The full potential of glauconite-based nanocomposites as micronutrient fertilizers remains underexplored, particularly their interaction with Zn, Cu, and B. Despite the promising applications, the mechanisms of nutrient sorption and their effects on plant growth require further investigation, especially concerning structural changes and nutrient delivery efficiency. This study investigates the modification of glauconite with Zn, Cu, and B solutions to create multifunctional nanocomposites with enhanced properties. It was established that the activation process preserves the primary globular–lamellar morphology of glauconite while introducing structural changes. Nanocomposites were synthesized using chemical activation and characterized using XRD, SEM-EDS, TEM, FTIR, and BET analyses. Agrochemical tests evaluated their effects on oat growth under controlled conditions. Nanocomposites with zinc sulfate exhibited an increase in specific surface area and mesoporosity, enhancing sorption capacity and facilitating the formation of inner-sphere complexes on the mineral’s basal surface. Modification with copper led to the formation of secondary phases, such as sulfates, on the surfaces of microflakes and globules while preserving the crystalline structure with inner-sphere coordination of Cu²⁺. Boron-modified nanocomposites were characterized by localized restructuring, pore channeling, and an increase in mesopore diameter, along with the formation of outer-sphere complexes relative to the basal surface of glauconite. Thermogravimetric and calorimetric analyses with mass spectrometry revealed specific endothermic and exothermic effects, particularly in Zn-modified samples, confirming changes in dehydration energetics. Agricultural tests on oats (Avena sativa) demonstrated the effectiveness of Cu- and B-modified nanocomposites in improving plant growth parameters, including a 7% increase in plant height and a 6.4% increase in dry weight. Zn-modified nanocomposites showed high germination rates (up to 100%) at low dosages but require optimization to avoid phytotoxicity at higher concentrations. The findings highlight the potential of adapting nanocomposites for targeted nutrient release. Additionally, glauconite nanocomposites have potential applications in restoring degraded soils, treating polluted runoff, and developing slow-release agrochemical systems.

Thermal transformation of glauconite involves coupled changes in interlayer organization, octahedral-sheet geometry, and the state of structural hydroxyl groups. In this study, the structural evolution of glauconite was investigated by high-temperature in situ X-ray diffraction from 25 to 900 °C with a temperature increment of approximately 10 °C. Temperature-resolved diffraction data were collected in the low- and high-angle regions to monitor basal periodicity and the 060-related reflection, respectively. The ~10.1–10.2 Å basal periodicity persisted throughout the heating sequence, although the corresponding diffraction profile changed progressively. A transient reflection at d ≈ 4.81 Å appeared at approximately 150–160 °C, reached its maximum intensity at ~180–300 °C, and disappeared above ~340–360 °C, indicating the development of an intermediate structural state during the low-temperature transformation of glauconite. The apparent b parameter, derived from the principal maximum of the 060-related high-angle region using b = 6d₀₆₀, evolved non-monotonically over the range 9.078–9.108 Å, initially increasing to 9.096 Å by ~155 °C, decreasing to 9.084 Å at 505–575 °C, and then increasing again to 9.108 Å at 635–795 °C. These changes are consistent with successive structural relaxation, dehydroxylation-related reorganization, and subsequent post-dehydroxylation rearrangement of the 2:1 structure. FTIR and SEM-EDS observations after heating to 900 °C independently confirmed structural and morphological reorganization. The results show that temperature-resolved laboratory in situ XRD can detect transient and non-monotonic structural changes in glauconite and demonstrate the potential of this approach to investigate thermal transformations in other 2:1 phyllosilicates.

Glauconite-bearing sediments and glauconite-based mineral materials may interact with waters of contrasting pH, but the response of intact glauconite globules under static water-mineral conditions remains poorly constrained. The present study evaluated whether pH-driven interaction modifies the layered structure, crystal chemistry, and near-surface texture of natural glauconite globules while preserving their natural granular morphology. Natural glauconite was reacted with distilled water-based solutions at pH 2, 3, 4, 6, 7, 8, 9, and 10 for 1, 3, 7, 14, 30, and 60 days under static conditions. The mineral fractions were examined by X-ray diffraction, scanning electron microscopy with energy-dispersive spectroscopy, and Fourier-transform infrared spectroscopy. The results show that the 10 Å layered TOT structure of glauconite was preserved in all experimental series. Under acidic conditions (pH 2–4), a slight, steady decrease in d ₀₀₁ was observed. This decrease was accompanied by peak broadening and reduced intensity of basal reflections, signifying increased structural disorder without structural destruction. The diagnostic (060) reflection was preserved in all samples ( d ₀₆₀ = 1.508–1.514 Å), confirming the stability of the dioctahedral octahedral framework. Crystal-chemical data showed a distinct pH- and time-dependent adaptive response in the interlayer and tetrahedral domains. In acidic solutions, interlayer K decreased by ~25–45% relative to the initial composition, with maximum deviations noted after 14 days of interaction. These changes were accompanied by an increase in Al in the tetrahedral sheet (up to +0.05–0.32 a.p.f.u.) relative to the initial state. In contrast, structural and crystal-chemical changes were minimal under neutral plus alkaline conditions. Morphological changes of glauconite globules were mainly confined to near-surface zones. Overall, the results indicate that glauconite globules show high structural stability in static aqueous environments, with only limited pH-dependent structural, chemical, and near-surface modifications.