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Conversion of chemical feedstocks derived from fossil fuels to virgin polymer, manufacturing of plastics in coal-dependent economies, and increasing consumption of virgin polymers for plastics packaging contribute significantly to environmental issues and the challenges we face. Nowadays, promoting sustainable development has become the consensus of more and more countries. Among them, the recycling of multilayer packaging is a huge challenge. Due to the complexity of its structure and materials, as well as the limitations of existing recycling frameworks, currently, multilayer packaging cannot be commercially recycled thus resulting in a series of circular economy challenges. It is undeniable that multilayer packaging offers many positive effects on products and consumers, so banning the use of such packaging would be unwise and unrealistic. Developing the appropriate processes to recycle multilayer packaging is the most feasible strategy. In recent years, there have been some studies devoted to the recycling process of multilayer packaging. Many of the processes being developed involve the use of solvents. Based on the recycled products, we categorised these recycling processes as solvent-based recycling, including physical dissolution and chemical depolymerisation. In physical dissolution, there are mainly two approaches named delamination and selective dissolution–precipitation. Focusing on these processes, this paper reviews the solvents developed and used in the last 20 years for the recycling of polymers from multilayer packaging waste and gives a summary of their advantages and disadvantages in terms of cost, product quality, ease of processing, and environmental impact. Based on existing research, one could conclude that solvent-based recycling methods have the potential to be commercialised and become part of a standard recycling process for polymer-based multilayer packaging. The combined use of multiple solvent-based recycling processes could be a breakthrough in achieving unified recycling of multilayer packaging with different components. [ABSTRACT FROM AUTHOR]

This study explores the stability of electrodeposited copper catalysts utilized in electrochemical CO2 reduction (ECR) across various amine media. The focus is on understanding the influence of different amine types, corrosion ramifications, and the efficacy of pulse ECR methodologies. Employing a suite of electrochemical techniques including potentiodynamic polarization, linear resistance polarization, cyclic voltammetry, and chronopotentiometry, the investigation reveals useful insights. The findings show that among the tested amines, CO2-rich monoethanolamine (MEA) exhibits the highest corrosion rate. However, in most cases, the rates remain within tolerable limits for ECR operations. Primary amines, notably monoethanolamine (MEA), show enhanced compatibility with ECR processes, attributable to their resistance against carbonate salt precipitation and sustained stability over extended durations. Conversely, tertiary amines such as methyldiethanolamine (MDEA) present challenges due to the formation of carbonate salts during ECR, impeding their effective utilization. This study highlights the effectiveness of pulse ECR strategies in stabilizing ECR. A noticeable shift in cathodic potential and reduced deposit formation on the catalyst surface through periodic oxidation underscores the efficacy of such strategies. These findings offer insights for optimizing ECR in amine media, thereby providing promising pathways for advancements in CO2 emission reduction technologies. [ABSTRACT FROM AUTHOR]

Porosity poses a challenge to the mechanical properties of cold sprayed coatings, especially when it is open or surface-connected, limiting the coatings' capabilities to act as a barrier. The porosity formation is dependent on the feedstock powder characteristics and the cold spray process parameters. We present a machine learning-based approach to predict porosity based on the above-mentioned factors. Nine different machine learning models based on linear regression (LR), decision trees, random forests, gradient boosting, support vector machine (SVM), and neural networks were explored. Considering the excellent properties of high entropy alloys, Cantor alloy was taken as the consumable. Our dataset, derived from the literature and experiments, identified SVM with a linear kernel and LR as the top-performing models based on the Pearson correlation coefficient (PCC) and root mean square error, where the PCC values exceeded 0.8. The SHapley Additive exPlanations method helped in identifying that the type of gas and powder are the top two factors in pore formation. [ABSTRACT FROM AUTHOR]

Zinc electrodeposition serves as a crucial electrochemical process widely employed in various industries, particularly in automotive manufacturing, owing to its cost effectiveness compared to traditional methods. However, traditional zinc electrodeposition using aqueous solutions faces challenges related to toxicity and hydrogen gas generation. Non-aqueous electrolytes such as ionic liquids (ILs) and deep eutectic solvents (DESs) have gained attention, with choline-chloride-based DESs showing promise despite raising environmental concerns. In this study, zinc electrodeposition on mild steel was investigated using three distinct electrolytes: (i) halide-free aqueous solutions, (ii) chloride-based DES, and (iii) halide-free acetate-based organic solutions. The study examined the influence of deposition time on the growth of Zn on mild steel substrates from these electrolytes using physical characterization techniques, including scanning electron microscopy (SEM) and X-ray diffraction (XRD). The results indicate that glycol + acetate-based non-aqueous organic solutions provide an eco-friendly alternative, exhibiting comparable efficiency, enhanced crystalline growth, and promising corrosion resistance. This research contributes valuable insights into the impact of electrolyte choice on zinc electrodeposition, offering a pathway towards more sustainable and efficient processes. Through a comprehensive comparison and analysis of these methods, it advances our understanding of the practical applications of zinc electrodeposition technology. [ABSTRACT FROM AUTHOR]

In recent years, there has been growing interest in thermal spray techniques using suspension or solution-based coatings. These techniques offer precise control over particle size and microstructure, improving feedstock flowability and allowing for high-quality coating customization. Spray parameters, such as stand-off distance (SOD) and feedstock flow rate, can alter the performance and characteristics of these coatings. Geothermal power plant heat exchangers often face issues like corrosion, scaling, and fouling. The literature suggests that these issues could be mitigated, at least in part, by the use of spray coatings. In this study, TiO2 coatings were applied on a carbon steel substrate using suspension plasma spray (SPS) to enhance the performance of geothermal heat exchanger materials. The impact of SOD (50, 75, and 100 mm) and feedstock flow rate (10, 20, and 30 mL/min) on these coatings was examined through various techniques, including scanning electron microscope (SEM), profilometry, X-ray diffraction (XRD), and adhesion testing. The results demonstrated that coatings deposited using a 10 mL/min feedstock flow rate were well adhered to the substrate due to the efficient melting of the coating material, but as the SOD and feedstock flow rate increased due to poor thermal and kinetic energy exchange between the torch and feedstock particles, adhesion between the coating and substrate decreased. [ABSTRACT FROM AUTHOR]

The main aim of this research work is to investigate the high-temperature cyclic corrosion performance of the wrought and direct metal laser sintered (DMLS) alloy 718 in the air and molten salts NaCl-90%Na2SO4 and three salt mixture (3SM) Na2SO4-10%V2O5-10%NaCl atmosphere for 120 h at 800°C. The microstructure of the wrought and DMLS alloy illustrated the austenitic and dendrite structure. Scanning electron microscope (SEM) and X-ray diffraction (XRD) were used to evaluate the structure and phase constitutions of the scale. Visual and microstructural evaluation of the alloy post-exposure indicates that corrosion is more prevalent in molten salt conditions, when compared to air, and Cl-species induced the active oxidation in molten salt. The oxide film development and damage mechanism were detailed and explained by a cross-sectional investigation. Significant spalling and sputtering were also noticed in the S3 salt mixture. This might be attributed to the rapid formation of oxide scales by vanadate, followed by dissolution of the oxide in molten sulphate and chloride. The results divulged that both AM-built and wrought alloy exhibited the similar corrosion properties and both the alloys were undergone severe degradation in MS condition. Highlights Alloy 718 was fabricated successfully by the direct metal laser sintering (DMLS) method. Cyclic high-temperature oxidation and corrosion of the alloy were studied at 800°C. The oxidised sample exhibits a lower weight gain with no damage. Due to chlorination and sulfidation, the corroded samples exhibited more oxidation and susceptible. [ABSTRACT FROM AUTHOR]

The aim of the EU 2020 GeoSmart project relies on the demonstration of innovative solutions to improve the flexibility and the efficiency of geothermal heat and power systems. This specific study focuses on issues related to silica scaling and its deposition on the reinjection wells. A limiting constraint for geothermal plants to fully utilize the thermal energy form well fluids is in fact the need to reinject geothermal brine at a high enough temperature to prevent thermodynamic fouling by silica scale deposition. GeoSmart aims to develop a solution based on retention system technology to control and reduce the silica scale formation before re-injection. Lowering reinjection temperature would strongly increase plant efficiency by providing extra useful heat. Based on silica scaling numerical simulation, the effects of parameters like pH, temperature and brine composition on silica polymerization and scaling deposition rates, the design and optimization of the retention system has been developed. The design aims to promote polymerization phenomena inside the tank so that scaling is consequently inhibited in the reinjection well pipes. Chemical additives and specific coatings have also been evaluated to guarantee the optimal required conditions. The case study is based on real-data referred to operational conditions and brine composition of the Zorlu Kizildere plant in Turkey. The economic and environmental impact of the retention system has been evaluated with positive outcomes. The in-site test and validation at industrial level of the above mentioned technology will be provided during the next activities of the GeoSmart project