Carbon Resources Conversion最新文献

Alkali contents with low melting points in the ash of woody biomass vaporize during the biomass gasification process, damaging various downstream energy conversion devices, such as the solid oxide fuel cells (SOFCs). In this study, the degradation of SOFC anodes by the deposition of potassium compounds (KCl, K₂CO₃, and KOH) was investigated. An aqueous solution of potassium compounds was dripped onto the anode surface of the SOFC button cell at room temperature. After drying at 343 K, 6.964 $\times$ 10^-6 mol KCl, 6.964 $\times$ 10^-6 mol KOH, and 3.482 $\times$ 10^-6 mol K₂CO₃ was deposited on the anode. Button cells with the deposition of K compounds were employed for power generation experiments at 1023 K with the supply of artificial syngas from biomass gasification. After the power generation experiments, the surface structures of the anodes were microscopically analyzed using the SEM and EDS. As a result, K compounds hardly affected the OCV of SOFC. With the addition of KCl, no apparent change in the anode structure was observed, and only a slight KCl deposit was detected. However, chloride tends to be chemisorbed on Ni, increasing the ohmic resistance as well as the adsorption/desorption resistance. However, KOH transformed to K₂CO₃ and then remained massively on the anode, which was clearly observed in the SEM images. K₂CO₃ significantly decreased the cell voltage under a current density of 100 mA·cm⁻². Through impedance analyses, this voltage drop was mainly attributed to the ohmic resistance and gas diffusion resistance. However, there is no evidence that this deposit degrades Ni particles.

This study explores the impact of granular activated carbon (GAC) and L-arginine supplementation on biogas upgrading and acetic acid production employing Clostridium thailandense. GAC and L-arginine concentrations ranged from 0 to 20 g/L and 0 to 5 g/L, respectively, with H₂ acting as the electron donor at an H₂ to CO₂ ratio of 2:1 (v/v). Experiments were conducted at 30 °C with an agitation speed of 150 rpm. Additionally, gene annotation of the C. thailandense genome using Rapid Annotations using Subsystems Technology (RAST) identified genes involved in CO₂ to acetic acid conversion. Results indicate that adding 7.5 g/L GAC boosts CH₄ purity in biogas, elevating CO₂ and H₂ consumption efficiencies to 88.3 % and 98.7 %, respectively. This enhancement leads to a CH₄ content increase to 93.3 %, accompanied by 0.90 g/L acetic acid production. Conversely, L-arginine demonstrates no significant impact on CO₂ conversion. Leveraging RAST, the study identifies hydrogenase genes and NADH-dependent ferredoxin-NADP⁺ oxidoreductase (Nfn), as crucial for heightened H₂ consumption efficiencies and cell growth facilitated by GAC, thus enhancing biogas upgrading efficiency in C. thailandense. This research provides vital insights into optimizing sustainable biogas production through strategic GAC utilization and elucidates the roles of hydrogenase genes and Nfn.

We report magnetically-separable, reusable, green-synthesized Fe₃O₄/rGO/ZnO, as heterogeneous catalyst for photo-Fenton degradation of organic pollutants in aqueous solution under certain treatments. Fe₃O₄ nanoparticles was green-synthesized using Moringa oleifera leaf extract, while rGO was synthesized utilizing Amaranthus viridis leaf extract. Fe₃O₄/rGO was composited under sonication treatment. Afterwards, Fe₃O₄/rGO was doped with ZnO with various concentration of ZnO. X-ray diffraction and selected area electron diffraction showed that Fe₃O₄ and ZnO had spinel cubic and hexagonal structure, respectively; another phase appeared as Fe₂O₃ spinel cubic structure. Crystallite size was decreased as the ZnO concentration increased. Morphology image showed almost spherical, non-uniform, and slightly dispersed particle under agglomerated condition, attaching to rGO sheets. The particle size of Fe₃O₄, Fe₃O₄/rGO, and Fe₃O₄/rGO/ZnO is 14.3; 14.1; and 10.4 nm, respectively. Fourier-transform infrared spectra showed metallic functional groups, such as Fe-O and Zn–O at 562–589 and 462–478 cm⁻¹ also suggests nanocomposite formation. However, blue-shift absorption and band gap widening were observed with ZnO addition. Raman spectroscopy revealed the formation as-synthesized GO and rGO. Vibrating sample magnetometer showed that green-synthesized Fe₃O₄/rGO/ZnO exhibited superparamagnetic properties. Removal efficiency of photodegradation methylene blue was optimal for green-synthesized Fe₃O₄/rGO/ZnO under sonication treatment, reached 100 % degradation within 180 min for uptake every 30 min. Photodegradation was also analyzed using Langmuir-Hinshelwood kinetic model, resulting rate constant of 24.7 × 10⁻³ min⁻¹ and half-life time of 28.1 min at optimum treatment. Reusability of photocatalytic activity after 3 cycles showed only a tiny drop in catalytic efficiency. Meanwhile, it possesses high stability in catalytic activity and structure. The green-synthesized Fe₃O₄/rGO/ZnO potential as an environmentally friendly reusable photocatalyst for wastewater degradation.

Hydrogenating carbon dioxide to formate using formate dehydrogenase (FDH) is a sustainable approach for CO₂ mitigation. Herein, we developed a biocatalytic system with cofactor regeneration by immobilizing multiple enzymes, namely FDH, carbonic anhydrase (CA), and glutamate dehydrogenase (GDH), on a hydrophobic surface modified MOF, SA-HKUST-1. The adsorption kinetics of the multiple enzymes on the SA-HKUST-1 surface were described using pseudo second-order model, while the equilibrium followed Freundlich isotherm. Formate production by the enzymes immobilized on SA-HKUST-1 was 3.75 times higher than that achieved by free enzymes and 8.4 times higher than that of FDH immobilized alone on SA-HKUST-1. The hydrophobic interaction between the enzymes and the support altered the secondary structure of enzymes, and the immobilized enzymes retained 94% of their activity after four reuse cycles. This study provides novel insights into the combined effect of hydrophobic support and multiple enzymes on the catalytic efficiency and stability of FDH. These findings can provide a basis for developing a highly stable biocatalytic system with cofactor regeneration for continuous hydrogenation of CO₂ to formate at the industrial level.