Carbon dot-based radiocontrast agents have recently sparked the interest of researchers owing to their better contrasting capabilities, simple synthesis protocols, high colloidal stability, and good biocompatibility. In this study, we propose for the first time the synthesis of iodine-doped carbon dots (I-CDs) using low-cost reagents such as citric acid (C₆H₈O₇), urea (CH₄N₂O) and potassium iodide (KI). The as-prepared I-CDs demonstrated excellent colloidal stability (with a zeta potential value of −64.7 mV), excitation-dependent fluorescent properties (with a maximum quantum yield of ∼8.9%), and a mean iodine concentration of ∼4.67 wt%. Notably, the as-prepared I-CDs displayed greater X-ray attenuation efficiency (42.87 HU mL mg⁻¹) as compared to the commercially employed iopromide radiocontrast agent (30.98 HU mL mg⁻¹). Furthermore, ATPase activity, cytotoxicity analysis with HeLa, NHDF, HEK293, and A549 cell lines, and live-cell imaging experiments of the Drosophila neuroblasts in intact brain lobes suggested high biocompatibility and nontoxicity of the prepared I-CDs. Overall, biocompatible and low-cost I-CDs show great promise as bifunctional radiocontrast and fluorescent agents for biomedical applications.

Silicate mineral powders (SMP) from weathered granite soil from Kazakhstan are proposed for the desalination of potash brines containing sodium, potassium and chloride ions. Batch adsorption experiments using acid-treated silicate (AS) achieved a Na⁺/K⁺/Cl⁻ recovery of ~13/28/6 mg/g. An isothermal study best fitted the Freundlich and Dubinin–Radushkevich models for Na⁺ and K⁺/Cl⁻. The kinetic data were best modeled by pseudo-second-order kinetics for Na⁺/K⁺ and pseudo-first-order for Cl⁻. Thermodynamic calculations showed spontaneity under natural conditions. For Na⁺/K⁺, physisorption is accompanied by ion exchange. To study the possibility of sorbent reuse, several cycles of K⁺/Na⁺ adsorption–desorption were carried out under optimal conditions. AS selectively adsorbed potassium ions, maintaining a high effectiveness during five cycles providing K-form silicate fertilizers. Leachates of spent AS contain high concentrations of K/Na/Ca/Mg and other microelements essential for plants. Thus, SMP resolve two issues: the desalination of brine and the provision of fertilizer.

The present work considers the production of a cheap and effective sorbent based on natural clay from the Kyzylsok deposit (Almaty region) in order to purify wastewater from heavy metal ions (Cd2+, Pb2+). It was found that the starting material is applicable for the extraction of Cd2+ ions (the degree of extraction is (97.00 ± 1.99) %), while for the extraction of Pb2+ ions the initial clay must be modified. The modification was carried out using polyvinylpyrrolidone (PVP). The degree of extraction of Pb2+ ions with modified clay increased from (70.00 ± 1.77)% to (98 ± 1.13)% The influence of PVP concentration in the composite material (modified clay) on its sorption properties was studied: the optimal concentration of PVP was 0.1 % solution. The desorption of metal ions was also investigated in the work, it does not exceed 2%. It was found that the sorption process is described by the monomolecular Langmuir isotherm model and the kinetic model of the pseudo-second order.

Clays and aluminosilicate materials are known as effective sorbents for purification of wastewater from various types of contaminants. Some properties and sorption activity of materials based on the zeolite of Shankanai deposit and Chamotte clay towards Cd2+ ions were analyzed in the present work. The structural characteristics of the studied objects, their qualitative and quantitative composition were determined by the SEM and EDAX methods. It was found that maximum adsorption capacity (qe) of the initial zeolite for extraction Cd2+ ions is (7.3±0.11) mg/g, while for Chamotte clay this value equals to (5.3±0.12) mg/g. After modification with polyvinylpyrrolidone, qe increased to (10.1±0.08) mg/g for zeolite, and (8.5±0.15) mg/g for Chamotte clay. Developed specific surface of the composite material (sorbent) and complexation with the active centres of thepolymer couldbe a resultof Cd2+ ions binding.