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Solid composites used in material extrusion additive manufacturing have experienced considerable expansion over the past 5 years, incorporating functional properties into 3D‐printed objects. This paper presents a systematic review that aims to: (I) analyze the current state of development in the field; (II) quantify and categorize the adopted polymeric matrices, reinforcing materials, feedstock shapes, characterization strategies, and extrusion mechanisms; and (III) identify the applications, limitations, and trends for future research. The PRISMA statement was followed and the databases Scopus, Web of Science, and PubMed were consulted. Among the 116 included studies, the use of customized filaments surpassed the commercially available ones, with particulate matter being the most common form of filler when melt‐mixed with the polymer. Polyamide is the most widely adopted matrix (30.3%), followed by PLA (22.0%) and ABS (17.4%). In terms of reinforcements, carbon fiber (32.4%), glass fiber (12.5%), and ceramics (12.5%) compose the podium as the most frequently used, with nanofillers receiving increasing attention. In the conducted analysis, no standardized protocols were identified that clearly encompassed the entire process from feedstock formulation to technical prototype fabrication. At last, recycling, exploration of biodegradable materials, and 4D printing were identified as the main opportunities for future research. Highlights: Reinforced polymers enable the enhancement of properties for 3D‐printed parts.Composite feedstock is usually formulated and mixed before printing.3D printers with filament‐ or screw‐based extrusion mechanisms have been used.Mechanical and morphological analyses are common in material characterization.No identified applications were employed in real‐world scenarios. [ABSTRACT FROM AUTHOR]

Nowadays an enormous effort has been made to impulse the incorporation of additive manufacturing (AM) approaches in the biomedical sector. One of the most recognized biomaterials for this end is bioceramics such as hydroxyapatite (HA), but unfortunately, ceramics present a lack of accessible technologies based on AM. Consequently, the development of new methodologies which enable the manufacture of bioceramic‐based scaffolds is imperative. A large number of publications on polymer–ceramic composite processed by Material Extrusion are available, so far, the maximum ceramic loading reached is still a parameter to improve. Recently an alternative colloidal processing technique to prepare ceramic‐based composite feedstock for material extrusion has been proposed. It has been demonstrated that tailoring the surface of the ceramic particles enables the processing of high ceramic loading composites by AM. This article shows the potential of the colloidal approach to process biocompatible PLA/HA feedstock increasing the homogeneity of the bioceramic phase into the composite. The feedstock characterization shows that HA surface modification makes possible the successful dispersion and the ceramic load increase without modifying the biocompatibility. The ceramic load increase does not modify the melting properties of the polymeric matrix required for the 3D printing process. This methodology allows for the first time the development of a final 3D printed composite structure with contents up to 72 wt% of HA by Material Extrusion. This colloidal approach paves the way to transfer the use of additive manufacturing techniques mainly devoted to polymeric biomaterials to other types of biomaterials such as bioceramics. Highlights: A colloidal approach for 3D printing of PLA/HA composites is proposed.HA surface modification made possible a load increase with high dispersion.The characterization of a PLA/HA feedstock for 3D printing is established.Biocompatible PLA/HA feedstock is processed by AM in customized structures.Colloidal approach allows the processing of 3D structures with 72 wt% of HA. [ABSTRACT FROM AUTHOR]

The research impact of catalysts on the hydrothermal carbonization (HTC) process remains an ongoing debate, especially regarding the quest to enhance biomass conversion into fuels and chemicals, which requires diverse catalysts to optimize bio-oil utilization. Comprehensive insights and standardized analytical methodologies are crucial for understanding HTC's potential benefits in terms of biomass conversion stages. This review seeks to understand how catalysts enhance the HTC of biomass for liquid fuel and hydrochar production, drawing from the following key sections: (a) catalyst types applied in HTC processes; (b) biochar functionality as a potential catalyst; (c) catalysts increasing the success of HTC process; and (d) catalyst's effect on the morphological and textural character of hydrochar. The performance of activated carbon would greatly increase via catalyst action, which would progress the degree of carbonization and surface modification, alongside key heteroatoms. As catalytic HTC technology advances, producing carbon materials for thermochemical activities will become more cost-effective, considering the ever-growing demands for high-performance thermochemical technologies. [ABSTRACT FROM AUTHOR]

A pyro-hydrometallurgical process is proposed in this study for the selective arsenic removal and the Pb and Sb recovery from lead softening slag, which incorporates NaOH roasting followed by water leaching, carbothermic reduction, and HNO3 leaching as process steps. Lead softening slag, containing 63.9 wt% Pb, 17.7 wt% Sb, and 4.4 wt% As, is first roasted with NaOH at 400°C, followed by water leaching at room temperature. The effect of the roasting temperature and NaOH dosage is investigated with regard to the removal yield of As, Pb, and Sb. The arsenic-free slag is reduced with carbon for Pb recovery as the antimonial lead. The reduction temperature and carbon dosage are optimized by applying FactSage modeling and performing experimental tests for selective Pb recovery. The residual slag is leached with HNO3 solution for the further removal of Pb and enrichment of Sb. The chemical and phase composition of the final leaching residue is determined to assess the possibility of using it as a feedstock for antimony trioxide production. The proposed process flowsheet enables the recovery of Pb and Sb as antimonial lead and antimony trioxide, respectively. [ABSTRACT FROM AUTHOR]

Biomass and biowastes stand as sustainable and cost-effective environmentally benign alternative feedstock. Chitosan is a biocompatible, bioactive, and biodegradable biopolymer derived from chitin to achieve eight aspects out of the 12 green chemistry principles. Chitosan got significant attention in several fields including chemical analysis, in addition to chemical functionally, which enabled its use as adsorbent and its structural crosslinking using various crosslinkers. The physicochemical, technological, and optical properties of chitosan have been extensively exploited in analysis. Mainly, deacetylation degree and molecular weight are controlling its properties and hence controlling its functions. This review presents a structure, properties, and functions relationships of chitosan. It also aims to provide an overview of the different functions that chitosan can serve in each analytical technique such as supporting matrix, catalyst...etc. The contribution of chitosan in improving the ecological performance is discussed in each technique. [ABSTRACT FROM AUTHOR]

Wood pellet is an important biomass-based source of cleaner and renewable energy with a growing global demand. Populus spp. (poplars) are fast-growing trees with high productivity potential in the southeastern US. Selected pellet-quality parameters were examined as a proxy for assessing if the feedstock quality of poplar stem wood was affected by stand location (Coastal, Piedmont, Mountains of North Carolina, clone "140"), stand age (five vs. seven years, clone-"140"), clones ("140", "176", "230", "185", "356") and stem sections (clone-"356") by examining sulfur, ash, volatile-matter, fixed-carbon, gross caloric, carbon, hydrogen, and nitrogen contents of moisture-free samples. Location-study samples significantly varied (p≤0.027) in ash (0.6–0.9 wt%), and gross caloric (19.75–19.89 MJ/kg) contents and study clones significantly differed (p≤0.0271) in ash (means: 0.75–0.97 wt%), volatile-matter (means: 80.5–82.7 wt%), fixed-carbon (means: 16.5–18.7 wt%) and hydrogen (means: 4.19–4.78 wt%) contents. The only other significant variations were hydrogen (mean: 4.19–4.67 wt%) content with stand age (p≤0.009) and gross caloric values (19.5–19.9 MJ/kg) among stem sections (p = 0.0003). This study showed that poplars have stem-wood quality suitable for pellet production and most of the studied feedstock samples had ash, nitrogen, sulfur, and caloric (at 10% moisture content) contents that would meet the ENplus pellet-quality standards. Results from this study can be used for facilitating decisions about managing poplar stands for sustainable pellet feedstock production in the southeastern US, including selecting optimum rotation length, pellet-suitable clones, and sites. [ABSTRACT FROM AUTHOR]

Microalgae harvesting includes conventional methods like centrifugation, sedimentation, and filtration, as well as advanced methods like flocculation, magnetic nanoparticle, and flotation. Biomass recovery using centrifugation is high but high gravitational force can alter the cell structure. Sedimentation is one of the most useful methods in wastewater microalgae harvesting, though it is applicable to large-cell microalgae (>70 μm). Filtration is a low-cost method and easy to process; however, fouling and clogging can result in low yield. Among several techniques, flocculation is one of the most effective and economical approaches for biomass harvesting. Nanomaterial-based flocculants are considered due to their efficiency and reusability. Nanoparticle-based flocculants have gained attention in recent years due to their unique properties, such as high surface area, small size, and enhanced reactivity. These nanoparticles can be engineered to interact with microalgal cells, causing agglomeration and facilitating the separation of biomass from the culture medium. Studies have demonstrated that using nanoparticle-based flocculants can significantly improve the efficiency of microalgae harvesting compared to traditional flocculation methods. This review emphasizes the mechanism of flocculation, types of flocculation, the dosages of flocculants, and the flocculation recovery efficiencies. The role of green routes in synthesizing nanoparticles for the advancement of flocculation technique is especially highlighted in this article for the sustainable biodiesel production from microalgae. Thorough evaluations, encompassing techno-economic and life cycle assessments, play a crucial role in appraising the economic feasibility and environmental ramifications of biofuels derived from microalgae. This article provides an overview of flocculation methods suitable for microalgal harvesting, their mechanisms, advantages, and drawbacks. [ABSTRACT FROM AUTHOR]

This is a prime time to develop and implement the "waste to energy" projects across the globe to attain a sustainable environment. Anaerobic digestion (AD) has attracted the scientific community due to its simplicity and easiness to handle, and has the potential to utilize any kind of organic waste to produce a mixture of combustible gases, i.e., biogas and digested slurry, which has further applications in agriculture, solid biofuels, and purification. The process, in turn, reduces the local waste and helps in recycling in a manner that reduces greenhouse gas (GHG) emission, conserves the resources, and establishes a circular economy in the time of undetermined future for the production of energy and safe disposal of the waste. However, the conventional processes encounter with the low biogas yield and long retention time, which discourage the developers. To enhance biogas yield and quality, the momentum of research has increased towards implementation of advanced techniques for development of efficient processes. The present article summarizes the effect of different operational parameters on AD and impact of advanced techniques for enhanced biomethane/biogas. The article further covers the life cycle assessment (LCA) and techno-economic aspect (TCA) of the AD process. This will provide the comparison of different advanced techniques in terms of biomethane/biogas yield. [ABSTRACT FROM AUTHOR]

The Energy Return On Investment (EROI) is a recognised indicator for assessing the relevance of an energy project in terms of net energy delivered to society. For woody biomass divergences remain on the right methodology to assess the EROI leading to large variations in the published estimates. This article presents an in‐depth discussion about the EROI of woody biomass in three different forms: woodchips, pellets and liquid fuels. The conceptualisation of EROI is further developed to reach a consistent definition for biomass post‐processed fuels. It considers, on top of the external energy investments, the grey energy associated with the energy used to enrich the fuel. With the proposed methodology, all woodchips have an EROI of the same order of magnitude, between 20 and 37, depending on forestry types, operations and machineries. For secondary residues, the first estimate is 170 if, as co‐products, no energy investment is allocated to the forestry operations and transport. On the basis of a mass allocation for forestry operations and transport, the EROI for secondary residues becomes of the same order of magnitude as that for wood chips. Woodchips can be further post‐processed into pellets or liquid fuels. Pellets have an EROI of 4–7 if the heat is externally supplied and 8–23 if internally supplied (self‐consumption of part of the raw material). Liquid fuels derived from primary wood and residues through gasification and Fischer‐Tropsch synthesis have an EROI between 4 and 16. Fuel enhancement with hydrogen (Power & Biomass to Liquids) impacts negatively the EROI due to the low EROI of hydrogen produced from renewable electricity. However, these fuels offer other advantages such as improved carbon efficiency. A correct estimate of EROI for forestry biomass, as proposed in this work, is a necessary dimension in assessing the suitability of a project. [ABSTRACT FROM AUTHOR]

Large amount of wastes are burnt or left to decompose on site or at landfills where they cause air pollution and nutrient leaching to groundwater. Waste management strategies that return these food wastes to agricultural soils recover the carbon and nutrients that would otherwise have been lost, enrich soils and improve crop productivity. The incorporation of liming materials can neutralize the protons released, hence reducing soil acidity and its adverse impacts to the soil environment, food security, and human health. Biochar derived from organic residues is becoming a source of carbon input to soil and provides multifunctional values. Biochar can be alkaline in nature, with the level of alkalinity dependent upon the feedstock and processing conditions. This study conducted a characterization of biochar derived from the pyrolysis process of eggplant and Acacia nilotica bark at temperatures of 300 °C and 600 °C. An analysis was conducted on the biochar kinds to determine their pH, phosphorus (P), as well as other elemental composition. The proximate analysis was conducted by the ASTM standard 1762-84, while the surface morphological features were measured using a scanning electron microscope. The biochar derived from Acacia nilotica bark exhibited a greater yield and higher level of fixed carbon while possessing a lower content of ash and volatile components compared to biochar derived from eggplant. The eggplant biochar exhibits a higher liming ability at 600 °C compared to the acacia nilotica bark-derived biochar. The calcium carbonate equivalent, pH, potassium (K), and phosphorus (P) levels in eggplant biochars increased as the pyrolysis temperature increased. The results suggest that biochar derived from eggplant could be a beneficial resource for storing carbon in the soil, as well as for addressing soil acidity and enhancing nutrients availability, particularly potassium and phosphorus in acidic soils. [ABSTRACT FROM AUTHOR]

The selective oxidation of 5‐(Hydroxymethyl)furfural (HMF) to 2,5‐Furandicarboxylic acid (FDCA) is highly attractive for the production of renewable monomers as substitute for fossil‐based monomers. To achieve a sustainable synthesis, we report on advances for a base‐free approach, reducing waste from the process, using air as oxidant and heterogeneous catalysts. Various Carbon‐based supports, which can be bio‐sourced and cost‐efficient, for Pt particles were investigated as they allow for an easy reuse and at the end‐of‐life Pt can be recycled to enable a closed cycle. Commercially available supports with varying properties, which might replace the base, were studied with Pt particles of similar size and loading. Significant differences in the catalytic activity were observed, which were correlated with the O‐functionalities and graphitization degree of the supports derived from Raman spectroscopy, temperature‐programmed desorption, and X‐ray photoelectron spectroscopy. An activated carbon (Norit ROX) rich in quinone/pyrone‐type groups and a carbon black‐based catalyst with graphene‐layers pushed the efficiency with enhanced FDCA‐yields enabling the complete substitution of the homogeneous base. This allows to circumvent the base in this process which together with high selectivity, air as oxidant, a reusable catalyst, and the use of bio‐based feedstock contributes to the sustainability of the production of renewable monomers. [ABSTRACT FROM AUTHOR]

Combining with the advantages from mature technologies of fused deposition modelling and powder injection molding, 3D NiFe 2 O 4 -based cermet with weight over 1.3 kg and relative density of 95.8 % were fabricated by composite extrusion modelling using polyoxymethylene-based feedstock. Microstructure and rheological properties of the feedstock, roles of printing parameters on the morphology green samples and related catalytic debinding, sintering properties of cermets were investigated in detail. Uniformly dispersed cermet powders in feedstock were confirmed, due to the good wettability between the powders and binders. The feedstock with high solid loading of 58 vol% exhibited shear-thinning behavior and contained high storage modulus for reliable shape retention. With optimized printing parameters, a high compression ratio (layer height/nozzle diameter) over 2.5 tended to shrink the size of stacking pores, resulting in dense green samples. Catalytic debinding was proved to be defect-free and efficient debinding route, which was successfully used to deal with dense cubic samples with thickness of 30 mm. Sintered samples showed uniform microstructure with interconnected FeCuNi and Ni(Fe)Fe 2 O 4 phases. Except for partial stacking pores in the fracture section, polished cermets exhibited mirror-like surfaces, indicating the good controlling of the final microstructure and performance of 3D cermets. [ABSTRACT FROM AUTHOR]

Bio-polybutylene succinate (PBS) is a biodegradable polymer obtained from renewable feedstock having physical–mechanical properties like traditional low-density polyethylene (LDPE). PBS is employed by many manufacturing sectors, from biomedical to agri-food and cosmetics. Although some studies have already evaluated the resistance of PBS to photodegradation caused by natural outdoor solar exposure (UVA-UVB), a systematic study on the resistance to degradation caused by exposure to UVC rays, which is the subject of this study, has not yet been carried out. PBS was exposed to UVC either neat or filled with 2% carbon black (CB). Mechanical and physical characterization (tensile, hardness, calorimetry, contact angle, morphology, and surface roughness analyses) indicates that the bulk and surface properties of the polymer matrix changes after exposure to UVC radiations, due to a severe degradation. However, the presence of carbon black compensates for the degradation phenomenon. Because UVC rays are used for the sterilization process, necessary in applications such as biomedical, cosmetic, pharmaceutical, food, and other products, a comparison of the protocol used in this paper with the literature's data has been reported and discussed. [ABSTRACT FROM AUTHOR]

The use of heavier feedstocks, or even the possibility of direct conversion of crude oil into chemicals has created new challenges for the steam cracking process, as severe fouling in the different sections of steam crackers is observed then. In order to obtain a more fundamental understanding about the fouling phenomenon and its relation to feedstock composition and process conditions the "Fouling Assessment SeTup (FAST)" was developed. This experimental unit was used to determine the fouling tendency of a heavy hydrocarbon mixture (HHM) in the different sections of a steam cracker, i.e. convection, radiant, and transfer line heat exchanger (TLE) sections via a post cracking decoking procedure and the continuous weighting of a suspended coupon in TLE with a Magnetic Suspension Balance (MSB). Additionally, a fouling mitigation concept of wetting fluid injection in TLE via an in-house apparatus was tested. The injection of a paraffinic fluid substantially reduced fouling in this section. [ABSTRACT FROM AUTHOR]

The objective of this study was to characterize ruminal degradation, intestinal digestion and total true nutrient supply to dairy cows from canola feedstock (canola seeds) and coproducts (meal and pellets) from bio‐oil processing which were impacted by source origin. The feedstocks and coproducts (mash, pellet) were randomly collected from five different bio‐oil processing plants with five different batches of samples in each bio‐processing plant in Canada (CA) and China (CH). In situ rumen degradation kinetics were determined using four fistulated Holstein cows with incubation times at 0, 2, 4, 8, 12, 24 and 48 h. Intestinal digestions were determined using the three‐step in vitro method with preincubation at 12 h. The DVE/OEB and National Research Council systems were applied to evaluate the truly absorbable nutrient supply to dairy cows and feed milk values (FMVs). The results showed that in situ undegradable fractions (U) (p = 0.025) were higher in CA meals, and potentially degradable fraction of D was higher (p = 0.016) in CH meals. CH meals had higher total digestible dry matter (TDDM, p = 0.018) and intestinal digestibility of protein (dIDP, p = 0.016). Canola meals from CA had lower MREE (microbial protein synthesized in the rumen based on available rumen degradable protein; p = 0.011) and DVME (rumen synthesized microbial protein digested in the small intestine; p = 0.011) and had higher ECP (endogenous protein in the small intestine, p = 0.001) and absorbed endogenous crude protein (truly absorbed ECP in the small intestine) than CH (p = 0.001). The FMV evaluated based on the metabolic protein and net energy showed no differences between CA and CH in both coproducts and feedstocks. [ABSTRACT FROM AUTHOR]

Carbon‐free aluminum electrolysis is crucial for achieving the low‐carbon development and carbon neutrality in the future aluminum industry. NiFe2O4‐based cermet is the potential candidate of inert anode, benefiting from the satisfactory corrosion resistance and high‐temperature conductivity. Herein, complex‐shaped 25(Cu–20Ni)/(NiFe2O4–10NiO) cermets were fabricated via a plastic shaping method using the polyformaldehyde (POM)‐based granular feedstock. The feedstock showed uniform microstructure with evenly dispersed powders wrapped in polymers, which exhibited shear‐thinning behavior during molding. Roles of the feedstock with different powder loadings in the morphology and bending strength of the cermets were investigated. High‐precision gear parts exhibited no deformation, a high relative density over 98%. Investigation of different powder loadings revealed that parts prepared with a 56 vol% loading demonstrate the excellent performance, and possessed an impressive flexural strength of 178.4 MPa. This achievement provided a foundation for the future utilization of complex‐shaped inert anode material components in industrial applications. [ABSTRACT FROM AUTHOR]

A circular economy based on symbiotic relationships among sectors, where the waste from one is resource to another, holds promise for cost-effective and sustainable production. This research explores such a model for the agriculture, energy, and construction sectors in California. Here, we develop new an understanding for the synergistic utilization mechanisms for rice hull, a byproduct from rice production, as a feedstock for electricity generation and rice hull ash (RHA) used as a supplementary cementitious material in concrete. A suite of methods including experimental analysis, techno-economic analysis (TEA), and life-cycle assessment (LCA) were applied to estimate the cost and environmental performance of the system. TEA results showed that the electricity price required for break even on expenses without selling RHA is $0.07/kWh, lower than the market price. As such, RHA may be available at little to no cost to concrete producers. Our experimental results showed the viability of RHA to be used as a supplementary cementitious material, meaning it can replace a portion of the cement used in concrete. LCA results showed that replacing 15% of cement with RHA in concrete can reduce carbon dioxide equivalent (CO2e) emissions by 15% while still meeting material performance targets. While the substitution rate of RHA for cement may be modest, RHA generated from California alone could mitigate 0.2% of total CO2e from the entire cement production sector in the United States and 1% in California. [ABSTRACT FROM AUTHOR]

The effect of average feedstock powder size on the evolution of microstructure and thermal conductivity are comprehensively analyzed. It was found that the porosity and thermal conductivity of the LaYbZr 2 O 7 coatings were positively correlated with the average powder size. The conventional notion that higher porosity results in lower thermal conductivity is challenged by the above results. The abnormal porosity and thermal conductivity relationship can be ascribed to the density of horizontal cracks which dominates the thermal conductivity reduction. Reducing the average powder size leads to a greater concentration of horizontal cracks and hence reduced thermal conductivity. Moreover, the LaYbZr 2 O 7 coatings not only show significantly lower initial thermal conductivity of under 0.70 W m−1 K−1, but also exhibit stronger sintering resistance in terms of porosity stability and thermal insulation ability compared to the conventional YSZ coatings. The present work affords a new insight in developing advanced thermal barrier coatings with ultralow thermal conductivity. [ABSTRACT FROM AUTHOR]

The current study focuses on the development of innovative bio‐based filaments using new natural lignocellulosic particles obtained from the bark of the Morinda citrifolia L. plant as reinforcement. Polylactic acid (PLA 4043D) filaments with a diameter of 1.75 mm were produced by varying the volume fraction of M. citrifolia bark particles (MCBP) in three compositions (i.e., 0%, 3%, and 6%). These filaments were then used to print test specimens, which underwent quasi‐static mechanical tests (i.e., tensile and flexural; thermal characterization, thermo‐mechanical tests, and visco‐elastic analysis). The experimental findings demonstrated a remarkable improvement in the tensile strength (i.e., +15%) when the PLA was reinforced with 6% in volume of lignocellulosic particles. Additionally, 3% MCBP and 6% MCBP composites showed substantial increases in flexural strength and modulus (i.e., +25% and +34%), respectively; in comparison to the neat matrix. Moreover, the 3D‐printed composites exhibited significant enhancements in storage modulus, glass transition temperature, and structural stability at elevated temperatures. Hence, this work highlights the potential of the developed bio‐based filaments as feedstock filament material, enabling the production of various customized lightweight products in the automotive and sports industries like cycling helmets, protective guards, knee guards, etc. Highlights: Innovative bio‐based filaments are developed for FDM 3D printing.Morinda citrifolia bark particles (MCBPs) reduce warping risk in PLA printing.The hot crystallization enthalpy of PLA increases with the addition of MCBP.6% MCBP‐PLA exhibits the best mechanical performances.MCBP reinforcement reduces the thermal expansion of PLA. [ABSTRACT FROM AUTHOR]

The additive manufacturing of components using material extrusion (MEX) enables the integration of several materials into one component, including functional structures such as electrically conductive structures. This study investigated the influence of the selected additive MEX process on the resistivity of MEX structures. Specimens were produced from filaments and granules of an electrically conductive PLA and filled with carbon nanotubes and carbon black. Specimens were produced with a full-factorial variation of the input variables: extrusion temperature, deposition speed, and production process. The resistivity of the specimens was determined by four-wire measurement. Analysis of the obtained data showed that only the extrusion temperature had a significant influence on the resistivity of the MEX specimens. Furthermore, the impact of the nozzle diameter was evaluated by comparing the results of this study with those of a previous study, with an otherwise equal experimental setup. The nozzle diameter had a significant influence on resistivity and a larger nozzle diameter reduced the mean variance by an order of magnitude. The resistivity was lower for most process parameter sets. As the manufacturing process had no significant influence on the resistivity of MEX structures, it can be selected based on other criteria, e.g., the cost of feedstock. [ABSTRACT FROM AUTHOR]

The recovery and recycling/upcycling of plastics and polymer-based materials is needed in order to reduce plastic waste accumulated over decades. Mechanical recycling processes have made a great contribution to the circularity of plastic materials, contributing to 99% of recycled thermoplastics. Challenges facing this family of processes limit its outreach to 30% of plastic waste. Complementary pathways are needed to increase recycling rates. Chemical processes have the advantage of decomposing plastics into a variety of hydrocarbons that can cover a wide range of applications, such as monomers, lubricants, phase change materials, solvents, BTX (benzene, toluene, xylene), etc. The aim of the present work is to shed light on different chemical recycling pathways, with a special focus on thermochemicals. The study will cover the effects of feedstock, operating conditions, and processes used on the final products. Then, it will attempt to correlate these final products to some petrochemical feedstock being used today on a large scale. [ABSTRACT FROM AUTHOR]

Biolubricants are oleochemical esters that are non-toxic to the environment, and they are preferred because of their high-performance activities in various automobile and industrial fields. In this study, chicken tallow has been explored as an alternative to a non-renewable source, which acts as a low-cost feedstock for synthesizing biolubricants in a two-step hydro esterification process catalysed by Candida rugosa lipase (CRL). The enzymatic hydrolysis of chicken tallow is optimized at different time intervals at 40 °C, and the maximum release of 160.2 µmol min−1 free fatty acids (FFAs) is observed at 100 min. The hydrolysed FFAs are characterized by the gas chromatography-mass spectrometry (GC-MS) analysis that has depicted the fatty acid methyl esters (FAMEs) composition of the tallow oil. The recovered FFA is then enzymatically esterified with trimethylolpropane (TMP) to produce TMP esters. Optimization studies are performed to explore the effect of factors such as time, temperature, amount of the enzyme, and TMP: FFA molar ratio for the esterification process. Thus, the optimal conditions for achieving a maximal hydroxyl group conversion of 60% during TMP ester production include incubation time (120 min), temperature (35 °C), lipase concentration (3% w/w), and TMP: FFA molar ratio (1:4). Fourier transform infrared spectroscopy (FT-IR), and nuclear magnetic resonance (NMR) studies confirm the synthesized TMP esters. Moreover, physicochemical properties such as viscosity, cloud point (CP), and calorific value (CV) are found to be 36 mm2/s, 7159.14 cal/g, and 20 °C, respectively. [ABSTRACT FROM AUTHOR]

Solid biomass can be used for energy generation and the production of various renewable bioproducts. The aim of this study was to determine the yield and characteristics of wood obtained as debarking residue from 14 genotypes of short-rotation woody crops (SRWCs). These included five Populus genotypes, one Robinia genotype, and eight Salix genotypes, harvested in both annual and quadrennial cycles. The results showed that the highest dry wood yield (12.42 Mg ha−1 y−1 DM) and yield energy value (244.34 GJ ha−1 y−1) were obtained from willow (cultivar Żubr) harvested in a quadrennial cycle. The best effect among the poplar genotypes was achieved for the Hybryda275, and it was particularly marked in the quadrennial harvest cycle. The poorest results were determined for black locust. The Robinia characteristics included the significantly lowest moisture content (31.6%), which was a positive attribute from the energy point of view, but, on the other hand, it had some adverse characteristics—the highest levels of sulfur (0.033% DM), nitrogen (0.38% DM), and ash (0.69% DM). More beneficial properties in this respect were determined for willow and poplar wood. Moreover, willow and poplar wood contained more cellulose—51.8 and 50.0% DM, respectively—compared with black locust. Extending the SRWC shoot harvest cycle from annual to quadrennial resulted in an increase in cellulose, lignin, and carbon, higher heating value, and a decrease in nitrogen, sulfur, ash, and moisture content. Therefore, extending the harvest cycle improved the parameters of SRWC wood as an energy feedstock. [ABSTRACT FROM AUTHOR]

The marine fish oil obtained during fishmeal production and shrimp shells through whole shrimp processing have less commercial importance, mostly considered as waste and are disposed to environment resulting in pollution. The current research focuses on exploiting fish industry wastes such as Fenneropenaeus indicus shrimp shell and marine fishmeal industry (MFMI) oil with a perspective of achieving sustainable biodiesel production and overcome disposal pollution issues. The physicochemical properties of MFMI oil indicated its suitability to be used as feedstock for biodiesel production. The catalyst characterization by X-ray diffraction (XRD), Fourier transform infrared spectroscopy, Scanning electron microscopy (SEM), and Brunauer–Emmett–Teller analysis revealed that calcination of shrimp shells resulted in the formation of crystalline mesoporous solid catalyst primarily composed of CaO. As per the central composite design of response surface methodology, the maximum biodiesel yield of 86.56wt% was obtained from MFMI oil at an oil to methanol molar ratio of 1:12 (mol/mol), catalyst concentration of 5 wt% of oil, reaction temperature of 65 °C, and reaction time of 120 min. Further, based on flask level optimized condition, the biodiesel production was scaled to a 50 L oil volume batch and achieved a good yield of 88.74 wt%. Further, the physicochemical properties and cold flow property of MFMI oil biodiesel ensured its application as fuel. Thus, MFMI oil and calcined shrimp shell catalyst could be utilized as promising feedstock and catalyst for sustainable biodiesel production. [ABSTRACT FROM AUTHOR]

Increased food, feed, and biofuel demands of the future will require a greater reliance upon crop production systems in arid and semi‐arid regions around the world. Diminishing freshwater resources and hotter and drier climatic conditions will also necessitate the use of highly drought tolerant and water‐use efficient crops. Cactus pear (Opuntia ficus‐indica) is a low‐water input, climate‐resilient crop capable of high biomass production due to its use of crassulacean acid metabolism (CAM). Cactus pear produces both food and forage/fodder, a wide variety of high‐value byproducts, and serves as a bioenergy feedstock for biogas or bioethanol production. Here, we evaluated the biomass productivity of 14 Opuntia spp. accessions from the National Arid Land Plant Genetic Resources Unit (NALPGRU) in Parlier, CA under semi‐arid conditions with a planting density of 6667 plants ha−1 over a 3‐year period to identify high‐yielding biomass producers. Mean annual cladode fresh weight (CFW) (73.7 Mg ha−1 year−1), cladode dry weight (CDW) (5.2 Mg ha−1 year−1), and cladode count (CC) (10.5 cladodes plant−1) increased by 2.9‐, 2.8‐, and 2.8‐fold in year 3 compared with year 1. PARL 845, hybrid no. 46 (O. ficus‐indica × O. lindheimerii), showed the highest annual mean CFW (152.8 Mg ha−1 year−1), CDW (13.3 Mg ha−1 year−1), CC (22.1 cladodes plant−1), and dry matter content (DMC, 11.2%) among all accessions tested. Non‐hybrid accessions PARL 242 (O. cochenillifera), PARL 582 (Opuntia sp.), and PARL 584 (Opuntia sp.) showed 100% cladode establishment rates and CDW productivity of >6 Mg ha−1 year−1. Such biomass productivity results indicate that cactus pear displays great potential as a crop with many uses with lower water inputs than conventional crops for arid and semi‐arid environments. [ABSTRACT FROM AUTHOR]

Biofuels are clean and renewable energy resources gaining increased attention as a potential replacement for non-renewable petroleum-based fuels. They are derived from biomass that could either be animal-based or belong to any of the three generations of plant biomass (agricultural crops, lignocellulosic materials, or algae). Over 130 studies including experimental research, case studies, literature reviews, and website publications related to bioethanol production were evaluated; different methods and techniques have been tested by scientists and researchers in this field, and the most optimal conditions have been adopted for the generation of biofuels from biomass. This has ultimately led to a subsequent scale-up of procedures and the establishment of pilot, demo, and large-scale plants/biorefineries in some regions of the world. Nevertheless, there are still challenges associated with the production of bioethanol from lignocellulosic biomass, such as recalcitrance of the cell wall, multiple pretreatment steps, prolonged hydrolysis time, degradation product formation, cost, etc., which have impeded the implementation of its large-scale production, which needs to be addressed. This review gives an overview of biomass and bioenergy, the structure and composition of lignocellulosic biomass, biofuel classification, bioethanol as an energy source, bioethanol production processes, different pretreatment and hydrolysis techniques, inhibitory product formation, fermentation strategies/process, the microorganisms used for fermentation, distillation, legislation in support of advanced biofuel, and industrial projects on advanced bioethanol. The ultimate objective is still to find the best conditions and technology possible to sustainably and inexpensively produce a high bioethanol yield. [ABSTRACT FROM AUTHOR]

Brown algae have gained attention as a sustainable feedstock for biorefineries due to their ability to sequester carbon dioxide, rapid growth, and high carbohydrate content. The carbohydrate content in brown algae has only been analyzed for a few species, and in most cases, access to fundamental data such as sugar composition is limited, which hinders the assessment of brown algal biomass-based biorefining potential. In this study, the carbohydrate composition of brown algae (Undaria pinnatifida, Saccharina japonica, Ecklonia cava, and Ecklonia stolonifera) was analyzed in detail and application directions were proposed. As a result, alginate and glucan were detected in all resources, and the contents (alginate and glucan wt%) were as follows: U. pinnatifida (39.6 and 4.9 wt%), S. japonica (34.0 and 6.3 wt%), E. cava (24.3 and 7.7 wt%), and E. stolonifera (39.1 and 9.7 wt%). All feedstocks contain trace amounts (2.9–4.9 wt%) or no xylan-mannan-galactan. Mannitol was detected only in S. japonica (26.7 wt%) in rich, showing high potential as a biorefinery feedstock. We highlight that the carbohydrate composition of E. cava and E. stolonifera was analyzed for the first time and the potential use of brown algal biomass in a biorefinery approach. [ABSTRACT FROM AUTHOR]

[Display omitted] • Fruit and vegetable waste has greater potential for LA production than kitchen waste. • Using LAB as inoculum improved the maximum LA concentration by 50.8%. • Optimal temperature of LA production was 37 °C for Fruit and vegetable waste and 50 °C for Kitchen waste. • Micro-oxygen limited Acetobacter growth then decreased VFAs formation. Lactic acid (LA) is an important chemical with broad market applications. To optimize LA production, food waste has been explored as feedstock. Due to the wide variety of food waste types, most current research studies have obtained different conclusions. This study focuses on carbohydrate-rich fruit and vegetable waste (FVW) and lipid-rich kitchen waste (KW), and the effect of inoculum, temperature, micro-oxygen, and initial pH were compared. FVW has a greater potential for LA production than KW. As an inoculum, lactic acid bacteria (LAB) significantly increased the maximum LA concentration (27.6 g/L) by 50.8 % compared with anaerobic sludge (AS). FVW exhibited optimal LA production at 37 °C with micro-oxygen. Adjustment of initial pH from 4 to 8 alleviated the inhibitory effect of accumulated LA, resulting in a 46.2 % increase in maximum LA production in FVW. The expression of functional genes associated with metabolism, genetic information processing, and environmental information processing was higher at 37 °C compared to 50 °C. [ABSTRACT FROM AUTHOR]

• Variability of food processor waste and derived hydrolysate quantified. • Addressing this variability is key for single-organism high-value bioproduct synthesis. • Hydrolysate assessed via bioproduct synthesis in yeast, bacteria, and archaea. • Importance of carbon and nitrogen levels, and specific substrates demonstrated. • Industrial-scale valorization strategies for variable food waste discussed in-depth. Unavoidable food wastes could be an important feedstock for industrial biotechnology, while their valorization could provide added value for the food processor. However, despite their abundance and low costs, the heterogeneous/mixed nature of these food wastes produced by food processors and consumers leads to a high degree of variability in carbon and nitrogen content, as well as specific substrates, in food waste hydrolysate. This has limited their use for bioproduct synthesis. These wastes are often instead used in anaerobic digestion and mixed microbial culture, creating a significant knowledge gap in their use for higher value biochemical production via pure and single microbial culture. To directly investigate this knowledge gap, various waste streams produced by a single food processor were enzymatically hydrolyzed and characterized, and the degree of variability with regard to substrates, carbon, and nitrogen was quantified. The impact of hydrolysate variability on the viability and performance of polyhydroxyalkanoates biopolymers production using bacteria (Cupriavidus necator) and archaea (Haloferax mediterranei) as well as sophorolipids biosurfactants production with the yeast (Starmerella bombicola) was then elucidated at laboratory-scale. After which, strategies implemented during this experimental proof-of-concept study, and beyond, for improved industrial-scale valorization which addresses the high variability of food waste hydrolysate were discussed in-depth, including media standardization and high non-selective microbial organisms growth-associated product synthesis. The insights provided would be beneficial for future endeavors aiming to utilize food wastes as feedstocks for industrial biotechnology. [ABSTRACT FROM AUTHOR]

Compared with loose biomass (LB), biomass briquettes (BBs) with high energy density and convenient transportation characteristics are more suitable as solid feedstock for preparing low-tar-content syngas through chemical looping gasification (CLG). Herein, the effects of key briquetting parameters, such as temperature, pressure, moisture content, and particle size, on the briquetting density (ρ), relaxation ratio, and crash resistance of waste sawdust are investigated, and the CLG performance of the briquetted sawdust is examined. Results show that pressure is the most critical factor affecting ρ. Briquetting of waste sawdust promotes the resultant syngas yield in CLG. Compared to LB, BBs exhibit increases in H 2 yield, syngas yield, H 2 /CO molar ratio, and maximum gasification rate. When ρ was 0.8–0.9 g/cm3, the briquetting feature and CLG performance were good, with the briquetting pressure being optimized to 10–15 MPa. Moreover, granular-shaped BBs exhibits the highest CO release strength and good CLG performance. This discovery provides favorable briquetting conditions for the effective application of BBs in the field of CLG. [Display omitted] • We use ρ as a key parameter to link briquetting and CLG process. • The briquetting feature and CLG performance were good when ρ was 0.8–0.9 g/cm3. • The ρ increases hydrogen yield and H 2 /CO molar ratio. • It provides favorable briquetting conditions for BBs in the field of CLG. [ABSTRACT FROM AUTHOR]

Biochars produced from different feedstocks and at different pyrolysis temperatures may have various chemical and physical properties, affecting their potential use as alternative microbial carrier materials. In this study, biochars were produced from pine wood and oak feedstocks at various temperatures (400°C, 500°C, 600°C, 700°C and 800°C), characterized, and assessed for their potential as carriers for Bradyrhizobium japonicum (CB1809) strain. The biochars were then stored at two different storage temperatures (28°C and 38°C) for up to 90 days. Furthermore, the study also explored the role of potentially ideal carriers as inoculants in the growth of Glycine max L. (soybean) under different moisture levels i.e., 55% water holding capacity (WHC) (D0), 30% WHC (D1) and, 15% WHC (D2) using a mixture of 50% garden soil and 50% sand. The results were compared to a control group (without inoculants) and a peat inoculant. Among all the materials derived from pine wood and oak, pine wood biochar pyrolyzed at 400℃ (P-BC400) exhibited the highest CFU count, with values of 10.34 and 9.74 Log 10 CFU g− 1 after 90 days of storage at 28℃ and 38℃, respectively. This was notably higher compared to other biochars and peat carriers. Significant (p < 0.05) increases in plant properties: shoot and root dry biomass (174% and 367%), shoot and root length (89% and 85%), number of leaves (71%), membrane stability index (27%), relative water content (26%), and total chlorophyll (140%) were observed in plants treated with P-BC400 carrier inoculant compared to the control at D2; however, lower enrichment of δ13C (37%) and δ15N (108%) with highest number of root nodules (8.3 ± 1.26) and nitrogenase activity (0.869 ± 0.04) were observed under D2, as evident through PCA analysis, showing more nitrogen (N) fixation and photosynthetic activity. Overall, this experiment concluded that biochar pyrolyzed at lower temperatures, especially P-BC400, was the most suitable candidate for rhizobial inoculum and promoted soybean growth. [ABSTRACT FROM AUTHOR]

A novel Ni-based catalyst was prepared with 5% and 10% loading of Ni on food waste ash, and then it was characterized using various physico-chemical methods. Thereafter, the steam gasification experiments were conducted at 850 °C and a steam flow rate (SFR) of 0.75 mL/min in a downdraft fixed bed gasifier. The gasification results showed that a 5% Ni-loaded catalyst was more effective than 10% in enhancing the syngas production with a high hydrogen fraction. It was found that the use of this catalyst increased the syngas yield significantly to 1.8 m3/kg on increasing the catalyst content in feedstock to 50%. Additionally, the hydrogen fraction in syngas increased to 71% which, together with higher syngas yield, increased the hydrogen yield by almost 100%. Furthermore, the performance parameters for gasification, such as carbon conversion efficiency (CCE) and cold gas efficiency (CGE), were also found to be highest at 50% catalyst content of 5% Ni-loaded catalyst in the feedstock. • Food waste was used as feedstock and its ash as support and promoter for Ni catalyst. • 5% and 10% loading of Ni on food waste ash was used. • 0, 25, 50, and 75% catalyst content (wt %) was used. • 5% Ni loading with 50% catalyst content was found to be most suitable combination. • 100% increase in Hydrogen yield (1.3 m3/kg) was obtained by this combination. [ABSTRACT FROM AUTHOR]

A practical electrochemical strategy for the direct synthesis of arenesulfonyl fluorides from industrial feedstock nitroarenes is described. The key to success lies in using a cheap ionic liquid N-methylimidazolium p-toluenesulfonate ([Mim]TolSO3) as an effective additive and electrolyte to facilitate the selective reduction of nitroarenes to the corresponding aniline intermediate, promoting the desired fluorosulfonylation with broad functional group tolerance under mild conditions. [ABSTRACT FROM AUTHOR]

Zirconium carbide (ZrC) disks were fabricated using binder jet printing to study the effect of powder feedstock, print parameters, and heat treatment on flowability and final materials properties. A median volumetric particle size smaller than 10 μm was shown to cause the powder to stop flowing during printing. Disks were printed using ZrC with suitable flowability and then heat-treated at temperatures between 1800 °C and 2200 °C for 1 or 5 h. The density, part shrinkage, thermal diffusivity, and fracture strength all increased with increasing temperature and time. The heat-treated disks were then heated to 2200 °C for 5 h and the properties converged for disks of the same particle size, indicating the hottest temperature and longest time of exposure dictates the final properties. Lastly, it was shown that larger particles produce lower density materials with worse thermal diffusivity, most likely because of poor connectivity between particles after heat treatment. [ABSTRACT FROM AUTHOR]

Background: The main challenge for large-scale production of bacterial cellulose (BC) includes high production costs interlinked with raw materials, and low production rates. The valorization of renewable nutrient sources could improve the economic effectiveness of BC fermentation while their direct bioconversion into sustainable biopolymers addresses environmental pollution and/or resource depletion challenges. Herein a green bioprocess was developed to produce BC in high amounts with the rather unexplored bacterial strain Komagataeibacter rhaeticus, using waste streams such as wine distillery effluents (WDE) and biodiesel-derived glycerol. Also, BC was evaluated as a bio-adsorbent for phenolics, dyes and metals removal to enlarge its market diversification. Results: BC production was significantly affected by the WDE mixing ratio (0–100%), glycerol concentration (20–45 g/L), type of glycerol and media-sterilization method. A maximum BC concentration of 9.0 g/L, with a productivity of 0.90 g/L/day and a water holding capacity of 60.1 g water/g dry BC, was achieved at 100% WDE and ≈30 g/L crude glycerol. BC samples showed typical cellulose vibration bands and average fiber diameters between 37.2 and 89.6 nm. The BC capacity to dephenolize WDE and adsorb phenolics during fermentation reached respectively, up to 50.7% and 26.96 mg gallic acid equivalents/g dry BC (in-situ process). The produced BC was also investigated for dye and metal removal. The highest removal of dye acid yellow 17 (54.3%) was recorded when 5% of BC was applied as the bio-adsorbent. Experiments performed in a multi-metal synthetic wastewater showed that BC could remove up to 96% of Zn and 97% of Cd. Conclusions: This work demonstrated a low-carbon approach to produce low-cost, green and biodegradable BC-based bio-adsorbents, without any chemical modification. Their potential in wastewater-treatment-applications was highlighted, promoting closed-loop systems within the circular economy era. This study may serve as an orientation for future research towards competitive or targeted adsorption technologies for wastewater treatment or resources recovery. [ABSTRACT FROM AUTHOR]

The effect of the H/C ratio of feedstock on soot formation was investigated in this study. Soot was continuously generated by pyrolyzing C2 hydrocarbons in an atmosphere without oxygenated species at a maximum temperature of 1683 K. H 2 was added to the feedstock to vary the H/C ratio, and the particle size distribution of soot was determined using a scanning mobility particle sizer. Most of our results indicate that the ease of thermal dissociation of the feedstock is more important than the degree of unsaturation in the feedstock. With increasing H/C ratio of the feedstock, more radicals are generated, and polycyclic aromatic hydrocarbons (PAHs) are easily formed, leading to the formation of soot. Interestingly, many previous studies on combustion have reported the opposite behavior, indicating that the ease of radical formation is important in pure pyrolysis without oxygenated species, which generate radicals easily. In the case of C 2 H 2 as a feedstock in this study, the addition of a small amount of H 2 increased the amount of radicals and promoted soot formation. However, with increasing amounts of H 2 , soot formation was inhibited because the inhibitory effect of H 2 on PAH formation increased. When H/C = 2, the H/C ratio of the feedstock was dominant for soot formation, while the degree of unsaturation of the chemical species in the feedstock was dominant when the H/C ratios were 3 and 4. • Impact of chemical structure and H/C ratio in C2 hydrocarbon pyrolysis. • Experiment about impact of impurities in acetylene. • Simulation reveals importance of chemical structure in radical formation. • Ethane pyrolysis showed highest soot formation propensity. [ABSTRACT FROM AUTHOR]

Fermentation-based biosynthesis in synthetic biology relies heavily on sugar-derived feedstocks, a limited and carbon-intensive commodity. Unconventional feedstocks from less-noble sources such as waste are being utilized to produce high-value chemical products. Azo dyes, a major pollutant commonly discharged by food, textile, and pharmaceutical industries, present significant health and environmental risks. We explore the potential of engineering Pseudomonas putida KT2440 to utilize azo dyes as a substrate to produce a polyketide, actinorhodin (ACT). Using the constrained minimal cut sets (cMCS) approach, we identified metabolic interventions that optimize ACT biosynthesis and compare the growth-coupling solutions attainable on an azo dye compared to glucose. Our results predicted that azo dyes could perform better as a feedstock for ACT biosynthesis than glucose as it allowed growth-coupling regimes that are unfeasible with glucose and generated an 18.28% higher maximum ACT flux. By examining the flux distributions enabled in different carbon sources, we observed that carbon fluxes from aromatic compounds like azo dyes have a unique capability to leverage gluconeogenesis to support both growth and production of secondary metabolites that produce excess NADH. Carbon sources are commonly chosen based on the host organism, availability, cost, and environmental implications. We demonstrated that careful selection of carbon sources is also crucial to ensure that the resulting flux distribution is suitable for further metabolic engineering of microbial cell factories. [ABSTRACT FROM AUTHOR]

In this study, the role of feedstock powder in influencing the characteristics of cold spray deposition is explored. Four distinct types of Cu feedstock powders, derived through electrolysis and employing varied gas atomization methods, are applied to a Cu substrate via low-pressure cold spray coating. We investigated the impact of feedstock powder on the resultant coatings' microstructure and mechanical properties. A comprehensive statistical model is developed, considering the cold spray parameters, weight change, coating thickness, and discerning their significance and interactions. Optimal conditions for carrier gas temperature and pressure are identified at approximately 400 °C and 1.99 MPa, respectively, consistent across all Cu powders. Velocity analysis reveals particle velocities ranging from 373 to 564 m/s under these optimal conditions. Coatings deposited using satellite-free gas-atomized powder, characterized by enhanced sphericity, exhibit superior characteristics, including minimal porosity (0.66 ± 0.35%), high flattening ratio (3.57 ± 1.51), elevated microhardness (107 ± 3 HV) and high bonding strength (20.7 ± 2.3 MPa). In contrast, coatings deposited with gas-atomized powder featuring microsatellite particles and electrolytic powder with irregular shapes display distinct properties. The observed trends are attributed to lower oxygen content and reduced oxide levels near the surface of the more spherical, satellite-free powder. This powder also demonstrates heightened plastic deformation during deposition. The increased peening effect of satellite-free gas-atomized powder during cold spray results in elevated dynamic recrystallization near the substrate surface, leading to smaller grains at the interface. Microstructural evolution analysis, utilizing electron backscatter diffraction, further elucidates the heterogeneous deformation and grain refinement occurring in Cu splats during cold spray coating. [ABSTRACT FROM AUTHOR]

High-performance polymers such as poly(ether ether ketone) (PEEK) are appealing as composite components for a wide variety of industrial and medical applications due to their excellent thermomechanical properties. However, conventional PEEK metallization methods can often lead to poor quality control, low deposition rate, and high cost. Cold spray is a promising potential alternative to produce polymer–metal composites rapidly and inexpensively due to its relatively mild operating conditions and high throughput. In this study, we investigated the deposition characteristics of metal–polymer composite feedstock, composed of PEEK powder and copper flake in varying ratios, onto a PEEK substrate. Copper-PEEK powder blends were prepared by both hand-mixing and cryogenic milling (cryomilling), which predominantly creates composite particles with micron-scale copper domains coating PEEK particle surfaces. This process non-monotonically affects the relative dominance and length scales of the multiple contributing deposition mechanisms present in mixed-material cold spray. In low-pressure cold spray, deposits showed significant changes in deposition efficiency and composition as a result of milling, with improvements in these characteristics most dramatic at lower Cu fractions. Deposits of a cryomilled blend of nominally 30 vol.% copper in PEEK exhibited minimal porosity under scanning electron microscopy, complete retention of powder composition, and the highest deposition efficiency among all samples tested. Notably, neither neat PEEK nor neat Cu meaningfully deposited at the same mild conditions as this 30 vol.% Cu blend, indicating a synergistic departure from linear mixing rules driven by the relative balance of local deposition interactions (e.g., hard–soft, soft–soft, etc.). Intentional powder and process design toward optimizing this balance may facilitate cold spray metallization applications. [ABSTRACT FROM AUTHOR]

Polymers have proven to be challenging to cold spray, particularly with high efficiency and quality when using inexpensive nitrogen (N2) and air propellants. Helium (He), when used as a process propellant, can improve spray deposit properties but is often undesirable due to its limited availability and high cost. In this study, additives of multiple particle sizes and materials were mixed with polymer powder in an effort to improve the performance of polymer sprays using mainly N2 as a process propellant. The effects of hard-phase additives on deposit microstructure were investigated by precise ion beam polishing of deposit cross sections and subsequent electron microscope imaging. Additional metrics including the density and post-spray composition of deposits were investigated to quantify the peening effect and the amount of embedded additive. Additives, regardless of size, were observed to embed in the spray deposits. Additionally, hard-phase additives demonstrated nozzle cleaning properties that continually remove polymer fouling on the nozzle walls. Inversely, sprays with polymer powder and no additives tended to clog the nozzle throat and diverging section because of continual fouling. [ABSTRACT FROM AUTHOR]

Additive manufacturing (AM) has become one of the most promising manufacturing techniques in recent years due to the geometric design freedom that this technology offers. The main objective of this study is to explore Composite Extrusion Modelling (CEM) with aluminium as an alternative processing route for aluminium alloys. This process allows for working with pellets that are deposited directly, layer by layer. The aim of the technique is to obtain aluminium alloy samples for industrial applications with high precision, without defects, and which are processed in an environmentally friendly manner. For this purpose, an initial and preliminary study using powder injection moulding (PIM), necessary for the production of samples, has been carried out. The first challenge was the design of a sustainable aluminium-based feedstock. The powder injection moulding technique was used as a first approach to optimise the properties of the feedstock through a combination of water-soluble polymer, polyethyleneglycol (PEG), and cellulose acetate butyrate (CAB) wich produces low CO2 emissions. To do this, a microstructural characterisation was carried out and the critical solid loading and rheological properties of the feedstocks were studied. Furthermore, the debinding conditions and sintering parameters were adjusted in order to obtain samples with the required density for the following processes and with high geometrical accuracy. In the same way, the printing parameters were optimised for proper material deposition. [ABSTRACT FROM AUTHOR]

Developing methylotrophic cell factories that can efficiently catalyze organic one-carbon (C1) feedstocks derived from electrocatalytic reduction of carbon dioxide into bio-based chemicals and biofuels is of strategic significance for building a carbon-neutral, sustainable economic and industrial system. With the rapid advancement of RNA sequencing technology and mass spectrometer analysis, researchers have used these quantitative microbiology methods extensively, especially isotope-based metabolic flux analysis, to study the metabolic processes initiating from C1 feedstocks in natural C1-utilizing bacteria and synthetic C1 bacteria. This paper reviews the use of advanced quantitative analysis in recent years to understand the metabolic network and basic principles in the metabolism of natural C1-utilizing bacteria grown on methane, methanol, or formate. The acquired knowledge serves as a guide to rewire the central methylotrophic metabolism of natural C1-utilizing bacteria to improve the carbon conversion efficiency, and to engineer non-C1-utilizing bacteria into synthetic strains that can use C1 feedstocks as the sole carbon and energy source. These progresses ultimately enhance the design and construction of highly efficient C1-based cell factories to synthesize diverse high value-added products. The integration of quantitative biology and synthetic biology will advance the iterative cycle of understand--design--build--testing--learning to enhance C1-based biomanufacturing in the future. [ABSTRACT FROM AUTHOR]

In transitioning to a carbon‐neutral chemical industry, the intake of fossil feedstocks will have to be reduced by maximizing end‐of‐life product recycling and introducing alternative feedstocks based on renewable carbon. This perspective article analyses the potential of domestically grown and sourced woody biomass for the supply of renewable carbon for chemicals in Europe. The European chemical industry can become a major consumer of woody biomass in a context where burning wood for energy production is viewed as an unsustainable practice. [ABSTRACT FROM AUTHOR]

Commercial cultivation of edible mushrooms utilizes a large amount of lignocellulosic material as a substrate. After harvest, the leftover substrate, referred to as a spent mushroom substrate (SMS), largely remains biochemically unaltered. In light of the global rise in the number of edible mushroom production facilities, it is pertinent to sustainably manage the by‐products of the mushroom production process, particularly SMS. Following the principles of the circular economy, SMS has shown potential for a variety of applications: SMS can be used as substrate for a new cycle of mushroom cultivation or as animal feed, fertilizer, soil amendment, bioremediation agent or a substrate for renewable energy production such as biogas, bioethanol, biohydrogen, solid biofuel, bio‐crude and bio‐oil. This article summarizes the current state of knowledge in various applications, highlights recent developments in the field, discusses potential barriers and offers suggestions for the long‐term growth of the mushroom industry worldwide. [ABSTRACT FROM AUTHOR]

Micro-distillation is one of the unit operation technologies that are looking toward innovation through on-site and on-demand production system. In this study, a simple structure microdistillator consisting of some plates was applied to reactive distillation, and its potential was investigated. As a target reaction, the heterogeneous esterification between acetic acid and methanol using a solid acid catalyst was employed. The effects of feedstock supply rate, feedstock composition, and device temperature on operation stability and conversion were examined. By controlling the feedstock supply rate and temperature properly, a stable operation with a conversion of approximately 100% was successfully achieved. The amount of methyl acetate produced per weight of catalyst was greater in the reactive distillation using a microdistillator than in the batch reaction, soon after the start of the reaction. Thus, it was demonstrated that the reactive distillation using a microdistillator was able to achieve highly efficient reactions with short reaction time and small amounts of catalyst. [ABSTRACT FROM AUTHOR]

Solid biofuels, including straw as production residue, are still the largest energy feedstock in the structure of primary energy production from renewable energy sources. However, the properties of straw as a solid biofuel can vary depending on the species from which it was produced and the harvest period and year. Therefore, this study aimed to assess the thermophysical properties and elemental composition of six types of straw (rye, oat, triticale, wheat, corn, and rapeseed straw) obtained over three consecutive years (2020, 2021, 2022). Rye straw had the lowest moisture (mean: 10.55%), ash (mean: 2.71% DM), nitrogen (mean: 0.54% DM) and chlorine (mean: 0.046% DM) contents and the highest carbon content (mean: 47.93% DM), a higher heating value—HHV (mean: 19.03 GJ Mg−1 DM) and a lower heating value—LHV (mean: 15.71 GJ Mg−1). Triticale straw had similar properties, classifying it into the same cluster as rye straw. Corn straw had a remarkably high moisture content (mean: 48.91%), low LHV and high chlorine content. Rapeseed straw contained high levels of Cl, S, N and ash, and they were 643%, 481%, 104% and 169% higher, respectively, than those in rye straw. The sulfur, chlorine and moisture contents of the six straw types under study were highly variable during the three years of the study. Knowledge of the properties of different types of straw as energy feedstocks facilitates the logistics and organization of the supply of bioenergy installations. However, further research is needed, especially studies assessing the energy intensity and logistical costs of different types of straw used for energy purposes. [ABSTRACT FROM AUTHOR]