Pub Date : 2026-01-01Epub Date: 2025-10-30DOI: 10.1016/j.clay.2025.108027
Stanislav Ferdov , Zhi Lin , Rositsa Titiorenkova , Nadia Petrova , Boris Shivachev , Rositsa Nikolova
Layered hydrated titanosilicates capable of topotactic transformations are known in nature. However, their preparation in laboratory conditions is challenging. This work demonstrated the synthesis and characterization of two novel layered titanosilcates, MSA-1, Na2[Ti2Si4O12(OH)2]∙1.6H2O (C2/c, a = 27.6518(12), b = 8.68987(37), c = 5.26316(21) Å, β = 90.8916(33)o, V = 1264.501(91) Å3) and MSA-2, HTi2Si4O11(OH)(OH)2∙nH2O (n is close to 1) (C2/c, a = 26.4573(21), b = 8.75932(72), c = 5.21790(39) Å, β = 92.2808(63)o, V = 1208.28(17) Å3), structurally similar to the minerals eliseevite and punkaruaivite, respectively. These materials were synthesized at room temperature by a 2D-2D transformation of AM-4 [Na3(Na,H)Ti2O2[Si2O6]2∙2H2O] titanosilicate, a synthetic sodium counterpart of the mineral lintisite. The transformations involved a gradual lattice contraction due to the removal of Na+ cations from the interlayer space. This loss of positive charge was compensated by the protonation of underbonded framework oxygen atoms, resulting in the formation of hydroxyl groups (OH−). These OH groups were structurally integrated into the titanosilicate framework, which helped to preserve charge neutrality. Other transformations were also found by heating MSA-2 to 200 °C which led to a lattice contraction, decreased symmetry (P21/c, a = 11.9484(6), b = 8.7067(4), c = 5.2227(2) Å, β = 101.043(4)o, V = 533.26(4) Å3) and resulted in the formation of the layered titanosilicate L3 [Ti(Si2O5)(OH)(OH)]. Further heating of MSA-2 to 300 °C led to the formation of a phase similar to L3 but with a substantially smaller lattice (P21/c, a = 11.6257(8), b = 8.6809(5), c = 5.2235 Å, β = 100.906(4)o, V = 517.65(5) Å3). The MSA-2 showed high CO2 adsorption capacity.
层状水合钛硅酸盐在自然界中是已知的。然而，它们在实验室条件下的制备是具有挑战性的。本文研究了两种新型层状硅酸钛的合成和表征，MSA-1, Na2[Ti2Si4O12(OH)2]∙1.6H2O (C2/c, a = 27.6518(12), b = 8.68987(37), c = 5.26316（21） Å， β = 90.8916（33)o, V = 1264.501（91） Å3）和MSA-2， HTi2Si4O11(OH)(OH)2∙nH2O (n接近1)(C2/c, a = 26.4573(21), b = 8.75932(72), c = 5.21790（39） Å， β = 92.2808(63)o, V = 1208.28（17） Å3)，结构分别与矿物eliseevite和punkaruaivite相似。这些材料是在室温下通过AM-4 [Na3(Na，H)Ti2O2[Si2O6]2∙2H2O]硅酸钛的2D-2D转化合成的，AM-4 [Na3(Na，H)Ti2O2[Si2O6]2∙2H2O]硅酸钛是一种合成的钠对应物。转变涉及到一个渐进的晶格收缩，由于从层间空间去除Na+阳离子。这种正电荷的损失由欠键框架氧原子的质子化补偿，导致羟基（OH−）的形成。这些羟基在结构上被整合到钛硅酸盐框架中，这有助于保持电荷中性。将MSA-2加热至200°C时，还发现了其他转变，导致晶格收缩，对称性降低(P21/ C, a = 11.9484(6), b = 8.7067(4), C = 5.2227(2) Å， β = 101.043(4)o, V = 533.26(4) Å3)，并导致层状钛硅酸盐L3 [Ti(Si2O5)(OH)(OH)]的形成。将MSA-2进一步加热到300℃，形成了与L3相似的相，但晶格要小得多(P21/ C, a = 11.6257(8), b = 8.6809(5), C = 5.2235 Å， β = 100.906（4)o, V = 517.65(5) Å3）。MSA-2具有较高的CO2吸附能力。
{"title":"Topotactic route to novel layered titanosilicates via mild solution treatment of AM-4 at ambient temperature","authors":"Stanislav Ferdov , Zhi Lin , Rositsa Titiorenkova , Nadia Petrova , Boris Shivachev , Rositsa Nikolova","doi":"10.1016/j.clay.2025.108027","DOIUrl":"10.1016/j.clay.2025.108027","url":null,"abstract":"<div><div>Layered hydrated titanosilicates capable of topotactic transformations are known in nature. However, their preparation in laboratory conditions is challenging. This work demonstrated the synthesis and characterization of two novel layered titanosilcates, MSA-1, Na<sub>2</sub>[Ti<sub>2</sub>Si<sub>4</sub>O<sub>12</sub>(OH)<sub>2</sub>]∙1.6H<sub>2</sub>O (<em>C</em>2<em>/c</em>, <em>a</em> = 27.6518(12), <em>b</em> = 8.68987(37), <em>c</em> = 5.26316(21) Å, <em>β</em> = 90.8916(33)<sup>o</sup>, <em>V</em> = 1264.501(91) Å<sup>3</sup>) and MSA-2, HTi<sub>2</sub>Si<sub>4</sub>O<sub>11</sub>(OH)(OH)<sub>2</sub>∙<em>n</em>H<sub>2</sub>O (<em>n</em> is close to 1) (<em>C</em>2<em>/c</em>, <em>a</em> = 26.4573(21), <em>b</em> = 8.75932(72), <em>c</em> = 5.21790(39) Å, <em>β</em> = 92.2808(63)<sup>o</sup>, <em>V</em> = 1208.28(17) Å<sup>3</sup>), structurally similar to the minerals eliseevite and punkaruaivite, respectively. These materials were synthesized at room temperature by a 2D-2D transformation of AM-4 [Na<sub>3</sub>(Na,H)Ti<sub>2</sub>O<sub>2</sub>[Si<sub>2</sub>O<sub>6</sub>]<sub>2</sub>∙2H<sub>2</sub>O] titanosilicate, a synthetic sodium counterpart of the mineral lintisite. The transformations involved a gradual lattice contraction due to the removal of Na<sup>+</sup> cations from the interlayer space. This loss of positive charge was compensated by the protonation of underbonded framework oxygen atoms, resulting in the formation of hydroxyl groups (OH<sup>−</sup>). These OH groups were structurally integrated into the titanosilicate framework, which helped to preserve charge neutrality. Other transformations were also found by heating MSA-2 to 200 °C which led to a lattice contraction, decreased symmetry (<em>P</em>2<sub>1</sub><em>/c</em>, <em>a</em> = 11.9484(6), <em>b</em> = 8.7067(4), <em>c</em> = 5.2227(2) Å, <em>β</em> = 101.043(4)<sup>o</sup>, <em>V</em> = 533.26(4) Å<sup>3</sup>) and resulted in the formation of the layered titanosilicate L3 [Ti(Si<sub>2</sub>O<sub>5</sub>)(OH)(OH)]. Further heating of MSA-2 to 300 °C led to the formation of a phase similar to L3 but with a substantially smaller lattice (<em>P</em>2<sub>1</sub><em>/c</em>, <em>a</em> = 11.6257(8), <em>b</em> = 8.6809(5), <em>c</em> = 5.2235 Å, <em>β</em> = 100.906(4)<sup>o</sup>, <em>V</em> = 517.65(5) Å<sup>3</sup>). The MSA-2 showed high CO<sub>2</sub> adsorption capacity.</div></div>","PeriodicalId":245,"journal":{"name":"Applied Clay Science","volume":"279 ","pages":"Article 108027"},"PeriodicalIF":5.8,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145414422","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 : 2026-01-01Epub Date: 2025-11-19DOI: 10.1016/j.clay.2025.108049
Julio Gonçalvès , Lucile Rouil , Stéphane Gaboreau , Jean-Charles Robinet , Jean Talandier
The nearly century-old DLVO (Derjaguin, Landau, Verview, and Overbeek) theory decomposes the interaction forces between solid surfaces separated by a fluid into attractive and repulsive components. In its standard version, it applies beyond solid surface separation distances of around 1 nm. For sub-nanometer distances, additional so-called hydration forces were widely invoked to explain the discrepancy between theory and measurements. Alternatively to this semi-empirical approach, either the validity of the theoretical expression for the electrostatic component of the disjoining pressure, or the adaptation of the Boltzmann distribution usually considered in the application of DLVO theory are questioned. Here, it is suggested that the introduction of a hydration component whose parameters cannot be predetermined but are a matter of calibration is unnecessary. Hydration effects, introduced in the calculation of ionic concentrations, directly influence ions distributions and therefore the repulsion of adjacent electric double layers. This effect is thus part of the electrostatic component of the disjoining pressure. An analytical expression extending DLVO theory to small surface separation distances together with a simplified electrical model, both proposed here, enable reproducing data for Na-smectite. Results are also in good agreement with thermodynamic and molecular dynamics calculations. It is confirmed that the discrepancy between theory and observations is mainly due to the underestimation of counterions concentration at the mid-plane identified using an inappropriate electrical model. For ions with radii around 0.1 nm, commonly found in natural media, the standard DLVO expression can still be used, but with mid-plane concentrations calculated using an appropriate electrical model.
{"title":"Reassessment of DLVO theory at sub-nanometric scale: Application to Na-smectite","authors":"Julio Gonçalvès , Lucile Rouil , Stéphane Gaboreau , Jean-Charles Robinet , Jean Talandier","doi":"10.1016/j.clay.2025.108049","DOIUrl":"10.1016/j.clay.2025.108049","url":null,"abstract":"<div><div>The nearly century-old DLVO (Derjaguin, Landau, Verview, and Overbeek) theory decomposes the interaction forces between solid surfaces separated by a fluid into attractive and repulsive components. In its standard version, it applies beyond solid surface separation distances of around 1 nm. For sub-nanometer distances, additional so-called hydration forces were widely invoked to explain the discrepancy between theory and measurements. Alternatively to this semi-empirical approach, either the validity of the theoretical expression for the electrostatic component of the disjoining pressure, or the adaptation of the Boltzmann distribution usually considered in the application of DLVO theory are questioned. Here, it is suggested that the introduction of a hydration component whose parameters cannot be predetermined but are a matter of calibration is unnecessary. Hydration effects, introduced in the calculation of ionic concentrations, directly influence ions distributions and therefore the repulsion of adjacent electric double layers. This effect is thus part of the electrostatic component of the disjoining pressure. An analytical expression extending DLVO theory to small surface separation distances together with a simplified electrical model, both proposed here, enable reproducing data for Na-smectite. Results are also in good agreement with thermodynamic and molecular dynamics calculations. It is confirmed that the discrepancy between theory and observations is mainly due to the underestimation of counterions concentration at the mid-plane identified using an inappropriate electrical model. For ions with radii around 0.1 nm, commonly found in natural media, the standard DLVO expression can still be used, but with mid-plane concentrations calculated using an appropriate electrical model.</div></div>","PeriodicalId":245,"journal":{"name":"Applied Clay Science","volume":"279 ","pages":"Article 108049"},"PeriodicalIF":5.8,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145576434","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 : 2026-01-01Epub Date: 2025-11-11DOI: 10.1016/j.clay.2025.108028
Luís H. Oliveira , Idglan S. de Lima , Denise B. França , Albert S. Silva , Santiago Medina-Carrasco , Maria del Mar Orta , Josy A. Osajima , Maria G. Fonseca , Edson C. da Silva-Filho
Incorporating essential oils or their components into inorganic matrices has been used as a strategy to slow release of these species, reducing the rapid volatility of the oils. Thymol and carvacrol are among the essential oil components that have diverse bioactivities. This study evaluated the incorporation of thymol and carvacrol in sodium bentonite (Na-Bent) and bentonite functionalized with aminopropyltrimethoxysilane (NH2-Bent). The systems were characterized by short- and long-range structural, morphological, and thermal techniques. The agar diffusion test evaluated the antibacterial activity of the hybrids against Staphylococcus aureus and Escherichia coli. X-ray diffraction (XRD) patterns confirmed the intercalation of silane into clay and the formation of intercalation hybrids of oils in both matrices. 29Si NMR suggested covalently immobilization of the silane on clay surface. 13C nuclear magnetic resonance (13C NMR), X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared spectroscopy (FTIR) spectra indicated the presence of oils in clays and the contribution of hydrogen bonding and Van der Waals force between the species. The maximum incorporation of the compounds occurred in the silylated sample, resulting in 2.14 and 2.40 mmol g-1 for thymol and carvacrol, respectively. The silylated samples also presented a slower release profile of thymol and carvacrol compared to the Na-Bent sample. The antibacterial action that resulted in inhibition diameters was more significant than that of the positive control. The promising data also included the controlled release of thymol and carvacrol, resulting in the antibacterial action of the hybrids.
{"title":"The incorporation of thymol and carvacrol in bentonites: Influence of functionalization and the resulting antibacterial activities","authors":"Luís H. Oliveira , Idglan S. de Lima , Denise B. França , Albert S. Silva , Santiago Medina-Carrasco , Maria del Mar Orta , Josy A. Osajima , Maria G. Fonseca , Edson C. da Silva-Filho","doi":"10.1016/j.clay.2025.108028","DOIUrl":"10.1016/j.clay.2025.108028","url":null,"abstract":"<div><div>Incorporating essential oils or their components into inorganic matrices has been used as a strategy to slow release of these species, reducing the rapid volatility of the oils. Thymol and carvacrol are among the essential oil components that have diverse bioactivities. This study evaluated the incorporation of thymol and carvacrol in sodium bentonite (Na-Bent) and bentonite functionalized with aminopropyltrimethoxysilane (NH<sub>2</sub>-Bent). The systems were characterized by short- and long-range structural, morphological, and thermal techniques. The agar diffusion test evaluated the antibacterial activity of the hybrids against <em>Staphylococcus aureus</em> and <em>Escherichia coli</em>. X-ray diffraction (XRD) patterns confirmed the intercalation of silane into clay and the formation of intercalation hybrids of oils in both matrices. <sup>29</sup>Si NMR suggested covalently immobilization of the silane on clay surface. <sup>13</sup>C nuclear magnetic resonance (<sup>13</sup>C NMR), X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared spectroscopy (FTIR) spectra indicated the presence of oils in clays and the contribution of hydrogen bonding and Van der Waals force between the species. The maximum incorporation of the compounds occurred in the silylated sample, resulting in 2.14 and 2.40 mmol g<sup>-1</sup> for thymol and carvacrol, respectively. The silylated samples also presented a slower release profile of thymol and carvacrol compared to the Na-Bent sample. The antibacterial action that resulted in inhibition diameters was more significant than that of the positive control. The promising data also included the controlled release of thymol and carvacrol, resulting in the antibacterial action of the hybrids.</div></div>","PeriodicalId":245,"journal":{"name":"Applied Clay Science","volume":"279 ","pages":"Article 108028"},"PeriodicalIF":5.8,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145526238","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 : 2026-01-01Epub Date: 2025-11-20DOI: 10.1016/j.clay.2025.108053
Gianfranco Ulian, Giacomo Trondoli, Francesca Ranellucci, Giovanni Valdrè
The adsorption of phospholipids on clay minerals is an important research topic for both increasing the knowledge of prebiotic chemistry processes and the development of new biotechnological/pharmaceutical applications using natural components. However, atomic-scale information on the intimate relationship between lipids and clays is still missing in the scientific literature. The present work reports a detailed Density Functional Theory investigation of the adsorption of a simple phospholipid molecular model, i.e., 1, 2-divaleroyl-sn-glycero-3-phosphatidic acid (DVPA) and clinochlore, a phyllosilicate presenting an alternate stacking of hydrophobic brucite-like (B) and hydrophilic talc-like (TOT) layers. The results of the simulations, in absence of solvents and considering different surface coverages, showed that both substrates could condense DVPA, albeit with a general preference of the biomolecule for the B surface over the TOT one. Polar contacts were established between the DVPA and the substrates, originating mainly from the – PO4H2 group of the phospholipids. The presence of acidic (AlIII/SiIV substitutions) and basic (AlIII/MgII) Brønsted-Lowry sites on the TOT and B layers, respectively, deeply increased the adsorption strength between DVPA and the substrates. The obtained results, encompassing both the molecular conformation on the clinochlore surface and the molecule/substrate binding energy, provided further knowledge on the phospholipid-mineral interactions, which could be very useful to devise innovative applications in biotechnology and environmental fields.
{"title":"Adsorption of phospholipids onto layered silicate surface: The case of clinochlore","authors":"Gianfranco Ulian, Giacomo Trondoli, Francesca Ranellucci, Giovanni Valdrè","doi":"10.1016/j.clay.2025.108053","DOIUrl":"10.1016/j.clay.2025.108053","url":null,"abstract":"<div><div>The adsorption of phospholipids on clay minerals is an important research topic for both increasing the knowledge of prebiotic chemistry processes and the development of new biotechnological/pharmaceutical applications using natural components. However, atomic-scale information on the intimate relationship between lipids and clays is still missing in the scientific literature. The present work reports a detailed Density Functional Theory investigation of the adsorption of a simple phospholipid molecular model, i.e., 1, 2-divaleroyl-<em>sn</em>-glycero-3-phosphatidic acid (DVPA) and clinochlore, a phyllosilicate presenting an alternate stacking of hydrophobic brucite-like (B) and hydrophilic talc-like (TOT) layers. The results of the simulations, in absence of solvents and considering different surface coverages, showed that both substrates could condense DVPA, albeit with a general preference of the biomolecule for the B surface over the TOT one. Polar contacts were established between the DVPA and the substrates, originating mainly from the – PO<sub>4</sub>H<sub>2</sub> group of the phospholipids. The presence of acidic (Al<sup>III</sup>/Si<sup>IV</sup> substitutions) and basic (Al<sup>III</sup>/Mg<sup>II</sup>) Brønsted-Lowry sites on the TOT and B layers, respectively, deeply increased the adsorption strength between DVPA and the substrates. The obtained results, encompassing both the molecular conformation on the clinochlore surface and the molecule/substrate binding energy, provided further knowledge on the phospholipid-mineral interactions, which could be very useful to devise innovative applications in biotechnology and environmental fields.</div></div>","PeriodicalId":245,"journal":{"name":"Applied Clay Science","volume":"279 ","pages":"Article 108053"},"PeriodicalIF":5.8,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145576429","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 : 2026-01-01Epub Date: 2025-10-30DOI: 10.1016/j.clay.2025.108022
Ze-Wei Ke , Yu-Xin Liu , Sheng-Jie Wei , Peng Shen , Kun Yang , Yun-Min Chen , Yu-Chao Li
Per- and polyfluoroalkyl substances (PFAS) pose significant environmental and human health concerns due to their extreme persistence and bioaccumulation potential, and widespread contamination. Conventional clay-based barriers, such as geosynthetic clay liners, exhibit limited PFAS containment capabilities owing to their inherently low adsorption capacity. To overcome this challenge, this paper synthesized hexadecyltrimethylammonium-modified bentonite (HDTMA-NaB) as a high-performance adsorbent for engineered containment applications. Comprehensive batch adsorption experiments demonstrated that HDTMA-NaB achieves substantially greater PFAS adsorption capacity compared to pristine bentonite, with adsorption kinetics following a pseudo-second-order model and isotherms were well-described by both Langmuir and Freundlich models. Molecular dynamics simulations unveiled a distinctive “head-attracted, tail-parallel” adsorption configuration, where PFAS molecules align with HDTMA surfactants within montmorillonite interlayers. Chain-length-dependent adsorption patterns were observed, with short-chain PFAS preferentially adsorbing at clay particle edges while long-chain PFAS penetrated deeper into interlayer spaces. Potential of mean force analysis quantitatively verified stronger adsorption affinity for long-chain PFAS, consistent with adsorption experiment observations, through deeper and more numerous energy minima. Thermodynamic analysis indicated that PFAS adsorption was driven by both enthalpic and entropic contributions, with entropy playing the dominant role. The entropic contribution primarily arose from hydrophobic interactions between PFAS fluorinated carbon chains and HDTMA alkyl chains, providing a mechanistic explanation for the observed chain-length-dependent adsorption behavior in adsorption experiments. Meanwhile, the enthalpic contribution arose from electrostatic attraction between PFAS anionic headgroups and HDTMA cationic trimethylammonium groups. These molecular-scale insights provide a fundamental basis for designing high-performance clay-based containment systems for PFAS mitigation.
{"title":"Hexadecyltrimethylammonium-modified bentonite for enhanced adsorption of per- and polyfluoroalkyl substances: Experiment and thermodynamic mechanism","authors":"Ze-Wei Ke , Yu-Xin Liu , Sheng-Jie Wei , Peng Shen , Kun Yang , Yun-Min Chen , Yu-Chao Li","doi":"10.1016/j.clay.2025.108022","DOIUrl":"10.1016/j.clay.2025.108022","url":null,"abstract":"<div><div><em>Per</em>- and polyfluoroalkyl substances (PFAS) pose significant environmental and human health concerns due to their extreme persistence and bioaccumulation potential, and widespread contamination. Conventional clay-based barriers, such as geosynthetic clay liners, exhibit limited PFAS containment capabilities owing to their inherently low adsorption capacity. To overcome this challenge, this paper synthesized hexadecyltrimethylammonium-modified bentonite (HDTMA-NaB) as a high-performance adsorbent for engineered containment applications. Comprehensive batch adsorption experiments demonstrated that HDTMA-NaB achieves substantially greater PFAS adsorption capacity compared to pristine bentonite, with adsorption kinetics following a pseudo-second-order model and isotherms were well-described by both Langmuir and Freundlich models. Molecular dynamics simulations unveiled a distinctive “head-attracted, tail-parallel” adsorption configuration, where PFAS molecules align with HDTMA surfactants within montmorillonite interlayers. Chain-length-dependent adsorption patterns were observed, with short-chain PFAS preferentially adsorbing at clay particle edges while long-chain PFAS penetrated deeper into interlayer spaces. Potential of mean force analysis quantitatively verified stronger adsorption affinity for long-chain PFAS, consistent with adsorption experiment observations, through deeper and more numerous energy minima. Thermodynamic analysis indicated that PFAS adsorption was driven by both enthalpic and entropic contributions, with entropy playing the dominant role. The entropic contribution primarily arose from hydrophobic interactions between PFAS fluorinated carbon chains and HDTMA alkyl chains, providing a mechanistic explanation for the observed chain-length-dependent adsorption behavior in adsorption experiments. Meanwhile, the enthalpic contribution arose from electrostatic attraction between PFAS anionic headgroups and HDTMA cationic trimethylammonium groups. These molecular-scale insights provide a fundamental basis for designing high-performance clay-based containment systems for PFAS mitigation.</div></div>","PeriodicalId":245,"journal":{"name":"Applied Clay Science","volume":"279 ","pages":"Article 108022"},"PeriodicalIF":5.8,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145414421","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 : 2026-01-01Epub Date: 2025-11-06DOI: 10.1016/j.clay.2025.108031
Ramon Machado Loureiro , David Lukas de Arruda , Artur Henrique Nascimento da Silva , Marcelo Metri Corrêa , Danilo de Lima Camêlo
The mineralogical composition of the clay fraction plays a fundamental role in the chemical evolution and natural fertility of tropical soils, particularly in mountainous environments where intense weathering interacts with slope-driven lateral fluxes. This study investigated the mineralogical transformations and pedogenetic processes that govern soil fertility in residual soils developed from syenogranite in the Caparaó mountain region, southeastern Brazil. An integrated analytical approach was employed, including X-ray diffraction (Newmod II modeling), geochemical mass balance (τ), specific surface area, and micromorphological characterization. Although kaolinite is the dominant clay mineral across profiles, surface horizons contained appreciable proportions of interstratified 2:1 clay minerals, including illite–vermiculite and kaolinite–illite, indicating ongoing transformation of primary micas (biotite > > muscovite). The progressive alteration of biotite, mainly in B horizons, together with positive τ values for Si and exchangeable bases in A and C horizons, reflects the combined action of vertical differentiation and colluvial renewal. The latter, through selective supply of weatherable minerals from upslope lithological sources, sustains the formation of more reactive clay phases, enhances cation exchange capacity, and contributes to nutrient retention even under advanced weathering conditions. Micromorphological evidence of clay coatings, b-fabrics, Fe/Mn hypo- and quasi-coatings, and mangano-ferruginous nodules supports the co-occurrence of limited clay illuviation and redox-mediated Fe/Mn redistribution, particularly in Bt and Bw horizons. These pedofeatures indicate the interplay between vertically driven differentiation and slope-controlled hydrological and redox oscillations. Altogether, the results demonstrate that the natural fertility of these tropical mountain soils is sustained by the integrated operation of vertical and lateral processes, which together maintain dynamic mineralogical renewal, chemical resilience, and long-term fertility, a mechanism particularly relevant for low-input agricultural systems such as specialty coffee production in southeastern Brazil.
{"title":"Mineralogical drivers of fertility and pedogenetic processes in tropical mountain soils of southeastern Brazil","authors":"Ramon Machado Loureiro , David Lukas de Arruda , Artur Henrique Nascimento da Silva , Marcelo Metri Corrêa , Danilo de Lima Camêlo","doi":"10.1016/j.clay.2025.108031","DOIUrl":"10.1016/j.clay.2025.108031","url":null,"abstract":"<div><div>The mineralogical composition of the clay fraction plays a fundamental role in the chemical evolution and natural fertility of tropical soils, particularly in mountainous environments where intense weathering interacts with slope-driven lateral fluxes. This study investigated the mineralogical transformations and pedogenetic processes that govern soil fertility in residual soils developed from syenogranite in the Caparaó mountain region, southeastern Brazil. An integrated analytical approach was employed, including X-ray diffraction (Newmod II modeling), geochemical mass balance (τ), specific surface area, and micromorphological characterization. Although kaolinite is the dominant clay mineral across profiles, surface horizons contained appreciable proportions of interstratified 2:1 clay minerals, including illite–vermiculite and kaolinite–illite, indicating ongoing transformation of primary micas (biotite > > muscovite). The progressive alteration of biotite, mainly in B horizons, together with positive τ values for Si and exchangeable bases in A and C horizons, reflects the combined action of vertical differentiation and colluvial renewal. The latter, through selective supply of weatherable minerals from upslope lithological sources, sustains the formation of more reactive clay phases, enhances cation exchange capacity, and contributes to nutrient retention even under advanced weathering conditions. Micromorphological evidence of clay coatings, b-fabrics, Fe/Mn hypo- and quasi-coatings, and mangano-ferruginous nodules supports the co-occurrence of limited clay illuviation and redox-mediated Fe/Mn redistribution, particularly in Bt and Bw horizons. These pedofeatures indicate the interplay between vertically driven differentiation and slope-controlled hydrological and redox oscillations. Altogether, the results demonstrate that the natural fertility of these tropical mountain soils is sustained by the integrated operation of vertical and lateral processes, which together maintain dynamic mineralogical renewal, chemical resilience, and long-term fertility, a mechanism particularly relevant for low-input agricultural systems such as specialty coffee production in southeastern Brazil.</div></div>","PeriodicalId":245,"journal":{"name":"Applied Clay Science","volume":"279 ","pages":"Article 108031"},"PeriodicalIF":5.8,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145463834","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 : 2026-01-01Epub Date: 2025-11-03DOI: 10.1016/j.clay.2025.108030
Jintao Li , Qinfu Liu , Kuo Li , Yakui Li , Naisheng Jiang
Utilizing kaolinitic coal gangue as raw material for cordierite synthesis presents substantial implications for environmental sustainability, economic viability, and technological advancement in coal mining areas. This study systematically investigated the crystalline phase evolution during thermal treatment of kaolinitic coal gangue (Ningwu Coalfield, Shanxi, China) with 0–20 wt% MgO doping. Characterization by multiple analytical methods (X-ray diffraction, differential scanning calorimetry, scanning electron microscopy, and high-resolution transmission electron microscopy) revealed distinct crystalline phase transformation pathways. Undoped systems exhibited sequential phase transitions from kaolinite to metakaolinite and ultimately to mullite. In MgO-doped systems, MgO preferentially reacts with amorphous SiO₂ and amorphous Al₂O₃ derived from high-temperature phase transformation of kaolinite/boehmite, initiating spinel and forsterite formation while competitively reducing mullite crystallization. Mullite serves as a critical intermediate phase for cordierite formation, supplying the essential aluminum required for its crystallization. MgO-doped systems exhibited three cordierite crystallization pathways governed by MgO content: (i) Spinel reacts with silica to form cordierite; (ii) Forsterite combines with mullite and silica to form cordierite under Mg-deficient conditions; (iii) Forsterite converting to enstatite, then reacting with mullite and silica to yield cordierite under Mg-enriched conditions. Furthermore, optimal cordierite yield was achieved at 10–15 wt% MgO. These findings validate coal gangue as a viable precursor for high-value ceramic production, proposing an innovative waste-to-resource strategy for the coal industry.
{"title":"Effect of MgO content on high-temperature phase transformation of kaolinitic coal gangue and on the production of cordierite","authors":"Jintao Li , Qinfu Liu , Kuo Li , Yakui Li , Naisheng Jiang","doi":"10.1016/j.clay.2025.108030","DOIUrl":"10.1016/j.clay.2025.108030","url":null,"abstract":"<div><div>Utilizing kaolinitic coal gangue as raw material for cordierite synthesis presents substantial implications for environmental sustainability, economic viability, and technological advancement in coal mining areas. This study systematically investigated the crystalline phase evolution during thermal treatment of kaolinitic coal gangue (Ningwu Coalfield, Shanxi, China) with 0–20 wt% MgO doping. Characterization by multiple analytical methods (X-ray diffraction, differential scanning calorimetry, scanning electron microscopy, and high-resolution transmission electron microscopy) revealed distinct crystalline phase transformation pathways. Undoped systems exhibited sequential phase transitions from kaolinite to metakaolinite and ultimately to mullite. In MgO-doped systems, MgO preferentially reacts with amorphous SiO₂ and amorphous Al₂O₃ derived from high-temperature phase transformation of kaolinite/boehmite, initiating spinel and forsterite formation while competitively reducing mullite crystallization. Mullite serves as a critical intermediate phase for cordierite formation, supplying the essential aluminum required for its crystallization. MgO-doped systems exhibited three cordierite crystallization pathways governed by MgO content: (i) Spinel reacts with silica to form cordierite; (ii) Forsterite combines with mullite and silica to form cordierite under Mg-deficient conditions; (iii) Forsterite converting to enstatite, then reacting with mullite and silica to yield cordierite under Mg-enriched conditions. Furthermore, optimal cordierite yield was achieved at 10–15 wt% MgO. These findings validate coal gangue as a viable precursor for high-value ceramic production, proposing an innovative waste-to-resource strategy for the coal industry.</div></div>","PeriodicalId":245,"journal":{"name":"Applied Clay Science","volume":"279 ","pages":"Article 108030"},"PeriodicalIF":5.8,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145463833","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 : 2026-01-01Epub Date: 2025-10-28DOI: 10.1016/j.clay.2025.108026
Derui Chen , Chao Sun , Keying Sun , Mingyu Yan , Shunyu Han , Longbin Xu , Xinyu Li , Yongri Liang
Eliminating organic dyes and heavy metal ions remains challenging in environmental remediation. Hectorite shows promise for this application due to its layered structure and negative surface charge, but conventional energy-intensive hydrothermal synthesis hinders scalable production. Herein, we develop a novel steam-assisted crystallization (SAC) strategy to synthesize mesoporous hectorite from leached natural clay. This one-step approach significantly reduces solvent use and energy requirements. According to the Langmuir model, the material exhibits exceptional adsorption capacities for methylene blue (MB, 603.3 mg·g−1) and copper ions (Cu2+, 68.72 mg·g−1), surpassing conventional adsorbents. Rapid equilibrium is achieved within 10 min (MB) and 5 min (Cu2+), facilitated by the abundance of active sites and mesoporous structure. MB adsorption involves electrostatic interactions, hydrogen bonding, and ion exchange, while Cu2+ uptake occurs primarily via complexation with secondary electrostatic contributions. This work enables the sustainable utilization of natural clay resources and the green, scalable production of high-performance mesoporous hectorite adsorbents.
{"title":"Steam-assisted-crystallization synthesis of mesoporous hectorite: A universal adsorbent for rapid capture of methylene blue and copper ions","authors":"Derui Chen , Chao Sun , Keying Sun , Mingyu Yan , Shunyu Han , Longbin Xu , Xinyu Li , Yongri Liang","doi":"10.1016/j.clay.2025.108026","DOIUrl":"10.1016/j.clay.2025.108026","url":null,"abstract":"<div><div>Eliminating organic dyes and heavy metal ions remains challenging in environmental remediation. Hectorite shows promise for this application due to its layered structure and negative surface charge, but conventional energy-intensive hydrothermal synthesis hinders scalable production. Herein, we develop a novel steam-assisted crystallization (SAC) strategy to synthesize mesoporous hectorite from leached natural clay. This one-step approach significantly reduces solvent use and energy requirements. According to the Langmuir model, the material exhibits exceptional adsorption capacities for methylene blue (MB, 603.3 mg·g<sup>−1</sup>) and copper ions (Cu<sup>2+</sup>, 68.72 mg·g<sup>−1</sup>), surpassing conventional adsorbents. Rapid equilibrium is achieved within 10 min (MB) and 5 min (Cu<sup>2+</sup>), facilitated by the abundance of active sites and mesoporous structure. MB adsorption involves electrostatic interactions, hydrogen bonding, and ion exchange, while Cu<sup>2+</sup> uptake occurs primarily via complexation with secondary electrostatic contributions. This work enables the sustainable utilization of natural clay resources and the green, scalable production of high-performance mesoporous hectorite adsorbents.</div></div>","PeriodicalId":245,"journal":{"name":"Applied Clay Science","volume":"279 ","pages":"Article 108026"},"PeriodicalIF":5.8,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145414420","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 : 2026-01-01Epub Date: 2025-11-19DOI: 10.1016/j.clay.2025.108056
Pierre Picot, Frédéric Gobeaux, Antoine Thill
Well-defined allophane nanospheres, with internal and external diameters of 3.0 and 3.9 nm, respectively, were successfully synthesized and characterized by cryo-TEM, SAXS, and IR spectroscopy. In addition, we propose a refined structural framework, clarifying the coexistence of open and closed imogolite- local structures, which are commonly grouped together under the term allophane.
{"title":"Synthesis of well-defined allophane nanospheres","authors":"Pierre Picot, Frédéric Gobeaux, Antoine Thill","doi":"10.1016/j.clay.2025.108056","DOIUrl":"10.1016/j.clay.2025.108056","url":null,"abstract":"<div><div>Well-defined allophane nanospheres, with internal and external diameters of 3.0 and 3.9 nm, respectively, were successfully synthesized and characterized by cryo-TEM, SAXS, and IR spectroscopy. In addition, we propose a refined structural framework, clarifying the coexistence of open and closed imogolite- local structures, which are commonly grouped together under the term <em>allophane</em>.</div></div>","PeriodicalId":245,"journal":{"name":"Applied Clay Science","volume":"279 ","pages":"Article 108056"},"PeriodicalIF":5.8,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145576171","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 : 2026-01-01Epub Date: 2025-10-24DOI: 10.1016/j.clay.2025.108024
Ahmed Yahya , Sherif Allam , Ola N. Almasarawi , Salwa A.M. Abdel-Hameed , Bastian Raab , AbdelMonem Soltan , Esmat M.A. Hamzawy
Lithium aluminosilicates glass ceramics were prepared from quarried kaolin and artificial lithium carbonate. Different techniques were used to characterize the starting batches, glasses and glass ceramics, these are: laser PSDs, XRD, XRF, DSC, SEM-EDAX, bulk density, CTE, microhardness, FTIR, UV-Vis spectrophotometer in addition to Factsage (8.3) thermodynamic modeling software. Results show that the Al/Si ratio and total impurities of kaolin-based batches influence the crystallization of non-cracked and directly bounded coated eucryptite with shielding rims of lithium metasilicates, nepheline, leucite and silicate glassy phase. Notably, the low-grade kaolin-based batch motivates the crystallization of mature lithium aluminosilicate glass ceramics microstructure which enhances the bulk density (2.41 g/cm3), apparent porosity (0.7%), water absorption (0.29%), microhardness (394 kg/mm2), thermal expansion coefficient (₋0.76×10-7°C-1) at (25-500°C) and UV-V reflectance up to 86%. The mature microstructure with shielded rimmed eucryptite exhibits outstanding photocatalytic performance, achieving up to 92% removal of MB dye. Such lithium aluminosilicate glass ceramics could be promising in microelectronics and photocatalysis applications.
{"title":"Microstructural, physico-mechanical, optical and photocatalytic characteristics of kaolin-based eucryptite glass ceramics","authors":"Ahmed Yahya , Sherif Allam , Ola N. Almasarawi , Salwa A.M. Abdel-Hameed , Bastian Raab , AbdelMonem Soltan , Esmat M.A. Hamzawy","doi":"10.1016/j.clay.2025.108024","DOIUrl":"10.1016/j.clay.2025.108024","url":null,"abstract":"<div><div>Lithium aluminosilicates glass ceramics were prepared from quarried kaolin and artificial lithium carbonate. Different techniques were used to characterize the starting batches, glasses and glass ceramics, these are: laser PSDs, XRD, XRF, DSC, SEM-EDAX, bulk density, CTE, microhardness, FTIR, UV-Vis spectrophotometer in addition to Factsage (8.3) thermodynamic modeling software. Results show that the Al/Si ratio and total impurities of kaolin-based batches influence the crystallization of non-cracked and directly bounded coated eucryptite with shielding rims of lithium metasilicates, nepheline, leucite and silicate glassy phase. Notably, the low-grade kaolin-based batch motivates the crystallization of mature lithium aluminosilicate glass ceramics microstructure which enhances the bulk density (2.41 g/cm<sup>3</sup>), apparent porosity (0.7%), water absorption (0.29%), microhardness (394 kg/mm<sup>2</sup>), thermal expansion coefficient (₋0.76×10<sup>-7</sup>°C<sup>-1</sup>) at (25-500°C) and UV-V reflectance up to 86%. The mature microstructure with shielded rimmed eucryptite exhibits outstanding photocatalytic performance, achieving up to 92% removal of MB dye. Such lithium aluminosilicate glass ceramics could be promising in microelectronics and photocatalysis applications.</div></div>","PeriodicalId":245,"journal":{"name":"Applied Clay Science","volume":"279 ","pages":"Article 108024"},"PeriodicalIF":5.8,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145360841","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}
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