Activation of natural sepiolite by means of grinding in a planetary mill followed by wet NaOH activation was studied for the purpose of endowing the product with enhanced basicity for potential catalytic/sorptive applications. Synthesized solids were characterized with X-ray powder diffraction (XRD), N₂ adsorption/desorption, scanning electron microscopy (SEM), energy dispersive (EDX), atomic absorption (AAS), Fourier-transform infrared (FTIR) and ²⁹Si magic angle spinning nuclear magnetic resonance (MAS NMR) spectroscopies. Surface basicity was determined by titration with benzoic acid. Grinding changed the pathway of sepiolite phase transformation upon NaOH treatment. The as-received sepiolite evolved to Na-sepiolite (loughlinite) with a micropore system blocked by nanocrystalline Mg(OH)₂, while ground samples yielded magnesium silicate hydrate phase (MSH), with well-developed microporous texture. In unmilled sepiolite desilication involved preferential leaching of Si from the center of the structural ribbons, while in ground samples additional loss of Si from ribbon-ribbon corner linkages was observed. In all cases treatment with NaOH led to enhancement of surface basicity. Synthesized materials were tested as catalysts in a base-catalyzed aldol self-condensation of acetone and oxidation of cyclohexanone to ε-caprolactone, as well as CO₂ sorbents. Catalytic trends depended not only on samples’ basicity, but also on texture and phase composition of the catalysts. Grinding combined with alkali activation proved a simple and effective method for boosting CO₂-sorption capacity of sepiolite to the level comparable to amine-functionalized, acid-activated sepiolite sorbents.

This paper summarizes information about recently worked bentonite deposits in Slovakia and presents the results of studies on bentonite from the Central Slovakia Volcanic Field (CSVF). The authors compared the mineralogy of commercial bentonites exploited in the Stara Kremnička (Jelšový potok), Kopernica, and Hliník nad Hronom deposits. X-ray diffraction (XRD), chemical analyses and microscopy showed that the main component is montmorillonite (37-88%), followed by opal C/CT (5-25%), clinoptilolite (up to 15%), feldspars (3-12%), quartz (up to 8%), biotite (2-5%), and kaolinite (up to 2%). The microscopic imaging provided information valuable for the technological assessment of bentonites, particularly the evaluation of mineralogy determined by XRD. The low variability of the mineral composition of commercial bentonites exploited in the western CSVF, together with the significant reserves and localization of deposits close to the Polish-Slovak state border prove that this raw material deserves more attention from Polish industry.

This study aimed at evaluation of air pollution control residues (APCR) and flue gas desulfurization residues (FGDR) from copper foundry in Southwestern Poland as adsorbents of Cu(II) and Pb(II) from simulated wastewater. Studies of the impact of pH and adsorbent dose, as well as sorption isotherms, and kinetic and thermodynamic studies were conducted in a series of batch experiments. The maximum adsorption capacities were equal to 42.9 mg g⁻¹ Cu(II) and 124.4 mg g⁻¹ Pb(II) for APCR and 98.8 mg g⁻¹ Cu(II) and 124.7 mg g⁻¹ Pb(II) for FGDR, which was comparable to mineral adsorbents examined in other studies. Adsorption isotherms followed the Langmuir model, except for Pb(II) for FGDR, which followed Freundlich model. Sorption kinetics for both materials was properly expressed by pseudo-second-order equation. Mean adsorption energy parameter suggested that the adsorption might have occurred via physical bonding. Thermodynamic study revealed that adsorption was spontaneous and endothermic for Cu(II) and not spontaneous and exothermic for Pb(II), with lower temperature favoring the process. The results suggested that both materials had high affinity towards Cu(II) and Pb(II) ions and could be conducted industrial scale research for consideration as potential adsorbents from aqueous solutions.

Structural characteristics of hydrolysates formed from the aqueous Ti-, Zr-, and Ti, Zr-pillaring solutions prepared from inorganic precursors (TiCl₄ and ZrOCl₂), was investigated and compared with that of precipitates obtained from the same solutions after a slight alkalization of pH to the values reported for the conditions of clay pillaring. The materials were recovered by lyophilization and subsequently subjected to calcination at 500, 800 and 1000 °C. Of special interest was the effect of pH on the possible formation of mixed Ti, Zr-oxide species. Powder X-ray diffraction (XRD), Raman spectroscopy and scanning electron microscope/energy dispersive spectrometer (SEM/EDS) analysis showed that even a relatively moderate alteration of pH in Ti-, Zr-, or Ti, Zr-precursor solutions caused substantial changes in the outcome of hydrolytic transformations, manifested by different phase and/or chemical composition of the resulting hydrolysates. Analysis of thermal evolution of hydrolysates showed that alkalization facilitated the transformation of anatase into rutile in materials obtained from Ti-pillaring solution, but retarded tetragonal to monoclinic zirconia conversion in samples derived from Zr-pillaring agent. The most striking effect was observed for the mixed Ti, Zr-pillaring solution, where an increase of pH enabled the formation of zirconium titanate as the only crystalline phase, rather than a multiphase mixture of anatase, monoclinic zirconia and zirconium titanate obtained from the more acidic precursor. The finding supports the model of mixed Ti-O-Zr network in props generated in Ti, Zr-pillared montmorillonites.

The problem of exposing to toxins in places frequented by people (especially children) for a longer time is an important aspect of environmental studies. Therefore, in Rabka-Zdrój, one of children health resorts, the contents of nine heavy metals, with a special focus on Cd, Pb and Zn, were determined in soils, grass, sands and dusts. The highest concentrations of Cd, Pb and Zn occur in soil samples: 2-3, 32-48 and 33-291 mg∙kg^-1, respectively. Slightly lower are the concentrations in the sands taken from sandboxes: 1-3, 25-36 and 7-20 mg∙kg^-1 of Cd, Pb and Zn, respectively. In the grass, commonly growing in playground areas, the average concentrations of the metals are: 1.8, 20 and 60 mg∙kg^-1 of Cd, Pb and Zn, respectively. While the contents of the three metals in soils and sands do not exceed natural concentrations, the contents of Cd and Pb in grass exceed the values considered natural. The urban atmospheric dusts, suspected to be the major source of pollution, were analysed for the three metals. Their ranges (in mg∙kg^-1) are: 6-15 for Cd, 80-215 for Pb and 104-260 for Zn. The lowest effects of pollution characterise the playground in the park no. III located in Orkana Street, whereas the highest the playground in the park no. I located in Parkowa Street. However, in none of the locations, the levels of Cd, Pb and Zn exceed the potentially harmful elements (PHE) considered as threatening the health and even life of children.