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[Display omitted] • Spray pyrolysis is used for lead-acid battery recycling for the first time. • Low-impurity PbO@C is prepared from the recovered lead acetate solution. • Recovered PbO@C shows better electrochemical performance than commercial PbO. • Computational fluid dynamics (CFD) is used for study of spray pyrolysis mechanisms. • The cell made from PbO@C runs 295 charging/discharging cycles (100%DOD). A one-step spray pyrolysis process is investigated for the first time in the field of spent lead-acid batteries (LABs) recycling. The spent lead paste that derived from spent LAB is desulfurized and then leached to generate the lead acetate (Pb(Ac) 2) solution, which is then sprayed directly into a tube furnace to prepare the lead oxide (PbO) product by pyrolysis. The low-impurity lead oxide product (9 mg/kg Fe and 1 mg/kg Ba) is obtained under the optimized conditions (the temperature of 700 °C, the pumping rate of 50 L/h, and the spray rate of 0.5 mL/min). The major crystalline phases of the synthesized products are identified to be α-PbO and β-PbO. In the spray pyrolysis process, Pb(Ac) 2 droplets are sequentially transformed into various intermediate products: H 2 O(g)@Pb(Ac) 2 solution, Pb(Ac) 2 crystals@PbO, and the final PbO@C product. Owning its carbon skeleton structure, the recovered PbO@C product (carbon content of 0.14%) shows better performance than the commercial ball-milled lead oxide powder in battery tests, with higher initial capacity and better cycling stability. This study could provide a strategy for the short-route recovery of spent LABs. [ABSTRACT FROM AUTHOR]

The addition of aluminum particles in composite propellants has a positive effect on the performance of solid rocket motor, while it also brings some changes in the ignition behaviors. To clarify the ignition process and performance of aluminized propellants, a visualization experimental system was built. It is found that the ignition process of aluminized propellants mainly includes heating and melting of the solid phase, evaporation, mixing and ignition of decomposed gas. Besides, few aluminum particles agglomerate together and they are not ignited during the ignition process of propellants. According to the process of ignition, the ignition delay time can be described as the sum of pyrolysis time, mixing time and chemical reaction time. After the propellants is ignited and the stable flame is formed, the aluminum particles on the burning surface mainly undergo exposure – accumulation – fusion – separation – ignition – combustion. And the structure of the agglomerate transitions from a coral-like to an oxidized cap. At the same time, the ignition of agglomerated products occurs in the stable flame. With the increase of aluminum content and initial aluminum particle size, the ignition delay time also increases, but the proportion of these three times in the ignition delay is not very much related to the formulation of propellants. With the increase of power density of ignition, the ignition delay time decreased markedly, but the decreasing trends continuously became more gradual and eventually flattened out. As the power density of ignition increases, the percentage of pyrolysis time in the ignition delay time decreases rapidly and gradually stabilizes, while the percentage of mixing time gradually increases and the chemical reaction time does not change much. A sufficiently large and reasonable ignition energy power can reduce the ignition delay time and also reduce the impact of the differences between formulations on ignition performance. • The full ignition process of composite propellants with aluminum particles was revealed. • The ignition moment of aluminum particles during the combustion of propellants was analyzed. • The effect of aluminum particle characteristics on the ignition delay time and each fraction time was studied. [ABSTRACT FROM AUTHOR]

Neural networks (NNs) have demonstrated the potential to recover finer textural details from lower-resolution images by superresolution (SR). Given similar grid-based data structures, some researchers have transferred image SR methods to digital elevation models (DEMs). These efforts have yielded better results than traditional spatial interpolation methods. However, terrain data present inherently different characteristics and practical meanings compared with natural images. This makes it unsuitable for existing SR methods on perceptually visual features of images to be directly adopted for extracting terrain features. In this paper, we argue that the problem lies in the lack of explicit terrain feature modeling and thus propose a terrain feature-aware superresolution model (TfaSR) to guide DEM SR towards the extraction and optimization of terrain features. Specifically, a deep residual module and a deformable convolution module are integrated to extract deep and adaptive terrain features, respectively. In addition, explicit terrain feature-aware optimization is proposed to focus on local terrain feature refinement during training. Extensive experiments show that TfaSR achieves state-of-the-art performance in terrain feature preservation during DEM SR. Specifically, compared with the traditional bicubic interpolation method and existing neural network methods (SRGAN, SRResNet, and SRCNN), the RMSE of our results is improved by 1.1% to 23.8% when recovering the DEM from 120 m to 30 m, by 4.9% to 22.7% when recovering the DEM from 60 m to 30 m, and by 7.8% to 53.7% when recovering the DEM from 30 m to 10 m. The source code that has been developed is shared on Figshare (https://doi.org/10.6084/m9.figshare.19597201). [ABSTRACT FROM AUTHOR]

• The efficiency of iron-carbon hydrogels for nitrate remediation was investigated. • The nitrate removal performance within the PRB and its downgradient aquifer was evaluated. • The microbial communities within the PRB and its downgradient aquifer were interpreted. • The response mechanisms of microbial communities and iron-carbon hydrogels were analyzed. Permeable Reactive Barriers (PRBs) have been utilized for mitigating nitrate pollution in groundwater systems through the use of solid carbon and iron fillers that release diverse nutrients to enhance denitrification efficiency. We conduct laboratory column tests to evaluate the effectiveness of PRBs in remediating nitrate pollution both within the PRB and in the downgradient aquifer. We use an iron-carbon hydrogel (ICH) as PRB filler, which has different weight ratios of polyhydroxybutyrate (PHB) and microscale zero-valent iron (mZVI). Results reveal that denitrification in the downgradient aquifer accounts for at least 19.5 % to 32.5 % of the total nitrate removal. In the ICH, a higher ratio of PHB to mZVI leads to higher contribution of the downgradient aquifer to nitrate removal, while a lower ratio results in smaller contribution. Microbial community analysis further reveals that heterotrophic and mixotrophic bacteria dominate in the downgradient aquifer of the PRB, and their relative abundance increases with a higher ratio of PHB to mZVI in the ICH. Within the PRB, autotrophic and iron-reducing bacteria are more prevalent, and their abundance increases as the ratio of PHB to mZVI in the ICH decreases. These findings emphasize the downgradient aquifer's substantial role in nitrate removal, particularly driven by dissolved organic carbon provided by PHB. This research holds significant implications for nutrient waste management, including the prevention of secondary pollution, and the development of cost-effective PRBs. [Display omitted] [ABSTRACT FROM AUTHOR]

Direct regeneration of cathode materials from spent lithium-ion batteries is efficient but suffers from the difficulty of accurately replenishing lithium, leading to poor performance of the regenerated materials. In this research, a solvothermal strategy for direct regeneration of spent cathode material into high electrochemical performances cathode material is reported. Spent LiNi 0.5 Co 0.2 Mn 0.3 O 2 is directly regenerated by combining CH 3 CH 2 OH-LiNO 3 solvothermal relithiation and thermal annealing step. The results indicate that lithium can be precisely replenished to the missing sites, and the regenerated materials return to a stable layered structure, corresponding to excellent cyclability (90.23 % capacity retention after 560 cycles at 1 C). Owing to solvent circulation and the low relithiation temperature, the regeneration process displays low energy consumption, low CO 2 emissions and high profit; thus, presenting a promising route for direct regeneration of high-performance cathode materials from spent lithium-ion batteries. [Display omitted] • A solvothermal strategy for direct regeneration of spent cathode material has been proposed. • Solvothermal strategy achieves restoration of composition and structure in spent cathode materials. • Regenerated cathode material exhibits excellent electrochemical performance. • The regeneration process displays low energy consumption, low CO 2 emissions and high profit. [ABSTRACT FROM AUTHOR]

A series of experiments was conducted to study the ignition and combustion characteristics of aluminum particle-laden flows in a propulsion system that used powder as the main fuel. In these experiments, a laminar flame produced by hydrocarbon fuel provided a high-temperature environment for the ignition and combustion of the aluminum particles. The effective oxidant content and flow velocity were adjusted by varying the mass flow rates of three gases (methane, air, and oxygen), and the ignition delay and burning time of the aluminum particles in the particle-laden flow were determined using a high-speed camera. The total time was the sum of the ignition delay time and burning time. The experimental results showed that the ignition delay time could be fitted as a function of the particle diameter, expressed as t i = a 0 + b 0 D ; the burning time and total time could also be fitted as functions of the particle diameter, expressed as t b = aD b . As the effective oxidant content increased, the burning time decreased significantly, and the total time decreased slightly. The ignition delay time, burning time, and total time were obviously decreased with an increase in the flow velocity of the hot gas. Compared with the effective oxidant content, the flow velocity of the hot gas played a greater role in the reduction of the total time for the aluminum particles in a low-oxidant environment. The agglomeration and separation processes for the burning particles in aluminum particle-laden flows were analyzed in detail. • A low-density powder feed device is developed. • The time of dynamic ignition delay and combustion is used to assess the combustion characteristics of aluminum particle. • The effects of oxidant concentration and velocity of hot gas on the total time are studied in low oxidant environment. • The agglomeration and separation processes of aluminum particle-laden flow are analyzed in detail. [ABSTRACT FROM AUTHOR]

Under considerations of material abundance, cost, redox potential, higher performance, and safety, solid-state sodium-metal batteries hold much promise. The development of solid electrolytes with superior electrical performances for the solid-state sodium batteries is at the infant stage and still remains a challenge. Herein, we for the first time report a synthetic strategy of Na 3 Zr 2 Si 2 PO 12 ceramic microtubes via a sol gel process with natural cotton fiber template. Moreover, an inorganic-organic composite electrolyte Na 3 Zr 2 Si 2 PO 12 microtube/poly (ethylene oxide) (PEO)-poly (vinylidene fluoride- co -hexafluoropropylene) (PVdF-HFP)-sodium perchlorate (NaClO 4)-1-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide (EmimFSI) is developed. The phase, microstructure, and electrochemical properties of the Na 3 Zr 2 Si 2 PO 12 microtubes and their composite electrolytes are systematically investigated based on X-ray diffraction, scanning electron microscope, energy dispersive spectroscopy, electrochemical impedance spectroscopy, linear sweep voltammetry, direct-current polarization, and galvanostatic cycling. The finding implies that the characteristic Na 3 Zr 2 Si 2 PO 12 microtubes and their composite electrolytes are promising for solid-state sodium-metal batteries. [ABSTRACT FROM AUTHOR]