Experimental data show that the adsorption of potassium on clinoptilolite after 7-hour relatively fast start eventually becomes diffusion-controlled and slows down. The rate and capacity of adsorption does not depend on the type of solution used – KNO3 or KCl, but favours higher temperatures. It was found that potassium adsorption is similar to chemisorption and this assumption was confirmed by both equilibrium and kinetic modeling. The applicability of Langmuir and Dubinin–Radushkevich models indicated a non-uniform nature of the clinoptilolite surface and suggested the formation of an adsorbate monolayer, which was used to calculate the clinoptilolite active surface area. The kinetic modeling showed that the pseudo-second order kinetic model was the most suitable for the obtained experimental data, which once more confirmed the chemical nature of potassium adsorption. Despite diffusion-limited potassium adsorption, the release of potassium proceeds at much higher rate in the presence of counter ions and equilibrium can be reached about 10 times faster.

In this work, the thermal stability, microstructure, and catalytic activity in oxidation reactions of calcium silicate hydrates formed in the CaO-SiO₂-Cr(NO₃)₃-H₂O system under hydrothermal conditions were examined in detail. Dry primary mixture with a molar ratio of CaO/SiO₂ = 1.5 was mixed with Cr(NO₃)₃ solution (c = 10 g Cr³⁺/dm³) to reach a solution/solid ratio of the suspension of 10.0:1. Hydrothermal synthesis was carried out in unstirred suspensions at 175 °C for 16 h. It was determined that, after treatment, semicrystalline calcium silicate hydrates C-S-H(I) and/or C-S-H(II) with incorporated Cr³⁺ ions (100 mg/g) were formed. The results of in situ X-ray diffraction and simultaneous thermal analyses showed that the products were stable until 500 °C, while, at higher temperatures, they recrystallized to calcium chromate (CaCrO₄, 550 °C) and wollastonite (800–850 °C). It was determined that both the surface area and the shape of the dominant pore changed during calcination. Propanol oxidation experiments showed that synthetic semicrystalline calcium silicate hydrates with intercalated chromium ions are able to exchange oxygen during the heterogeneous oxidation process. The obtained results were confirmed by XRD, STA, FT-IR, TEM, SEM, and BET methods, and by propanol oxidation experiments.

Volatile organic compounds (VOCs) are pollutants that pose significant health and environmental risks, necessitating effective mitigation strategies. Catalytic oxidation emerges as a viable method for converting VOCs into non-toxic end products. This study focuses on synthesizing a catalyst based on calcium silicate hydrates with chromium ions in the CaO-SiO₂-Cr(NO₃)₃-H₂O system under hydrothermal conditions and evaluating its thermal stability and catalytic performance. A catalyst with varying concentrations of chromium ions (10, 25, 50, 100 mg/g Cr³⁺) was synthesized in unstirred suspensions under saturated steam pressure at a temperature of 220 °C. Isothermal curing durations were 8 h, 16 h, and 48 h. Results of X-ray diffraction and atomic absorption spectroscopy showed that hydrothermal synthesis is effective for incorporating up to 100 mg/g Cr³⁺ into calcium silicate hydrates. The catalyst with Cr³⁺ ions (50 mg/g) remained stable up to 550 °C, beyond which chromatite was formed. Catalytic oxidation experiments with propanol and propyl acetate revealed that the Cr³⁺ catalyst supported on calcium silicate hydrates enhances oxygen exchange during the heterogeneous oxidation process. Kinetic calculations indicated that the synthesized catalyst is active, with an activation energy lower than 65 kJ/mol. This study highlights the potential of Cr³⁺-intercalated calcium silicate hydrates as efficient catalysts for VOC oxidation.

Experimental data show that the adsorbent–catalyst CuO/NaX is hydrophilic with a similar water vapour adsorption capacity and adsorption rate to zeolite NaX. Equilibrium parameters were best described by a Freundlich-like equation. BET studies and Kelvin equation calculations confirmed that, at an ambient relative humidity of 37% or higher, water vapour condensation will occur in the prevailing 2.0–2.3 nm pores of the adsorbent–catalyst CuO/NaX. The kinetic parameters for the adsorption of water vapour are presented.

This study presents an integrated approach for producing antioxidant-rich polar fractions from Inula salicina L. via pressurised ethanol/water extraction (PLE-EtOH/H₂O), optimised by coupling a central composite design and response surface methodology (CCD-RSM) with Aspen Plus^® simulation. The effects of PLE temperature, extraction time, and EtOH/H₂O ratio for yield, total phenolic (TPC) and flavonoid (TFC) content, and Trolox equivalent antioxidant capacity (TEAC) measured in ABTS^•+-scavenging, cupric ion reducing antioxidant (CUPRAC) and oxygen radical absorbance (ORAC) assays were assessed via a multi-response optimisation approach. Optimal conditions were set at 82 °C, 27 min, and 60% EtOH (v/v), yielding ~29 g extract per 100 g plant material, characterised by high TPC (227 mg GAE/g), TFC (34 mg QE/g), and TEAC values in the CUPRAC (1473 mg TE/g), ABTS (869 mg TE/g), and ORAC assays (1165 mg TE/g). The TPC and TEAC values of the post-extraction residue were >92% lower than those of unextracted I. salicina, confirming efficient recovery of the major portion of antioxidant-active constituents by PLE-EtOH/H₂O. The high in vitro radical scavenging capacity, reducing power, and photoprotective potential (sun protection factor ~50 at 0.5 mg/mL) of the I. salicina extract are consistent with its phenolic-rich composition, with chlorogenic acid (~97 mg/g extract) and its derivatives being the major constituents. The validated Aspen Plus^® model closely aligned with the CCD-RSM predictions, supporting process scale-up and energy feasibility and demonstrating an industry-relevant, green-solvent PLE process for producing higher value-added I. salicina fractions with potential applications in the food, pharmaceutical, nutraceutical, and cosmetic sectors.

Polyisocyanurate (PIR) insulation boards are widely used in buildings because of their low thermal conductivity, however their long-term performance is affected by aging. This study investigates the effect of accelerated thermal aging at +70 °C on the thermal conductivity and gas composition of pentane-blown PIR boards. Thermal conductivity was monitored over time, while changes in blowing-agent composition were analyzed using gas chromatography/mass spectrometry (GC/MS). Thermal conductivity increased from 0.0201–0.0211 W/(m·K) to 0.0243–0.0247 W/(m·K), corresponding to an increase of approximately 18–22%, with the most pronounced changes occurring during the first 40–50 days before stabilizing. GC/MS identified isopentane, cyclopentane, and pentane as the main gases in the foam cells, with isopentane as the dominant component. Accelerated aging caused a progressive decrease in blowing-agent concentration, explaining the deterioration in thermal insulation performance. Thermal outgassing proved more reliable than solvent extraction, providing higher sensitivity and reproducibility. Sample location, sample size, and outgassing temperature significantly affected the measured gas quantities, while higher outgassing temperatures improved analytical sensitivity without changing gas composition trends. The results confirm that the aging-induced increase in thermal conductivity is primarily caused by the loss of low-conductivity blowing agents, improving understanding of the long-term performance of PIR insulation materials.