The present study investigated the adsorption mechanism of titanium dioxide nanoparticles (nTiO₂) on polyethylene microplastics (MPs) and the resulting photocatalytic properties. This effort was supported by ecotoxicological assessments of MPs with adsorbed nTiO₂ on the immobility and behaviour of Daphnia magna in presence and absence of UV irradiation. The results showed that nTiO₂ were rapidly adsorbed on the surface of MPs (72% of nTiO₂ in 9 h). The experimental data fit well with the pseudo-second order kinetic model. Both suspended nTiO₂ and nTiO₂ immobilized on MPs exhibited comparable photocatalytic properties, with the latter showing a lower effect on Daphnia mobility. A likely explanation is that the suspended nTiO₂ acted as a homogeneous catalyst under UV irradiation and generated hydroxyl radicals throughout the test vessel, whereas the nTiO₂ adsorbed on MPs acted as a heterogeneous catalyst and generated hydroxyl radicals only locally and thus near the air-water interface. Consequently, Daphnia, which were hiding at the bottom of the test vessel, actively avoided exposure to hydroxyl radicals. These results suggest that the presence of MPs can modulate the phototoxicity of nTiO₂ - at least the location at which it is active - under the studied conditions.

Cigarette filters comprise plasticised cellulose acetate, a synthetic polymer categorized as bioplastic. They represent a significant source of microplastics (MPs), in particular microfibers, and associated chemicals, yet their impact on organisms, especially soil invertebrates, is not well-studied. This research examines the effects of MPs milled from smoked (SCF-MPs) and unsmoked cigarette filters (UCF-MPs) on terrestrial invertebrates (Porcellio scaber, Tenebrio molitor) and aquatic invertebrates (Daphnia magna, Brachionus calyciflorus). SCF-MPs and UCF-MPs were found to be 9.06 ± 4.1 μm and 12.71 ± 6.82 μm in size, respectively. Both samples contained triacetin and potentially toxic metals, while SCF-MPs also contained nicotine and a larger number of trace organic compounds. While exposure to SCF-MPs or UCF-MPs (up to 1.5 % MPs, w/w in soil) did not affect the survival of either terrestrial invertebrate, several physiological responses were observed. These included changes in immune parameters, energy-related biomarker levels, and altered glutathione S-transferase and acetylcholinesterase activities. Both types of MPs were acutely toxic to aquatic invertebrates, reducing the survival rates of B. calyciflorus (10 mg L^-1 of either particle after 48h exposure) and D. magna (100 mg L^-1 of SCF-MPs after 48h exposure). SCF-MPs generally caused more pronounced effects than UCF-MPs. This study highlights the need for effective environmental management to address both smoked and unsmoked cigarette filters.

The stability of ceramic suspensions is a key factor in the preparation and shaping of ceramic bodies. The presented work offers an experimental determination of ceramics suspensions stability using the LUMiSizer analytical centrifuge, focusing on kinetic behaviour using transmission profiles and instability indexes. Multiple ceramic systems comprising corundum, metakaolin, and zirconia suspensions were experimentally examined under varying solid contents, dispersant dosages, and additive concentrations. Results showed that highly loaded corundum suspensions with dispersant (Dolapix CE64) achieved excellent stability, with an instability index below 0.05. Compared to classical sedimentation tests, which are time-consuming and not highly sensitive, LUMiSizer offers a suitable alternative by guaranteeing correct kinetic data and instability indexes indicating suspension behaviour using centrifugal force. Comparisons of the LUMiSizer results and data obtained using the modified Stokes law confirmed increased terminal velocities in experiments with metakaolin suspensions, indicating the sensitivity of the centrifuge to the effect of dispersion medium shape. The influence of porogen (waste coffee grounds) on the stability of corundum suspensions was also investigated, followed by slip casting to create and characterize a ceramic body, confirming the possibility of shaping based on stability results. Furthermore, instability indices are suggested as a rapid, quantitative method for comparing system stability and as an auxiliary criterion to the rheological measurements. Optimal dispersant concentration for zirconia-based photocurable suspensions was identified as 8.5 wt.%, which minimized viscosity and, at the same time, assured maximal kinetic stability. Integrating the LUMiSizer analytical centrifuge with standard methods, including sedimentation tests and rheological measurements, highlights its value as a powerful tool for characterizing and optimizing ceramic suspensions.

The widespread replacement of conventional plastics with biodegradable alternatives raises questions about their long-term effects in agricultural soils. We investigated the impact of microplastics (MPs) cryo-milled from home-compostable (PBAT_HOME) and industrial-compostable (PBAT_IND) polybutylene adipate terephthalate bags and compared it to the toxicity of MPs from conventional polyethylene (PE) bags. Sunflowers (Helianthus annuus L.) were grown in pots with soil spiked with 0 %, 0.05 %, 0.5 %, and 1.0 % (w/w) MPs for eight weeks under a 16/8 day-night photoperiod at room temperature (22/18 °C). Plant responses differed notably between biodegradable and conventional MPs as revealed by two-way hierarchical clustering analysis: both PBAT_HOME and PBAT_IND significantly reduced shoot and root biomass at 0.5 % and 1 %, while PE had no effect. At higher PBAT concentrations, proline levels increased, consistent with activation of drought-like stress response pathways that merit confirmation with additional molecular biomarkers. Soil water holding capacity increased at 1 % of all three MPs, indicating a lower water availability for plants in the MP-spiked soil. pH was slightly increased at 1 % PBAT_HOME and significantly at 1 % PBAT_IND soil. Despite differences in particle size, polymer composition, and starch content, no single factor explained the observed effects, suggesting a combined influence. These results highlight that biodegradable MPs can alter soil properties and trigger physiological responses in plants, emphasizing the need to assess their ecological impacts, especially in agricultural systems where soil health and resilience are critical for crop production.

Up to date, the development of highly efficient, visible light-active catalysts remains a formidable challenge due to the enhanced rising of atmospheric CO2 concentration. This study discusses a class of ceria-based high-entropy oxides designed to optimize charge carrier dynamics, surface reactivity, and CO2 activation efficiency. Due to the advantages of high configurational entropy and multi-element synergy, these materials achieved improved photocatalytic performance, surpassing conventional ceria-based systems. Structural and spectroscopic analyses reveal that Pr3+/Pr4+ redox pairs and abundant oxygen vacancies create an electronically disordered yet thermodynamically stable environment, which enhances charge separation and suppresses electron-hole recombination. Photocatalytic experiments demonstrated that Ce0.2Zr0.2La0.2Pr0.2Sm0.2O2−δ (CZLPS) achieves the highest CO2 conversion rate, reaching a conversion of 20.3% under visible light irradiation, significantly surpassing pure ceria (1.4%), with a calculated space-time yield (STY) of 10.15 molCOkg–1h–1 under the same conditions. First-principles density functional theory (DFT) simulations were employed to investigate the CO2 reduction mechanism on CZLPS catalysts. The study elucidates the Gibbs free energy changes (ΔG) for each step of the reaction pathways leading to CO and HCOOH formation, highlighting the Zr site of CZLPS as the most active for the CO2RR, which is responsible for the outstanding catalytic activity.