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Optimization of chemical precipitation for valuable metal recovery from spent lithium nickel manganese cobalt oxide batteries
(2026-05-01)
Morawan, Nattaya
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Kruthun, Orathai
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Katers, John F.
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Attaphong, Chodchanok
This study investigated the optimized conditions for chemical precipitation to recover nickel manganese cobalt hydroxide (NiCoMn-OH) and lithium carbonate (Li<inf>2</inf>CO<inf>3</inf>) from spent lithium nickel manganese cobalt oxide (sLi-NMC) batteries. The research focused on establishing optimized conditions to maximize recovery efficiency and product purity. The process involved dismantling and incinerating the batteries to produce black powder, followed by acid leaching using H<inf>2</inf>SO<inf>4</inf> and H<inf>2</inf>O<inf>2</inf>, and a two-step precipitation to recover NiCoMn-OH and Li<inf>2</inf>CO<inf>3</inf>. Results indicated that the optimized incineration conditions for efficient black powder production were 600 °C for 30 min. During the leaching process, the optimized extraction of lithium, nickel, cobalt, and manganese was achieved using 1 M H<inf>2</inf>SO<inf>4</inf> with 2% H<inf>2</inf>O<inf>2</inf> at a liquid-to-solid ratio of 30:1 mL/g. In the first precipitation stage, the optimized conditions for co-precipitating the solid NiCoMn-OH using saturated NaOH were identified as pH 10, 25 °C, and a contact time of 90 min. The results showed that nickel, manganese, and cobalt were precipitated at 92.04%, 90.35%, and 86.78%, respectively (a purity of 98.67%). Finally, lithium was successfully recovered as Li<inf>2</inf>CO<inf>3</inf> using saturated Na<inf>2</inf>CO<inf>3</inf>, at pH 12, 100 °C, and a contact time of 120 min up to 96.51% (a purity of 98.98%). Ultimately, the optimized conditions obtained from this study can provide valuable data for waste management and serve as a comparative baseline for environmental impact assessment of conventional metal recovery, enabling direct comparisons with optimized alternative methods in future research.
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Multi-temporal scale of urban rainfall in the Eastern Northeast based on observed data and gridded products: physiographic factors and changes in land use and occupation
(2026-02-01)
da Silva, Luis Felipe Francisco Ferreira
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de Oliveira Romão, William Max
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Lyra, Gustavo Bastos
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da Silva, Elania Barros
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da Silva Costa, Micejane
Rainfall is one of the most important meteorological variables in the daily lives of urban populations. The city of Maceió, the capital of Alagoas, located in the eastern part of the Northeast of Brazil (ENEB), has 50 neighborhoods and a population of approximately one million people, with few studies on the subject. The objectives were: (i) to validate the CHIRPS product; (ii) to identify the preferential rainfall periods in Maceió via GIS; (iii) to map areas for the installation of in situ stations in the city with the aim of supporting the prevention of hydrometeorological disasters; and (iv) creation of a theoretical-conceptual rainfall model. The statistical indicators (R², ρ, BIAS, MAPE and RMSE) were used to validate the gridded precipitation product CHIRPS from 11 CEMADEN rain gauge stations. Monthly rain occurrence maps via Spline tension were developed by QGIS (Quantum GIS) software. The HAND model was applied at neighborhood level for the assessment of urban floods. Waterborne disease data were obtained from SINAN, Natural Disaster data via S2iD from the period 2000 to 2023, and the NDVI and EVI indices in the years 2015 and 2022 were evaluated in the study. All stations were monotonically positive (ρ > 0.65) and significant (p-value < 0.001), indicating that CHIRPS is able to capture rainfall variability despite the influences of the coast, Lagoa Mundaú, and topography. Most stations showed underestimation (negative BIAS) and lower errors (MAE and RMSE). Spatially, the increase in rainfall on the coastal plateau is due to the interaction of the wind regime with the relief, driven by the circulation of breezes and the influence of trade winds. The preferential rainfall period occurs between 04:00 am and 07:00 am. The HAND model identified very high and high susceptibility, mainly on the coast, in areas adjacent to Lagoa Mundaú, and in neighborhoods crossed by rivers and urban canals, and low susceptibility in densely populated neighborhoods. Waterborne diseases together with transformations via NDVI and EVI indicated that rainfall amplifies risk scenarios for the most vulnerable and densely populated populations. In light of this, it is perceived that the rainfall patterns in Maceió are due to the interaction of physiographic and/or anthropogenic factors and meteorological systems – theoretical-conceptual model – which requires improvements in infrastructure and an active monitoring system.
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Rainfall variability, land use and land cover dynamics, and implications for climate risk through a theoretical-conceptual model for the Eastern Northeast of Brazil
(2025-06-01)
da Silva Costa, Micejane
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Francisco de Oliveira Júnior, José
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Godoy de Barros, Bárbara
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Francisco Ferreira da Silva, Luís Felipe
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Alencar Cardoso, Kelvy Rosalvo
The study assessed the variability of rainfall, land use and land cover (LULC), the influence of meteorological systems and their interactions, followed by the increase in climate risks in Maceió – Alagoas – ENEB. Monthly rainfall data were obtained from the 64-year historical series (1958–2022) of the TerraClimate platform. The TerraClimate precipitation data were validated ANA and SEMARH data, resulting in R<sup>2</sup> = 0.72 and r = 0.85. Spatially, the highest rainfall accumulations occurred from April to July (rainy season), with May and June being the wettest months (>800 mm). In contrast, the months from October to February (dry season) and March, August, and September (transition season) recorded lower rainfall, with November and December being the driest months (150–201 mm). The seasonal occurrence of rainfall and the relief in Maceió were associated with areas of climate risk. Maceió is a region vulnerable to extreme rainfall events due to its geographical location, the influence of the Atlantic Ocean and the Mundaú/Manguaba Lagoons, and the interaction with multi-scale meteorological systems. With LULC, there was an expansion of forest areas in rural areas and a reduction of agricultural areas, followed by increased urbanization in neighborhoods in the western part of the city (coastal plateau). The theoretical-conceptual model of climate risk provides essential information for planning and supports decision-making for public policies. The ability to assess the impacts of extreme rainfall underscores the importance of adaptive responses by local communities through the management of public policies and strategies for adapting to climate risk.
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Precipitation hardening and structure evolution in hypereutectic Al-6 % Fe-Zr alloys subjected to ultrasonic melt processing
(2024-01-05)
Chankitmunkong, S.
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Wang, F.
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Pandee, P.
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Limmaneevichitr, C.
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Eskin, D. G.
The objective of this research was to study the influence of Zr concentration and ultrasonic melt processing (USP) on the microstructure and precipitation hardening of a hypereutectic Al-6% Fe alloy. Such alloys have a good potential in high-temperature, wear-resistant, and conducting applications but suffer from coarse structure and low strength/ductility, which prevents their processing. The microstructure of the studied alloys consisted of primary Al<inf>13</inf>Fe<inf>4</inf> intermetallics and (Al)+Al<inf>13</inf>Fe<inf>4</inf> eutectic colonies, which were successfully refined by adding Zr and performing USP. The mechanisms of USP and Zr were confirmed for the Al-6 % Fe alloys with a range of Zr additions. The structure refinement led to improved hardness and tensile properties of the alloys. All studied alloys demonstrated strong precipitation hardening effect with hardness increasing 4–5 times, reaching 170 HV for the alloy with 0.4 % Zr after annealing at 400 ℃ for 20 hrs. The electrical conductivity increased from 25 % IACS in the as-cast alloy to 40% IACS in the annealed Al-6% Fe-0.4 % Zr alloy. The prime novelty of this work is a considerable increase of hardness upon annealing, i.e. more than 100 HV, in the Al-6 % Fe alloy with only minute traces of Zr (<0.01 %). The precipitation phenomena were investigated by transmission electron microscopy. The precipitation of the semi-coherent Al<inf>13</inf>Fe<inf>4</inf> phase with Zr segregated to its surface was observed for the first time. All studied alloys (with minute and larger Zr additions) showed the precipitation of this phase, while the alloys with the larger amount of Zr also demonstrated the precipitation of the metastable L1<inf>2</inf> Al<inf>3</inf>Zr phase. Therefore, the properties improvement was attributed to the structure refinement and the formation of Zr-modified Al<inf>13</inf>Fe<inf>4</inf> and Al<inf>3</inf>Zr precipitates in the microstructure.

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