Open Access

Approximately 13% of the waste generated in Germany (2023) is processed in municipal solid waste incinerators (MSWI). MSWI in Europe operate under strict regulatory requirements defined by the Industrial Emissions Directive (IED), resulting in very low overall emissions, including PCDD/F. A more recent and widely discussed group of pollutants are per‐ and polyfluoroalkyl substances (PFAS), which are thermally degraded to hydrogen fluoride (HF), carbon dioxide (CO 2 ) and other thermodynamic end point compounds depending on elemental composition under complete combustion conditions. This study investigates the completeness of PFAS degradation in laboratory‐ and pilot‐scale incinerators. The conversion of PFAS to HF is assessed using several analytical techniques for detecting fluorine‐containing species in flue gas, liquids and solids, and their impact on establishing a consistent fluorine balance (F‐balance). Depending on the analytical method employed, the achieved F‐balance ranges from 59 to 100 wt% when ‘products of incomplete combustion’ (PICs) are not considered.

By evaluating the long-wavelength limit of Khachaturyan’s microelasticity theory, we show that it recovers the Kamachali–Wang continuum formulation for multi-component solid solutions [Scripta Mater 206 (2022) 114226]. A corresponding expression for the elastic energy of multi-component solid solutions under cubic anisotropy is also obtained and discussed in comparison with the isotropic case. The framework is demonstrated on the Fe–Mn–Ni–Co–Cu alloy system to perform phase stability analysis at 873 K, including spinodal and binodal part of the phase diagram. The resulting cubic-anisotropic (incoherent) phase diagrams show that the spinodal promotion is reduced compared to the isotropic case, consistent with the derivations. The limit transition is examined using a Gaussian window function, which allows the definition of a critical coarse-graining length above which the continuum description becomes valid. This study provides a rigorous microscopic foundation for continuum multi-component elastic energy formulations, with broad computational implications in thermodynamic and phase-field modeling of chemically complex alloys and microstructures.

Water under nanoscale confinement exhibits structural and dynamical states distinct from bulk behavior, yet the role of pore chemistry in governing these states remains insufficiently understood. Herein, the hydration kinetics and molecular-scale fluctuations of water confined within a comprehensive series of MOF-74 metal-organic frameworks incorporating Mg, Ni, Co, and mixed-metal compositions were investigated and compared with those observed in mesoporous MCM-41 silica. In situ impedance spectroscopy resolves a pronounced multistep hydration mechanism in MOF-74, initiated by rapid coordinative binding at open metal sites, followed by cluster formation and final capillary condensation. In contrast to MCM-41 silica, where capillary condensation dominates, the presence of coordinatively unsaturated metal centers fundamentally alters adsorption pathways. Mixedmetal MOF-74 exhibits accelerated and temporally broadened hydration, reflecting heterogeneous distributions of adsorption energies. Broadband dielectric spectroscopy reveals a distinct water-specific relaxation process (w-relaxation) attributed to fluctuations of water clusters interacting with metal nodes. Relaxation rates follow Arrhenius behavior with activation energies increasing in the order Mg < Ni < Co and further enhanced in mixed-metal systems. Remarkably, water confined within MOF-74 remains liquid-like down to 133 K without crystallization, whereas crystallization is observed in MCM-41 silica. All activation data of the MOF-74 systems obey a common Meyer−Neldel compensation relation, indicating cooperative molecular dynamics and suggesting a hindered glass-transition−like process of confined water clusters. These findings demonstrate that open metal sites and metal composition enable programmable control over hydration kinetics and collective water dynamics in microporous frameworks. MOF-74 thus provides a tunable model platform for engineering water-driven transport, catalysis, and energy-relevant processes atthe nanoscale.

In the European Union’s railway system, more than 100 million prestressed concrete sleepers have been installed. Loads and weathering lead to a continuous degradation during the service life of several decades. Corrosion of the reinforcement, chemical reactions, and freeze-thaw damages at the bottom side may all lead to crack generation. For a long time, these internal degradations remain invisible from the outside, even though a reduction in load capacity may already endanger structural integrity. Non-destructive testing based on acoustic methods is investigated in this study. The focus is the detection of internal cracks and degradations of the material structure. In laboratory, six B70 sleepers were investigated, two of which were factory new. The other four had been in service for several years and manifold cracks had developed. With the purpose to measure in motion in the field, air-coupled impact-echo was adapted. The eigen frequency is excited based on the aeroacoustics of a supersonic jet flow. In the area of serious cracks, a significant decrease of the eigen-frequency is observed. These findings were compared with the excitation using a manual impacthammer. An accelerometer and an acoustic camera were used for signal recording.

Industrial sectors, especially those with significant global CO2 emissions like the cement and concrete industries, are striving to achieve net-zero emissions by 2050. It is anticipated that carbon dioxide removal will be required to meet these goals. Hydrated cement in concrete can react with atmospheric CO2 to form carbonate minerals (i.e. carbonation), and in doing so, act as a carbon uptake mechanism. This carbonation process can be accelerated via various engineering interventions, such as crushing concrete after demolition. In this literature review, we examine key parameters, including porosity, exposure conditions, CO2 concentration, curing methods, coatings, and the use of supplementary cementitious materials, that affect CO2 uptake in concrete to inform better quantification of life cycle emissions. These findings can inform the feasibility of implementing carbonation as a method for reducing emissions from cement-based materials and identify data limitations that need further study for future modeling efforts. Presently, it has been estimated that 9%–17% of concrete production emissions could be re-adsorbed during use and end of life. However, such estimates of uptake have only considered limited data sets, without fully addressing the comingled effects of the parameters impacting carbonation. Further, some carbon uptake modeling efforts may require input values that are not readily available, or may be challenging to repeat, and do not accurately account for carbon fluxes over the life cycle. Findings from this review highlight the importance of development of systematic approaches to assess cradle-to-grave life cycle assessments using dynamic carbon accounting when measuring concrete carbonation.