Higher CO2 Production Research Articles

Rational design of CdCO3 nanoparticles decorated carbon nanofibers for boosting electrochemical CO2 reduction

Efficient, robust and inexpensive catalysts are highly desirable to drive the electrochemical CO2 reduction reaction (CO2RR) to value-added fuels. Herein, low-cost CdCO3 nanoparticles (NPs) decorated carbon nanofibers (CdCO3-CNFs) were synthesized by a facile one-pot method to boost the performance of CO2RR to CO. The obtained CdCO3-CNFs show a high Faradaic efficiency (93.4%) and a good partial current density (~10 mA cm−2) at a potential of −0.83 V. Moreover, CdCO3-CNFs achieve high CO production rates at moderately negative potentials and a good stability of 24 h with negligible degradation. The superior performance is attributed to the increased number of catalytically active sites, and the strong interaction between CdCO3 NPs and CNFs which promotes electron transfer and secures active sites. This study provides a promising strategy for the efficient and durable CO2RR by designing a carbonate/carbon system with a strong catalyst-support interaction.

The role of oxygen in stimulating methane production in wetlands.

Methane (CH4), a potent greenhouse gas, is the second most important greenhouse gas contributor to climate change after carbon dioxide (CO2). The biological emissions of CH4 from wetlands are a major uncertainty in CH4 budgets. Microbial methanogenesis by Archaea is an anaerobic process accounting for most biological CH4 production in nature, yet recent observations indicate that large emissions can originate from oxygenated or frequently oxygenated wetland soil layers. To determine how oxygen (O2) can stimulate CH4 emissions, we used incubations of Sphagnum peat to demonstrate that the temporary exposure of peat to O2 can increase CH4 yields up to 2000‐fold during subsequent anoxic conditions relative to peat without O2 exposure. Geochemical (including ion cyclotron resonance mass spectrometry, X‐ray absorbance spectroscopy) and microbiome (16S rDNA amplicons, metagenomics) analyses of peat showed that higher CH4 yields of redox‐oscillated peat were due to functional shifts in the peat microbiome arising during redox oscillation that enhanced peat carbon (C) degradation. Novosphingobium species with O2‐dependent aromatic oxygenase genes increased greatly in relative abundance during the oxygenation period in redox‐oscillated peat compared to anoxic controls. Acidobacteria species were particularly important for anaerobic processing of peat C, including in the production of methanogenic substrates H2 and CO2. Higher CO2 production during the anoxic phase of redox‐oscillated peat stimulated hydrogenotrophic CH4 production by Methanobacterium species. The persistence of reduced iron (Fe(II)) during prolonged oxygenation in redox‐oscillated peat may further enhance C degradation through abiotic mechanisms (e.g., Fenton reactions). The results indicate that specific functional shifts in the peat microbiome underlie O2 enhancement of CH4 production in acidic, Sphagnum‐rich wetland soils. They also imply that understanding microbial dynamics spanning temporal and spatial redox transitions in peatlands is critical for constraining CH4 budgets; predicting feedbacks between climate change, hydrologic variability, and wetland CH4 emissions; and guiding wetland C management strategies.

Effect of the Nanostructured Zn/Cu Electrocatalyst Morphology on the Electrochemical Reduction of CO2 to Value-Added Chemicals.

Zn/Cu electrocatalysts were synthesized by the electrodeposition method with various bath compositions and deposition times. X-ray diffraction results confirmed the presence of (101) and (002) lattice structures for all the deposited Zn nanoparticles. However, a bulky (hexagonal) structure with particle size in the range of 1–10 μm was obtained from a high-Zn-concentration bath, whereas a fern-like dendritic structure was produced using a low Zn concentration. A larger particle size of Zn dendrites could also be obtained when Cu2+ ions were added to the high-Zn-concentration bath. The catalysts were tested in the electrochemical reduction of CO2 (CO2RR) using an H-cell type reactor under ambient conditions. Despite the different sizes/shapes, the CO2RR products obtained on the nanostructured Zn catalysts depended largely on their morphologies. All the dendritic structures led to high CO production rates, while the bulky Zn structure produced formate as the major product, with limited amounts of gaseous CO and H2. The highest CO/H2 production rate ratio of 4.7 and a stable CO production rate of 3.55 μmol/min were obtained over the dendritic structure of the Zn/Cu–Na200 catalyst at −1.6 V vs. Ag/AgCl during 4 h CO2RR. The dissolution and re-deposition of Zn nanoparticles occurred but did not affect the activity and selectivity in the CO2RR of the electrodeposited Zn catalysts. The present results show the possibilities to enhance the activity and to control the selectivity of CO2RR products on nanostructured Zn catalysts.

Efficient synthesis of tunable band-gap CuInZnS decorated g-C3N4 hybrids for enhanced CO2 photocatalytic reduction and near-infrared-triggered photodegradation performance

By rationally adjusting the band position of CuInZnS in CuInZnS/g-C3N4 hybrids, we reveal the effects of fine turning the band matching on CO2 reduction and methyl orange near-infrared degradation. The novel design strategy of CuInZnS/g-C3N4 hybrids, including orderly energy band regulation of CuInZnS and surface carboxylation of g-C3N4, effectively enhances the light absorption capacity and separation efficiency of photogenerated carriers. In addition, L-cysteine was used as sulfur source for in situ synthesis of hybrids. Using the abundant functional groups of L-cysteine molecules to form bonds and interactions with carboxylated g-C3N4 can effectively improve the dispersion and interface binding of CuInZnS/g-C3N4 hybrids, thus enhancing the transport of carriers at the interface. Benefitting from band matching and interface binding characteristics, the optimized CuInZnS/g-C3N4 hybrids manifest remarkable performance for CO2 reduction with high CO production rate of 50.04 μmol/g in 8 h and excellent activity for methyl orange near-infrared degradation with 96.5% efficiency in 5 h.

Unique structure of active platinum-bismuth site for oxidation of carbon monoxide

As the technology development, the future advanced combustion engines must be designed to perform at a low temperature. Thus, it is a great challenge to synthesize high active and stable catalysts to resolve exhaust below 100 °C. Here, we report that bismuth as a dopant is added to form platinum-bismuth cluster on silica for CO oxidation. The highly reducible oxygen species provided by surface metal-oxide (M-O) interface could be activated by CO at low temperature (~50 °C) with a high CO2 production rate of 487 μmolCO2·gPt−1·s−1 at 110 °C. Experiment data combined with density functional calculation (DFT) results demonstrate that Pt cluster with surface Pt−O−Bi structure is the active site for CO oxidation via providing moderate CO adsorption and activating CO molecules with electron transformation between platinum atom and carbon monoxide. These findings provide a unique and general approach towards design of potential excellent performance catalysts for redox reaction.

The impact of perceived corporate social responsibility on value-in-use through customer engagement in non-profit sports clubs: the moderating role of co-production

ABSTRACT Research question Despite the increasing importance of customer engagement (CE) as a significant facet to facilitate increased profitability for organisations, little sport management research has examined antecedents and consequences of CE. Using the service-dominant logic as a theoretical framework, this study examines whether perceived corporate social responsibility (CSR) predicts value-in-use through CE, considering the moderating role of co-production. Research methods Participants (n = 483) were recruited from non-profit sports clubs in Iran. Structural equation modelling was applied to test the research model. Results and Findings The findings revealed positive associations between perceived CSR, CE, and value-in-use. Perceived CSR had a positive indirect effect on value-in-use through CE. Furthermore, co-production had a moderating effect on the relationship between perceived CSR and CE, where the relationship was stronger for individuals with higher co-production. Findings from this study suggest perceived CSR is a key antecedent of CE, highlighting the importance of co-production and CE in promoting value-in-use in non-profit sports clubs. Implications Non-profit sports clubs can co-create value by engaging customers through CSR. Findings from this study highlight the importance of CE and co-production in promoting value-in-use in non-profit sports clubs.

Indirect Z-scheme heterojunction of NH2-MIL-125(Ti) MOF/g-C3N4 nanocomposite with RGO solid electron mediator for efficient photocatalytic CO2 reduction to CO and CH4

Well-designed Z-scheme photocatalyst of NH2-MIL-125(Ti) MOF coupled g-C3N4 with RGO mediator synthesized with a facile hydrothermal method has been investigated for stimulating photocatalytic CO2 reduction under visible light. The amino-functionalized Ti-based MOF boosted the photocatalytic efficiency due to its high surface area and porous structure. Moreover, the NH2-MIL-125(Ti) MOF has a great ability for CO2 gas adsorption. The novel RGO-linked g-C3N4/NH2-MIL-125(Ti) nanocomposite exhibited efficient photocatalytic CO2 conversion to CH4 and CO. The experimental results showed that CO was the predominant reaction product with a production of 383.79 μmol g−1 achieved after 4 h irradiation which is 5 and 2.5 times higher compared to pure g-C3N4 and zero-MOF g-C3N4-RGO composite, respectively. However, the composite also exhibited a CH4 evolution of 13.8 μmol g−1. The amino functionality provided the MOF with antenna-like reaction sites with high affinity to CO2 molecules which improved the photocatalytic reduction of CO2 towards high CO production selectivity. An effective spatial separation and transfer of photogenerated charge carriers was also obtained as a result of RGO incorporation which constructed an effective Z-scheme bridge for the transfer of charges and limiting the high recombination rate of g-C3N4. The stability analysis of the newly developed composite revealed a continuous production of CO and CH4 in multiple cycles without any obvious deactivation under visible light. This work provides a new approach for the construction of Z-scheme heterojunction composites that would be beneficial for further investigations in selective CO2 conversion to solar fuels.

Oxygen vacancy engineering of BiOBr/HNb3O8 Z-scheme hybrid photocatalyst for boosting photocatalytic conversion of CO2

Photo-chemical conversion of CO2 into solar fuels by photocatalysts is a promising and sustainable strategy in response to the ever-increasing environmental problems and imminent energy crisis. However, it is unavoidably impeded by the insufficient active site, undesirable inert charge transfer and fast recombination of photogenerated charge carriers on semiconductor photocatalysts. In this work, all these challenges are overcome by construction of a novel defect-engineered Z-scheme hybrid photocatalyst, which is comprised of three-dimensional (3D) BiOBr nanoflowers assembled by nanosheets with abundant oxygen vacancies (BiOBr-VO) and two-dimensional (2D) HNb3O8 nanosheets (HNb3O8 NS). The special 3D-2D architecture structure is beneficial to preventing photocatalyst stacking and providing more active sites, and the introduced oxygen vacancies not only broaden the light absorption range but also enhance the electrical conductivity. More importantly, the constructed Z-scheme photocatalytic system could accelerate the charge carriers transfer and separation. As a result, the optimal BiOBr-VO/HNb3O8 NS (50%-BiOBr-VO/HNb3O8 NS) shows a high CO production yield of 164.6 μmol·g−1 with the selectivity achieves to 98.7% in a mild gas-solid system using water as electron donors. Moreover, the BiOBr-VO/HNb3O8 NS photocatalyst keeps high photocatalytic activity after five cycles under the identical experimental conditions, demonstrating its excellent long-term durability. This work provided an original strategy to design a new hybrid structure photocatalyst involved VOs, thus guiding a new way to further enhance CO2 reduction activity of photocatalyst.

Greenhouse gas production and lipid biomarker distribution in Yedoma and Alas thermokarst lake sediments in Eastern Siberia.

Permafrost thaw leads to thermokarst lake formation and talik growth tens of meters deep, enabling microbial decomposition of formerly frozen organic matter (OM). We analyzed two 17-m-long thermokarst lake sediment cores taken in Central Yakutia, Russia. One core was from an Alas lake in a Holocene thermokarst basin that underwent multiple lake generations, and the second core from a young Yedoma upland lake (formed ~70years ago) whose sediments have thawed for the first time since deposition. This comparison provides a glance into OM fate in thawing Yedoma deposits. We analyzed total organic carbon (TOC) and dissolved organic carbon (DOC) content, n-alkane concentrations, and bacterial and archaeal membrane markers. Furthermore, we conducted 1-year-long incubations (4°C, dark) and measured anaerobic carbon dioxide (CO2 ) and methane (CH4 ) production. The sediments from both cores contained little TOC (0.7±0.4 wt%), but DOC values were relatively high, with the highest values in the frozen Yedoma lake sediments (1620mgL-1 ). Cumulative greenhouse gas (GHG) production after 1year was highest in the Yedoma lake sediments (226±212µgCO2 -Cg-1 dw, 28±36µg CH4 -Cg-1 dw) and 3 and 1.5 times lower in the Alas lake sediments, respectively (75±76µgCO2 -Cg-1 dw, 19±29µg CH4 -Cg-1 dw). The highest CO2 production in the frozen Yedoma lake sediments likely results from decomposition of readily bioavailable OM, while highest CH4 production in the non-frozen top sediments of this core suggests that methanogenic communities established upon thaw. The lower GHG production in the non-frozen Alas lake sediments resulted from advanced OM decomposition during Holocene talik development. Furthermore, we found that drivers of CO2 and CH4 production differ following thaw. Our results suggest that GHG production from TOC-poor mineral deposits, which are widespread throughout the Arctic, can be substantial. Therefore, our novel data are relevant for vast ice-rich permafrost deposits vulnerable to thermokarst formation.

Soil biodegradation of cotton fabrics treated with common finishes

Cotton is one of the most widely used natural fibers available. However, to overcome some of its shortcomings, manufacturers have placed various finishes on cotton fabrics to improve wrinkle recovery, flame retardancy, anti-microbial behavior, water repellency, etc. This study measures the impact of common finishes on the biodegradability of 100% cotton fabrics in a soil laboratory environment. Under a controlled laboratory environment, cotton fabrics treated with 9 different finishing chemicals or chemical combinations were tested according to the standard test method, ASTM D5988-12, for up to 154 days. Results indicate crosslinked fibers show better protection from biodegradation when compared to the control fabric and non-crosslinked fabrics. The production of carbon dioxide (CO2) as a function of time was measured to determine the degree of biodegradation. Untreated cotton samples produced 2500 mg of CO2 after 154 days, approximately 40% more than that of the crosslinked treated fabric. Weightless studies showed the untreated fabrics and non-crosslinked finished having 40–60% weight loss after 154 days, while the crosslinked fabrics had unless than 20% weight loss over the same time period. Scanning electron microscope (SEM) images were used to observe the visual degradation level for each sample showed certain treated fabrics showed a less evidence of cracking on the fiber surface along with less microorganism growth. Fourier-transform infrared spectroscopy (FTIR) analysis showed that in general, treated fabrics with higher CO2 production and higher weight loss showed greater evidence of microorganism growth when analyzing peak bands typically associated with microorganism growth irreversibly bonded to the fibers.

Robust Biological Hydrogen‐Bonded Organic Framework with Post‐Functionalized Rhenium(I) Sites for Efficient Heterogeneous Visible‐Light‐Driven CO2 Reduction

AbstractA robust 2,2′‐bipyridine (bpy)‐derived biological hydrogen‐bonded framework (HOF‐25) has been realized depending on guanine‐quadruplex with the assistance of π‐π interaction, which reacts with Re(CO)5Cl to give a post‐functionalized HOF‐25‐Re. X‐ray absorption fine structure spectroscopic study on HOF‐25‐Re confirms the covalent attachment of Re(bpy)(CO)3Cl segments to this HOF. Robust and recycled HOF‐25‐Re bearing photocatalytic Re(bpy)(CO)3Cl centers displays good heterogeneous catalytic activity towards carbon dioxide photoreduction in the presence of [Ru(bpy)3]Cl2 and triisopropanolamine in CH3CN under visible‐light irradiation, with both high CO production rate of 1448 μmol g−1 h−1 and high selectivity of 93 %. Under the same conditions, the experimental turnover number of HOF‐25‐Re (50) is about 8 times as that of the homogeneous control Re(bpy)(CO)3Cl. The sustainably regenerated HOF‐25‐Re via crystallization and post‐modification processes shows recovered photocatalytic performance.

Robust Biological Hydrogen-Bonded Organic Framework with Post-Functionalized Rhenium(I) Sites for Efficient Heterogeneous Visible-Light-Driven CO2 Reduction.

A robust 2,2'-bipyridine (bpy)-derived biological hydrogen-bonded framework (HOF-25) has been realized depending on guanine-quadruplex with the assistance of π-π interaction, which reacts with Re(CO)5 Cl to give a post-functionalized HOF-25-Re. X-ray absorption fine structure spectroscopic study on HOF-25-Re confirms the covalent attachment of Re(bpy)(CO)3 Cl segments to this HOF. Robust and recycled HOF-25-Re bearing photocatalytic Re(bpy)(CO)3 Cl centers displays good heterogeneous catalytic activity towards carbon dioxide photoreduction in the presence of [Ru(bpy)3 ]Cl2 and triisopropanolamine in CH3 CN under visible-light irradiation, with both high CO production rate of 1448 μmol g-1 h-1 and high selectivity of 93 %. Under the same conditions, the experimental turnover number of HOF-25-Re (50) is about 8 times as that of the homogeneous control Re(bpy)(CO)3 Cl. The sustainably regenerated HOF-25-Re via crystallization and post-modification processes shows recovered photocatalytic performance.

Effect of transition metal oxide cocatalyst on the photocatalytic activity of Ag loaded CaTiO3 for CO2 reduction with water and water splitting

Various dual cocatalysts consisting of Ag and transition metal oxide (TMOx) were loaded on a CaTiO3 (CTO) photocatalyst by different loading methods and examined for the photocatalytic CO2 reduction with water as an electron donor. Compared to the results provided with the single Ag cocatalyst, the dual cocatalyst loaded CTO photocatalyst exhibited a similar or less CO evolution rate and higher H2 production, meaning that these photocatalyst showed photocatalytic activity for both CO2 reduction and water splitting. Dual cocatalysts of Ag and TMOx loaded by a photodeposition gave higher CO production rate than those loaded by an impregnation method. The CTO photocatalysts with a single TMOx cocatalyst showed higher activities in both H2 evolution and O2 evolution test than the bare CTO and dual cocatalyst loaded CTO photocatalysts, indicating that the photocatalytic activity for water splitting is suppressed by the Ag cocatalyst but improved by the TMOx.

Water nanodomains for efficient photocatalytic CO2 reduction to CO

Here water nanodomains were applied to photocatalytic CO2 reduction under ambient conditions, which shows a high CO production rate with selectivity >99%.

135 Production of a fifty percent functional protein concentrate from the dry grind ethanol process and use of the product in diets for Atlantic salmon

Abstract The corn distilling industry is a major processor of grain, but the high fiber co-product (DDGS), has limited application in feed. Simple mechanical stillage separation downstream of fermentation produces a high protein (52.4 % DM), highly digestible, low crude fiber (4.4% DM) product containing approximately 25% DM spent brewer’s yeast (high density distillers’ protein: HDDP). Currently, approximately 300 ktons of HDDP are produced annually in the USA, and the volume will double in 2020. The effect of graded inclusion levels of HDDP on growth, feed efficiency, nutrient utilization, blood chemistry and gut histology of 525 post-smolt Atlantic salmon (initial body weight 304 ± 10.7g), randomly allocated to three tanks per treatment, was tested in a salt-water recirculating aquaculture system. One control diet with no HDDP was formulated to meet the nutrient requirements of Atlantic salmon. Four test diets were formulated to contain graded levels of HDDP at 5, 10, 15 and 20% respectively. HDDP partially replaced soy protein concentrate and corn protein concentrate in the diets. Salmon were hand-fed to satiety, 3 times daily during the 84-day trial. Throughout the trial the performance of fish on all treatments exceeded commercial growth rates with thermal growth coefficients (TGC) in excess of 0.160 and feed conversion efficiency of ≤ 1.0. Overall HDDP was a nutritious feed ingredient and had no significant impact on performance. Overall TGC was highest (0.200 over the 84-day trial period) in fish fed the diet containing 10% HDDP. Both villi length and villi width in the distal intestine of salmon fed diets containing HDDP tended to be higher than in the controls. Overall, HDDP derived from the dry grind ethanol process was a safe and nutritious novel feed ingredient for Atlantic salmon, and the potential beneficial effect on gut morphology merits investigation.

PSVI-4 Digestible and metabolizable energy content, and standardized ileal digestibility of amino acids in novel corn co-products for swine

Abstract The objective of this study was to determine and compare the digestible energy (DE) and metabolizable energy (ME) content, and standardized ileal digestibility (SID) of amino acids in novel corn co-products and dried distillers’ grains with solubles (DDGS) for swine. Seven corn co-products were evaluated including 2 conventional DDGS (DDGS-A and DDGS-B), 1 corn fiber and solubles (CFS), 2 high protein distillers’ grains (HPDG-A and HPDG-B), and 2 high yeast and protein co-products (HYP-A and HYP-B). In Exp.1, 32 barrows (BW = 24.2 ± 3.4 kg) were housed individually in metabolism crates and randomly allotted to a corn-soybean meal basal diet or 1 of 7 diets containing 30% of a co-product in a randomized two-period crossover design. Feces and urine were collected in 2 periods (7-d adaptation and 4-d collection). In Exp.2, 16 ileal-cannulated barrows (BW = 37.0 ± 3.8 kg) were assigned to 1 of 8 diets in a repeated 8 × 4 Youden square design. An N-free diet, and 7 test diets containing 1 of 7 corn co-products as the sole protein source were used. Diets were fed to pigs for four 7-d periods (5-d adaptation and 2-d ileal digesta collection). The HYP-A and HYP-B had the greatest (P < 0.05) DE (4,309 and 4,183 kcal/kg DM, respectively) and ME (4,118 and 3,972 kcal/kg DM, respectively), and HPDG-B had the lowest (P < 0.05) DE and ME (2,266 and 2,168 kcal/kg DM, respectively) among all corn co-products. The SID of Arg, His, Ile, Lys, Met, Thr, and Val were similar among DGS-B, HPDG-A, HYP-A, and HYP-B, while HPDG-B had the lowest (P < 0.05) SID coefficients for all AA and CP. The high ME and SID Lys, Met, Thr, and Trp content of HYP-A and HYP-B indicate greater feeding value for swine compared to other co-products evaluated.

PSVIII-1 Determination of in vitro DM, N and NDF digestibility and fermentability in novel corn co-products for swine

Abstract New process technologies are being implemented in the ethanol industry resulting in new high protein corn co-products (HPCP) containing more gross energy and amino acids than conventional distillers dried grains with solubles (DDGS). Thus, estimates of nutrient digestibility for HPCP are needed to assess potential feeding value for swine. Furthermore, yellow dent corn is the predominant grain source in U.S. ethanol and co-product production whereas flint corn is used in Brazil. This study determined and compared in vitro dry matter (DM), nitrogen (N), and neutral detergent fiber (NDF) digestibility and fermentability of U.S. and Brazil corn DDGS and new HPCP. In vitro methods evaluated DM, N, and NDF digestibility and fermentability of 2 corn DDGS samples from U.S. (POET and ICM), 2 DDGS samples from Brazil (BR1 and BR2), 1 corn fiber and solubles sample (CF+S), 3 high protein distillers grains (HP-DDG) samples (BR-HP, US-HP, US-HPG1.5), and 2 HP-DDG samples containing high yeast (Ultramax; UM) and StillPro (SP). Digestibility of DM from hydrolysis varied and was greatest for UM (87.13%; P < 0.001) compared with all other co-products. Fermentability of DM was greater (P < 0.001), and similar for UM (85.6%), SP (76.8%), and US-HP-DDG (72.8%) compared with other co-products. Digestibility of N was greater for UM (91.2%; P < 0.001) compared with all other co-products. NDF digestibility was greater (P < 0.001) for UM (62.5%) and SP (60.5%) compared with all other co-products. POET and ICM DDGS had greater (P < 0.001) DM hydrolysis (78.7% and 68.2%, respectively), than BR1 (37.2%) and BR2 (35.0%) and N digestibility (POET = 65.0%; ICM = 58.9%) compared with BR1 (54.4%) and BR2 (43.4%). These results suggest greater nutritional value for Ultramax and StillPro than conventional DDGS and HP-DDG sources (U.S. and Brazilian) due to greater DM, N, and NDF digestibility.

247 The effect of diet on the microbial community structure and composition in lactating Jersey cows consuming a mixture of straw and dry distillers grains plus solubles in replacement of alfalfa hay

Abstract The rumen microbial community is responsible for producing a majority of the energetic needs for the animal, yet our understanding of the rumen microbiome is in its infancy. To better understand the effect of corn-ethanol coproducts on rumen microbial communities, a replicated 4 × 4 Latin square design study utilizing 12 cows in three squares was conducted to evaluate the replacement of alfalfa hay with a mixture (CoP) containing straw and dried distillers grains plus solubles (DDGS) in lactating Jersey cows. The experimental treatments were (proportions on a dry matter basis): a control diet (CON) containing 18.2% of alfalfa hay with no straw or DDGS. A low coproduct diet (LCoP) containing 12.1% alfalfa, 2.1% straw, and 6.0% DDGS. A medium coproduct diet (MCoP) containing 6.1% alfalfa, 4.2% straw, and 12.1% DDGS. A high coproduct diet (HCoP) containing 6.2% straw, 18.1% DDGS with no alfalfa. Rumen digesta samples were collected via an esophageal tube. No differences were observed for milk production and dry matter intake (P ≥ 0.307) (mean ± SEM) 19.5 kg ± 0.60, 29.6 kg ± 0.91, across treatments, while a decrease in methane was observed (P < 0.01) for the HCoP treatment. The bacterial community was assessed by sequencing the V4 region of the 16S rRNA gene. Additionally, the archaeal community was assessed by sequencing the V4-V5 region of the 16S rRNA gene on the Illumina MiSeq platform. Amplicon Sequence Variants were identified using the DADA2 pipeline. No significant differences were observed for the bacterial (P = 0.334) and archaeal (P = 0.593) communities. Although global effects in microbial community dynamics were not observed, differential taxa were observed with Lachnospiraceae being the major differentially abundant Family. The archaeal community composition demonstrated that Methanobacteriales to be the differentially abundant Order across treatments, and may contribute to methane production.

Membrane-Based Zero Gap CO2 Electrolyzer with Au Cathode Prepared By Electrodeposition

Electrochemical CO2 conversion has been recognized as a promising technology that can overcome the global warming. Also, the production of useful fuels (e.g. CO, HCOOH, CH4, CH3OH and C2H4) is capable via electrochemical reduction of CO2. It was demonstrated that at least 200 mA cm–2 of partial current density should be required for commercial operation. However, in conventional aqueous system, the CO2 electroreduction was limited to 35 mA cm–2 of current density due to low CO2 solubility into the electrolyte. Furthermore, the diffusion length of CO2 from bulk to catalyst is much longer in H-type cell system causing prevent easy supply of CO2. To overcome these problems, a single cell based on a membrane electrode assembly (MEA) with zero gap between the electrodes was introduced to facilitate CO2 mass transfer to the catalyst surface.In this study, we investigate the MEA-based CO2 electrolyzer with anion exchange membrane. The electrodeposited Au on gas diffusion electrode (GDL), which exhibits the high CO production selectivity in CO2 electroreduction, was directly used as a cathode of CO2 electrolyzer. The humidified CO2 gas is supplied into cathode to promote the CO2 mass transfer to the catalysts-membrane interfaces. Furthermore, the content of polytetrafluoroethylene on GDL was controlled in order to prevent the product crossover between compartments that is feasible to exhibit stable performance. Compared to conventional H-type cell system, the 2-order magnitude improvement of partial current density was shown in MEA-based zero gap CO2 electrolyzer owing to low ohmic resistance and facile CO2 mass transfer.

Kinetics of Biotic and Abiotic CO Production during the Initial Phase of Biowaste Composting

Knowledge of kinetic parameters of CO production during biowaste composting is significantly important for the prediction of its course and estimation of total gas quantity. This allows increasing the control of the process, to minimize its negative impact on the environment and to protect the occupational safety of employees exposed to CO in the biowaste composting plant. For the first time, a full study of the influence of temperature and biowaste sterilization on the kinetics of CO production is presented. The lab-scale experiments used a mixture of green waste, dairy cattle manure, and sawdust in two variants: sterilized and non-sterilized samples. The process was carried out in controlled temperature reactors with measuring the concentrations of CO, O2, and CO2 every 12 h.CO production and k value increased with temperature. However, higher CO production was observed in biotic conditions between 10~50 °C, suggesting the biotic CO formation and 1st-order kinetics. The abiotic (thermochemical) process was more efficiently generating CO above 50 °C, described with a 0-order kinetic model. Additionally, the rate constant (k) value of CO production under biotic conditions was increasing up to a temperature of 60 °C, above which a slight decrease in CO production rate was observed at 70 °C. The presented results are the basis for further studies focused on the feasibility of (1) the mitigation and (2) valorization of CO production during the biowaste biostabilization are warranted.