modeling of Infrared Images Provides Signature of Cracking in Cross-Linked Polyethylene Pipe

Hyperspectral infrared (IR) images contain a large amount of highly spatially resolved information about the chemical composition of a sample. However, the analysis of hyperspectral IR imaging data for complex heterogeneous systems can be challenging because of the spectroscopic and spatial complexity of the data. We implement a deep generative modeling approach using a β-variational autoencoder to learn disentangled representations of the generative factors of variance in a data set of cross-linked polyethylene (PEX-a) pipe. We identify three distinct physicochemical factors of aging and degradation learned by the model and apply the trained model to high-resolution hyperspectral IR images of cross-sectional slices of unused virgin, used in-service, and cracked PEX-a pipe. By mapping the learned representations of aging and degradation to the IR images, we extract detailed information on the physicochemical changes that occur during aging, degradation, and cracking in PEX-a pipe. This study shows how representation learning by deep generative modeling can significantly enhance the analysis of high-resolution IR images of complex heterogeneous samples.

A non-target screening study of high-density polyethylene pipes revealed rubber compounds as main contaminant in a drinking water distribution system

Polyethylene (PE) pipes are often the material of choice for water supply systems, thanks to their favorable properties, such as high strength-density ratio and corrosion resistance. However, previous studies have shown that organic compounds can migrate from PE pipes to the water. This study aimed to identify potential organic compounds migrating from high-density PE (HDPE) pipes used to distribute drinking water in Denmark, based on laboratory experiments and sampling in the distribution system using a two-tiered study design. In the first tier, migration of volatile and semi-volatile organic compounds (VOCs and semi-VOCs) from HDPE pipes were investigated over one, three, and nine days in laboratory experiments, performed according to modified standards for migration testing (EN 12,873-1). The analytical workflow consisted of solid-phase extraction (SPE) for 10,000 times enrichment and gas chromatography - mass spectrometry (GC-MS) analysis from the water phase after migration. A total of 133 compounds originating from the PE pipes were detected. Thirty-one compounds were detected by suspect screening (SS), while the remaining 102 compounds were detected by non-target screening (NTS) analysis. Among the detected compounds were also hindered amine stabilizers (HALS), flame retardant, and plasticizer tris(2-chloroethyl) phosphate. In the second tier, drinking water from a water distribution system in Copenhagen, Denmark, with a newly installed HDPE pipe was sampled and analyzed with GC-MS and liquid chromatography high-resolution mass spectrometry (LCHRMS). A total of 51 compounds were detected in the water, 12 of which were assigned to migration from HDPE. Surprisingly, HDPE antioxidants and their degradation products contributed only a relatively small percentage of the total measured compound intensities in the drinking water distribution system. Instead, a larger proportion of the compounds detected were assigned to rubber seals, used upstream in the water system from the abstraction site to delivery at the consumer tap. Seals are considered trifle in the larger picture of materials in contact with drinking water, however these results may cause a reconsideration of this position.

Divergent Forms of Pyroplastic: Lessons Learned from the M/V X-Press Pearl Ship Fire

In late May 2021, the M/V X-Press Pearl container ship caught fire while anchored 18 km off the coast of Colombo, Sri Lanka and spilled upward of 70 billion pieces of plastic or "nurdles" (∼1680 tons), littering the country's coastline. Exposure to combustion, heat, chemicals, and petroleum products led to an apparent continuum of changes from no obvious effects to pieces consistent with previous reports of melted and burned plastic (pyroplastic) found on beaches. At the middle of this continuum, nurdles were discolored but appeared to retain their prefire morphology, resembling nurdles that had been weathered in the environment. We performed a detailed investigation of the physical and surface properties of discolored nurdles collected on a beach 5 days after the ship caught fire and within 24 h of their arrival onshore. The color was the most striking trait of the plastic: white for nurdles with minimal alteration from the accident, orange for nurdles containing antioxidant degradation products formed by exposure to heat, and gray for partially combusted nurdles. Our color analyses indicate that this fraction of the plastic released from the ship was not a continuum but instead diverged into distinct groups. Fire left the gray nurdles scorched, with entrained particles and pools of melted plastic, and covered in soot, representing partial pyroplastics, a new subtype of pyroplastic. Cross sections showed that the heat- and fire-induced changes were superficial, leaving the surfaces more hydrophilic but the interior relatively untouched. These results provide timely and actionable information to responders to reevaluate cleanup end points, monitor the recurrence of these spilled nurdles, gauge short- and long-term effects of the spilled nurdles to the local ecosystem, and manage the recovery of the spill. These findings underscore partially combusted plastic (pyroplastic) as a type of plastic pollution that has yet to be fully explored despite the frequency at which plastic is burned globally.

Gravimetric analysis of stability of polymeric materials during exposure to chemical disinfectants at different temperatures

The goal of this study was to evaluate the impact of thermal and chemical aging processes on high-density polyethylene (HDPE), low-density polyethylene (LDPE), unplasticized polyvinyl chloride (U-PVC), and high-impact polyvinyl chloride (Hi-PVC) pipes. The materials were exposed to 1-10 ppm chemical disinfectants [chlorine dioxide (ClO₂) and hypochlorite (HOCl)] at 40-80 °C for 1200 h. The diffusion properties of the materials were systematically analyzed based on the change in their sorption characteristics and activation energies according to the Arrhenius model. Moreover, the structural changes were analyzed with scanning electron microscopy (SEM), Fourier transform infrared (FTIR) radiation, and thermogravimetric analysis (TGA). The results show that the materials have Fickian characteristics in the aging environment. Specifically, the water sorption rates of HDPE and LDPE increase first and then decrease after reaching saturation (Ms); those of U-PVC and Hi-PVC its increasing continuously with different rate. This behavior of materials was prominent for ClO₂ at high temperature and disinfectant dose because of polymeric chains crosslinking and rearrangement, extraction of monomers, and stable compounds removal during aging under exposed conditions. The deleterious effects decreased the activation energies of the materials and increased the concentrations of carbonyl groups [CO] via the formation of ketones, aldehydes, and carboxylic acids. The decomposition temperature increased with the changes in the material morphology and elemental contents under the investigated conditions. Moreover, LDPE and Hi-PVC were more severely affected in the thermal aging process with 10 mg.L^-1 ClO₂ at 80 °C.

An Effective Package of Antioxidants for Avoiding Premature Failure in Polypropylene Random Copolymer Plastic Pipes under Hydrostatic Pressure and High Temperature

Pipes of polypropylene random (PP-R) copolymers are the best choice for hot- and cold-water networks. Validation of a severe test, accomplishing the ISO 1167 standard, is mandatory to assess their service lifetime expectancy. This work evaluates the behavior shown by three commercial pipes, either the original ones (new pipes) or after being subjected to a hydrostatic pressure test at elevated temperature (aged pipes). Several features with relevance for the final performance have been examined: crystalline characteristics, phase transitions in crystalline regions, effect of high temperature and pressure on these transitions, and oxidation induction time. Moreover, the presence of inorganic fillers, and the content of different antioxidants together with their depletion, have also been analyzed. Films from the new pipes were also prepared for replication of the different environments in order to achieve a better and complete understanding of the phase transitions in the crystalline regions and of the consumption of antioxidants. Distinct environments surrounded the inner and outer parts of the pipes exposed to the failure aging test at 110 °C: hot water and warm dry air, respectively. These features play a key role in the loss of additives and in the subsequent initiation of degradation. Even if the crystalline characteristics are appropriate in the polymeric matrix, the success of a pipe lies in the homogeneous dispersion of components for avoiding damage at interfacial properties, and in a correct package of antioxidants used in its formulation.

Molecular background of the undesired odor of polypropylene materials and insights into the sources of key odorants

Screening the volatiles isolated from a standard polypropylene material consisting of a polypropylene homopolymer, the filler talcum, and a mixture of antioxidants, for odor-active compounds by application of an aroma extract dilution analysis revealed 30 odorants with flavor dilution factors ranging from 1 to 64. Eighteen odor-active compounds were subsequently quantitated by gas chromatography-mass spectrometry using stable isotopically substituted odorants as internal standards, and their odor activity values (OAVs) were calculated as ratios of the concentrations to the odor threshold values. Five odorants showed OAVs ≥1, among which were hex-1-en-3-one (OAV 12), butanoic acid (OAV 3), as well as 4-methylphenol, butan-1-ol, and 2-tert-butylphenol (all OAV 1). A comparative analysis of polypropylene materials with different additives suggested plastic-like, pungent smelling hex-1-en-3-one as an ubiquitous key odorant. Odor-active amounts of alkylphenols, in particular plastic-like, phenolic smelling 2-tert-butylphenol, were additionally formed in the presence of talcum and phenolic antioxidants. Whereas the precursors of the phenols were thus obvious, the origin of hex-1-en-3-one was unknown. Injection molding showed only little influence on odorant concentrations.

Extraction of stabilizers from polymers: Separation of oligomeric hindered amine light stabilizers and phenolic antioxidants from polyolefins using liquid chromatography and high-temperature solid-phase extraction

The extraction of different stabilizers from a polymer matrix and the subsequent separation of said stabilizers is one of the most important as well as challenging undertakings in polymer chemistry. A multitude of stabilizers exists, each of which may be hard to extract, be difficult if not impossible to separate from other stabilizers or necessitate very selected and time-consuming intermediate stages for separation. Certain polymer matrices even pose additional challenges, such as polyolefins being only soluble at elevated temperatures. One of the most well-established approaches for the extraction of stabilizers is Soxhlet extraction. However, even this highly successful approach shows only limited success with regard to the extraction of the ever more relevant oligomeric stabilizers or the extraction of multiple stabilizers in a one-shot approach. Moreover, performing Soxhlet extractions often necessitates ≥24 h. For these reasons, alternative approaches for the extraction of stabilizers from polymers are highly sought after. An approach with enormous potential is solid-phase extraction, which allows the selective retention and enrichment of stabilizers. Herein, the very first application of high-temperature solid-phase extraction for the extraction of stabilizers from polyolefin matrices is described; as with other extraction techniques, the identification and quantification of the stabilizers is then allowed. At temperatures of 140-160°C, it was possible to adsorb common polyolefin stabilizers selectively on a silica solid phase from their polyolefin matrix. To predict high-temperature solid-phase extraction test conditions, first LC tests are necessary, offering an elegant approach for the separation of polyolefins from oligomeric stabilizers, which was not achievable until now.

Towards More Sustainable Materials for Geo-Environmental Engineering: The Case of Geogrids

Plastic materials are widely used in geotechnical engineering, especially as geosynthetics. The use of plastic-based products involves serious environmental risks caused by their degradation. Innovative research has been focusing on biodegradable polymers of natural origin, especially on poly(lactic acid) (PLA), to reduce the use of plastics. This study aims to explore the potentiality of biopolymers for the production of geogrids, measuring the chemical and mechanical characteristics of raw materials and of prototype samples, similar to those available on the market. First, chemical composition and optical purity were determined by hydrogen nuclear magnetic resonance (1H-NMR) and polarimetry. Furthermore, samples of uniaxial and biaxial geogrids were custom-molded using a professional 3D printer. Mechanical properties were measured both on the filament and on the prototype geogrids. The maximum tensile resistance was 6.76 kN/m for the neat-PLA filament and 10.14 kN/m for uniaxial prototype geogrids produced with PLA-based polymer mixed with titanium dioxide. PLA-based materials showed higher tensile properties than polypropylene (PP), the most common petroleum derivative. Conversely, such biomaterials seem to be more brittle and with scarce elongation rate respect PP. Nonetheless, these results are encouraging and can support the use of PLA-based materials for innovative biodegradable geosynthetics production, especially if used in combination with live plants.

Polypropylene-Based Nanocomposite with Enhanced Aging Stability by Surface Grafting of Silica Nanofillers with a Silane Coupling Agent Containing an Antioxidant

Simultaneous improvement in the mechanical properties and lifetime of polymer nanocomposites is crucially significant to further extend the versatility of polymer materials and reduce environmental impact. In this study, we fabricated reinforced polypropylene (PP)-based nanocomposites with improved aging stability by the addition of surface-modified well-ordered silica nanospheres with a silane coupling agent (SCA) containing hindered phenol antioxidant as a filler. Uniform grafting of the SCA on the filler surface contributed to homogeneous dispersion of the filler into the matrix, leading to improved properties (e.g., stiffness and ductility) and uniform distribution of the antioxidant component into the entire nanocomposite by filler dispersion. The grafting of SCA also likely provides an inhibitory effect on antioxidant migration, which leads to loss of polymer stability during the aging process. This novel idea for the material design of PP-based nanocomposites, which simultaneously enhances their mechanical properties and lifetime, is promising for application in the fabrication of various types of polymer nanocomposites.

Oleamide, a Bioactive Compound, Unwittingly Introduced into the Human Body through Some Plastic Food/Beverages and Medicine Containers

The purpose of the study was to investigate the migration of oleamide, a polymer lubricant, and a bioactive compound, from various plastic, marketed containers for food/beverages and medicines into polymer contact liquid. Methanol, food/medicine simulants or real samples were used to extract polymer leachables and extractables. Migrated oleamide into polymer contact liquids was determined by ultra-high performance liquid chromatography coupled to mass spectrometry (UHPLC-MS). The concentration of oleamide in the extracts of medicinal and insulin syringes was 7351 ng mL^-1 and 21,984 ng mL^-1, respectively. The leachates of intravenous (i.v.) infusion bottle, medicinal and insulin syringes contained 17 ng mL^-1, 12 ng mL^-1 and 152 ng mL^-1, respectively. Oleamide in the extracts of dummies ranged from 30 to 39 ng mL^-1, while in the leachates of baby bottles, from 12 to 23 ng mL^-1. Leachates of soft drink bottles contained from 6 to 15 ng mL^-1 oleamide, milk bottles from 3 to 9 ng mL^-1, liquid yogurt bottles 17 ng mL^-1 and water bottles from 11 to 18 ng mL^-1. Bottled real matrices of oil and milk contained oleamide in the range from 217 to 293 ng mL^-1. Moreover, the source of migrated oleamide (e.g., containers, caps, other parts) was identified. Oleamide is listed in the current EU regulations without a specific migration limit. Accordingly, these values are considered of no concern, unless future toxicological studies prove the opposite.

Identification of Additives in Polypropylene and Their Degradation under Solar Exposure Studied by Gas Chromatography-Mass Spectrometry

Additives are absolutely essential in the development of commercial polymeric materials. Accordingly, an exhaustive control of composition and evolution in these additives over time is necessary to validate their performance and safety during their shelf life and, consequently, their ultimate applications. Gas chromatography coupled with mass spectrometry, GC-MS, is described in the present work to identify and analyze the content of a wide variety of additives, commonly used in industrial polymeric materials. First, the identification under the present experimental protocol of additives with a relatively high molecular weight (Irganox 1330 and Irganox 1010) has been successfully attained. Second, the evolution under solar exposure over time has been analyzed by GC-MS for 11 additives and derived substances, which have been identified in a commercial polypropylene sample, estimating the corresponding depletion times. In addition, the resultant increase of carbonyl groups in the polymeric macrochains along the photo-oxidation has been also determined by infrared spectroscopy. Therefore, GC-MS is found to be a reliable tool for the analysis of the evolution of commonly used polymer additives under specific degradation conditions, which can be very useful in the formulation of improved future additivations.

Global CO2 Emission-Related Geotechnical Engineering Hazards and the Mission for Sustainable Geotechnical Engineering

Global warming and climate change caused by greenhouse gas (GHG) emissions have rapidly increased the occurrence of abnormal climate events, and both the scale and frequency of geotechnical engineering hazards (GEHs) accordingly. In response, geotechnical engineers have a responsibility to provide countermeasures to mitigate GEHs through various ground improvement techniques. Thus, this study provides a comprehensive review of the possible correlation between GHG emissions and GEHs using statistical data, a review of ground improvement methods that have been studied to reduce the carbon footprint of geotechnical engineering, and a discussion of the direction in which geotechnical engineering should proceed in the future.

Chlorinated Water Induced Aging of Pipe Grade Polypropylene Random Copolymers

Polypropylene random copolymers (PP-R) are common materials for pressurized hot water pipes. In many pipe systems, potable water is disinfected by chlorine to prevent waterborne diseases. This paper deals with hot chlorinated water induced aging of two PP-R grades with varying morphology. One material had a conventional monoclinic α crystal form (PP-Rα), whereas the other was explicitly beta-nucleated resulting in a trigonal β crystal form with a fine spherulite structure (PP-Rβ). Micro-sized specimens with a thickness of 100 µm were used for aging experiments at 60 °C in chlorinated water with 5 mg/L free chlorine, and aging indicators were monitored for exposure times of up to 2000 h. On the other hand, superimposed mechanical-environmental tests were carried out by using cracked round bar specimens with a diameter of 14 mm to determine the fatigue crack growth (FCG) resistance of both PP-R grades at 60 °C in non-chlorinated and chlorinated water. PP-Rβ was found to outperform PP-Rα with an about 30% higher time-to-embrittlement value of 2000 h. Furthermore, PP-Rβ exhibited an enhanced FCG resistance in both non-chlorinated and chlorinated water. The effect of chlorine content on the deterioration of the FCG resistances was significantly more pronounced for PP-Rα.

Physico-chemical properties of excavated plastic from landfill mining and current recycling routes

In Europe over 5.25 billion tonnes of waste has been landfilled between 1995 and 2015. Among this large amount of waste, plastic represents typically 5-25 wt% which is significant and has the potential to be recycled and reintroduced into the circular economy. To date there is still however little information available of the opportunities and challenges in recovering plastics from landfill sites. In this review, the impacts of landfill chemistry on the degradation and/or contamination of excavated plastic waste are analysed. The feasibility of using excavated plastic waste as feedstock for upcycling to valuable chemicals or liquid fuels through thermochemical conversion is also critically discussed. The limited degradation that is experienced by many plastics in landfills (>20 years) which guarantee that large amount is still available is largely due to thermooxidative degradation and the anaerobic conditions. However, excavated plastic waste cannot be conventionally recycled due to high level of ash, impurities and heavy metals. Recent studies demonstrated that pyrolysis offers a cost effective alternative option to conventional recycling. The produced pyrolysis oil is expected to have similar characteristics to petroleum diesel oil. The production of valuable product from excavated plastic waste will also increase the feasibility of enhanced landfill mining projects. However, further studies are needed to investigate the uncertainties about the contamination level and degradation of excavated plastic waste and address their viability for being processed through pyrolysis.

An untargeted evaluation of food contact materials by flow injection analysis-mass spectrometry (FIA-MS) combined with independent components analysis (ICA)

Food contact materials (FCMs), especially plastics, are known to be a potential source of contaminants in food. In fact, various groups of additives are used to protect the integrity of the material during processing and life time. However, these intentionally added substances (IAS) could also lead to degradation products called non-intentionally added substances (NIAS), due to reactions occurring in the polymeric material. Complex mixtures of components may therefore be generated within the material, creating a source of potential migrating substances towards food in contact. In this context, an innovative analytical approach is proposed in order to assess IAS and NIAS in plastic FCMs for a fast screening of their composition. For this purpose, solvent extracts of polyethylene (PE) pellets, containers and films were analyzed by flow injection analysis-mass spectrometry (FIA-MS). This direct approach offers the ability to perform a large number of analyses in a short time. Mass spectral fingerprints were then treated by a multivariate data analysis technique called independent components analysis (ICA) in order to overcome the complexity of such data and to highlight hidden information related to IAS and NIAS molecules. ICA applied on mass spectral fingerprints of PE extracts highlighted group discriminations related to different m/z values which were putatively assigned to IAS and also to NIAS. In order to confirm these putative annotations, a hybrid LTQ-Orbitrap was used for high resolution mass spectrometry analysis. Moreover, MS/MS experiments were performed on some discriminant ions to improve their putative identification. The proposed methodology combining FIA-MS fingerprints and ICA proved its efficiency in identifying IAS and NIAS in plastic FCMs and its capability to discriminate different PE samples, in a relatively fast approach compared to classical analytical techniques. This approach may help the FCMs classification for compounders in the selection of the starting substances in plastic formulation and for plastic converters in the control of manufacturing processes as well as for the monitoring of final products.

Geosynthetics in geoenvironmental engineering

Geosynthetics are planar polymeric products, which are used in connection with soil, rock or other soil-like materials to fulfill various functions in geoenvironmental engineering. Geosynthetics are of ever-growing importance in the construction industry. Sealing of waste storage facilities to safely prevent the emission of wastewater, landfill gas and contaminated dust as well as the diffusion of pollutants into the environment and coastal protection against storms and floods and reconstruction after natural disaster are important fields of application. We will give an overview of the various geosynthetic products. Two examples of the material problems related to geosynthetics are discussed in detail: the effect of creep on the long-term performance of geocomposite drains and the numerical simulation of the interaction of soil with geogrids. Both issues are of importance for the use of these products in landfill capping systems. The various functions, which geosynthetics may fulfill in the protection of coastal lines, are illustrated by case studies. The geosynthetic market is evaluated and economical and environmental benefits, as well as environmental side effects related to the use of geosynthetics, are discussed.