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The pervasion of plastic and the inadequacies of the current plastic waste management processes are the premise of various studies that aimed to find sustainable solutions to the plastic waste issues. Amongst these solutions, plastic pyrolysis is particularly promising due to its commercial maturity and complementarity to mechanical recycling. In this paper, recent studies of plastic pyrolysis are reviewed and scrutinised, with particular attention given to feedstock composition, operating conditions, and catalytic choices. Our systematic review found that the success of plastic pyrolysis is dependent on many inter-related operational factors, such as temperature, residence time, and feedstock characteristics. Thus, the application of Artificial Intelligence (AI) can enhance our understanding of the various interconnected parameters involved in plastic pyrolysis. However, AI capacity must be further improved to incorporate more variables such as contaminants, fluctuating feedstocks, and mixed polymers. Many Life Cycle Assessments (LCA) studies have provided abundant evidence showing that plastic pyrolysis is more environmentally beneficial incineration and landfill. Hence, future LCA studies should shift from a comparative perspective to a more holistic approach where plastic pyrolysis is considered as an integrated part of a sustainable waste management system. The review has also identified that more research efforts should be directed towards catalytic pyrolysis and monomer recovery. [Display omitted] • Performance of plastic pyrolysis depends on temperature and feedstock composition. • Product quality of raw plastic waste is different than virgin plastics. • Lab-scale plastic pyrolysis did not reflect industrial feedstock composition. • Microwave pyrolysis has significant operational benefits over conventional pyrolysis. • AI can accelerate the adoption of plastic pyrolysis in waste management. [ABSTRACT FROM AUTHOR]

Abstract: The characterization of materials in historical artifacts can contribute significantly to their preservation and understanding; however, sampling and characterization are ideally performed using non-destructive approaches. The analysis of green pigments from Egyptian artifacts presents a further challenge as responses to laboratory based techniques have proven unsuccessful in many cases. An alternative approach is the use of non-destructive X-ray absorption near-edge structure spectroscopy, which was performed on a reference set of copper-containing green minerals and other compounds. Data projection using principal component analysis was used to explore the spectral data structures and to illustrate the relationship between the spectra and copper speciation, resulting in a calibration or training set of the reference materials used. Data from the training set were compared with samples from Egyptian artifacts. The combination of X-ray absorption spectroscopy with principal components analysis provides a novel approach in archeometry and the characterization of objects of cultural heritage. [Copyright &y& Elsevier]

Chemical recycling is a promising technology that can help alleviate the environmental burdens of plastic waste. This paper developed a comprehensive, scenario-based life cycle assessment (LCA) to quantify the environmental profile of different management options to treat polyethylene (PE) and polypropylene (PP), including landfill, pyrolysis, and gasification. Using a system expansion method and inventory data from various sources, the result showed that the recovery of ethylene and propylene monomers for plastic re-manufacturing, which resembled closed-loop recycling systems, offered the highest environmental benefits. Most notably, fossil fuel depletion, climate change, and human toxicity impacts were 36,761%, 1063%, and 329% lower than those of landfill disposal, respectively. Open-loop recycling scenarios, such as high-value chemical (HVC) and energy recovery from pyrolysis and gasification, were also investigated. Amongst these scenarios, pyrolysis for HVC recovery was the most environmentally favourable, followed by HVC recovery using gasification. Energy recovery scenarios offered limited benefits and had worse results than landfill in terrestrial acidification, freshwater and marine eutrophication impact categories. The main driver of impacts during end-of-life treatment using chemical recycling is the energy consumption needed to achieve appropriate temperature for the necessary reactions to take place. In terms of material consumption, the use of nitrogen gas to purge the reactor is the biggest contributor for pyrolysis whereas zeolite usage accounts for the majority of material impacts for gasification. [Display omitted] [ABSTRACT FROM AUTHOR]

Expanded polystyrene (EPS) pollution in the marine environment is a pressing issue in Queensland, Australia due to a recent flood that scattered hundreds of EPS-containing pontoons along the coastline, causing severe ecological damage. To assist in the clean-up effort and provide crucial data for developing management guidelines, this study investigates the environmental performance of different end-of-life (EoL) disposal/recycling methods, including (i) landfill; (ii) on-site mechanical re-processing using a thermal densifier (MR); and (iii) on-site dissolution/precipitation using d -limonene (DP). Applying the life cycle assessment framework, the results showed that DP was the most environmentally favourable option. Its impacts in climate change (GWP), acidification (TAP), and fossil fuel depletion (FFD) were 612 kg CO 2 eq, 4.3 kg SO 2 eq, and 184.7 kg oil eq, respectively. For comparison, the impacts of landfilling EPS in these categories were found to be 700 kg CO 2 eq, 3.5 kg SO 2 eq, and 282 kg oil eq, respectively. Landfill also contributed considerably to eutrophication potential (MEP), at 3.77 kg N eq. Impacts from MR were most significant due to the need to transport the densifier unit to the site. The analysis also revealed that the transportation of personnel and heavy machinery to the site, was the biggest contributor to impacts in the EoL stage. Its impacts in GWP, TAP, MEP, and FFD were 1369.8 kg CO 2 eq, 6.5 kg SO 2 eq, 0.2189 kg N eq, and 497.7 kg oil eq, respectively. Monte Carlo analysis showed that the conclusions made from these results were stable and reliable. Limitations of this model and recommendations for future investigations were also discussed in this work. [Display omitted] • Transportation imposed the highest impacts during disposal of missing pontoons. • Mechanical re-processing had highest impacts. • d -limonene dissolution showed the best environmental performance. • Further research is needed to optimise d -limonene dissolution process. • Recovery of PS is desirable, but not feasible. [ABSTRACT FROM AUTHOR]

Abstract: Carbon nanotubes (CNTs) grown on substrate-bound catalysts by CVD are influenced by the catalyst, which changes over the course of the process. The evolution of the CNT growth is revealed by breaking the process into recycling increments and using the phenomenon of ‘direct spinnability’ as a target characteristic. Using acetylene alone, it was found that the first four cycles gave 100% regrowth in height and mass yield of CNTs, with both properties falling to around 20% on the 5th cycle. A decrease in nanotube diameter was observed whilst the areal density increased. With the addition of hydrogen a 100% regrowth for the second cycle was observed, followed by a decrease to around 55%, 18% and 11% in both height and yield for subsequent cycles. The diameter increased, whilst the areal density decreased in subsequent cycles. In the absence of hydrogen the CNTs have around seven walls, decreasing to about three by the seventh cycle. With hydrogen, CNTs have five or six walls for all cycles. Raman spectroscopy indicates an increase in disorder in later cycles. Spinnability is high for initial cycles but drops sharply on the fourth cycle, or third cycle with hydrogen, as the nanotube forest tortuosity markedly increases. [Copyright &y& Elsevier]