Evolution Of Gaseous Products Research Articles

Development of a pyrolysis reaction model for epoxy based flame retardant composites: Relationship between pyrolysis behavior and material composition

This paper presents a methodology to develop a pyrolysis reaction model that captures the flammability behavior of epoxy-based intumescent flame retardant coatings (EP/IFR) as a function of material composition. This approach adopted Thermogravimetric Analysis (TGA), Differential Scanning Calorimetry (DSC), and Microscale Combustion Calorimetry (MCC) experiments as well as the inverse modeling of the experimental results using ThermaKin2Ds and COMSOL Multiphysics modeling framework. The interactive reactions between EP and IFR were identified and quantified in the resulting lumped model, which is based on fitting of experimental data. It was found that the developed model was able to reproduce the TGA/DSC/MCC data within the prescribed criteria for EP/IFR blends with different material compositions. The model’s extrapolating capability was further validated through accurately predicting the experimental TGA data under different thermal conditions and for blends with different IFR ratios which were not used for model development. Additional TG-FTIR and XPS experiments were conducted to quantify the effect of IFR additive on the evolution of gaseous products and char formation. With a higher ratio of IFR, the amount of fuel dilution gases (i.e., CO2, NH3) was increased and the amount of combustible organic gaseous products was reduced. This work provides the core subset parameters for comprehensive pyrolysis modeling and enables the intelligent design of EP/IFR coatings with enhanced flame resistance.

Synergistic effects of mechanochemical activation and selective O-alkylation on the chemical structure and gaseous products evolution during coal flash pyrolysis

Mechanochemical activation offers significant advantages in enhancing the pore structure and active sites of materials, while selective O-alkylation boosts both the homogeneous and heterogeneous reactivity of coal. In this work, mechanochemical activation and selective O-alkylation are synergistically applied to modify pulverized coal. The evolution of the chemical structure was thoroughly characterized using ultimate analysis, Fourier-transform infrared spectroscopy (FTIR), and nuclear magnetic resonance (NMR). Pyrolysis gas chromatography-mass spectrometry (PY-GC-MS) was utilized to investigate the release of crucial gaseous products during the pyrolysis. Additionally, this study focuses on the synergistic effects of mechanochemistry and selective O-alkylation on the chemical structure and pyrolysis characteristics. The results reveal that alkylation boosts the formation of C-O bonds and aliphatic carbon while reducing the presence of aromatic carbon. Moreover, by disrupting intermolecular forces, alkylation induces the fragmentation of expansive aromatic layers into smaller aromatic fragments, thereby generating additional structural defects. Furthermore, the electron transfer process facilitates the conversion of aromatic carbon into aliphatic forms through ring-opening reactions. On the other hand, incorporating alkyl functional groups and initiating ring-opening reactions of aromatic carbons lead to a rise in aliphatic hydrocarbons during the pyrolysis of alkylated coal. However, intensified mechanochemical action hinders the production of aliphatic hydrocarbons. Additionally, during alkylation, the creation of esters and ethers with elevated thermal stability delays the release of oxygen-containing gas products. The findings propose a new pretreatment method for coal utilization, promoting the development of new low-NOx combustion technology.

How microplastics affect sludge pyrolysis behavior: Thermogravimetry-mass spectrum analysis and biochar characteristics

The concentration of microplastics (MPs) in sewage sludge (SS) ranged from 1600 to 56400 particles per kilogram of dried SS (MPs: dried SS = 0.14–5.09), so its effect on SS pyrolysis performance should not be negligible. This study attempted to investigate the effect of typical MPs, including polypropylene (PP), polyethylene (PE), and polyvinyl chloride (PVC), on the pyrolysis performance (pyrolysis characteristics and major gaseous product evolution) of SS and their biochar characteristics via thermogravimetry-mass spectrometry (TG-MS) and physicochemical property analysis of biochar. The results showed that the PVC MPs enhanced the pyrolysis of SS, while the PP and PE MPs had an inhibitory effect. The total amounts of gas products tended to decrease with all MPs addition. However, the proportions of combustible components (H2, CH4, and C2H2) increased. Among the biochar products, the presence of PVC MPs during the pyrolysis of SS resulted in a more porous, stable and aromatic biochar.

Exothermic processes in nitric acid solutions imitating highly active raffinate

The thermal stability of nitric acid solutions after contact with non-irradiated and irradiated tributyl phosphate (TBP) and its solution in Isopar-M has been studied. It has been established that exothermic processes occur during heating due to the interaction of soluble radiolysis products and the decomposition of the extractant with nitric acid. Such processes can occur at temperatures below 100 °C, but unlike a thermal explosion that occurs in seconds, they are longer in time and are accompanied by weak heat evolution. Their intensity depends on the composition of the extractant, the concentration of HNO3, and the volume ratio of the organic and aqueous phases. The presence of extractant degradation products in raffinates does not pose a risk of a rapid evolution of gaseous products during evaporation, however, the presence of reducing agents can significantly increase the intensity of the exothermic decomposition of raffinates.

Effect of addition of K2CO3 on the structure of coals with different ranks by FTIR and TG/MS

K2CO3 was considered as the effective catalyst on the pyrolysis performance of coal, however, its effect on coals with different ranks and coalification jumps is unknown until now. This study aims to explore the catalytic mechanism of K2CO3 on coals with different ranks. 8 coals with a vitrinite reflectance (Ro,max) ranging from 0.68% to 1.71% were catalyzed by K2CO3. Thermogravimetric-Mass spectrometry analyzer (TG/MS) and Fourier Transform Infrared (FTIR) spectroscopy were used to characterize the structural variation before and after the addition of K2CO3. FTIR results showed that the length of aliphatic chains (CH2/CH3) decrease and then increase with the turning point near Ro,max = 1.53%, the degree of condensation of aromatic ring (DOC),aromaticity (I) decreased and the concentration of aliphatic hydrogen (Hal/H) increased for all coal samples except for DQ coal (Ro,max = 1.53%) after the addition of K2CO3, indicating the abrupt changes occurred at Ro,max = 1.53%. TG/MS results showed that both the weight loss rate and the maximum weight loss rate temperature exhibit reflection changes near 0.68% and 1.2% of Ro,max. The evolution rate of hydrogen and ethane showed turning changes near Ro,max = 1.21%, while the evolution rate of methane and benzene present transitive changes near Ro,max = 1.53%. Ro,max = 1.21% and Ro,max = 1.53% are consistent with the second and the third coalification jump, respectively. Both TG/MS and FTIR results demonstrated that the effect of K2CO3 is related to coal rank, especially the coalification jump. K2CO3 may tend to act on CC structures furthermore promote the evolution of gaseous products during pyrolysis. The results provide deeply understanding for the coalification jumps and theoretical basis for the selection of suitable catalysts with different coal ranks.

In Situ Catalytic Pyrolysis of Municipal Sewage Sludge under Calcined Copper Slag: Thermokinetic Analysis and Real-Time Monitoring of Evolved Gases

Copper slag (CS) is a solid waste from the copper pyrometallurgical process. Calcined CS is rich in Fe2O3 and Fe3O4 and has micro amounts of CaO, MgO, Al2O3, ZnO, and CuO, which can be used as catalysts in the thermochemical conversion of municipal sewage sludge (SS). This work aimed to study the in situ catalytic pyrolysis of SS under Calcined CS, including thermal degradation characteristics, pyrolysis kinetics, thermodynamics, and evolution of gaseous products. The results showed that devolatilization of organic substances in SS mainly happened at 150–600 °C. The addition of Calcined CS caused the thermal decomposition rate of SS to accelerate and the mass loss to increase. The kinetics of SS pyrolysis with and without Calcined CS were calculated by deconvolution, the Friedman method, and the generalized master plots method, and the results showed that Calcined CS led to a decrease in the apparent activation energy (Eα) and pre-exponential factor (A), while there was no significant influence on the pyrolysis reaction mechanism (f(α)). Online monitoring of SS pyrolysis gases revealed that Calcined CS promoted the formation of CO2, CO, CH4, NH3, C═O, and C═C. However, it had a negative impact on C–O. This study provides insights into coprocessing of the two solid wastes and promotes integrated resource recycling of CS and SS.

Steam gasification of yak manure: Kinetic modeling by a sequential and coupling method

Considering yak manure’s low moisture and biomass-rich properties, steam gasification to produce hydrogen-rich gas provides a feasible approach for waste management and energy usage, which is important in Tibet regions. Prior to large-scale application, kinetic study of the multi-stage thermochemical process is necessary for mechanistic understanding and process design. By employing a sequential and coupling method, a comprehensive kinetic model was built to elucidate reaction mechanisms of each stage, and key kinetic parameters were obtained with the help of Flynn-Wall-Ozawa (FWO)/Kissinger-Akahira-Sunose (KAS), Coats-Redfern (CR)/Kissinger and distributed activation energy model (DAEM) methods. The effects of steam concentration and heating rate on mass loss behavior and gaseous product evolution were examined. During the thermal decomposition, the presence of steam slightly inhibited the pyrolysis reaction, and significantly improved the gas–solid reactions when steam concentration was over 20 %. For pyrolysis stage, the activation energy associated was around 175 kJ/mol. For gas–solid reaction stage, parallel reactions including both char condensation (215 kJ/mol) and steam-char reaction (307 kJ/mol) were confirmed by DAEM modelling. Based on Thermal Gravimetric Analysis (TGA) study, investigation of yak manure steam gasification to produce hydrogen-rich gases was further conducted in a semi-batch reactor by changing temperature and steam flow rate. It was found that the increase of temperature greatly promoted tar cracking and gas–solid reactions. Temperature and steam flow rate exerted positive impacts to increased hydrogen concentration of dry gas through enhanced water–gas shift reactions.

Investigation on the pyrolysis process, products characteristics and BP neural network modelling of pine sawdust, cattle dung, kidney bean stalk and bamboo

To realize resource utilization of waste and alleviate associated environmental pollution, the pyrolysis behaviour of pine sawdust (PS), cattle dung (CD), kidney bean stalk (KS) and bamboo (BA) was investigated. The mass loss, gaseous product evolution and kinetic parameters of these four materials during pyrolysis were analysed via TG-MS. According to the TG-MS results, a back propagation (BP) neural network model was developed for the mass loss prediction of different biomass pyrolysis. More importantly, FTIR and SEM-EDX were used to analyse the characteristics of bio-oil and biochar to facilitate further utilization of these pyrolysis products. The results indicated that PS exhibited the highest mass loss (87.25%) during pyrolysis at 800 °C, and the higher D value (1.23E-05) indicated that PS was more easily decomposed than other materials. In terms of gaseous products, PS produced more H2, C2H6, C3H8 and CO2 than did the other materials during pyrolysis, while BA produced more CH4 and H2O. In addition, the content of phenols or aromatic compounds in PS bio-oil was the highest, and the surface pores in the obtained PS biochar were uniform and regular, which verified that PS achieved a higher utilization value than that of the other materials considered. Finally, the established BP neural network models realized a satisfactory mass loss prediction performance with increasing temperature.

Investigation on the co-pyrolysis of agricultural waste and high-density polyethylene using TG-FTIR and artificial neural network modelling

To realize utilization of agricultural and plastic waste to alleviate environmental pollution, the individual pyrolysis and co-pyrolysis characteristics of kidney beans stalk (KS) and high-density polyethylene (HDPE) were investigated. Thermogravimetry coupled with Fourier transform infrared spectroscopy (TG-FTIR) was used to investigate the pyrolysis behaviour, synergistic effect, kinetics and gaseous product evolution of different samples. In addition, an artificial neural network (ANN) model was established to predict the mass change with temperature during sample pyrolysis or co-pyrolysis. The results showed that the decomposition of HDPE was easier than that of KS, and synergistic and inhibitive effects occurred during co-pyrolysis. The synergistic or inhibitive effect was most significant from 470 to 510 ℃. The FTIR analysis results showed that gaseous products of KS pyrolysis were mainly oxygen-containing compounds including CO2, CO, ketones, aldehydes, esters, etc., while those of HDPE pyrolysis were mainly hydrocarbons including alkanes, alkenes, aromatic rings, etc. The co-pyrolysis of samples with different proportions promoted or inhibited the production of some gaseous products to different degrees. Moreover, the activation energy of the two stages during co-pyrolysis was lower than that of the pure sample. The established ANN model can effectively predict the mass loss of a sample with temperature.

Effects of laser annealing on polymer sheets using a laser-diode with a wavelength of 408 nm

Transparent polymer sheets (PET, PEN, PI) were treated in a vacuum condition by a laser-diode (wavelength: 408 nm). The polymers were decomposed thermally with an endothermic reaction by the laser heating, and carbonization, due to the evolution of gaseous products including CO and CO2, occurred on the surface. The heating mechanism of the polymers was summarized as the formation of carbonized layer on polymer sheets and the thermal conduction due to the heating of carbonized layer by the laser-diode. Thus, it is concluded that the choice of an appropriate wavelength for the laser-diode can facilitate modification processes for various transparent polymers.

Mechanistic study on the formation of silicon carbide nanowhiskers from biomass cellulose char under microwave

The paper reports the synthesis of SiC nanowhiskers via a process that utilizes carbon and silica from the same renewable source without the addition of external Si precursors as a sustainable and cost-effective method. This study reports an improved and sustainable method of synthesizing silicon carbide (SiC) nanowhiskers using cornstalk cellulose char under microwave heating. The aim was to optimize the process and gain a deeper understanding of the formation and growth mechanism of SiC nanowhiskers from biomass under microwave treatment in a temperature range of 1200–1400 °C. The synthesized product was then characterized by various analytical techniques. The formation of SiC nanowhiskers (β-SiC) was promoted at higher reaction temperatures, increasing from 6.83 wt% at 1200 °C to 9.35 wt% at 1400 °C. The SiC nanowhiskers displayed straight rod and smooth cylindrical structures. The nanostructure of β-SiC was confirmed along the d-spacing (111) plane, with a characteristic lattice fringe spacing of 0.25 nm. The growth mechanism of the SiC nanowhiskers followed two reaction pathways of vapor-solid (VS) and the vapor-liquid-solid (VLS). Increased CO and CO2 concentrations due to the evolution of gaseous products (SiO and CO) from the reactive cellulose char led to the growth of SiC nanowhiskers under the solid-vapor mechanism. The presence of inherent metallic species, such as Fe in biochar was found to catalyze the formation and growth of SiC nanowhiskers.

A comprehensive evaluation on pyrolysis behavior, kinetics, and primary volatile formation pathways of rice husk for application to catalytic valorization

Catalytic fast pyrolysis is a prospective and effective route to produce value-added products from rice husk (RH). Understanding the volatile compositions and its formation pathways as well as kinetics during RH pyrolysis is crucial and fundamental to regulate the quality of the target products since catalysts interact directly with primary volatiles. In this study, two pyrolysis coupled real-time volatile monitoring techniques (TG-FTIR and Py-GC/TOF-MS) were employed to conduct comprehensive experiments for RH. The results showed that RH presented three mass loss and gaseous product evolution stages in the temperature range of 200 to 330 °C, 330 to 390 °C, and 390 to 600 °C, respectively. After speculating the formation pathways of the 24 main volatile species, it was indicated that 2,3-dihydro-benzofuran was the major product for hemicellulose, while 2-methoxy-4-(1-propenyl)-phenol was potentially a key active intermediate and very unstable during pyrolysis of lignin constituent in RH. In addition, pyrolysis of RH could be divided into two kinetic stages at cut-off point of 25% conversion. The first kinetic stage obeyed three-dimensional (D3) diffusion model and Ea was within 140–170 kJ/mol. In the secondary kinetic stage, Ea raised gradually to about 200 kJ/mol and pyrolysis reactions followed the second-order reaction model.

Pyrolysis behaviors, kinetics and gaseous product evolutions of two typical biomass wastes

Rice husk (RH) and poplar bark (PB) as the staple biomass wastes represent herbaceous and woody plants, respectively. Thermo-chemical conversion of these wastes is a practical approach for value-added reclamation of bioenergy in large-quantity and pyrolysis plays core role in this process. In this work, RH and PB were subjected to comprehensive investigations on pyrolysis behavior, kinetics and gaseous product evolution in a thermogravimetry-Fourier transform infrared spectroscopy at different heating rates. The results demonstrated that both RH and PB underwent three consecutive pyrolysis stages, the TG/DTG curves shifted to higher temperature and the peak temperature intervals also enhanced as heating rate increased. It was observed CO2 was the most dominated species among oxygenated products, followed by CO bond containing species, while CH4 and arenes were abundant in hydrocarbon gases. In comparison, pyrolysis of RH could generate larger amounts of oxygenated products, and more hydrocarbons like CH4, arenes, and C2+ aliphatics were observed in the pyrolytic products of PB. Model-free kinetic methods showed that the average Ea were 209.1 kJ/mol and 203.9 kJ/mol for RH and PB, respectively. Criado model-fitting method indicated that pyrolysis of RH and PB both obeyed F1 reaction mechanism first and turned into one-dimensional diffusion and reaction mechanism, respectively at higher conversion of 0.25−0.60.

Waste Organic Compounds Thermal Treatment and Valuable Cathode Materials Recovery from Spent LiFePO4 Batteries by Vacuum Pyrolysis

This study investigated the gaseous products evolution behaviors and the recovery performance of cathode materials from spent LiFePO₄ batteries by vacuum pyrolysis. The thermogravimetric-differential scanning calorimetry analysis coupled with electron ionization mass spectrometry (TG-DSC-EI-MS) results indicated that inorganic gases (H₂O, CO, CO₂), alkane gases (CH₄, C₂H₄, C₂H₆, CH₃OH, C₃H₆, C₃H₄O₃, C₄H₈O₃), and fluoride-containing gases (HF, OPF₃, C₂H₂F₂) were the resulting gaseous products in the vacuum pyrolysis of cathode materials. At the same time, the gaseous product species and relative yield were significantly affected by pyrolysis temperature. Combined with the GC-MS analysis of pyrolysis tar obtained from vacuum pyrolysis simulation experiments, it could be inferred that pyrolysis tar was formed as a result of the cleavage and recombination of chemical bonds in solvents. The simulation experiments also showed that the increase of vacuum pyrolysis temperature and decrease of residual gas pressure enhanced the recovery efficiency of cathode materials. Further, the carbon and fluorine content of the cathode materials were found to decrease slowly during vacuum pyrolysis, while the aluminum content increased. When the vacuum pyrolysis temperature was above 600 °C, Al foils ablated and even melted to strips. The phase composition of cathode materials was still LiFePO₄ after vacuum pyrolysis. The leaching performance tests of cathode materials demonstrated that the increase of vacuum pyrolysis temperature and decrease of residual gas pressure can lead to the decrease of leaching efficiency for Fe. This technology offers an efficient way to recycle organic compounds and valuable materials from spent LiFePO₄ batteries, and it has been demonstrated to be of good economic benefit and energy savings.

The corona of a surface bubble promotes electrochemical reactions

The evolution of gaseous products is a feature common to several electrochemical processes, often resulting in bubbles adhering to the electrode’s surface. Adherent bubbles reduce the electrode active area, and are therefore generally treated as electrochemically inert entities. Here, we show that this general assumption does not hold for gas bubbles masking anodes operating in water. By means of imaging electrochemiluminescent systems, and by studying the anisotropy of polymer growth around bubbles, we demonstrate that gas cavities adhering to an electrode surface initiate the oxidation of water-soluble species more effectively than electrode areas free of bubbles. The corona of a bubble accumulates hydroxide anions, unbalanced by cations, a phenomenon which causes the oxidation of hydroxide ions to hydroxyl radicals to occur at potentials at least 0.7 V below redox tabled values. The downhill shift of the hydroxide oxidation at the corona of the bubble is likely to be a general mechanism involved in the initiation of heterogeneous electrochemical reactions in water, and could be harnessed in chemical synthesis.

Investigation on the thermal degradation behavior of enzymatic hydrolysis lignin with or without steam explosion treatment characterized by TG-FTIR and Py-GC/MS

In this study, enzymatic hydrolysis lignin (EHL) extracted from bio-ethanol production residue by enzymatic hydrolysis method was utilized as the raw material, which was subsequently purified to remove cellulose and hemicellulose for gaining the purified lignin (EHL-P) through alkaline solution extraction. Compared with EHL-P, thermal performance and pyrolytic product distribution of EHL-P-SE (which was obtained from EHL-P by steam explosion) were also analyzed by thermogravimetric analyzer coupled with Fourier transform infrared spectroscopy (TG-FTIR) and pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS). Results showed that the degradation process of EHL-P and EHL-P-SE was similarly divided into three stages: a drying stage, a rapid decomposition stage, and a slow carbonization stage. However, their initial weight loss (i.e., ˂ 3 wt% for EHL-P, while ~ 5 wt% for EHL-P-SE before 200 °C), primary weight loss (i.e., ~ 55 wt% for EHL-P, while ~ 48 wt% for EHL-P-SE between 200 and 600 °C), and char yields (i.e., ~ 33 wt% for EHL-P, while ~ 42 wt% for EHL-P-SE at 900 °C) were different. FTIR showed that the evolution of gaseous products changed significantly due to the effect of SE treatment, especially for organic components (i.e., the absorbance of peaks corresponding to carbonyl-containing components such as aldehydes, ketones, and acids decreased, while that related to phenols and aromatics increased). Finally, Py-GC/MS tracked variations of the relative content (%) of phenols (e.g., guaiacol (G), phenol (P), syringol (S), and catechol (C) types) with the increase of degradation temperature (from 300 to 500 °C), and results showed that demethoxylation was more likely to occur at higher degradation temperatures (≥ 400 °C) to realize the transformation from G- and S-type phenols to P- and C-type phenols.

Valorization of plastics and paper mill sludge into carbon composite and its catalytic performance for acarbon material consisted of the multi-layerzo dye oxidation

In this work, polyvinyl chloride (PVC) and paper mill sludge (PMS) were co-pyrolyzed under two environments of N2 and CO2. The pyrolysis process was assessed by conducting thermogravimetric analysis (TGA) and monitoring the evolution of gaseous products. The resulting solid composites were characterized using XRD, XPS, BET, and Raman analyzers, and their ability to catalytically activate persulfate (S2O82−) was tested by conducting methyl orange (MO) degradation experiments. Co-pyrolysis of PVC and PMS at the same mass ratio (1:1) in CO2 resulted in the highest production of H2 and CO (0.36 mol % H2 at 480 °C & 1.53 mol % CO at 700 °C). The characterization results revealed that the composite consisted of Fe3O4, highly graphitic carbon, and mesoporous structure. In MO oxidation experiments, the co-pyrolyzed composite actively generated OH and SO4− by activating S2O82− to achieve complete removal of 5 mg L-1 of MO during 100 min at acidic-neutral pH condition. The composite was also able to complete 3 successive cycles of MO oxidation without deactivation. Consequently, the feasibility of achieving the simultaneous production of energy resources and catalyst via industrial wastes utilization in pyrolytic process was demonstrated.

Pyrolysis behavior and product distributions of biomass six group components: Starch, cellulose, hemicellulose, lignin, protein and oil

Pyrolysis of more biomass group components should be studied in order to obtain a more comprehensive understanding of various biomass pyrolysis. In this study, chemical properties of six biomass group components, namely, starch, cellulose, Hemicellulose (Hem), lignin, protein and oil, were evaluated and their pyrolysis behavior, gaseous product evolution, kinetics and product distributions were investigated using TG-FTIR and Py-GC/MS. The results indicated that their devolatilization sensitivity to heating rate followed the order of Hem > starch > oil > cellulose ≈ protein > lignin. Kinetic results revealed that it was difficult to pyrolyze for biomass rich in oil and lignin but easy to pyrolyze for biomass rich in cellulose, starch, Hem and protein. During their pyrolysis, polysaccharides (starch, cellulose and Hem) mainly generated oxygen-containing components such as CO and O-heterocycles; lignin mainly contributed to the formation of phenols (up to 81.4%); protein produced nitrogen-containing components (up to 52.71%), including N-heterocycles, pyrroles, pyridines, nitriles, and amines/amides; oil generated large quantities of alkenes (46.48%). Finally, this research would serve to gain further insight into biomass pyrolysis containing different group components.

Sodium Biphenyl as Anolyte for Sodium–Seawater Batteries

AbstractSodium‐based battery systems have recently attracted increasing research interest due to the abundant resources employed. Among various material candidates for the negative electrode, sodium metal provides the highest capacity of theoretically 1165 mAh g−1 and a very low redox potential of −2.71 versus the standard hydrogen electrode. However, the high reactivity of sodium metal toward the commonly used electrolytes results in severe side reactions, including the evolution of gaseous decomposition products, and, in addition, the risk of dendritic sodium growth, potentially causing a disastrous short circuit of the cell. Herein, the use of sodium biphenyl (Na‐BP) as anolyte for the Na–seawater batteries (Na–SWB) is investigated. The catholyte for the open‐structured positive electrode is natural seawater with sodium cations dissolved therein. Remarkably, the significant electronic and ionic conductivities of the Na‐BP anolyte enable a low overpotential for the sodium deposition upon charge, allowing for high capacity and excellent capacity retention for 80 cycles in full Na–SWB. Additionally, the Na‐BP anolyte suppresses gas evolution and dendrite growth by forming a homogeneous surface layer on the metallic negative electrode.

Combustion aided in situ consolidation of high strength porous ceramic structures with a minimum thermal budget

The exothermic reaction between a pair of combustible pore formers (urea-ammonium nitrate) is the driving force in realizing low-temperature consolidation of hydroxyapatite (HA) particles. The particles are allowed to sinter in the proximity to the combustible pore formers. The exothermic (ΔH°rea = -898 kJ/mol) redox reaction between combustible pore formers is successfully utilized in deriving high compressive strength (~24 MPa) of HA at 300 °C. The evolution of gaseous products of combustion results in an interconnected porous network of HA. The estimated compressive strength of sintered HA at 300 °C is comparable with high temperature (1100 °C) conventionally sintered HA, at a fixed open porosity (~40%); which depicts nearly ~82% achievement with a reduction of sintering temperature by ~72%. Also, the pellets sintered at 600 °C have shown ~90% achievement in compressive strength of sintered HA. Further, the saturated pore area of 15% requires a sintering time of 9.58 h at a sintering temperature of 600 °C. Thus, combustion-assisted sintering is an alternative technique proves its potentiality in achieving remarkable compressive strength and paves the way for low-cost porous ceramics.