A mock-up test on decimetric scale in an innovative column test device and small-scale element tests were carried out on a German Ca/Mg bentonite, which is investigated as a suitable material for engineered barrier systems in nuclear waste disposal. Key hydro-mechanical parameters such as relative humidity, water content and swelling pressure were monitored and spatially resolved over the 30 cm height of the column in the mock-up test. The test was hydrated from the bottom and ran for 370 days. To compare the material behaviour at different scales, swelling pressure tests and water retention measurements were performed at the element-test scale. The results of the column test showed a heterogeneous evolution of swelling pressure and hydration state variables along the column height. Simultaneous measurement of vertical and radial swelling pressure indicated swelling anisotropy. Transient measurement of relative humidity and water content revealed a redistribution of porosity within the sample, which was confirmed by sampling after completion of the test. Comparison with the results of the element test showed that the two test scales are comparable in similar hydraulic states. The column test is therefore suitable as a precursor to the field test and provides valuable insights into the spatially and temporally resolved hydration behaviour of a buffer material, which helps for the design of in-situ experiments, the validation of numerical models and supports the overall process understanding.
{"title":"Swelling behaviour of compacted Ca/Mg bentonite during hydration on different scales","authors":"Antonia Nitsch , Ali Asaad , Torsten Wichtmann , Katja Emmerich , Wiebke Baille","doi":"10.1016/j.clay.2025.108067","DOIUrl":"10.1016/j.clay.2025.108067","url":null,"abstract":"<div><div>A mock-up test on decimetric scale in an innovative column test device and small-scale element tests were carried out on a German Ca/Mg bentonite, which is investigated as a suitable material for engineered barrier systems in nuclear waste disposal. Key hydro-mechanical parameters such as relative humidity, water content and swelling pressure were monitored and spatially resolved over the 30 cm height of the column in the mock-up test. The test was hydrated from the bottom and ran for 370 days. To compare the material behaviour at different scales, swelling pressure tests and water retention measurements were performed at the element-test scale. The results of the column test showed a heterogeneous evolution of swelling pressure and hydration state variables along the column height. Simultaneous measurement of vertical and radial swelling pressure indicated swelling anisotropy. Transient measurement of relative humidity and water content revealed a redistribution of porosity within the sample, which was confirmed by sampling after completion of the test. Comparison with the results of the element test showed that the two test scales are comparable in similar hydraulic states. The column test is therefore suitable as a precursor to the field test and provides valuable insights into the spatially and temporally resolved hydration behaviour of a buffer material, which helps for the design of in-situ experiments, the validation of numerical models and supports the overall process understanding.</div></div>","PeriodicalId":245,"journal":{"name":"Applied Clay Science","volume":"281 ","pages":"Article 108067"},"PeriodicalIF":5.8,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145683963","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-03-01Epub Date: 2025-12-05DOI: 10.1016/j.clay.2025.108084
Carlos Mota-Heredia, Jaime Cuevas, Raúl Fernández
Carbon steel and bentonite are chosen as engineered barriers for high-level radioactive waste containment in deep geological repositories, which requires an evaluation of their long-term interactions to ensure durability. Two laboratory experiments were conducted under hydrothermal gradients with steel-Ca-Mg-Na-bentonite and Na-bentonite unsaturated columns over 25 and 27 months, respectively. The experiments measured changes in the porewater distribution, the specific surface area, the cation exchange capacity of the bentonites, and the oxidation state of Fe. These were determined in different sections along the columns. Mineralogical analyses were performed using X-ray diffraction and scanning electron microscopy. The results obtained showed water saturation at the conclusion of the experimental time. The specific surface area of bentonites decreased near the steel interface, while the cation exchange capacity exhibited an overall increase. The corrosion rate decreased over time, with bentonite showing enriched Fe content within the first 3.5 mm from the steel interface. New Fe-bearing minerals, including ferri-chlorite, magnetite, hematite, maghemite, and siderite, were identified as reaction products at the steel-bentonite interface. Aqueous species are redistributed in the bentonite's porewater, increasing with time the concentrations of Na+, Ca2+, Mg2+ and SO42− and decreasing those of Fe, due to the imposed hydraulic gradient and the precipitation reactions. This study compares the evolution of these bentonite properties with a previous study at short experimental times of 1 and 6 months of reaction. These findings are relevant to deep geological disposal conditions, where bentonite influences the formation and nature of iron clay minerals over time.
{"title":"Evolution of steel-bentonite interactions under hydrothermal gradients: Mineralogical and geochemical implications for nuclear waste disposal","authors":"Carlos Mota-Heredia, Jaime Cuevas, Raúl Fernández","doi":"10.1016/j.clay.2025.108084","DOIUrl":"10.1016/j.clay.2025.108084","url":null,"abstract":"<div><div>Carbon steel and bentonite are chosen as engineered barriers for high-level radioactive waste containment in deep geological repositories, which requires an evaluation of their long-term interactions to ensure durability. Two laboratory experiments were conducted under hydrothermal gradients with steel-Ca-Mg-Na-bentonite and Na-bentonite unsaturated columns over 25 and 27 months, respectively. The experiments measured changes in the porewater distribution, the specific surface area, the cation exchange capacity of the bentonites, and the oxidation state of Fe. These were determined in different sections along the columns. Mineralogical analyses were performed using X-ray diffraction and scanning electron microscopy. The results obtained showed water saturation at the conclusion of the experimental time. The specific surface area of bentonites decreased near the steel interface, while the cation exchange capacity exhibited an overall increase. The corrosion rate decreased over time, with bentonite showing enriched Fe content within the first 3.5 mm from the steel interface. New Fe-bearing minerals, including ferri-chlorite, magnetite, hematite, maghemite, and siderite, were identified as reaction products at the steel-bentonite interface. Aqueous species are redistributed in the bentonite's porewater, increasing with time the concentrations of Na<sup>+</sup>, Ca<sup>2+</sup>, Mg<sup>2+</sup> and SO<sub>4</sub><sup>2−</sup> and decreasing those of Fe, due to the imposed hydraulic gradient and the precipitation reactions. This study compares the evolution of these bentonite properties with a previous study at short experimental times of 1 and 6 months of reaction. These findings are relevant to deep geological disposal conditions, where bentonite influences the formation and nature of iron clay minerals over time.</div></div>","PeriodicalId":245,"journal":{"name":"Applied Clay Science","volume":"281 ","pages":"Article 108084"},"PeriodicalIF":5.8,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145683965","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-03-01Epub Date: 2025-12-12DOI: 10.1016/j.clay.2025.108087
Denise Eulálio , Mariana Pires Figueiredo , Simone S. Silva , Luísa C. Rodrigues , Emanuel M. Fernandes , Albino Martins , Albina Franco , Diana Soares da Costa , Richard Landers , Fabrice Leroux , Christine Taviot-Gueho , Dalva Lúcia Araújo de Faria , Rui L. Reis , Vera Regina Leopoldo Constantino
Zinc ions and N-acetylcysteine (NAC) are bioactive agents with key physiological roles. When associated with biomacromolecules such as silk fibroin (SF), they offer a promising pathway for advanced biomedical applications. This study reports the synthesis of layered zinc hydroxide (LZH) intercalated with NAC as well as the development of LZH-NAC/SF scaffolds. The synthesis of LZH-NAC was conducted using a constant-pH method, and experimental parameters were controlled to obtain a monophasic LZH. Comprehensive structural, spectroscopic, textural, and thermal characterisation confirmed the successful intercalation of NAC into the LZH. The employed methodology enabled the production of an LZH-NAC nanomaterial with an encapsulation efficiency of approximately 80 % by mass and a loading capacity of around 30 %. To evaluate its biomedical potential, LZH-NAC/SF 3D composite scaffolds were prepared by dispersing LZH-NAC in SF solution, followed by freezing and freeze-drying. The average pore sizes observed in the scaffolds ranged from 75 to 87 μm, and the swelling capacity was approximately 1700 % after incubation in phosphate-buffered saline (pH 7.4). Cytocompatibility assays revealed that LZH-NAC/SF scaffolds supported cell viability at a zinc concentration of 0.189 mg/mL, similar to that of the SF and NAC/SF scaffolds. These results underscore the potential of LZH-NAC/SF scaffolds as multifunctional biomaterials for the controlled delivery of therapeutic agents, with significant implications for tissue engineering and drug delivery systems.
{"title":"Layered zinc hydroxide–dipeptide hybrid integrated into silk-based 3D scaffolds aiming for biomedical applications","authors":"Denise Eulálio , Mariana Pires Figueiredo , Simone S. Silva , Luísa C. Rodrigues , Emanuel M. Fernandes , Albino Martins , Albina Franco , Diana Soares da Costa , Richard Landers , Fabrice Leroux , Christine Taviot-Gueho , Dalva Lúcia Araújo de Faria , Rui L. Reis , Vera Regina Leopoldo Constantino","doi":"10.1016/j.clay.2025.108087","DOIUrl":"10.1016/j.clay.2025.108087","url":null,"abstract":"<div><div>Zinc ions and <em>N</em>-acetylcysteine (NAC) are bioactive agents with key physiological roles. When associated with biomacromolecules such as silk fibroin (SF), they offer a promising pathway for advanced biomedical applications. This study reports the synthesis of layered zinc hydroxide (LZH) intercalated with NAC as well as the development of LZH-NAC/SF scaffolds. The synthesis of LZH-NAC was conducted using a constant-pH method, and experimental parameters were controlled to obtain a monophasic LZH. Comprehensive structural, spectroscopic, textural, and thermal characterisation confirmed the successful intercalation of NAC into the LZH. The employed methodology enabled the production of an LZH-NAC nanomaterial with an encapsulation efficiency of approximately 80 % by mass and a loading capacity of around 30 %. To evaluate its biomedical potential, LZH-NAC/SF 3D composite scaffolds were prepared by dispersing LZH-NAC in SF solution, followed by freezing and freeze-drying. The average pore sizes observed in the scaffolds ranged from 75 to 87 μm, and the swelling capacity was approximately 1700 % after incubation in phosphate-buffered saline (pH 7.4). Cytocompatibility assays revealed that LZH-NAC/SF scaffolds supported cell viability at a zinc concentration of 0.189 mg/mL, similar to that of the SF and NAC/SF scaffolds. These results underscore the potential of LZH-NAC/SF scaffolds as multifunctional biomaterials for the controlled delivery of therapeutic agents, with significant implications for tissue engineering and drug delivery systems.</div></div>","PeriodicalId":245,"journal":{"name":"Applied Clay Science","volume":"281 ","pages":"Article 108087"},"PeriodicalIF":5.8,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145734457","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-03-01Epub Date: 2025-12-12DOI: 10.1016/j.clay.2025.108088
Andrea Bloise , Ilaria Fuoco , Carmine Apollaro , Giovanni Vespasiano , Ekaterina Khrapova , Andrei Krasilin
Chrysotile, the fibrous form of serpentine, is characterized by the chemical formula Mg3Si2O5(OH)4. Over the past seventy years, significant research has focused on synthesizing chrysotile, initially for petrological studies and more recently for applications in nanotechnology, particularly high-purity chrysotile nanotubes and doped variants. Common synthesis methods involve hydrothermal reactions using cristobalite and periclase or magnesium hydroxide and silica gel mixtures. Most frequently used synthesis conditions generally include temperatures between 200 °C and 400 °C and pressures from 0.5 to 100 MPa, though these often result in impure chrysotile with unwanted phases. Despite the promise of doped chrysotile, natural fibers are often unsuitable for nanoscience due to foreign ions and mineral intergrowths. Recent studies explore the potential for creating isomorphic series as Mg3Si2O5(OH)4 – Ni3Si2O5(OH)4 or Mg3Si2O5(OH)4 - (Fe2+, Fe3+)3-2Si2O5(OH)4, examining the impact of nickel and iron on chrysotile's properties. This study provides a review of the reported synthesis methods for chrysotile, emphasizing the synthesis techniques, precursor materials, and the resulting crystal chemistry. The findings highlight the dynamic nature of chrysotile synthesis research, with implications for materials science, including the development of novel nanostructures and environmental remediation technologies.
{"title":"Retrospective of chrysotile synthesis: From tough geoinspired process up to soft chemical design","authors":"Andrea Bloise , Ilaria Fuoco , Carmine Apollaro , Giovanni Vespasiano , Ekaterina Khrapova , Andrei Krasilin","doi":"10.1016/j.clay.2025.108088","DOIUrl":"10.1016/j.clay.2025.108088","url":null,"abstract":"<div><div>Chrysotile, the fibrous form of serpentine, is characterized by the chemical formula Mg<sub>3</sub>Si<sub>2</sub>O<sub>5</sub>(OH)<sub>4</sub>. Over the past seventy years, significant research has focused on synthesizing chrysotile, initially for petrological studies and more recently for applications in nanotechnology, particularly high-purity chrysotile nanotubes and doped variants. Common synthesis methods involve hydrothermal reactions using cristobalite and periclase or magnesium hydroxide and silica gel mixtures. Most frequently used synthesis conditions generally include temperatures between 200 °C and 400 °C and pressures from 0.5 to 100 MPa, though these often result in impure chrysotile with unwanted phases. Despite the promise of doped chrysotile, natural fibers are often unsuitable for nanoscience due to foreign ions and mineral intergrowths. Recent studies explore the potential for creating isomorphic series as Mg<sub>3</sub>Si<sub>2</sub>O<sub>5</sub>(OH)<sub>4</sub> – Ni<sub>3</sub>Si<sub>2</sub>O<sub>5</sub>(OH)<sub>4</sub> or Mg<sub>3</sub>Si<sub>2</sub>O<sub>5</sub>(OH)<sub>4</sub> - (Fe<sup>2+</sup>, Fe<sup>3+</sup>)<sub>3-2</sub>Si<sub>2</sub>O<sub>5</sub>(OH)<sub>4</sub>, examining the impact of nickel and iron on chrysotile's properties. This study provides a review of the reported synthesis methods for chrysotile, emphasizing the synthesis techniques, precursor materials, and the resulting crystal chemistry. The findings highlight the dynamic nature of chrysotile synthesis research, with implications for materials science, including the development of novel nanostructures and environmental remediation technologies.</div></div>","PeriodicalId":245,"journal":{"name":"Applied Clay Science","volume":"281 ","pages":"Article 108088"},"PeriodicalIF":5.8,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145734948","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-03-01Epub Date: 2025-12-02DOI: 10.1016/j.clay.2025.108062
Balamurugan Senthil Kumar , Raja Nehru , Cheng-Di Dong
Sulfamerazine (SMR), a widely used sulfonamide antibiotic, has become a significant pollutant in surface water, posing risks to ecosystems and human health. This study presents the development of an innovative electrochemical sensor for detecting SMR in environmental water samples, addressing a critical need for sustainable water monitoring technologies. A composite material based on polypyrrole (PPy) and halloysite nanotubes (HNTs) was synthesized and characterized using comprehensive physicochemical and electrochemical analyses. The polypyrrole decorated halloysite nanotubes (HNT/PPy) composite demonstrated an exceptional electrochemically active surface area, enhanced charge transfer, and superior electrocatalytic performance. The glassy carbon electrode (GCE) modified composite enabled highly sensitive and selective detection of SMR across a broad linear range (0.005–601.985 μM) with a low detection limit (LOD) of 29 nM. The sensor exhibited excellent reproducibility, stability, and anti-interference properties in complex matrices, underscoring its robustness for practical applications. The affordability and scalability of the HNT/PPy composite offer a cost-effective solution for environmental monitoring.
{"title":"The electrochemical sensor for sulfamerazine detection in water based on polypyrrole-decorated halloysite nanotubes","authors":"Balamurugan Senthil Kumar , Raja Nehru , Cheng-Di Dong","doi":"10.1016/j.clay.2025.108062","DOIUrl":"10.1016/j.clay.2025.108062","url":null,"abstract":"<div><div>Sulfamerazine (SMR), a widely used sulfonamide antibiotic, has become a significant pollutant in surface water, posing risks to ecosystems and human health. This study presents the development of an innovative electrochemical sensor for detecting SMR in environmental water samples, addressing a critical need for sustainable water monitoring technologies. A composite material based on polypyrrole (PPy) and halloysite nanotubes (HNTs) was synthesized and characterized using comprehensive physicochemical and electrochemical analyses. The polypyrrole decorated halloysite nanotubes (HNT/PPy) composite demonstrated an exceptional electrochemically active surface area, enhanced charge transfer, and superior electrocatalytic performance. The glassy carbon electrode (GCE) modified composite enabled highly sensitive and selective detection of SMR across a broad linear range (0.005–601.985 μM) with a low detection limit (LOD) of 29 nM. The sensor exhibited excellent reproducibility, stability, and anti-interference properties in complex matrices, underscoring its robustness for practical applications. The affordability and scalability of the HNT/PPy composite offer a cost-effective solution for environmental monitoring.</div></div>","PeriodicalId":245,"journal":{"name":"Applied Clay Science","volume":"281 ","pages":"Article 108062"},"PeriodicalIF":5.8,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145651705","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
For the geological disposal of high-level radioactive waste (HLW), maintaining a buffer density after emplacement in a disposal pit is crucial. Given the abundance of groundwater in Japan, it is necessary to estimate the amount of eroded bentonite from the buffer due to groundwater inflows. Previous quantitative evaluations have been based on the cumulative amount of eroded bentonite, making it difficult to generalize the results.
In this study, bentonite piping erosion was directly measured and quantitatively evaluated using spectrophotometry and X-ray computed tomography (CT). Piping erosion tests were performed by placing the simulated buffer block samples in polycarbonate cells, with deionized water injected from the bottom to the top. After piping developed and stabilized, X-ray CT measurements were conducted to obtain density distribution information and extract piping geometry. Furthermore, the concentration of eroded bentonite in outlet solutions was determined using spectrophotometry. The apparent erosion rate constant (i.e., specific erosion rate) of bentonite was calculated based on X-ray CT measurements and analysis of outlet solutions.
The tests confirmed a strong correlation between water flow rate and actual arc length of piping in the horizontal cross-section, as well as a negative correlation between water flow rate and effluent bentonite concentration. Based on these test results, the apparent erosion rate constants of bentonite remained nearly constant regardless of the water flow rate. Additionally, similar results were obtained when using samples with different montmorillonite content ratios. These findings suggest that the apparent erosion rate constant can be used to estimate the amount of bentonite erosion. Furthermore, this study demonstrates that X-ray CT is a highly effective non-destructive tool for understanding bentonite behavior in buffer materials and providing time-dependent data.
{"title":"Measuring piping erosion rate in bentonite using spectrophotometry and X-ray computed tomography","authors":"Norihisa Osawa , Tomoko Ishii , Kenji Ishii , Yuichi Niibori","doi":"10.1016/j.clay.2025.108065","DOIUrl":"10.1016/j.clay.2025.108065","url":null,"abstract":"<div><div>For the geological disposal of high-level radioactive waste (HLW), maintaining a buffer density after emplacement in a disposal pit is crucial. Given the abundance of groundwater in Japan, it is necessary to estimate the amount of eroded bentonite from the buffer due to groundwater inflows. Previous quantitative evaluations have been based on the cumulative amount of eroded bentonite, making it difficult to generalize the results.</div><div>In this study, bentonite piping erosion was directly measured and quantitatively evaluated using spectrophotometry and X-ray computed tomography (CT). Piping erosion tests were performed by placing the simulated buffer block samples in polycarbonate cells, with deionized water injected from the bottom to the top. After piping developed and stabilized, X-ray CT measurements were conducted to obtain density distribution information and extract piping geometry. Furthermore, the concentration of eroded bentonite in outlet solutions was determined using spectrophotometry. The apparent erosion rate constant (i.e., specific erosion rate) of bentonite was calculated based on X-ray CT measurements and analysis of outlet solutions.</div><div>The tests confirmed a strong correlation between water flow rate and actual arc length of piping in the horizontal cross-section, as well as a negative correlation between water flow rate and effluent bentonite concentration. Based on these test results, the apparent erosion rate constants of bentonite remained nearly constant regardless of the water flow rate. Additionally, similar results were obtained when using samples with different montmorillonite content ratios. These findings suggest that the apparent erosion rate constant can be used to estimate the amount of bentonite erosion. Furthermore, this study demonstrates that X-ray CT is a highly effective non-destructive tool for understanding bentonite behavior in buffer materials and providing time-dependent data.</div></div>","PeriodicalId":245,"journal":{"name":"Applied Clay Science","volume":"280 ","pages":"Article 108065"},"PeriodicalIF":5.8,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145616140","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-02-01Epub Date: 2025-11-26DOI: 10.1016/j.clay.2025.108050
Haonan Zhao , Kunyue Ling , Yi Cao , Xuefei Liu , Lin Xu , Shuilong Wang , Wenbin Yu , Hanjie Wen
Granite-type lithium deposits are an important global Li resource and occur widely in South China. Thick regolith layers on Li-rich granites enrich Li to industrial-grade levels, with some containing up to 1.0 wt% Li2O, double the content of the underlying granite. Lithium is highly mobile in the supergene environment, commonly leaching from primary minerals during weathering. However, the mechanism of Li enrichment in granite regolith is enigmatic. Lithium-rich muscovite is the predominant Li-bearing mineral in granite and its weathered regolith in the Xikeng Li deposit in northwest Jiangxi, South China. High resolution techniques (time-of-fight secondary-ion mass spectrometry and high resolution transmission electron microscopy) reveal that the higher Li content in the regolith relative to that in the granite is attributed to the strong resistance of Li-rich muscovite to weathering and the neoformation of cookeite (Li-bearing chlorite) under moderate weathering conditions. Cookeite was formed from muscovite alteration through solid-state transformation during granite weathering. These findings highlight the importance of weathering-induced Li mineralization on Li-rich granites, driven by the different weathering behaviours of the main granite minerals. The principal Li-bearing minerals in granites of South China, such as muscovite and lepidolite, have structures and weathering resistance similar to those of Li-rich muscovite. It follows that moderately weathered regolith developed on Li-rich granites has significant potential as an exploration target for regolith-hosted Li deposits.
{"title":"Weathering-induced lithium mineralization on granite in South China: Li-rich muscovite accumulation and cookeite neoformation","authors":"Haonan Zhao , Kunyue Ling , Yi Cao , Xuefei Liu , Lin Xu , Shuilong Wang , Wenbin Yu , Hanjie Wen","doi":"10.1016/j.clay.2025.108050","DOIUrl":"10.1016/j.clay.2025.108050","url":null,"abstract":"<div><div>Granite-type lithium deposits are an important global Li resource and occur widely in South China. Thick regolith layers on Li-rich granites enrich Li to industrial-grade levels, with some containing up to 1.0 wt% Li<sub>2</sub>O, double the content of the underlying granite. Lithium is highly mobile in the supergene environment, commonly leaching from primary minerals during weathering. However, the mechanism of Li enrichment in granite regolith is enigmatic. Lithium-rich muscovite is the predominant Li-bearing mineral in granite and its weathered regolith in the Xikeng Li deposit in northwest Jiangxi, South China. High resolution techniques (time-of-fight secondary-ion mass spectrometry and high resolution transmission electron microscopy) reveal that the higher Li content in the regolith relative to that in the granite is attributed to the strong resistance of Li-rich muscovite to weathering and the neoformation of cookeite (Li-bearing chlorite) under moderate weathering conditions. Cookeite was formed from muscovite alteration through solid-state transformation during granite weathering. These findings highlight the importance of weathering-induced Li mineralization on Li-rich granites, driven by the different weathering behaviours of the main granite minerals. The principal Li-bearing minerals in granites of South China, such as muscovite and lepidolite, have structures and weathering resistance similar to those of Li-rich muscovite. It follows that moderately weathered regolith developed on Li-rich granites has significant potential as an exploration target for regolith-hosted Li deposits.</div></div>","PeriodicalId":245,"journal":{"name":"Applied Clay Science","volume":"280 ","pages":"Article 108050"},"PeriodicalIF":5.8,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145616301","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This study investigated the speciation of hexavalent chromium (Cr(VI)) anion when inserted in layered double hydroxides (LDH). Nitrated magnesium/aluminum (Mg/Al-NO3) LDH nanoparticles (NP) were synthesized via fast coprecipitation followed by hydrothermal treatment with a Mg/Al molar ratio of 2. The saturation with hexavalent chromium (Cr(VI)) was easily performed by mixing the colloidal dispersion of LDH NP and a solution of chromate ion. Comprehensive characterization using powder X-ray diffraction (PXRD), Raman, Fourier-transform infrared (FTIR), and X-ray photoelectron spectroscopies, scanning electron microscopy (SEM) and transmission electron microscopy (TEM), thermogravimetric analysis (TGA) were performed on LDH nanoparticles in dry state. Ultraviolet-visible spectroscopy (UV–vis) captured the evolution of the Cr(VI) speciation during the hydration of the solid into colloidal aqueous suspension. The structural characterization data of both hydrated CrO42−-LDH in colloidal state and dried Cr2O72−-LDH nanoparticles in the solid state was interpreted with the help of density functional theory (DFT) calculation.
Cr(VI) was demonstrated to keep its oxidation state and remain in the interlamellar space and not inserted in the cationic layer. The existence of Cr2O72− along with CrO42− in the dry state was unexpected, particularly when it was surrounded by hydroxide molecules in the interlamellar space of LDH, as this species is known to exist only in acidic solution. CrO42− became fully predominant upon hydration, indicating that study only on the dry solid, usually performed, could not be used to explain phenomenon in wet conditions such as the ionic exchange in LDH.
{"title":"Condensation of chromate into dichromate within magnesium/aluminum layered double hydroxide: An experimental and theoretical study","authors":"Abdelhak Fezraoui , Damien Cornu , Gwladys Steciuk , Jaafar Ghanbaja , Marc Hebrant","doi":"10.1016/j.clay.2025.108064","DOIUrl":"10.1016/j.clay.2025.108064","url":null,"abstract":"<div><div>This study investigated the speciation of hexavalent chromium (Cr(VI)) anion when inserted in layered double hydroxides (LDH). Nitrated magnesium/aluminum (Mg/Al-NO<sub>3</sub>) LDH nanoparticles (NP) were synthesized via fast coprecipitation followed by hydrothermal treatment with a Mg/Al molar ratio of 2. The saturation with hexavalent chromium (Cr(VI)) was easily performed by mixing the colloidal dispersion of LDH NP and a solution of chromate ion. Comprehensive characterization using powder X-ray diffraction (PXRD), Raman, Fourier-transform infrared (FTIR), and X-ray photoelectron spectroscopies, scanning electron microscopy (SEM) and transmission electron microscopy (TEM), thermogravimetric analysis (TGA) were performed on LDH nanoparticles in dry state. Ultraviolet-visible spectroscopy (UV–vis) captured the evolution of the Cr(VI) speciation during the hydration of the solid into colloidal aqueous suspension. The structural characterization data of both hydrated CrO<sub>4</sub><sup>2−</sup>-LDH in colloidal state and dried Cr<sub>2</sub>O<sub>7</sub><sup>2−</sup>-LDH nanoparticles in the solid state was interpreted with the help of density functional theory (DFT) calculation.</div><div>Cr(VI) was demonstrated to keep its oxidation state and remain in the interlamellar space and not inserted in the cationic layer. The existence of Cr<sub>2</sub>O<sub>7</sub><sup>2−</sup> along with CrO<sub>4</sub><sup>2−</sup> in the dry state was unexpected, particularly when it was surrounded by hydroxide molecules in the interlamellar space of LDH, as this species is known to exist only in acidic solution. CrO<sub>4</sub><sup>2−</sup> became fully predominant upon hydration, indicating that study only on the dry solid, usually performed, could not be used to explain phenomenon in wet conditions such as the ionic exchange in LDH.</div></div>","PeriodicalId":245,"journal":{"name":"Applied Clay Science","volume":"280 ","pages":"Article 108064"},"PeriodicalIF":5.8,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145616302","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This study presents the development of a novel hydrogel formulation containing caffeic acid (CA) and Zinc‑aluminum layered double hydroxide (Zn-Al-LDH) nanohybrid, aimed at enhancing wound healing performance. The intricate process of wound healing involves various cellular interactions and the supply of essential metal ions, with hydrogels emerging as promising materials due to their ability to maintain a moist environment, absorb exudate, and facilitate painless dressing changes. The synthesized CA-LDH nanohybrid exhibited an average particle size of 345.43 ± 5.12 nm and a polydispersity index (PDI) of 0.41 ± 0.03, indicating a uniform size distribution. The encapsulation efficiency (EE %) was found to be 93.06 ± 3.64 %, with a drug loading (DL %) of 32.80 ± 1.10 %. In vivo studies using Wistar rats demonstrated that the CA-LDH/hydrogel significantly accelerated wound closure, achieving 96.57 % closure by day 14, compared to control groups. Histological assessments revealed enhanced collagen deposition and fibroblast maturation in the CA-LDH/hydrogel group. These findings suggest that the incorporation of CA into the hydrogel matrix not only improves the physicochemical properties but also significantly enhances its biological performance, highlighting the potential of CA-LDH-loaded hydrogels as innovative therapeutic options for wound management.
{"title":"Development of a novel hydrogel formulation containing caffeic acid and ZnAl layer double hydroxide intercalated nanohybrid with wound healing performance","authors":"Zahra Rezanejad-Gatabi , Vajihe Alinezhad , Fatemeh Asadi , Ghazal Mollaeian , Hamidreza Mohammadi , Rezvan Yazdian-Robati , Mehri Mirhoseini","doi":"10.1016/j.clay.2025.108059","DOIUrl":"10.1016/j.clay.2025.108059","url":null,"abstract":"<div><div>This study presents the development of a novel hydrogel formulation containing caffeic acid (CA) and Zinc‑aluminum layered double hydroxide (Zn-Al-LDH) nanohybrid, aimed at enhancing wound healing performance. The intricate process of wound healing involves various cellular interactions and the supply of essential metal ions, with hydrogels emerging as promising materials due to their ability to maintain a moist environment, absorb exudate, and facilitate painless dressing changes. The synthesized CA-LDH nanohybrid exhibited an average particle size of 345.43 ± 5.12 nm and a polydispersity index (PDI) of 0.41 ± 0.03, indicating a uniform size distribution. The encapsulation efficiency (EE %) was found to be 93.06 ± 3.64 %, with a drug loading (DL %) of 32.80 ± 1.10 %. In vivo studies using Wistar rats demonstrated that the CA-LDH/hydrogel significantly accelerated wound closure, achieving 96.57 % closure by day 14, compared to control groups. Histological assessments revealed enhanced collagen deposition and fibroblast maturation in the CA-LDH/hydrogel group. These findings suggest that the incorporation of CA into the hydrogel matrix not only improves the physicochemical properties but also significantly enhances its biological performance, highlighting the potential of CA-LDH-loaded hydrogels as innovative therapeutic options for wound management.</div></div>","PeriodicalId":245,"journal":{"name":"Applied Clay Science","volume":"280 ","pages":"Article 108059"},"PeriodicalIF":5.8,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145571115","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-02-01Epub Date: 2025-11-21DOI: 10.1016/j.clay.2025.108060
Luowen Xiang , Qiancheng Qiao , Xiumei Qiu , Sen Zhou , Hongquan Wang , Xiaoyan Zhu , Chunjie Yan , Yi Liu
Binder-free zeolite NaX foams were successfully prepared through a novel one-step geopolymer-gels-conversion approach using H2O2 solution as a foaming agent. Unlike traditional methods that utilize clay materials combined with expensive chemical SiAl reagents as precursors, metakaolin and natural clinoptilolite (mass ratio = 1:1) were selected as SiAl sources for zeolite NaX synthesis. Zeolite foams were systematically characterized and their CO2 adsorption performance was evaluated. Crystalline phases in natural clinoptilolite (clinoptilolite, albite, illite and quartz) and impurity phases in metakaolin (anatase and quartz) were found to be partially or completely dissolved during alkaline activation process. The resultant foam products exhibit hierarchical porosity, featuring macropores (∼1–2 mm) and zeolite micropores, with compressive strength of 0.83–2.6 MPa, bulk density of 0.51–0.84 g/cm3, BET surface area of 33.18–188.79 m2/g and CO2 adsorption capacity of 0.24–1.84 mmol/g (1 bar). Pure phase binder-free zeolite NaX foam with the relatively high crystallinity, suitable compressive strength (1.48 MPa), and high BET surface area (188.79 m2/g) was synthesized at SiO2/Al2O3 molar ratio = 3.4, SiO2/Na2O molar ratio = 3.8, NaOH activator concentration = 10 M, crystallization temperature of 80 °C and crystallization time of 24 h. This work presents an innovative perspective on developing clay materials as promising SiAl sources for zeolite synthesis.
{"title":"A novel green approach for the synthesis of binder-free zeolite NaX foams by joint utilization of metakaolin and clinoptilolite as Si-Al precursors","authors":"Luowen Xiang , Qiancheng Qiao , Xiumei Qiu , Sen Zhou , Hongquan Wang , Xiaoyan Zhu , Chunjie Yan , Yi Liu","doi":"10.1016/j.clay.2025.108060","DOIUrl":"10.1016/j.clay.2025.108060","url":null,"abstract":"<div><div>Binder-free zeolite NaX foams were successfully prepared through a novel one-step geopolymer-gels-conversion approach using H<sub>2</sub>O<sub>2</sub> solution as a foaming agent. Unlike traditional methods that utilize clay materials combined with expensive chemical Si<img>Al reagents as precursors, metakaolin and natural clinoptilolite (mass ratio = 1:1) were selected as Si<img>Al sources for zeolite NaX synthesis. Zeolite foams were systematically characterized and their CO<sub>2</sub> adsorption performance was evaluated. Crystalline phases in natural clinoptilolite (clinoptilolite, albite, illite and quartz) and impurity phases in metakaolin (anatase and quartz) were found to be partially or completely dissolved during alkaline activation process. The resultant foam products exhibit hierarchical porosity, featuring macropores (∼1–2 mm) and zeolite micropores, with compressive strength of 0.83–2.6 MPa, bulk density of 0.51–0.84 g/cm<sup>3</sup>, BET surface area of 33.18–188.79 m<sup>2</sup>/g and CO<sub>2</sub> adsorption capacity of 0.24–1.84 mmol/g (1 bar). Pure phase binder-free zeolite NaX foam with the relatively high crystallinity, suitable compressive strength (1.48 MPa), and high BET surface area (188.79 m<sup>2</sup>/g) was synthesized at SiO<sub>2</sub>/Al<sub>2</sub>O<sub>3</sub> molar ratio = 3.4, SiO<sub>2</sub>/Na<sub>2</sub>O molar ratio = 3.8, NaOH activator concentration = 10 M, crystallization temperature of 80 °C and crystallization time of 24 h. This work presents an innovative perspective on developing clay materials as promising Si<img>Al sources for zeolite synthesis.</div></div>","PeriodicalId":245,"journal":{"name":"Applied Clay Science","volume":"280 ","pages":"Article 108060"},"PeriodicalIF":5.8,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145571116","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}