Novel CO₂- and H₃PO₄-modified biochars were successfully synthesized from raw honeycomb biomass. They were characterized via several instrumental techniques. The optimal Pt(II) and Pt(IV) adsorption onto the studied biochars was reached for the initial pH of 1.5 and a contact time of 5 min (Pt(II)) and 24–48 h (Pt(IV)). The highest static adsorption capacities for Pt(II) and Pt(IV) were obtained for the H₃PO₄-modified biochar: 47 mg g⁻¹ and 35 mg g⁻¹, respectively. The Freundlich model described the Pt(II) adsorption isotherms onto both materials and the Pt(IV) adsorption isotherm onto the CO₂-activated material, and the Langmuir model was the best fitted to the Pt(IV) adsorption isotherm onto the H₃PO₄-activated biochar. The best medium for the quantitative desorption of the Pt form from the H₃PO₄-modified biochar was 1 mol L⁻¹ thiourea in 1 mol L⁻¹ HCl. The adsorption mechanism of both the studied ions onto the synthesized H₃PO₄-modified biochar was complex and should be further investigated. The H₃PO₄-modified biochar was successfully applied for the first time for Pt(IV) removal from a spent automotive catalyst leaching solution.

The removal of Cr(VI) from wastewater is a crucial task due to its high toxicity. In this study, slumgum-originated biochar materials were obtained by three different methods: high-temperature pyrolysis with H₃PO₄ or CO₂ and the high-temperature treatment of CO₂-activated slumgum-originated biochar in an Ar atmosphere. The obtained materials were subjected to physicochemical characterization (nitrogen adsorption/desorption isotherms, CHN elemental analysis, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy) and tested for their adsorption properties towards Cr(VI) ions. The solution pH, contact time, and effects of the Cr(VI) concentration on Cr(VI) adsorption onto biochar materials were studied. The kinetics and isotherm experimental data were best fitted to the Elovich (R² = 0.848) and Freundlich (R² = 0.965) theoretical models for H₃PO₄-modified biochar. The highest adsorption capacity (45.0 mg g⁻¹) for Cr(VI) was obtained for biochar modified with H₃PO₄. It was stated that the relatively fast rate of Cr(VI) adsorption onto this biochar (equilibrium reached within 120 min) is related to its mesoporous structure. The mechanism of Cr(VI) adsorption onto H₃PO₄-modified biochar was studied in detail. The obtained biochar was successfully applied for efficient Cr(VI) removal from wastewater originating from spent bricks with a low biochar dosage (4.0 g L⁻¹).

Pt complexes have been used in human and veterinary oncology for more than 50 years and represent one of the most significant groups of cytostatics. There are a lot of Pt-based compounds, such as cisplatin, carboplatin and oxaliplatin, which exhibit high efficiency against many tumors. Their broad application in oncology medicine and improper waste disposal induce environmental pollution by platinum cytostatics and their metabolites. They can cause toxic effects to fauna and flora, even at low concentration levels. Currently used technologies for wastewater treatment are not sufficient in the case of platinum-based metabolites. Their high resistance and toxicity of their degradation byproducts pose a serious problem. In this review, currently applied platinum-based cytostatics, their possible metabolic mechanisms, environmental impact and technological methods for their removal from wastewater and patients’ urine are summarized. Special attention is paid to adsorption methods.

The pristine CMK-3 carbon was ozonized and then chemically modified by the Zr and Fe compounds. The synthesized carbonaceous materials were characterized with physicochemical methods. The obtained carbons had a high specific surface area (ca. 800 m² g⁻¹) and an acidic surface. The Cr(VI) adsorption properties of the oxidized and Zr/Fe-modified carbon were studied. The highest static adsorption capacity towards Cr(VI) ions was evaluated for Zr/Fe-modified carbon (50.1 mg g⁻¹) at pH_eq = 5.8 after 240 min. The Elovich and Freundlich theoretical models were well fitted to the Cr(VI) adsorption kinetic and isotherm data on the Zr/Fe-modified CMK-3-type carbon. The leading Cr(VI) adsorption mechanism acting on the Zr/Fe-modified carbon was probably based on the redox reactions between Cr(VI) and the carbonaceous surface. Electrostatic attraction and surface complexation processes could also occur during Cr(VI) adsorption in the studied system. The effect of the competitive anions on the concentration level, such as in the galvanic wastewater for Cr(VI) adsorption onto chemically modified carbon, was negligible. The HCl and HNO₃ media were insufficient for the Zr/Fe-modified carbon regeneration after Cr(VI) adsorption. The Zr/Fe-modified carbon was successfully applied for the efficient (>90%) Cr(VI) removal from the model galvanic wastewater.

Newly synthesized cerium oxide was successfully obtained by the hard templating route. The optimal As(III) and As(V) adsorption onto the studied adsorbent was reached for the initial pH of 4.0 and a contact time of 10 h. The highest static adsorption capacities for As(III) and As(V) were 92 mg g⁻¹ and 66 mg g⁻¹, respectively. The pseudo-second-order model was well fitted to the As(III) and As(V) experimental kinetics data. The Langmuir model described the As(III) and As(V) adsorption isotherms on synthesized material. The adsorption mechanism of the studied ions onto the synthesized cerium oxide was complex and should be further investigated. The optimal solid–liquid ratio during the proposed aqueous extraction of inorganic As from the Fucus vesiculosus algae was 1:50. The optimal dosage of the synthesized cerium oxide (0.06 g L⁻¹) was successfully applied for the first time for inorganic As removal from the aqueous algal extract.