Carbonization Process Research Articles

Estimating CO2 flows in urban parks: knowns and unknowns

The life cycle climate impacts of urban parks are poorly known. Whereas vegetation and soils can be carbon sinks, building products, energy use, and processes cause emissions. Several studies acknowledge the need for further assessment of urban parks, especially regarding vegetation, soil organic carbon, management and design, together with the development of supportive tools for climate-wise planning. To deepen our understanding of carbon flows of urban parks, we applied life cycle assessment (LCA) and studied the carbon dioxide (CO2) emissions and removals of five urban parks in Helsinki, Finland. The components of the parks were divided into four categories: site preparation, covering and surface structures, vegetation and growing media, and systems and installations. According to our findings, CO2 emissions ranged from 27.08 to 61.45 kgCO2e/m2 and CO2 removals from 11.35 to 16.23 kgCO2e/m2 with uncertainty. Planted woody vegetation and existing forested areas had the highest CO2 uptake among the vegetation types. Moreover, growing media caused on average 35% of total CO2 emissions. As significant volumes of growing media remain necessary to support the growth and establishment of plantings, finding less emission intensive alternatives to peat-based growing medium becomes essential. Other main emissions sources included transportation, and replacements of surface materials, but their dominance is highly dependent on the design, use and maintenance of the park. LCA offers a robust assessment framework for the quantification of greenhouse gas emissions and is evolving towards the including of greenhouse gas removals and storages. However, the inclusion of living organisms would require changes in the mindset of LCA. The level of maturity in the assessment methods differs significantly between the park components. Data and methods are especially lacking for nursery production, maintenance and end-of-life phases of vegetation, soils, and mulches. We also identified uncertainties regarding the estimations of CO2 uptake by woody vegetation, lawns, and meadows due to software limitations and lack of data for local context. Simulating dynamic plantings raises additional questions, together with the forecast of accurate meteorological conditions of a changing climate. This research highlights the need for more holistic life cycle assessment of urban parks to inform low-carbon landscape industries.

Diurnal temperature variation in surface soils: an underappreciated control on microbial processes

Large diurnal temperature changes (ΔT) (or the diurnal temperature range (DTR)) in surface soils, ranging from 5°C to often greater than 20°C, are generally acknowledged to occur yet largely disregarded in studies that seek to understand how temperature affects microbially-mediated carbon and nitrogen cycling processes. The soil DTR is globally significant at depths of 30 cm or less, occurring from spring through summer in temperate biomes, during summer periods in the arctic, and year-round in the tropics. Thus, although temperature has long been considered an important factor in controlling microbial processes, our understanding of its effects remains incomplete when considering natural soil temperature cycles. Here we show: (1) documented impacts of diurnal temperature changes on microbial respiration rates; (2) documented observations of surface soils with large DTR (>5°C) that affect soil microbial mineralization rates and redox potentials of important biogeochemical reactions; and (3) direct evidence that the constant temperature regime typically used in laboratory soil incubation studies may therefore lead to mischaracterization of in situ temperature controls on microbially influenced processes in the environment. The overall effect is that the DTR yields process rates that are often higher than what has been observed under experimental mean temperature incubation. We suggest that overlooked genetic mechanisms, such as the presence of a circadian clock or thermophilic activity during summer months, are likely contributing to the observed effects of the DTR. To improve our understanding of climate change effects on soil greenhouse gas emissions, nutrient cycling, and other biogeochemical soil processes, we propose a paradigm shift in approach to temperature-inclusive process modeling and laboratory incubation studies that accounts for the important role of natural diurnal temperature fluctuations.

Exploring the impact of CO2 sequestration on plastic properties, mechanical performance, and microstructure of concrete

In view of global warming, carbon sequestration techniques are being employed across the globe to minimize the damaging effects of greenhouse gases on the environment. Studies have revealed that adding CO2 during the mixing or curing stage of concrete enhances its mechanical properties and long-term durability. This study aims to examine the effect of CO2 addition during the mixing stage on the plastic, mechanical and microstructural properties of concrete. Various CO2 dosages, ranging from 0.1 to 1%, were injected during mixing to analyze the plastic and hardened properties of concrete. CO2 primarily reacts with calcium hydroxide in concrete to form calcium carbonate (CaCO3), thereby densifying its microstructure and improving its compressive strength by 10–20%. An optimum strength of up to 20% was achieved with 0.75% dosage. Additionally, the results show a 5–10% improvement in flexural and split tensile strength with CO2 addition over the control mix, with 0.75% dosage yielding optimal strength. Semi-adiabatic calorimetry test on early hydrating concrete shows a 14% peak temperature rise at 0.75% CO2 dosage compared to control concrete, indicating enhanced early-age strength development. Thermal Pyrolysis tests, microscopy and infrared spectroscopy indicated the presence of CaCO3, thereby confirming the carbonation process. However, CO2 dosages above 0.5% by weight of cement resulted in a drop in the workability of concrete in the plastic stage. This research attempts to create a simplified CO2 sequestration process in concrete, develop a predictive model to estimate the compressive strength and utilize material characterization techniques to identify the mineralization process.HighlightsInjecting CO2 into fresh concrete improves its strength and lowers its environmental impact.A multiple linear regression model predicts the compressive strength of CO2-injected concrete.Semi-adiabatic calorimetry shows that CO2 injection speeds up early hydration.Thermal Pyrolysis detects mass loss stages linked to dehydration and calcite breakdown.Microscopy and spectroscopy indicate CaCO3 crystal formation in CO2-sequestered concrete.

Revalorisation of Vine Pruning Waste Through the Production of Zero CO2 Emission Charcoal

This research studies the production of charcoal from a by-product of viticulture such as the vine pruning remains of vine (vine shoots). During this study, several carbonisation tests were carried out in an electric muffle furnace where vine shoot samples were tested at different temperature ranges (150–450 °C) and with test durations of 2 h and 3 h. From these tests, the mass yields and carbon yields were studied, as well as the characterisation of the chemical composition of the resulting charcoals, obtaining the maximum results of the fixed carbon content of up to 80.4%. Subsequently, the tests’ energy consumptions were also recorded in order to optimise the amount of grammes of carbon per kWh of energy used. The average value obtained in the trials was 18.55 g of carbon per kWh of energy used in the carbonisation process. Finally, special emphasis was placed on studying the sustainability of this charcoal through the net balance of CO2 eq emissions. To this end, the CO2 eq emissions associated with the energy consumption of the trials and how, through the use of this waste to produce 10–12 g of charcoal, the negative net emission values of up to −522.74 g of CO2 eq were achieved were evaluated. This demonstrates the possibility of charcoal production with a zero-carbon footprint. This acts as evidence of the possibility of zero carbon footprint charcoal production, a key innovative aspect that helps to achieve greater sustainability in industrial sectors with a high impact on the region.

Production of High Specific Surface Area Activated Carbon from Tangerine Peels and Utilization of Its By-Products

Biomass waste, generated globally in vast quantities, represents an underutilized yet highly valuable resource for advanced material production. This study highlights a novel valorization pathway for waste tangerine peels, sourced from Jeju Island, South Korea, by converting them into high-performance activated carbon (T-AC) with exceptional pore characteristics, specifically designed for volatile organic compound (VOC) removal. Utilizing a unique combination of hydrothermal carbonization (HTC) and dry carbonization (DC) processes, the structural properties of the biomass were optimized, significantly enhancing the fixed carbon content. Subsequent chemical activation with an alkaline agent yielded T-AC with an outstanding specific surface area (1530–3375 m2/g) and total pore volume (0.73–2.00 cm3/g), with a tailored pore distribution favoring the sub-mesopore range (2.0–4.0 nm). The T-AC demonstrated remarkable performance in removing methylene chloride (MC), a hazardous VOC, with methylene chloride activity (MA) increasing from 44.7% to 76.3% as the activation agent ratio increased, while methylene chloride working capacity (MWC) improved significantly from 17.1% to 55.9%. These results underscore the transformative potential of tangerine peel-derived AC as a sustainable solution for VOC remediation, combining environmental waste management with advanced adsorption technology. The findings not only advance the field of biomass utilization but also offer a scalable approach for tackling pressing environmental and industrial challenges.

Experimental formation of carbonates from perchlorate and sulphate brines: Implications for Jezero crater, Mars.

Extensive carbonate precipitation has occurred on Mars. To gain insight into the carbonation mechanisms and formation processes under ancient Martian aqueous conditions, we examine the precipitation of carbonates resulting from atmospheric carbon fixation, focusing on interactions between various brines and silicate and perchlorate solutions in alkaline environments. The micro-scale morphology and composition of the resulting precipitates are analysed using ESEM micrographs, EDX chemical compositional analysis, X-ray diffraction, and micro-Raman spectroscopy. Our findings indicate a significant atmospheric carbonation process involving chlorate and sulphate brines reacting with alkaline perchlorate solutions, leading to the precipitation of calcium carbonate polymorphs, including vaterite, aragonite, and calcite, as well as other carbonates like siderite (iron carbonate) and zaratite (nickel carbonate). Some precipitates exhibit biomorphic structures (such as globular spherical aggregates, fine branched tubes, and flower-like morphologies) that should not be mistaken for fossils. These experiments demonstrate that various precipitates can form simultaneously in a single reaction vessel while being exposed to different micro-scale pH conditions. We propose that systematic laboratory studies of such precipitate reactions should be conducted in preparation for the analysis of the Mars Sample Return collection on Earth, aiding in the interpretation of carbonate presence in natural brine-rock carbonation processes under Martian conditions while also helping to distinguish potential biosignatures from purely geochemical processes.

Lanthanum and cerium added to soil influence microbial carbon and nitrogen cycling genes

The soil microbiome plays an important role in carbon (C) and nitrogen (N) processing and storage and is influenced by rare earth elements (REEs), which can have both direct and indirect effects on plant metabolic processes. Using conventional physicochemical methods and metagenomic-based analyses, we investigated REEs effects on soil respiration, soil mineral N, soil microbial community structure and functional genes related to C and N metabolism. High doses of cerium (0.16 and 0.32 mmol kg−1 soil) increased CO2 net production rate by 59 and 42%, and N2O net production rate by 255 and 609%, respectively, compared to no REEs. Similarly, high doses of lanthanum (0.16 and 0.32 mmol kg−1 soil) increased CO2 net production rate by 47 and 39%, and N2O net production rate by 105 and 187%, respectively. Increased soil respiration from altered relative abundances of key soil microorganisms associated with soil N cycling and organic matter degradation and functional genes encoding enzymes involved in C and N metabolism, accelerated N mineralization. Elevated REEs levels substantially increased the relative abundances of functional genes related to cellulose, chitin, glucans, hemicellulose, lignin, and peptidoglycan degradation. REEs also influenced multiple functional genes associated with the N cycle. The abundance of genes responsible for organic N degradation and synthesis, such as asnB, gdh_K15371, glsA, and gs, increased with elevated cerium and lanthanum concentrations. Similarly, the abundances of denitrification genes, including narl, narJ, narZ, and nosZ, also rose with increasing amounts of cerium and lanthanum. However, the decrease in narB and nirB gene abundance with increasing REE concentrations was attributed to the reduction of nitrate to amino groups. Our findings highlight the influence of REEs on key soil microorganisms associated with soil N cycling and organic matter degradation and key functional genes in soil C and N metabolism, with implications for agriculture, environmental protection, and human health.

Ambient Pressure Carbonation Curing of Cold-bonded Fly Ash Lightweight Aggregate Using Coal-fired Flue Gas for Properties Enhancement and CO2 Sequestration

In the current CO2 curing process, pure CO2 gas with a concentration exceeding 99% is primarily used. However, flue gas, which typically contains 10-30% CO2, can also be utilized for carbonization. This study sought to explore the viability of employing flue gas for carbonation and assessed the impact of impurity gases such as SO2. Two typical industrial solid wastes (fly ash and coal gangue) were used to substitute a portion of the cement to prepare light aggregates, which were carbonized under varying concentrations of CO2 and SO2. The porosity and water absorption of the samples decreased after carbonation. A higher degree of carbonation was observed at increasing CO2 concentration. Aggregates carbonated with 15% CO2 improved the CO2 absorption by 48%. The actual CO2 uptake reached up to 58.3% of the theoretical value. The presence of SO2 has been found to impact the uptake of CO2. The CO2 uptake initially declined and then increased as the SO2 concentration increased. The existence of SO2 led to varied increases in the leaching concentrations of the aggregates following the process of carbonation, and some even exceed standard limits. In the presence of both CO2 and SO2, SO2 reacted with the aggregates, resulting in the creation of calcium sulfate. This reaction disrupted the structure of the aggregate, facilitating the diffusion of CO2 into the samples.

Hydrodynamic and reaction kinetic responses of CaO/CaCO3 carbonation in bubbling fluidized bed reactors for thermochemical energy storage: Influence of CO2 mole fraction, grain size, and reactor dimensions

The CaO/CaCO3 thermochemical energy storage system offers a promising method for the efficient utilization of solar energy. However, the reactor design remains underdeveloped. In this study, the Eulerian-Eulerian two-fluid model is employed to systematically investigate the effects of CO2 mole fraction, particle size, and reactor dimensions on the carbonation process in a bubbling fluidized bed reactor. Increasing the CO2 mole fraction from 50 % to 80 % reduces the duration of the chemical-reaction-kinetics controlled stage from 118.5 s to 65.3 s, and the transition stage from 64.6 s to 36.7 s, with minimal impact on the final conversion rate. High CO2 concentrations cause insufficient bed fluidization and uneven local conversion rate distribution within the bed. As the grain size increases from 150 nm to 300 nm and 600 nm, the duration of the chemical-reaction-kinetics controlled stage decreases from 118.5 s to 104.0 s and 76.2 s, respectively. This causes the reaction to enter the transition phase earlier, ultimately leading to a reduction in the maximum conversion rate. Altering the height and width of the reactor does not significantly impact the conversion processes within the reactor. These findings provide valuable insights for the optimization and practical industrial application of efficient reactors.

Enhancing the water resistance properties of bamboo particleboard by reconstructing lignocellulose through carbonization treatment

Bamboo particleboards are recognized as a highly promising alternative to traditional wood particleboards owing to their short growth cycle, abundant availability, and exceptional mechanical properties. However, bamboo particleboards frequently exhibit undesirable hygroscopicity, which limits their broader applications. This study introduces a straightforward and inhibitor-free carbonization treatment method to enhance the water resistance properties of bamboo particleboards. During the carbonization process, the degradation of hemicelluloses and amorphous cellulose, combined with the condensation reactions among lignin molecules, leads to a significant reduction in the hydrophilic hydroxyl and carbonyl group content, resulting in a more compact micro-fibril structure. Concurrently, the degradation of specific macromolecules within the cell wall facilitates the crushing of bamboo during particleboard pressing, thereby reducing the macroscopic pore size between the particles in the board. When compared to the original bamboo particleboard, the moisture absorption, 24-h water absorption (at a relative humidity of 50 %), 24-h thickness swelling, and bound water content of the deep carbon bamboo particleboard decreased by 32.28 %, 81.57 %, 67.16 %, and 66.7 %, respectively, while the water contact angle increased by 88.89 %.

Ni2P/Cu3P bimetallic phosphide embedded in nitrogen-doped carbon as SIB anode: Constructed hetero interface promoting fast Na+ diffusion and storage performance

Transition metal phosphides (TMPs) have attracted widespread attention as electrode materials for sodium-ion batteries (SIBs) due to their high theoretical specific capacity, various bonding types, metallic characteristics, and low cost. However their sluggish reaction kinetics and inferior capacity decay severely hamper their application. Designing TMPs with novel nano/microstructures effectively overcomes these challenges. Herein, Nickel Phosphide/Copper Phosphide embedded in nitrogen-doped carbon (Ni2P/Cu3P@NC) was synthesized by carbonization and phosphidation process. When used as an SIB anode, Ni2P/Cu3P@NC exhibited a reversible specific capacity of 530 mAh/g after 200 cycles at 0.2 A/g, 428 mAh/g after 1000 cycles at 1.0 A/g, and good rate capability (334 mAh/g at 2.0 A/g). Ex-situ XRD combined with in-situ EIS confirm the irreversible conversion mechanism. Density Functional Theory (DFT) calculations show that the heterointerface formed between Ni2P and Cu3P serves as a channel for fast ion delivery and promotes Na+ storage performance. Furthermore, the practical application was further investigated by assembling Ni2P/Cu3P@NC//Na3V2(PO4)3 full cells.

BioRT-HBV 1.0: A Biogeochemical Reactive Transport Model at the Watershed Scale.

Reactive Transport Models (RTMs) are essential tools for understanding and predicting intertwined ecohydrological and biogeochemical processes on land and in rivers. While traditional RTMs have focused primarily on subsurface processes, recent watershed-scale RTMs have integrated ecohydrological and biogeochemical interactions between surface and subsurface. These emergent, watershed-scale RTMs are often spatially explicit and require extensive data, computational power, and computational expertise. There is however a pressing need to create parsimonious models that require minimal data and are accessible to scientists with limited computational background. To that end, we have developed BioRT-HBV 1.0, a watershed-scale, hydro-biogeochemical RTM that builds upon the widely used, bucket-type HBV model known for its simplicity and minimal data requirements. BioRT-HBV uses the conceptual structure and hydrology output of HBV to simulate processes including advective solute transport and biogeochemical reactions that depend on reaction thermodynamics and kinetics. These reactions include, for example, chemical weathering, soil respiration, and nutrient transformation. The model uses time series of weather (air temperature, precipitation, and potential evapotranspiration) and initial biogeochemical conditions of subsurface water, soils, and rocks as input, and output times series of reaction rates and solute concentrations in subsurface waters and rivers. This paper presents the model structure and governing equations and demonstrates its utility with examples simulating carbon and nitrogen processes in a headwater catchment. As shown in the examples, BioRT-HBV can be used to illuminate the dynamics of biogeochemical reactions in the invisible, arduous-to-measure subsurface, and their influence on the observed stream or river chemistry and solute export. With its parsimonious structure and easy-to-use graphical user interface, BioRT-HBV can be a useful research tool for users without in-depth computational training. It can additionally serve as an educational tool that promotes pollination of ideas across disciplines and foster a diverse, equal, and inclusive user community.

Deactivated Ca-based sorbent derived from calcium looping CO2 capture as a partial substitute for cement to obtain low-carbon cementitious building materials

Calcium looping CO2 capture is a highly promising technology for carbon capture, utilization, and storage. Nevertheless, the disposal of deactivated calcium-based sorbents following cyclic carbonation and calcination processes presents an unresolved challenge. Concurrently, the development of low-carbon cement products is also a critical priority. Given the calcium-rich composition and carbon-negative nature of the calcium-based sorbent, it is proposed that the deactivated sorbent could be utilized as a partial substitute for cement in the production of building materials. This paper explored the potential of using two types of deactivated calcium sorbent (DPC/DGC) to partial substitute cement for low-carbon cementitious materials production. The effects of partial substitution of cement materials on volume stability, compressive/flexural strength, hydration kinetics, and carbon emission of the composite cementitious materials were investigated. The results indicate that a 5% and 10% replacement of cement with DPC/DGC has modest impact on volumetric stability and compressive strength. The composite cement with 5% DPC replacement achieves a 28-day compressive strength of 48.1MPa, representing a 0.4% increase compared to the 47.9MPa observed in the reference sample. Specimens with 15% DPC/DGC substitution exhibit inferior volume stability and mechanical performance than the control sample. The total hydration heat releases decrease with the increasing substitution ratio due to the dilution effect by the introduction of DPC/DGC. Additionally, substituting cement with Ca-based sorbents significantly reduced the carbon footprint of construction materials. The net carbon footprints for the building materials that containing 1 ton of binder (substitued with 10wt% DPC and DGC) were 152.5kg and 43.5kg, corresponding to reductions of 79.6% and 94.2% compared to reference cement mortar. These carbon footprints are projected to further decrease to -108.5kg and -375.5kg when DPC and DGC were obtained after 100 CO2 capture cycles. A novel technological route combining the high-temperature calcium looping CO2 capture and CO2 mineralization curing was proposed, and the associated challenges of this method were also discussed.

The effect of corn cob, cotton shell and rice straw mixture during carbonization on charcoal yield using mixture design

This study investigated the carbonization of mixture of agricultural by-products (corn cob, cotton shell and rice straw) from Tchad in view to produce charcoal as alternative environmentally friendly source of energy. The structural analysis of the selected biomasses was assessed. The best mixture was identified by the mean of mixture design methodology. The structural analysis (cellulose, hemicellulose and protein) was different from one biomass to another, predicting the possibility to increase charcoal yield by suitable mixture design before carbonization. The result also revealed that taking individually, charcoal yields were 43.56%, 37.20% and 30.07% respectively for rice straw, cotton shell and corn cob. For the optimised mixture of biomasses, the validation conditions presented an adjusted R2 of 98%, a mean absolute deviation (AAD) of 3%, a bias factor of 1.00 and an accuracy factor of 1.04, within the interval to validate. The high charcoal yield was 49.70% and was obtained for the mixture made from19.0 wt.% of corn cob, 68.7 wt.% of rice straw and 12.3 wt.% of cotton shell. This result shows that the mixture of rice straw, cotton shell and corn cob increased the charcoal yield by approximately 6.14%. This percentage is however lower than the 10% increase often observed for hydrothermal carbonization, possibly due to carbonization conditions. Therefore, the mixture of corn cob, cotton shell and rice straw before carbonization process provide a sustainable pathway for the conversion of biomass into solid products with improved charcoal yield compared to those produced by carbonizing the feedstocks separately.

Oxidation anchoring strategy for the retention of nanostructures in high temperature carbonization process to enhance hard carbon sodium storage performance

Oxidation anchoring strategy for the retention of nanostructures in high temperature carbonization process to enhance hard carbon sodium storage performance

Preparation of nitrogen-doped lignin porous carbon using low dosage KHCO3 for efficient methylene blue adsorption: Activation mechanism and adsorption performance

The previous requirement for activation of porous carbon adsorbents commonly exceeded several times the mass of the carbon precursor. Therefore, it was crucial to develop cost-effective and efficient carbon adsorbent materials for long-term environmental remediation. In this study, biorefinery lignin was utilized to fabricate porous carbon with an ultrahigh specific surface area (3423 m2 g−1) and pore volume (1.52 cm3 g−1) by employing melamine as the nitrogen source and a low dosage of KHCO3 as the activator. Multiple activations during the carbonization process contributed to the exceptional characteristics of the porous carbon, including well-developed pore structure, high specific surface area, and reasonable nitrogen doping. The porous carbon demonstrated remarkable adsorption capabilities with a maximum methylene blue (MB) adsorption capacity of 1457 mg g−1. Structural characterization conducted before and after adsorption revealed that electrostatic interactions, pore filling, hydrogen bonding, and π-π stacking were among the main mechanisms employed by lignin porous carbon for effective MB adsorption. The proposed method is a simple, green, highly efficient, and environmentally friendly approach that can be applied to treat lignin from various industrial sources. It provides valuable insights into the development of advanced carbon materials suitable for adsorption and capacitor applications.

Comparison of the Quaternary Treatment Technologies in Municipal Wastewater Purification

The removal of micropollutants during wastewater treatment is an essential element of pollution control due to the last amendment of the Directive 91/271/EEC. Reducing and control at the source is usually the most cost-effective measure for a given substance or group of substances, but wastewater treatment plants with load above 150.000 PE (and between 10.000 and 150.000 PE based on the recieving watercourse or environmental risk assessment) have to reduce and remove the micropollutant in the future. The treatment plants have to install technologies which are optimal to eliminate the micropollutant (fourth stage or quaternary treatment technologies). The main quaternary treatment technologies are the different form of activated carbon filtration, membrane technologies (e.g. nanofiltration or reverse osmosis) and Advanced Oxidation Processes, AOP (e.g. ozone treatment). Among the options available for the removal of micropollutants, the most cost-effective solutions are activated carbon processes, ozone treatment, and their combination in different process configurations. At present, the combination of ozone treatment and activated carbon filtration is an effective technology to degrade the micropollutants, also the antibiotic resistant genes, and also remove the harmful by-products from the AOP treatment. For each wastewater treatment plant, it is necessary to individually examine which technology will be the most optimal to accomplish the new requirements.

Enhanced photo-thermal conversion in phase change materials by Cu-Zn Bi-metallic metal-organic framework and expanded graphite

Photothermal phase change materials (PCM) are employed for the efficient conversion and storage of solar energy. In this work, a Cu-Zn bi-metallic metal-organic framework (MOF) was synthesized and combined with expanded graphite (EG), followed by high-temperature carbonization to prepare the supporting material for polyethylene glycol (PEG). Through the high-temperature carbonization process, nano-metallic copper is uniformly dispersed on the surface of the EG, accompanied by the formation of a new porous structure resulting from the evaporation of Zn vapour. The nano metallic copper particles enhance the thermal conductivity and photo-thermal conversion efficiency of the composite PCM, while the porous structure generated by Zn vapour improves the adsorption capacity of PEG. The composite PCM demonstrated a high phase change enthalpy of 174.6 J/g and excellent thermal reliability, with only a 2.29 % reduction in enthalpy after 200 melting-freezing cycles. Additionally, the thermal conductivity of the composite PCM reached 6.096 W/(m·K) which is 26.1 times higher than that of pure PEG, while the photo-thermal conversion efficiency achieved was 88.69 %. These properties indicate that the PEG/EG/Cu-Zn-MOF derived carbon composite PCM has great potential for applications in solar energy storage and conversion.

Comprehensive Comparative Review of the Cement Experimental Testing Under CO2 Conditions

Global warming is presently one of the most pressing issues the planet faces, with the emission of greenhouse gasses being a primary concern. Among these gasses, CO2 is the most detrimental because, among all the greenhouse gasses resulting from anthropogenic sources, CO2 currently contributes the largest share to global warming. Therefore, to reduce the adverse effects of climate change, many countries have signed the Paris Agreement, according to which net zero emissions of CO2 will be achieved by 2050. In this respect, Carbon Capture and Sequestration (CCS) is a critical technology that will play a vital role in achieving the net zero goal. It allows CO2 from emission sources to be injected into suitable subsurface geological formations, aiming to confine CO2 underground for hundreds of years. Therefore, the confinement of CO2 is crucial, and the success of CCS projects depends on it. One of the main components on which the confinement of the CO2 relies is the integrity of the cement. As it acts as the barrier that restricts the movement of the sequestrated CO2 to the surface. However, in a CO2-rich environment, cement reacts with CO2, leading to the deterioration of its physical, chemical, transfer, morphological, and mechanical properties. This degradation can create flow paths that enable the leakage of sequestered CO2 to the surface, posing risks to humans, animals, and the environment. To address this issue, numerous studies have investigated the use of various additives in cement to reduce carbonation, thus enhancing the cement’s resistance to supercritical (sc) CO2 and maintaining its integrity. This paper provides a comprehensive review of current research on cement carbonation tests conducted by different authors. It includes detailed descriptions of the additives used, testing setups, curing conditions, methodologies employed, and experimental outcomes. This study will help to provide a better understanding of the carbonation process of the cement sample exposed to a CO2-rich environment, along with the pros and cons of the additives used in the cement. A significant challenge identified in this research is the lack of a standardized procedure for conducting carbonation tests, as each study reviewed employed a unique methodology, making direct comparisons difficult. Nonetheless, the paper provides an overview of the most commonly used temperatures, pressures, curing durations, and carbonation periods in the studies reviewed.

Controllable Microwave Heating for Energy-Efficient and Universal Synthesis of Atomically Dispersed Metals on Nitrogen-Doped Carbon Nanofibers.

Carbon-supported single-atom catalysts (SACs) have shown great potential in electrocatalysis, whereas traditional synthesis methods typically involve energy-intensive carbonization processes and unfavorable atomic migration and aggregation. Herein, an energy-efficient and universal strategy is developed to rapidly fabricate various SACs on nitrogen-doped hierarchically porous carbon nanofibers (M-TM/NPCNFs, TM = Fe, Co, Ni, FeCo, and FeNi) by electrospinning and controllable microwave heating technique. Such microwave heating technique enables an ultrafast heating rate (ramping to 900°C in 5 min) to greatly suppress the random migration and aggregation of metal species. Meanwhile, the energy consumption and time can be reduced to 2.5% and less than half an hour, respectively, compared to traditional pyrolysis methods. As a proof of concept, the synthesized M-Fe/NPCNFs with abundant Fe-N4 sites exhibit remarkable oxygen reduction reaction (ORR) activity with a high half-wave potential (E1/2 = 0.88 V) in alkaline media, excellent performance in Zn-air battery with a large discharge specific capacity (801 mAh g-1) and long-term cycle durability (over 1000 h), demonstrating the great potential of the microwave heating technique in efficient fabrication of SACs for energy related applications.