Institutional Repository of GuangZhou Institute of Energy Conversion, CAS
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Micro-structure change and crystal-structure modulated of oxygen carriers for chemical looping: Controlling local chemical environment of lattice oxygen
No full textChemical looping conversion shows great potential in the renewable energy sector. The successful execution of chemical looping conversions relies heavily on oxygen carrier, which is also referred to as the redox catalyst or metal oxide materials. The oxygen carrier supplies the necessary quantity of oxygen ions (specifically lattice oxygen) for the conversion of fuels during the process of reduction. The oxygen-deficient oxygen carrier is refilled with molecular oxygen from air in an oxidizer. The redox-driven ionic diffusion and the formation of surface oxygen vacancies leads to a modification in the microstructure and crystal-Structure of oxygen carrier particles, resulting in the development of a new local chemical environment and the creation of oxygen vacancies. These are considered as active sites in chemical looping. Significant research has been conducted in recent years to enhance the performance of oxygen carrier through the modulation of their component design, structural construction, and modification for different chemical looping conversions. Nevertheless, the oxygen carriers' micro-structure and crystal-structure has been given inadequate focus, encompassing aspects such as lattice deformation, site asymmetry, strength of Me-O bonds, and tilting of the crystal lattice, among others. The focus of this review is on the progress made in controlling the diffusion of ions, phase segregation, and manipulating the local chemical environment of O in oxygen carrier. These advancements will aid in the investigation of oxygen carrier for effective chemical looping conversion
Biochar and modified magnetic biochar enhanced anaerobic digestion of swine wastewater under ammonia stress: Performance and microbial dynamics
No full textThis study aimed to investigate the effectiveness and mechanism of biochar and modified magnetic biochar addition in improving the anaerobic digestion (AD) efficiency of swine wastewater under ammonia stress. Two batches of serial experiments were carried out with ammonia levels of 3000, 4500, and 6000 mg/L. The results indicated that a one-time addition of 15 g/L of both types of carbon materials could sustainably optimize the AD performance of swine wastewater at ammonia nitrogen levels of 3000 and 4500 mg/L. In the second batch of experiments, at 4500 mg/L ammonia, groups with C and FeC additions showed 6.5%, 16.2% higher cumulative methane yield and 45.5%, 60.0% greater maximum gas production rates than controls. However, under the ammonia stress condition of 6000 mg/L, the reactor exhibited a mismatch between the carbon material addition and the degree of stress. The maximum methane production rate was intensified only in the first batch, which was 71.8% and 105.1% higher in the C and FeC groups, respectively, than in the control group. The microbiological analysis revealed that biochar optimized the AD performance by enriching the abundance of fermentative bacteria and enhancing the activity of Methanosaeta. In contrast, modified magnetic biochar promoted the enrichment of acetogens and shifted the dominant methanogens from sensitive Methanosaeta to the highly ammonia-tolerant Methanosarcina, thus causing the optimization of AD performance. The findings of this study provided new insights into the mitigation of inhibition and enhancement of efficacy in the anaerobic digestion of swine wastewater
Cellulose-based carbon nanotubes array with lawn-like 3D architecture for oxygen reduction reaction
No full textThe conversion of biomass into high-performance carbon -based materials provides an opportunity to valorize biomass for advanced applications. Achieving this necessitates requires dedicated efforts and innovations in biocarbon synthesis, design, and applications. This study proposes the controllable conversion of biomassderived cellulose into well -distributed carbon nanotubes (CNTs) by tuning the precipitation of cellulose pyrolysis generated vapors with in -situ formed ferric metal nanoparticles. The obtained CNTs exhibited lawn -like 3D architecture with similar length, uniform alignment, and dense distribution. The combined use of ferric chloride and dicyandiamide as the reagents with a mass ration of 0.162:1.05, demonstrated optimal performance in controlling the morphology of CNTs, enhancing the graphitization, and increasing the content of graphitic -N and pyridine -N. This multi -dimensional modification enhanced the electrocatalytic performance of the obtained CNTs, achieving an onset potential of 0.875 V vs. relative hydrogen electrode (RHE), a half -wave potential of 0.703 V vs. RHE, and a current density of -4.95 mA cm -2 during the oxygen reduction reaction. Following microbial fuel cells (MFCs) tests achieved an output voltage of 0.537 V and an output power density of 412.85 mW m- 2, comparable to MFC with Pt/C as the cathode catalyst. This biomass -derived catalyst is recommended as a high -quality, non -noble metal alternative to traditional noble -metal catalysts
Reconstruction of Long-Chain Polyunsaturated Acid Synthesis Pathways in Marine Red Microalga <i>Porphyridium cruentum</i> Using Lipidomics and Transcriptomics
No full textThe marine red microalga Porphyridium can simultaneously synthesize long-chain polyunsaturated fatty acids, including eicosapentaenoic acid (C20:5, EPA) and arachidonic acid (C20:4, ARA). However, the distribution and synthesis pathways of EPA and ARA in Porphyridium are not clearly understood. In this study, Porphyridium cruentum CCALA 415 was cultured in nitrogen-replete and nitrogen-limited conditions. Fatty acid content determination, transcriptomic, and lipidomic analyses were used to investigate the synthesis of ARA and EPA. The results show that membrane lipids were the main components of lipids, while storage lipids were present in a small proportion in CCALA 415. Nitrogen limitation enhanced the synthesis of storage lipids and omega 6 fatty acids while inhibiting the synthesis of membrane lipids and omega 3 fatty acids. A total of 217 glycerolipid molecular species were identified, and the most abundant species included monogalactosyldiglyceride (C16:0/C20:5) (MGDG) and phosphatidylcholine (C16:0/C20:4) (PC). ARA was mainly distributed in PC, and EPA was mainly distributed in MGDG. Among all the fatty acid desaturases (FADs), the expressions of Delta 5FAD, Delta 6FAD, Delta 9FAD, and Delta 12FAD were up-regulated, whereas those of Delta 15FAD and Delta 17FAD were down-regulated. Based on these results, only a small proportion of EPA was synthesized through the omega 3 pathway, while the majority of EPA was synthesized through the omega 6 pathway. ARA synthesized in the ER was likely shuttled into the chloroplast by DAG and was converted into EPA by Delta 17FAD
Adsorption experiments and mechanisms of methylene blue on activated carbon from garden waste via deep eutectic solvents coupling KOH activation
No full textCarbon-based adsorbents derived from biomass waste are validly capable of adsorbing and purifying dye wastewater. Herein, a novel adsorbent (p-DES-GHC(KOH)) from garden waste was developed by a two-stage coupling strategy of deep eutectic solvents (DES) modification and KOH activation for methylene blue (MB) adsorption. The properties and adsorption behaviors of p-DES-GHC(KOH) were investigated, and the adsorption mechanisms were thus proposed based on experiments and density functional theory (DFT) calculations. The results indicated that p-DES-GHC(KOH) exhibited superior pore structures with a surface area of 883.95 m(2)/g and substantial oxygenated functional groups. The maximum absorption capacity of MB was 351.72 mg/g at 25 degrees C, with isotherms and kinetics fitting well to the Freundlich model along with the pseudo-second-order kinetic model, respectively. The Elovich fitting results indicated that the adsorption process of MB on the p-DES-GHC(KOH) surface was not mainly dominated by chemisorption, but also regulated by other adsorption processes. The endothermic and spontaneous absorption processes with the stochasticity of MB molecules on the p-DES-GHC(KOH) surface were verified by thermodynamic analysis. DFT calculations revealed that the introduction of hydroxyl and carbonyl groups reduced the adsorption energy and reinforced the adsorption capacity of p-DES-GHC(KOH) for MB through synergistic effects. The adsorption of MB on p-DES-GHC(KOH) might be affected by pore filling, pi-pi interaction, and electrostatic attraction. The potential of p-DES-GHC(KOH) as a promising adsorbent for MB removal from wastewater was confirmed in this study
Utilization of short-term high temperature pretreatment for food waste composting: Effects of end-products on soil properties and plant growth
No full textShort-term high-temperature pretreatment helps accelerate the composting process and improve compost product quality. The aim of this research was to clarify the role of high-temperature pretreatment compost (PHC) on soil and plant growth. We conducted an experiment in which PHC, traditional compost (PTC), and high-temperature pretreatment food waste (PFW) were used as organic amendments (OA). Each type of compost was mixed into purple soil at mass ratios of 3, 5, 10, and 20% to establish a soil-compost mixture; they were then used in pot experiments with Lolium perenne L. Plant growth-promoting effects were stronger in the three experimental groups with 10% OA than in groups with other mixing ratios (p < 0.05). Plant growth-promoting effects were strongest in the experimental group with 10% PHC, and Lolium perenne L. biomass, the chlorophyll content, and plant height were 1.1-1.3 times higher in this group than in the PTC and PFW groups. Soil physicochemical analyses revealed that OA at various mixing ratios could enhance soil nutrient levels, the humification degree, and enzyme activity, and the strength of the positive effects increased with the mixing ratio. The most pronounced soil amendment effects were observed in the PHC group at all mixing ratios (p < 0.05). Microbial analysis revealed that both the microbial diversity and relative abundances of unclassified_f_Rhizobiaceae and Terrimonas were significantly higher in the 10% PHC group than in the 10% PTC and PFW groups (p < 0.01). Correlation analyses indicated that urease, peroxidase, and sucrase activities were positively correlated with plant growth indexes. The correlation coefficients of unclassified_f_Rhizobiaceae with urease and Terrimonas with peroxidase and sucrase were 0.997, 0.878, and 0.863, respectively. PHC can promote plant growth by altering the dominant microbial communities and enzyme activity in the soil. This study provides a theoretical basis for the application of high-temperature pretreated compost products
Blow-Off Limits, Flame Structure, and Emission Characteristics of Lean Partially Premixed Swirl-Stabilized Flames with NH<sub>3</sub>/CH<sub>4</sub>
No full textRecently, ammonia/methane mixtures have been considered as potential alternative fuels. The present study experimentally investigates the blow-off limits, flame structure, and pollutant emission of ammonia/methane mixtures in a partially premixed swirl-stabilized burner. The effects of fuel composition and the equivalence ratio are also studied. The results show that the NH3/CH4 flame can be stabilized at an equivalence ratio of 0.55. The addition of methane has a positive effect on the blow-off limits. For the chemiluminescence profile, the OH* distribution and CH* distribution of NH3/CH4 flames show a similar tendency under various conditions. The peak OH* and CH* radiances monotonically decrease with increasing ENH3, while the maximum NH2* shows an opposite trend. The influence of the equivalence ratio on OH* and CH* in the NH3/CH4 flames is negligible. However, when ENH3 is 60%, the equivalence ratio has a significant effect on NH2*. In terms of pollutant emissions, the peaks of NO and NO2 emissions are all found around an ENH3 of 20%. When the equivalence ratio reaches 1.0, NO and NO2 emissions are as low as 15 and 10 mg/m3, respectively. At the same time, both CO and unburned NH3 emissions increase. Therefore, further studies on the application of secondary air or improvement of the fuel injection method to improve the combustion efficiency and reduce the pollutant emissions for ammonia combustion are still needed
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