Lead (Pb(II)) contamination in water poses severe environmental and health risks due to its toxicity and persistence. This study compares almond shell-derived biochars produced by slow pyrolysis (SP) and microwave pyrolysis (MW), with and without KOH activation, focusing on structural properties and Pb(II) adsorption performance. Biochars were characterized by proximate and elemental analysis, BET surface area, FTIR spectroscopy, and adsorption experiments including pH dependence, kinetics, and equilibrium isotherms. Non-activated SP exhibited the highest surface area (S_BET = 693 m²·g⁻¹), pronounced mesoporosity (≈73% of total pore volume), and the largest observed equilibrium capacities. KOH activation increased surface hydroxyl content but degraded textural properties; in MW samples, it induced severe pore collapse. Given the very fast uptake, kinetic modeling was treated cautiously: for non-activated biochars, Elovich adequately captured the time-course trend, whereas activated samples returned non-physical kinetic constants (e.g., negative k₂) likely due to high post-adsorption pH (>11) and probable Pb(OH)₂ precipitation. Equilibrium data (fitted over 50–500 mg·L⁻¹) were better captured by the Freundlich and Redlich–Peterson models, indicating a mixed adsorption behaviour with contributions from heterogeneous site distribution and site-specific interactions. Optimal Pb(II) removal occurred at pH 4, with no measurable leaching from the biochar matrix. Overall, non-activated SP biochar is the most effective, sustainable and low-cost option among the tested materials for Pb(II) removal from water, avoiding aggressive chemical activation while maximizing adsorption performance.

Cork-derived biochars produced by slow pyrolysis (C-SP) and microwave-assisted pyrolysis (C-MWP) were evaluated for the removal of hexavalent chromium [Cr(VI)] from aqueous solutions. The materials were characterized by proximate/elemental analysis, N₂ physisorption (BET), thermogravimetry and FTIR. C-SP exhibited a higher specific surface area (174.5 m²·g⁻¹), a larger micropore volume and stronger O–H/C–O surface signatures than C-MWP, which showed partial aromatization and less-developed texture. Batch equilibrium adsorption experiments at pH 2.0 with initial Cr(VI) concentrations of 5–150 mg·L⁻¹ and kinetic experiments (c₀ = 40 mg·L⁻¹) were analyzed by nonlinear fitting to standard isotherm and kinetic models. The experimentally observed maximum uptakes were qmax,obs = 32.7 mg·g⁻¹ (C-SP) and 35.9 mg·g⁻¹ (C-MWP) at pH 2.0. Under screening conditions (pH 1.1, 45 min), removals reached 72% (1.44 mg·g⁻¹) for C-SP and 87% (1.73 mg·g⁻¹) for C-MWP. The Freundlich model provided the best fit to the equilibrium data for C-SP, consistent with adsorption on an energetically heterogeneous surface, whereas for C-MWP the fitted isotherm models did not yield physically meaningful parameters. Kinetic modeling showed rapid initial uptake consistent with energetic heterogeneity of surface sites. However, kinetic fits alone do not determine whether uptake is dominated by physical adsorption, chemical binding or redox reactions; direct surface/speciation analyses would be required to substantiate mechanistic assignments.

Fly ash from biomass combustion was used as an adsorbent for zinc removal from model solutions. Its properties were characterized using XRF, FTIR, and SEM-EDS. Batch experiments showed that the Langmuir model fit the data. The untreated ash can be used only for polishing acidic industrial wastewater.

This study evaluates the performance of a semi-synthetic emulsifiable fluid with anticorrosive properties, tested as a potential substitute for temporary corrosion protection during the production of thrust bearings. Samples were exposed to 48 h in a condensation chamber in accordance with ČSN 03 8131. The fluid provided partial protection; however, initial signs of pitting corrosion were observed. Although the emulsion reduced the extent of corrosion, it was not fully effective under the tested conditions, indicating the need for further formulation improvements or alternative protective measures.

This article deals with legislative and environmental safety gaps in tailings management facilities handling within the Czech Republic and the EU (European Union). Through analysis of regulatory frameworks, incidents and old environmental burdens, it highlights deficiencies, aiming to bolster the effective management of environmental risks and improve the lack of information, transparency and cross-border cooperation.