Life Cycle Assessment of Composites Additive Manufacturing Using Recycled Materials

Additive manufacturing (AM) of composite materials is promising to create customizable products with enhanced properties, utilizing materials like carbon fibers (CFs). To increase their circularity, composite recycling has been proposed to re-introduce the recovered components in AM. A careful evaluation of recycling is necessary, considering the sustainability and functionality (i.e., mechanical properties) of the recovered components. Thus, Life Cycle Assessment (LCA) is applied to estimate the environmental impacts of AM via Fused Filament Fabrication (FFF), using virgin or recycled CFs via solvolysis at a laboratory scale. This study aims to provide a detailed Life Cycle Inventory (LCI) of FFF and evaluate the sustainability of using recycled CFs in AM. For both virgin CF manufacturing and CF recycling, electricity consumption was the main contributor to environmental impacts. CF recovery via solvolysis resulted in lower impacts across most impact categories compared to AM with virgin CFs. Different scenarios were examined to account for the mechanical properties of recycled CFs. AM with 75% recycled CFs, compared to 100% virgin CFs undergoing landfilling, resulted in over 22% reduction in climate change potential, even after a 50% loss of recycled CF functionality. Overall, this study offers insights into the LCI of FFF and shows that CF recycling from composites is worth pursuing

Cadmium uptake kinetics in parts of the seagrass Cymodocea nodosa at high exposure concentrations

Abstract Background Seagrass species have been recommended as biomonitors of environmental condition and as tools for phytoremediation, due to their ability to concentrate anthropogenic chemicals. This study aims to provide novel information on metal accumulation in seagrasses under laboratory conditions to support their use as a tool in the evaluation and abatement of contamination in the field. We investigated the kinetics of cadmium uptake into adult leaf blades, leaf sheaths, rhizomes and roots of Cymodocea nodosa in exposure concentrations within the range of cadmium levels in industrial wastewater (0.5–40 mg L−1). Results A Michaelis–Menten-type equation satisfactorily described cadmium accumulation kinetics in seagrass parts, particularly at 0.5–5 or 10 mg L−1. However, an S equation best described the uptake kinetics in rhizomes at 5 mg L−1 and roots at 10 and 20 mg L−1. Equilibrium concentration and uptake rate tended to increase with the exposure concentration, indicating that seagrass displays a remarkable accumulation capacity of cadmium and reflect high cadmium levels in the surrounding medium. Concerning leaf blades and rhizomes, the bioconcentration factor at equilibrium (range 73.3–404.3 and 14.3–86.3, respectively) was generally lower at higher exposure concentrations, indicating a gradual reduction of available binding sites. Leaf blades and roots accumulated more cadmium with higher rate than sheaths and rhizomes. Uptake kinetics in leaf blades displayed a better fit to the Michaelis–Menten-type equation than those in the remaining plant parts, particularly at 0.5–10 mg L−1. A marked variation in tissue concentrations mainly after the steady state was observed at 20 and 40 mg L−1, indicative of the stress induced on seagrass cells. The maximum concentrations observed in seagrass parts at 5 and 10 mg L−1 were comparatively higher than those previously reported for other seagrasses incubated to similar exposure concentrations. Conclusions Cymodocea nodosa displays a remarkable cadmium accumulation capacity and reflects high cadmium levels in the surrounding medium. Kinetic models satisfactorily describe cadmium uptake in seagrass parts, primarily in adult leaf blades, at high exposure concentrations, permitting to predict cadmium accumulation in field situations. Cymodocea nodosa appeared to be a valuable tool in the evaluation and abatement of cadmium contamination in coastal areas

CO₂ Conversion by Combining a Copper Electrocatalyst and Wild-type Microorganisms

Carbon dioxide (CO2) can be converted to valuable products using different catalysts, including metal or biological catalysts (e. g. microorganisms). Some products formed by metal electrocatalysts can be further utilized by microorganisms, and therefore catalytic cooperation can be envisioned. To prevent cumbersome separations, it is beneficial when both catalyst work under the same conditions, or at least in the same reaction medium. Here, we will show that a formate-producing copper electrocatalyst can function in a biological medium. Furthermore, we will show that the effluent of the copper-containing reactor can be used without purification as the sole medium for a bio-reactor, inoculated with a mixed culture of microorganisms. In that second reactor, formate, H2 and CO2 are consumed by the microorganisms, forming acetate and methane. Compared to simple buffer electrolyte, catalytic activity of copper was improved in the presence of microbial growth medium, likely due to EDTA (Ethylenediaminetetraacetic acid) present in the latter.</p

Concentration-dependent effects of nickel doping on activated carbon biocathodes

In microbial electrosynthesis (MES), microorganisms grow on a cathode electrode as a biofilm, or in the catholyte as planktonic biomass, and utilize CO2for their growth and metabolism. Modification of the cathode with metals can improve MES performance, due to their catalytic activity for H2 production, which can be consumed by microorganisms, or via modifying the cathode properties. On the other hand, metals can have an inhibiting effect on MES. While these single roles of metals and their oxides have been identified, an investigation of the simultaneous effects on MES is still lacking. Here, we modify activated carbon (AC) electrodes with nickel (Ni) at high (5%) and low (0.01%) loadings, to investigate its combined effects on MES. Upon Ni impregnation, multiple factors explained the MES performance, including electrocatalytic H2 production, trace element availability, metal toxicity, Ni leaching and redeposition/bio-crystalization. Instead, the electrode surface properties (i.e., surface area and pore structure) were not affected by Ni addition. Compared to unmodified AC, low Ni loading did not improve abiotic H2 production, whereas at high Ni loading a 6-fold increase was observed. During biological experiments, low Ni loading resulted in over a 3-fold increase of acetate production and 35% higher planktonic growth, compared to unmodified AC. Instead, high Ni loading resulted in 25-fold increase of acetate production, 21% decrease of planktonic growth, and improved biofilm growth. Unmodified AC, and low and high Ni loading each resulted in unique microbial community composition. The effect of Ni on MES is therefore concentration-dependent, with apparently different mechanisms of interaction being prevalent at low or high Ni loadings.BT/Bioprocess Engineerin

Catalytic Cooperation between a Copper Oxide Electrocatalyst and a Microbial Community for Microbial Electrosynthesis

Electrocatalytic metals and microorganisms can be combined for CO2 conversion in microbial electrosynthesis (MES). However, a systematic investigation on the nature of interactions between metals and MES is still lacking. To investigate this nature, we integrated a copper electrocatalyst, converting CO2 to formate, with microorganisms, converting CO2 to acetate. A co-catalytic (i. e. metabolic) relationship was evident, as up to 140 mg L-1 of formate was produced solely by copper oxide, while formate was also evidently produced by copper and consumed by microorganisms producing acetate. Due to non-metabolic interactions, current density decreased by over 4 times, though acetate yield increased by 3.3 times. Despite the antimicrobial role of copper, biofilm formation was possible on a pure copper surface. Overall, we show for the first time that a CO2 -reducing copper electrocatalyst can be combined with MES under biological conditions, resulting in metabolic and non-metabolic interactions.</p

Catalytic Cooperation between a Copper Oxide Electrocatalyst and a Microbial Community for Microbial Electrosynthesis

Electrocatalytic metals and microorganisms can be combined for CO2 conversion in microbial electrosynthesis (MES). However, a systematic investigation on the nature of interactions between metals and MES is still lacking. To investigate this nature, we integrated a copper electrocatalyst, converting CO2 to formate, with microorganisms, converting CO2 to acetate. A co-catalytic (i. e. metabolic) relationship was evident, as up to 140 mg L-1 of formate was produced solely by copper oxide, while formate was also evidently produced by copper and consumed by microorganisms producing acetate. Due to non-metabolic interactions, current density decreased by over 4 times, though acetate yield increased by 3.3 times. Despite the antimicrobial role of copper, biofilm formation was possible on a pure copper surface. Overall, we show for the first time that a CO2 -reducing copper electrocatalyst can be combined with MES under biological conditions, resulting in metabolic and non-metabolic interactions.BT/Bioprocess EngineeringEnvironmental Technology and Desig

CO₂ Conversion by Combining a Copper Electrocatalyst and Wild-type Microorganisms

Carbon dioxide (CO2) can be converted to valuable products using different catalysts, including metal or biological catalysts (e. g. microorganisms). Some products formed by metal electrocatalysts can be further utilized by microorganisms, and therefore catalytic cooperation can be envisioned. To prevent cumbersome separations, it is beneficial when both catalyst work under the same conditions, or at least in the same reaction medium. Here, we will show that a formate-producing copper electrocatalyst can function in a biological medium. Furthermore, we will show that the effluent of the copper-containing reactor can be used without purification as the sole medium for a bio-reactor, inoculated with a mixed culture of microorganisms. In that second reactor, formate, H2 and CO2 are consumed by the microorganisms, forming acetate and methane. Compared to simple buffer electrolyte, catalytic activity of copper was improved in the presence of microbial growth medium, likely due to EDTA (Ethylenediaminetetraacetic acid) present in the latter.Accepted Author ManuscriptBT/Bioprocess EngineeringEnvironmental Technology and Desig