Increasing the stream of recycled plastic necessitates an approach beyond the traditional recycling via melting and re‐extrusion. Various chemical recycling processes have great potential to enhance ...recycling rates. In this Review, a summary of the various chemical recycling routes and assessment via life‐cycle analysis is complemented by an extensive list of processes developed by companies active in chemical recycling. We show that each of the currently available processes is applicable for specific plastic waste streams. Thus, only a combination of different technologies can address the plastic waste problem. Research should focus on more realistic, more contaminated and mixed waste streams, while collection and sorting infrastructure will need to be improved, that is, by stricter regulation. This Review aims to inspire both science and innovation for the production of higher value and quality products from plastic recycling suitable for reuse or valorization to create the necessary economic and environmental push for a circular economy.
Plastic fantastic: Plastic can rise again and again as a new product. Researchers now know methods with which new plastics can be produced from 100 % recycled material, products that can even be used for food applications. This development is possible thanks to chemical recycling, through which polymer chains are first broken to then be reformed into new molecules, such as plastics but also other chemicals.
Lignin is an abundant and heterogeneous waste byproduct of the cellulosic industry, which has the potential of being transformed into valuable biochemicals via microbial fermentation. In this study, ...we applied a fast‐pyrolysis process using softwood lignin resulting in a two‐phase bio‐oil containing monomeric and oligomeric aromatics without syringol. We demonstrated that an additional hydrodeoxygenation step within the process leads to an enhanced thermochemical conversion of guaiacol into catechol and phenol. After steam bath distillation, Pseudomonas putida KT2440‐BN6 achieved a percent yield of cis, cis‐muconic acid of up to 95 mol% from catechol derived from the aqueous phase. We next established a downstream process for purifying cis, cis‐muconic acid (39.9 g/L) produced in a 42.5 L fermenter using glucose and benzoate as carbon substrates. On the basis of the obtained values for each unit operation of the empirical processes, we next performed a limited life cycle and cost analysis of an integrated biotechnological and chemical process for producing adipic acid and then compared it with the conventional petrochemical route. The simulated scenarios estimate that by attaining a mixture of catechol, phenol, cresol, and guaiacol (1:0.34:0.18:0, mol ratio), a titer of 62.5 (g/L) cis, cis‐muconic acid in the bioreactor, and a controlled cooling of pyrolysis gases to concentrate monomeric aromatics in the aqueous phase, the bio‐based route results in a reduction of CO2‐eq emission by 58% and energy demand by 23% with a contribution margin for the aqueous phase of up to 88.05 euro/ton. We conclude that the bio‐based production of adipic acid from softwood lignins brings environmental benefits over the petrochemical procedure and is cost‐effective at an industrial scale. Further research is essential to achieve the proposed cis, cis‐muconic acid yield from true lignin‐derived aromatics using whole‐cell biocatalysts.
A fast‐pyrolysis process using softwood lignin resulting in a two‐phase bio‐oil was applied. Van Duuren and co‐workers have shown that after steam bath distillation, Pseudomonas putida KT2440‐BN6 achieved a percent yield of cis, cis‐muconic acid of up to 95 mol% from catechol derived from the aqueous phase. Based on a limited life cycle and cost analysis of an integrated biotechnological and chemical process for producing adipic acid, the authors have estimated its environmental benefits and cost‐effectiveness.
In systems involving quantitative data, such as probabilistic, fuzzy, or
metric systems, behavioural distances provide a more fine-grained comparison of
states than two-valued notions of behavioural ...equivalence or behaviour
inclusion. Like in the two-valued case, the wide variation found in system
types creates a need for generic methods that apply to many system types at
once. Approaches of this kind are emerging within the paradigm of universal
coalgebra, based either on lifting pseudometrics along set functors or on
lifting general real-valued (fuzzy) relations along functors by means of fuzzy
lax extensions. An immediate benefit of the latter is that they allow bounding
behavioural distance by means of fuzzy (bi-)simulations that need not
themselves be hemi- or pseudometrics; this is analogous to classical
simulations and bisimulations, which need not be preorders or equivalence
relations, respectively. The known generic pseudometric liftings, specifically
the generic Kantorovich and Wasserstein liftings, both can be extended to yield
fuzzy lax extensions, using the fact that both are effectively given by a
choice of quantitative modalities. Our central result then shows that in fact
all fuzzy lax extensions are Kantorovich extensions for a suitable set of
quantitative modalities, the so-called Moss modalities. For nonexpansive fuzzy
lax extensions, this allows for the extraction of quantitative modal logics
that characterize behavioural distance, i.e. satisfy a quantitative version of
the Hennessy-Milner theorem; equivalently, we obtain expressiveness of a
quantitative version of Moss' coalgebraic logic. All our results explicitly
hold also for asymmetric distances (hemimetrics), i.e. notions of quantitative
simulation.
•Wheat straw was fractionated by an acetic and formic acid based organosolv process.•A thorough mass balance of main compounds in the different fractions was made.•Cellulose and lignin were ...efficiently recovered in different process fractions.•The process led to extensive hydrolysis of hemicellulose.•The organosolv process is a solid base for biorefining.
To assess the potential of acetic and formic acid organosolv fractionation of wheat straw as basis of an integral biorefinery concept, detailed knowledge on yield, composition and purity of the obtained streams is needed. Therefore, the process was performed, all fractions extensively characterized and the mass balance studied. Cellulose pulp yield was 48% of straw dry matter, while it was 21% and 27% for the lignin and hemicellulose-rich fractions. Composition analysis showed that 67% of wheat straw xylan and 96% of lignin were solubilized during the process, resulting in cellulose pulp of 63% purity, containing 93% of wheat straw cellulose. The isolated lignin fraction contained 84% of initial lignin and had a purity of 78%. A good part of wheat straw xylan (58%) ended up in the hemicellulose-rich fraction, half of it as monomeric xylose, together with proteins (44%), minerals (69%) and noticeable amounts of acids used during processing.
The ex-situ catalytic pyrolysis of sugarcane bagasse with various HZSM-5 (23, 50, and 80) catalysts was studied in a tandem micro reactor-GC/MS at 400 °C, 450 °C, 500 °C and 550 °C with a catalyst to ...biomass (C/B) ratios ranging from 2 to 23. The yields of benzene, toluene and xylenes (BTX) were significantly affected by pyrolysis temperature and C/B ratio. The highest BTX yield of 22% was obtained for the HZSM-5 (23) catalyst at C/B ratio of 12.5 and a temperature of 475 °C. Finally, an experimental design was performed to determine the optimal process conditions for BTX yields.
•New value-added application of wood torrefaction wastes.•Phenol-formaldehyde adhesives with torrefaction condensates.•Novel plywood panels competitive to conventional ones.
The last decades, ...investigators have been striving to find alternatives to materials and products from fossil sources in response to the need to get independent from petroleum. So far, the most attractive renewable source has been found to be biomass and especially wood that is easily accessible and offers a wide range of building blocks with diverse chemistries and structures that can then be used to build materials for the modern world. In this study, wood from Aspen, Pine and Birch as well as a mixture of Spruce and Pine was subjected to torrefaction and the fraction of the condensables with a dew point above 140 °C was used for the partial replacement of phenol (up to 40% wt) in the synthesis of resol phenol-formaldehyde resins suitable to be used as adhesives in the manufacturing of plywood panels. The condensables and the resins were subjected to typical lab analysis and thermal study with TGA and DSC while the plywood panels were tested and evaluated according to the European standards used by the relative industry. It was found that the studied torrefaction condensables may be successfully used in this application while the one from pine was the best performed overall.
PDF
