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Keywords = calcium leaching

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16 pages, 6440 KiB  
Article
Effect of Calcium Sulfate and Silica Gel on Vanadium Leaching Characteristics from Vanadium Titanomagnetite via Calcification Roasting–Sulfuric Acid Leaching: Formation Mechanism and Process Enhancement
by Jianli Chen, Yu Zheng, Benliu He, Shuzhong Chen, Shuai Wang, Feng Chen, Shiyuan Cui, Jing Liu, Lingzhi Yang, Yufeng Guo and Guanzhou Qiu
Metals 2025, 15(8), 870; https://doi.org/10.3390/met15080870 (registering DOI) - 3 Aug 2025
Viewed by 130
Abstract
Compared with vanadium extraction by sodium roasting followed by water leaching, the calcification roasting–sulfuric acid leaching method is considered a promising approach for the comprehensive utilization of vanadium titanomagnetite, as it avoids the introduction of alkali metals. However, during vanadium extraction by sulfuric [...] Read more.
Compared with vanadium extraction by sodium roasting followed by water leaching, the calcification roasting–sulfuric acid leaching method is considered a promising approach for the comprehensive utilization of vanadium titanomagnetite, as it avoids the introduction of alkali metals. However, during vanadium extraction by sulfuric acid heap leaching, the diffusion of leaching reagents and leaching products was hindered by the deposition of leaching solid products. To address this issue, this study systematically investigated the leaching kinetics and the mechanisms underlying the deposition of leaching solid products. The results indicated that vanadium leaching was governed by a combination of liquid film diffusion and internal diffusion through solid-phase products during days 0–2, and by internal diffusion alone from day 2 to day 9. The primary solid products formed during leaching were calcium sulfate and silica gel. Calcium sulfate precipitated and grew within the pore via two-dimensional nucleation, while silicates formed silica gel through dehydration. By optimizing the sulfuric acid leaching conditions—specifically, maintaining an H+ concentration of 2 mol/L, a leaching temperature of 40 °C, and a liquid-to-solid ratio of 5:1—the formation of calcium sulfate and silica gel was effectively suppressed. Under these conditions, the vanadium leaching efficiency reached 75.82%. Full article
(This article belongs to the Section Extractive Metallurgy)
20 pages, 3657 KiB  
Article
Numerical Study of Chemo–Mechanical Coupling Behavior of Concrete
by Feng Guo, Weijie He, Longlong Tu and Huiming Hou
Buildings 2025, 15(15), 2725; https://doi.org/10.3390/buildings15152725 - 1 Aug 2025
Viewed by 189
Abstract
Subsurface mass concrete infrastructure—including immersed tunnels, dams, and nuclear waste containment systems—frequently faces calcium-leaching risks from prolonged groundwater exposure. An anisotropic stress-leaching damage model incorporating microcrack propagation is developed for underground concrete’s chemo–mechanical coupling. This model investigates stress-induced anisotropy in concrete through the [...] Read more.
Subsurface mass concrete infrastructure—including immersed tunnels, dams, and nuclear waste containment systems—frequently faces calcium-leaching risks from prolonged groundwater exposure. An anisotropic stress-leaching damage model incorporating microcrack propagation is developed for underground concrete’s chemo–mechanical coupling. This model investigates stress-induced anisotropy in concrete through the evolution of oriented microcrack networks. The model incorporates nonlinear anisotropic plastic strain from coupled chemical–mechanical damage. Unlike conventional concrete rheology, this model characterizes chemical creep through stress-chemical coupled damage mechanics. The numerical model is incorporated within COMSOL Multiphysics to perform coupled multiphysics simulations. A close match is observed between the numerical predictions and experimental findings. Under high stress loads, calcium leaching and mechanical stress exhibit significant coupling effects. Regarding concrete durability, chemical degradation has a more pronounced effect on concrete’s stiffness and strength reduction compared with stress-generated microcracking. Full article
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16 pages, 1658 KiB  
Article
Environmentally Friendly Chelation for Enhanced Algal Biomass Deashing
by Agyare Asante, George Daramola, Ryan W. Davis and Sandeep Kumar
Phycology 2025, 5(3), 32; https://doi.org/10.3390/phycology5030032 - 23 Jul 2025
Viewed by 302
Abstract
High ash content in algal biomass limits its suitability for biofuel production by reducing combustion efficiency and increasing fouling. This study presents a green deashing strategy using nitrilotriacetic acid (NTA) and deionized (DI) water to purify Scenedesmus algae, which was selected for its [...] Read more.
High ash content in algal biomass limits its suitability for biofuel production by reducing combustion efficiency and increasing fouling. This study presents a green deashing strategy using nitrilotriacetic acid (NTA) and deionized (DI) water to purify Scenedesmus algae, which was selected for its high ash removal potential. The optimized sequential treatment (DI, NTA chelation, and DI+NTA treatment at 90–130 °C) achieved up to 83.07% ash removal, reducing ash content from 15.2% to 3.8%. Elevated temperatures enhanced the removal of calcium, magnesium, and potassium, while heavy metals like lead and copper were reduced below detection limits. CHN analysis confirmed minimal loss of organic content, preserving biochemical integrity. Unlike traditional acid leaching, this method is eco-friendly after three cycles. The approach offers a scalable, sustainable solution to improve algal biomass quality for thermochemical conversion and supports circular bioeconomy goals. Full article
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18 pages, 1812 KiB  
Article
Testing Concrete for the Construction of Winemaking Tanks
by Eleftherios K. Anastasiou, Alexandros Liapis, Eirini-Chrysanthi Tsardaka, Alexandros Chortis and Argyris Gerovassiliou
Appl. Sci. 2025, 15(14), 7816; https://doi.org/10.3390/app15147816 - 11 Jul 2025
Viewed by 213
Abstract
This work focuses on the design of concrete for the construction of winemaking tanks, as well as coating behaviour and stability of the systems in wine immersion. More specifically, alternative laboratory concrete mixtures were investigated by replacing cement with natural pozzolan and using [...] Read more.
This work focuses on the design of concrete for the construction of winemaking tanks, as well as coating behaviour and stability of the systems in wine immersion. More specifically, alternative laboratory concrete mixtures were investigated by replacing cement with natural pozzolan and using silicate aggregates and quartz sand as filler in order to obtain self-compacting concrete of strength class C 20/25. The optimal mixture was selected and further tests were carried out on the mechanical properties of permeability, durability and thermal conductivity. Three coatings and plain concrete were tested for their leachability of heavy metals in wine. The results show that the selected composition with 20% cement replacement by natural pozzolan has the desired workability and strength and is comparable to a reference concrete without natural pozzolan. The leachability tests show that heavy metals do not leach out upon contact with wine, but only calcium and potassium oxide, which can be easily addressed by coating or treating the surface of the concrete. Also, the optimum coating did not influence the pH of the wine. Full article
(This article belongs to the Special Issue Emerging Concrete Technologies and Applications)
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16 pages, 3403 KiB  
Article
IoT-Enabled Soil Moisture and Conductivity Monitoring Under Controlled and Field Fertigation Systems
by Soni Kumari, Nawab Ali, Mia Dagati and Younsuk Dong
AgriEngineering 2025, 7(7), 207; https://doi.org/10.3390/agriengineering7070207 - 1 Jul 2025
Viewed by 503
Abstract
Precision agriculture increasingly relies on real-time data from soil sensors to optimize irrigation and nutrient application. Soil moisture and electrical conductivity (EC) are key indicators in irrigation and fertigation systems, directly affecting water-use efficiency and nutrient delivery to crops. This study evaluates the [...] Read more.
Precision agriculture increasingly relies on real-time data from soil sensors to optimize irrigation and nutrient application. Soil moisture and electrical conductivity (EC) are key indicators in irrigation and fertigation systems, directly affecting water-use efficiency and nutrient delivery to crops. This study evaluates the performance of an IoT-based soil-monitoring system for real-time tracking of EC and soil moisture under varied fertigation conditions in both laboratory and field scenarios. The EC sensor showed strong agreement with laboratory YSI measurements (R2 = 0.999), confirming its accuracy. Column experiments were conducted in three soil types (sand, sandy loam, and loamy sand) to assess the EC and soil moisture response to fertigation. Sand showed rapid infiltration and low retention, with EC peaking at 420 µS/cm and moisture 0.33 cm3/cm3, indicating high leaching risk. Sandy loam retained the most moisture (0.35 cm3/cm3) and showed the highest EC (550 µS/cm), while loamy sand exhibited intermediate behavior. Fertilizer-specific responses showed higher EC in Calcium Ammonium Nitrate (CAN)-treated soils, while Monoammonium Phosphate (MAP) showed lower, more stable EC due to limited phosphorus mobility. Field validation confirmed that the IoT system effectively captured irrigation and fertigation events through synchronized EC and moisture peaks. These findings highlight the efficacy of IoT-based sensor networks for continuous, high-resolution soil monitoring and their potential to support precision fertigation strategies, enhancing nutrient-use efficiency while minimizing environmental losses. Full article
(This article belongs to the Section Agricultural Irrigation Systems)
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19 pages, 7987 KiB  
Article
Nitrogen-Induced Soil Acidification Reduces Soil Carbon Persistence by Shifting Microbial Keystone Taxa and Increasing Calcium Leaching
by Ding Wang, Jie Wang, Yuting Zhang, Xinping Chen, Ji Chen and Xiaojun Shi
Agronomy 2025, 15(7), 1586; https://doi.org/10.3390/agronomy15071586 - 29 Jun 2025
Viewed by 656
Abstract
Anthropogenic nitrogen (N) enrichment alters soil biotic (e.g., microbial metabolism) and abiotic (e.g., pH and mineralogy) properties, substantially affecting the persistence and storage of soil organic carbon (SOC). However, the response of relatively persistent mineral-associated organic carbon (MAOC) to N enrichment and the [...] Read more.
Anthropogenic nitrogen (N) enrichment alters soil biotic (e.g., microbial metabolism) and abiotic (e.g., pH and mineralogy) properties, substantially affecting the persistence and storage of soil organic carbon (SOC). However, the response of relatively persistent mineral-associated organic carbon (MAOC) to N enrichment and the underlying mechanisms are not well understood, leading to significant uncertainties regarding SOC stability under continuous N input. Based on a 15-year field N fertilisation experiment (0, 28.5, 60.0, 72.0 g N m−2 yr−1), we studied the responses of MAOC to N input and the associated changes in soil mineralogy and microbiology. N fertilisation significantly reduced MAOC content by 16.0%. The loss of MAOC was primarily attributed to soil acidification (pH decreased from 6.4 to 4.2), leading to exchangeable calcium (Ca) leaching and loss of Ca-bound organic carbon by 37.9% on average. Furthermore, N-induced shifts in dominant microbial keystone taxa from K-strategists (e.g., Actinobacteriota and Sordariomycetes) to r-strategists (e.g., Subgroups 4 and 6 Acidobacteriota) impeded the formation of MAOC through the reduction of microbial carbon use efficiency and oxidase activity (e.g., phenol oxidases and peroxidases). These results suggest that keystone taxa play crucial roles in regulating carbon metabolism and are responsible for MAOC reduction. Moreover, our data pinpoint the importance of Ca leaching for SOC destabilisation, particularly in near-neutral and neutral soils. Full article
(This article belongs to the Section Soil and Plant Nutrition)
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19 pages, 3723 KiB  
Article
Calcium or Sodium Carbonate Influence on Calcium Sulfoaluminate Clinker Hydration
by Pilar Padilla-Encinas and Ana Fernández-Jiménez
Molecules 2025, 30(13), 2759; https://doi.org/10.3390/molecules30132759 - 26 Jun 2025
Viewed by 329
Abstract
This work shows how the presence of calcium carbonate and sodium carbonate (5% and 20%) affects the hydration of a commercial calcium sulfoaluminate clinker (KCSA). For this study, water-hydrated pastes were prepared and the mechanical compressive strength and hydration rate were determined. The [...] Read more.
This work shows how the presence of calcium carbonate and sodium carbonate (5% and 20%) affects the hydration of a commercial calcium sulfoaluminate clinker (KCSA). For this study, water-hydrated pastes were prepared and the mechanical compressive strength and hydration rate were determined. The hydration products were characterised by XRD, DTA/TG, FTIR and SEM. The incorporation of CaCO3 can have a beneficial effect on the development of the mechanical strength of KCSA, especially at 90 days. It does not significantly alter the hydration kinetics and the hydration products formed are mainly ettringite and AH3. However, sodium carbonate has a detrimental effect, slowing down the hydration kinetics and reducing the development of mechanical strength, especially at early ages. The 20% Na2CO3 favours the formation of calcium aluminate, gaylusite and thenardite over ettringite. These phases are metastable in the presence of sodium and decompose to form calcite, alumina gel and a large amount of thenardite, which leaches out as efflorescence, causing microcracks and loss of strength in the material. Full article
(This article belongs to the Section Materials Chemistry)
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13 pages, 741 KiB  
Article
Reducing Cation Leaching and Improving Greenhouse Cucumber’s Nutritional Yield Through Optimized Organic–Inorganic Fertilization
by Xilin Guan, Wenqing Cao, Dunyi Liu, Huanyu Zhao, Ming Lu, Xinhao Gao, Xinping Chen, Yumin Liu and Shenzhong Tian
Agronomy 2025, 15(7), 1523; https://doi.org/10.3390/agronomy15071523 - 23 Jun 2025
Viewed by 379
Abstract
Excessive nutrient inputs from manure and synthetic fertilizers have caused great challenges for sustainable vegetable production. There is limited information about the nutritional yields and leaching losses of potassium (K), calcium (Ca), and magnesium (Mg) under various organic–inorganic fertilization practices. We hypothesized that [...] Read more.
Excessive nutrient inputs from manure and synthetic fertilizers have caused great challenges for sustainable vegetable production. There is limited information about the nutritional yields and leaching losses of potassium (K), calcium (Ca), and magnesium (Mg) under various organic–inorganic fertilization practices. We hypothesized that nutritional yields and cation leaching would be influenced by different fertilization practices. A two-year cucumber-cultivating experiment was conducted in North China with the following three treatments: Farmers’ Traditional Practice (FP), based on local farmers’ practices; Current Recommended Nutrient Management (CRNM), based on pieces of literature, bio-organic fertilizer, and kaolin replacing chicken manure in FP; Nutrient Balance Management (DBNM), based on target yields and plant-based amendments replacing bio-organic fertilizers. The nutritional yields of Ca and Mg under CRNM and DBNM were 26.4–39.6% and 20.3–32.5% higher than FP. The K, Ca, and Mg leaching under CRNM were significantly reduced by 41.1%, 18.9%, and 18.5%, compared with FP. Ca leaching under DBNM was further significantly reduced by 7.9%. A significant negative relationship was observed between the leaching losses of K, Ca, and Mg and the surface soil pH (0–20 cm). These findings suggest that DBNM could play an important role in obtaining higher nutritional yields, reducing leaching losses, and alleviating soil acidification in vegetable production. Full article
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16 pages, 2956 KiB  
Article
Utilization of Red Mud from Processing of Low-Quality Bauxites
by Sergey Gladyshev, Nazym Akhmadiyeva, Rinat Abdulvaliyev, Leila Imangaliyeva, Kenzhegali Smailov, Yerkezhan Abikak, Asya Kasymzhanova and Leila Amanzholova
Processes 2025, 13(7), 1958; https://doi.org/10.3390/pr13071958 - 20 Jun 2025
Viewed by 321
Abstract
Red mud from bauxite processing is among the large-tonnage technogenic waste that poses a significant ecological threat. At the same time, red mud serves as a raw material source for expanding the resource base for obtaining iron, rare metals, and rare earth elements. [...] Read more.
Red mud from bauxite processing is among the large-tonnage technogenic waste that poses a significant ecological threat. At the same time, red mud serves as a raw material source for expanding the resource base for obtaining iron, rare metals, and rare earth elements. Numerous studies on their utilization have shown that only through comprehensive processing, combining pyrometallurgical and hydrometallurgical methods, is it possible to maximize the extraction of all the useful components. This work addresses the first stage of a comprehensive technology for processing red mud through reduction smelting, separating iron in the form of pig iron, and producing slag. Studies were conducted on the reductive smelting of red mud using waste slurry from alumina production as the calcium-containing material, taken in proportions calculated to obtain a fluid slag with a hydraulic modulus of 0.55–0.8. The permissible mixing range of red mud with waste slurry was determined to be in the ratio of 0.56–1.2. In cases where the charge was prepared in violation of the required hydraulic modulus value, pig iron was not obtained during smelting. When the hydraulic modulus requirement was met, the temperature of the reductive smelting process was 1350–1400 °C. The total amount of recovered iron obtained as pig iron and fine fractions amounted to 99.5% of the original content. The low iron content (0.23–0.31%) in the non-magnetic slag fraction allows for the production of high-quality titanium oxide and rare earth element concentrates in the subsequent stages of the comprehensive hydrometallurgical processing of red mud, involving acid leaching. Based on the results of a phase analysis of the slag, pig iron, and melt, the reactions of the reductive smelting process were established, and their thermodynamic likelihood was determined. In fluid slags, the content of the sodium aluminosilicate phase is twice as high as that in slag with a higher hydraulic modulus. The reductive smelting of 100% red mud with the addition of calcium oxide, calculated to achieve a hydraulic module of 0.55 at a temperature of 1350–1400 °C, produced pig iron and slag with high alkali and iron contents. Full article
(This article belongs to the Topic Advanced Materials in Chemical Engineering)
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23 pages, 2883 KiB  
Article
Effectiveness of Rain Gardens for Managing Non-Point Source Pollution from Urban Surface Storm Water Runoff in Eastern Texas, USA
by Shradhda Suman Jnawali, Matthew McBroom, Yanli Zhang, Kevin Stafford, Zhengyi Wang, David Creech and Zhongqian Cheng
Sustainability 2025, 17(10), 4631; https://doi.org/10.3390/su17104631 - 18 May 2025
Viewed by 1438
Abstract
Extreme precipitation events are one of the common hazards in eastern Texas, generating a large amount of storm water. Water running off urban areas may carry non-point source (NPS) pollution to natural resources such as rivers and lakes. Urbanization exacerbates this issue by [...] Read more.
Extreme precipitation events are one of the common hazards in eastern Texas, generating a large amount of storm water. Water running off urban areas may carry non-point source (NPS) pollution to natural resources such as rivers and lakes. Urbanization exacerbates this issue by increasing impervious surfaces that prevent natural infiltration. This study evaluated the efficacy of rain gardens, a nature-based best management practice (BMP), in mitigating NPS pollution from urban stormwater runoff. Stormwater samples were collected at inflow and outflow points of three rain gardens and analyzed for various water quality parameters, including pH, electrical conductivity, fluoride, chloride, nitrate, nitrite, phosphate, sulfate, salts, carbonates, bicarbonates, sodium, potassium, aluminum, boron, calcium, mercury, arsenic, copper iron lead magnesium, manganese and zinc. Removal efficiencies for nitrate, phosphate, and zinc exceeded 70%, while heavy metals such as lead achieved reductions up to 80%. However, certain parameters, such as calcium, magnesium and conductivity, showed increased outflow concentrations, attributed to substrate leaching. These increases resulted in a higher outflow pH. Overall, the pollutants were removed with an efficiency exceeding 50%. These findings demonstrate that rain gardens are an effective and sustainable solution for managing urban stormwater runoff and mitigating NPS pollution in eastern Texas, particularly in regions vulnerable to extreme precipitation events. Full article
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22 pages, 6349 KiB  
Article
Influence of Different Binders on the Municipal Solid Waste Incineration Fly Ash Granulation-Based Stabilization Process
by Maryna Shevtsova, Jurgita Malaiškienė, Jelena Škamat and Valentin Antonovič
Sustainability 2025, 17(10), 4573; https://doi.org/10.3390/su17104573 - 16 May 2025
Viewed by 555
Abstract
Municipal solid waste incineration fly ash (MSWI FA) is a hazardous waste that must be kept in special landfills due to the high amounts of chlorides, sulfates, and heavy metals. The granulation of MSWI FA could be used as a solidification/stabilization (S/S) of [...] Read more.
Municipal solid waste incineration fly ash (MSWI FA) is a hazardous waste that must be kept in special landfills due to the high amounts of chlorides, sulfates, and heavy metals. The granulation of MSWI FA could be used as a solidification/stabilization (S/S) of fly ash to immobilize hazardous chemical elements and to reduce dust emissions. In this work for granulation, three different binders were used: calcium aluminate cement (CAC), geopolymer (GEO), and Portland cement (PC). Chemical (XRF), mineral (XRD), granulometric compositions, and leaching of prepared granules are presented in the article. Furthermore, the impact of different binders on bulk density, compressive strength, and granule structure was analyzed. The results show that the granules with CAC binder have the best initial compressive strength (about 10 MPa), but these granules were destroyed after the leaching test or connection with water. The geopolymer as a binder did not provide the required compressive strength and immobilization of harmful elements. Granules with a Portland cement binder have a suitable compressive strength, a slight leaching of chemical elements, and good durability in the alkaline and acidic environment; they are also resistant to freezing and thawing cycles. Full article
(This article belongs to the Section Waste and Recycling)
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19 pages, 7249 KiB  
Article
Effect of Calcium Chloride on the Reinforcement of Uranium Tailings with Sodium Hydroxide–Sodium Silicate–Metakaolin
by Qianjin Niu and Xiujuan Feng
Minerals 2025, 15(5), 526; https://doi.org/10.3390/min15050526 - 15 May 2025
Viewed by 343
Abstract
The uranium tailings mineral body is large and loose, and this could lead to radioactive contamination. Nuclides and heavy metals released from uranium tailings can be reduced through reinforcement treatment. The current study investigated the effect of CaCl2 solutions with the same [...] Read more.
The uranium tailings mineral body is large and loose, and this could lead to radioactive contamination. Nuclides and heavy metals released from uranium tailings can be reduced through reinforcement treatment. The current study investigated the effect of CaCl2 solutions with the same volume and different mass fractions on uranium tailing reinforcement under the premise of fixing the dosage of metakaolin, sodium hydroxide, sodium silicate, and the water reducer. It was found that, when 20.0% CaCl2 was injected, the hydration reaction occurred more efficiently, and a more uniform gel polymer was produced. The degree of polymerization was higher, as well as the degree of aggregation near macropores. A large number of closed mesopores formed on the solidified surface. The pore structure of the solidified body was significantly improved; uranium ore particles had smaller gaps between them; the solidified body was better compacted; the leaching rates of uranium and its heavy metal ions were significantly reduced; and the compressive strength of the solidified body improved. In the triaxial test, the solidified body had a strength increase of 4.7 times. In addition to SEM, XPS, and XRD, the solidified samples were analyzed. In uranium slag solidified bodies, C-S-H and C-A-H gels and C-A-S-H and N-A-S-H polymers were formed. The gel polymers were wrapped around the uranium tailing particles, resulting in an 82.6% reduction in uranium leaching and a 57.2% reduction in radon exhalation. Full article
(This article belongs to the Section Environmental Mineralogy and Biogeochemistry)
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16 pages, 7728 KiB  
Article
Modelling Leaching Using C-S-H Solid Solutions
by Niall Holmes and Mark Tyrer
Appl. Sci. 2025, 15(10), 5296; https://doi.org/10.3390/app15105296 - 9 May 2025
Viewed by 390
Abstract
Leaching from cement can lead to a loss in performance and durability and can also have an environmental impact. Therefore, it is an important aspect to consider when new cements are being developed and where concrete is to be placed that could lead [...] Read more.
Leaching from cement can lead to a loss in performance and durability and can also have an environmental impact. Therefore, it is an important aspect to consider when new cements are being developed and where concrete is to be placed that could lead to the contamination of groundwater. Calibrated thermodynamic models can provide very useful predictions in a matter of seconds for any cement-based material. However, such models need to include accurate representations of the solid-solution nature of the C-S-H gels that are included for the incongruent dissolution of calcium and silica. This study presents the calibration of a thermodynamic model employing the pH-REdox-Equilibrium geochemical software 3.8.7, written in C (PHREEQC 3.8.7), to model the change in the pH and the leaching of calcium (Ca) and silica (Si) from cement against the Ca/Si ratio and over time. The predicted concentrations of Ca and Si and the pH in the leachate were calculated using three solid-solution C-S-H gel models that were taken from the cemdata18 database, namely, CSHQ, CSH3T, and tobermorite–jennite, which have not been analysed before and show good agreement. The calibrated model was used to predict leaching from a CEM II/A-L cement and a blended CEM I + fly-ash with a cement replacement level of 35%. The effect of a sulphate environment (Na2SO4) was also analysed. Full article
(This article belongs to the Section Materials Science and Engineering)
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14 pages, 1973 KiB  
Article
Geographic Exposomics of Cardiac Troponin I Reference Intervals in Chinese Adults: Climate-Topography Coupling-Driven Spatial Prediction and Health Risk Assessment
by Tianyu Li, Jiayu Zhang, Xinfeng Zhao and Zihao Wu
Water 2025, 17(10), 1426; https://doi.org/10.3390/w17101426 - 9 May 2025
Cited by 1 | Viewed by 466 | Correction
Abstract
This study elucidates soil–climate regulatory mechanisms on regional health baselines in China and hydrogeochemical roles in cardiovascular biomarker differentiation. Utilizing data from 26,759 healthy adult samples across 286 Chinese cities/counties, seven core factors were identified via Pearson correlation analysis from 25 indicators, including [...] Read more.
This study elucidates soil–climate regulatory mechanisms on regional health baselines in China and hydrogeochemical roles in cardiovascular biomarker differentiation. Utilizing data from 26,759 healthy adult samples across 286 Chinese cities/counties, seven core factors were identified via Pearson correlation analysis from 25 indicators, including longitude (X1, r = −0.192, p = 0.009), elevation (X3, r = 0.377, p = 0.001), and precipitation (X7, r = −0.200, p = 0.006). Ridge regression analysis (R2 = 0.714) was subsequently applied to simulate predicted values for 2232 cities/counties. The synergistic effects of soil calcium sulfate content and salinity (X25) on serum cardiac troponin I (cTnI) reference values were rigorously validated, explaining 25.5% of regional cTnI elevation (ΔR2 = 0.183). The findings demonstrate that precipitation leaching and groundwater recharge processes collectively drive a 25.5% elevation in cTnI levels in northwestern regions (e.g., Nagqu, Tibet: altitude > 4500 m, annual sunshine > 3000 h) compared to southeastern areas. To mitigate salinity transport dynamics, optimization strategies targeting soil cation exchange capacity (X18/X19) were proposed, providing a theoretical foundation for designing gradient water treatment schemes in high-calcium-sulfate zones (CaSO4 > 150 mg/L). Crucially, regression equations derived from the predictive model enable the construction of a geographically stratified reference framework for cTnI in Chinese adults, with spatial analysis delineating its latitudinal (R2 = 0.83) and longitudinal (R2 = 0.88) distribution patterns. We propose targeted strategies optimizing soil cation exchange capacity to mitigate sulfate transport in groundwater, informing geographically tailored water treatment and cardiovascular disease prevention efforts. Our findings provide localized empirical evidence critical for refining WHO drinking water sulfate guidelines, demonstrating direct integration of hydrogeochemistry, water quality management, and public health. Full article
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26 pages, 12548 KiB  
Article
Sustainable Utilization of Modified Electrolytic Manganese Residue as a Cement Retarder: Workability, Mechanical Properties, Hydration Mechanisms, Leaching Toxicity, and Environmental Benefits
by Liang Tang, Jan Fořt, Robert Černý and Zhaoyi He
Buildings 2025, 15(10), 1586; https://doi.org/10.3390/buildings15101586 - 8 May 2025
Viewed by 461
Abstract
This study aims to enhance the sustainable utilization of electrolytic manganese residue (EMR), an industrial solid waste rich in sulfates and pollutants, by modifying it with appropriate proportions of granulated blast furnace slag (GBFS) and carbide slag (CS) and evaluating its potential as [...] Read more.
This study aims to enhance the sustainable utilization of electrolytic manganese residue (EMR), an industrial solid waste rich in sulfates and pollutants, by modifying it with appropriate proportions of granulated blast furnace slag (GBFS) and carbide slag (CS) and evaluating its potential as a cement retarder. The influence of both the GBFS/CS ratio and the dosage of modified EMR on the performance of cement mortar was systematically investigated, focusing on workability, mechanical properties, hydration behavior, leaching toxicity, and carbon emissions. Results showed that GBFS and CS significantly reduced pollutant concentrations in EMR while improving gypsum crystallinity. Modified EMR exhibited retarding properties, extending the initial and final setting times of cement mortar from 98 min and 226 min to 169 min and 298 min. With an 8 wt.% dosage, the 28-day compressive strength reached 58.76 MPa, a 1.3-fold increase compared to cement mortar (45.21 MPa). The content of reactive SiO2, Al2O3, Ca(OH)2, and CaSO4·2H2O promoted secondary hydration of cement and generated significant ettringite (AFt) and calcium silicate hydrate (C-S-H) gels, forming a dense microstructure. Pollutants in the modified EMR-cement mortar were reduced through precipitation, substitution, and encapsulation, meeting leaching toxicity standards. This study highlights the feasibility and environmental benefits of employing modified EMR as a cement retarder, demonstrating its potential in sustainable building materials. Full article
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