A peculiar green variety of dolomite has been described in several deposits in Europe (Miemo and Malentrata, Tuscany, Italy; Tarasp, the Grisons, Switzerland; Vučkovica, Serbia). This variety has attracted the interest of researchers and collectors for its aesthetic quality, which has led to its use as a semi-precious gemstone. In the present study, a thorough multi-method characterisation of the green dolomite sampled at the Malentrata magnesite mine (Pomarance, Tuscany, Italy) has been carried out. The investigation included X-ray powder diffraction, electron probe microanalysis, X-ray fluorescence, X-ray absorption spectroscopy, scanning electron microscopy, thermal analysis, optical spectroscopy (UV–visible–NIR), and electron paramagnetic resonance spectroscopy. As a result, two main pieces of evidence were described: (1) a peculiar reduction in cell volume, due to an anomalous excess of small-ionic-radius metal cations (i.e. Mg and Fe) with respect to Ca, and (2) the origin of the peculiar green colour, mainly determined by the Fe electronic transitions, probably in combination with those of Cr. In fact, the green dolomite of Malentrata contains aliquots of a number of environmentally relevant elements, in particular Mn, Cr, and Ni, whose mobility is consequently affected.

This study investigates potassium-L zeolite (K-L) as an adsorbent for the removal of thallium (Tl⁺) from aqueous solutions, focusing on the relationship between cation exchange and framework structural response. X-ray powder diffraction (XRPD), thermal analysis, and Rietveld refinements were employed to monitor structural modifications upon Tl⁺ uptake, combined with batch adsorption experiments to evaluate the removal performance. At low Tl⁺ uptake, only minor structural perturbations occur, mainly involving slight shifts in extra-framework cation positions and limited rearrangement of channel water molecules. At higher Tl⁺ concentrations, a measurable anisotropic expansion of the zeolite framework is observed, consistent with partial substitution of K⁺ by Tl⁺ and progressive modification of the hydration environment within the pores. Moreover, the crystallographic distribution of Tl⁺ differs from that of the original K⁺ cations, suggesting a specific site preference during the uptake process. Batch experiments reveal rapid uptake kinetics, with equilibrium reached within minutes, and high removal efficiency up to 99.5%. The adsorption behaviour is well described by the Langmuir model, with a maximum adsorption capacity of 631 mg g⁻¹. These findings highlight the coupling between ion exchange and structural flexibility in K-L zeolite and support its potential application for efficient thallium removal from contaminated water.

The widespread occurrence of pharmaceutical residues in aquatic environments necessitates the development of advanced porous materials for efficient remediation. This study investigates the adsorption mechanisms of ibuprofen and atenolol within the high-silica zeolite Y. Batch adsorption experiments demonstrated significant uptake, with loading capacities of 191.6 mg/g for ibuprofen and 273.0 mg/g for atenolol, confirming the material’s effectiveness. Using a combination of neutron and X-ray powder diffraction, complemented by Rietveld refinement and simulated annealing algorithms, we achieved the exact localization of the guest molecules. While the pristine zeolite maintains cubic symmetry $Fd\overline{3}$, the incorporation of pharmaceutical molecules induces significant residual nuclear density and anisotropic lattice distortions. To accurately model these perturbations, a systematic symmetry reduction to the acentric triclinic space group F1 was implemented. This approach enabled an ab initio refinement of the structure, revealing that drug uptake of each guest is governed by distinct chemical drivers. Ibuprofen is stabilized via steric confinement and long-range dispersive interactions. In contrast, atenolol stability is governed by electrostatic charge compensation within the zeolitic voids. Our results suggest that the final adsorption geometry is dictated by the spatial orientation of functional groups and host–guest proximity rather than molecular chirality. These results provide a microscopic model describing the fundamental host–guest interactions in FAU zeolites. This structural understanding is an essential step towards the potential use of zeolitic materials in environmental remediation and complex guest sequestration.