Arsenic contamination in drinking water poses significant health risks worldwide, making the development of efficient removal technologies a critical area of research. This study explores the enhancement of graphene's arsenic (As) adsorption capabilities through metal doping at various positions on its surface. Using density functional theory, the interactions between arsenic and graphene doped with selected metals were simulated, evaluating the influence of different doping positions on adsorption efficiency. The results demonstrated that metal doping significantly improves the arsenic removal capacity of graphene, with variations observed depending on the doping configuration. These findings contribute to a deeper understanding of the adsorption mechanisms in graphene-based materials and offer a computational approach for designing advanced adsorbents for environmental remediation.

This paper reports the synthesis of a substituted aminomethyl zinc phthalocyanine (AmPcZn) and its covalent grafting onto chitosan via an ethyl chloroformate-mediated reaction. Chitosan-based copolymers containing 10%, 20%, 30%, and 60% (w/w) AmPcZn were successfully obtained. The chemical structure of the synthesized AmPcZn was confirmed by 1H-NMR spectroscopy and elemental analysis, which were consistent with the expected molecular composition. The grafting reaction and structural integrity of the resulting copolymers were investigated using Fourier-transform infrared (FTIR) and UV-Vis spectroscopies. FTIR spectra revealed characteristic amide and carbonyl stretching bands, confirming covalent bond formation between chitosan and AmPcZn. UV-Vis measurements showed a concentration-dependent increase in absorbance and a typical splitting of the Q-band with band at 605 nm and 715 nm, indicating the successful incorporation of the phthalocyanine moiety into the polymeric matrix.

Zinc oxide nanoparticles were synthesized via a green route using Nicotiana plumbaginifolia plant extract, serving as a novel bio-reducing and stabilizing agent. Structural analysis through X-ray diffraction confirmed the hexagonal wurtzite crystalline structure, while Fourier-transform infrared spectroscopy and energy-dispersive X-ray spectroscopy affirmed the presence of Zn-O bonds and high purity. Morphological characterization by scanning electron microscopy and transmission electron microscopy revealed spherical nanoparticles with sizes ranging from 16 to 24 nm. The calculated optical band gap was 3.33 eV. A prominent FTIR peak at 480 cm⁻¹ indicated Zn-O stretching vibrations. The Zinc oxide nanoparticles exhibited significant antibacterial activity against Pseudomonas aeruginosa (18 mm), Escherichia coli (19 mm), Klebsiella pneumoniae (19 mm), and Staphylococcus aureus (18 mm) at 100 μL, as evaluated by the well diffusion method. Additionally, the nanoparticles showed strong antioxidant activity, achieving 75.59% DPPH radical scavenging at 250 μg/mL, indicating potential biomedical applications.

Novel spectrophotometric methods and bioassays have been developed and validated for clarithromycin quantitation in tablets. Spectrophotometric techniques were based on charge transfer complexation through naphthoquinone derivatives. Reactions were carried out in alkaline medium using 1,2-naphthoquinone-4-sulphonate and phylloquinone, which showed an absorption maximum at 452 and 455 nm, respectively. While bioassay was conducted dependent on the inhibitory effect upon the strain of Bacillus subtilis ATCC 9372, by applying cylinder-plate. Linear calibration curves with correlation coefficients of 0.9980-0.9998 were obtained. Molar absorptivity and Sandell's sensitivity were less than 10.73 L/mole/cm and 0.0099 μg/cm, respectively, with a detection limit down to 0.27 μg/mL and quantification limits of 0.68-0.78 μg/mL. The validation of the developed methods was performed for selectivity, precision, accuracy and robustness. Recoveries were found between 97.5-101.9% with % RSD being bellow to 3.5%. A comparative analysis was established and the methods were successfully applied for clarithromycin quantification in dosage forms.

This study involved the synthesis of magnetic materials derived from pomelo peel (PP@Fe3O4), durian peel (DP@Fe3O4), and banana peel (BP@Fe3O4). The characteristics of these materials were examined using SEM, FTIR, XRD, and BET techniques. The adsorption parameters for methylene blue using these magnetic materials, including pH, material concentration, and adsorption duration, were investigated to optimise adsorption efficiency. Results indicated that the most effective material amounts were 0.09 g, 0.18 g, and 0.06 g for PP@Fe3O4, DP@Fe3O4, and BP@Fe3O4, respectively, in 25 mL of methylene blue solution, corresponding to concentrations of 3.6 g/L, 7.2 g/L, and 2.4 g/L. Similarly, the optimal pH values for adsorption were found to be 5.9, 7.7, and 7.4, while the most efficient adsorption times were determined to be 95.3, 42.2, and 128.4 minutes, respectively. Under these conditions, the highest methylene blue adsorption efficiencies achieved were 97.7%, 97%, and 98.9%, respectively. These materials were also employed to assess the chemical oxygen demand index in select water samples

The purpose of the work was to investigate the effectiveness of using a previously regenerated spent food industry sorbent modified with sulphide and hydrosulphide ions for the removal of copper(II) ions from water. A comparative analysis of the degree of removal and adsorption of copper(II) ions by the regenerated sorbent (RS) and its modified form (MS) was carried out. Insignificant adsorption of Cu2+ on the surface of the RS is explained both by the nature of the adsorbate and the morphology of the adsorbent after its acid-alkaline activation. Modification of the surface of the regenerated sorbent with more active sulphide and hydrosulphide ions leads to an increase in the removal of copper(II) cations from the studied solutions by 65.5 times. IR-spectroscopy and X-ray phase analysis have shown that topochemical reactions occur on the surface of the MS, leading to the formation of copper(II) sulphide CuS and elemental sulphur. The obtained results allow us to recommend the use of a RS of the

It has been evaluated the dynamics of the self-purification processes of the Dniester River waters in the section from Dubasari to Vadul lui Voda based on the analysis of the parameters: biochemical oxygen demand (BOD5), chemical oxygen demand (CODCr), thiol content, and the inhibition capacity of the waters in carrying out chemical self-purification processes through free radicals (ΣkiSi). According to the BOD5 values, the Dniester waters belong to quality classes II and I, and according to the CODCr parameter, they fall into quality classes II and III. The thiol content is typical of fresh waters (10⁻6 M), and they are of natural origin. The inhibition capacity classifies the river's waters as slightly and moderately polluted. Along the river, were observed a decrease in biological self-purification processes and an increase in the intensity of free radical processes in the Criuleni area, indicating an additional inflow of reducing compounds into the Dniester waters from its tributary, the Raut River. Additionally, a tendency was noted for the aquatic environment quality restoration in the Vadul lui Voda area.

Scale formation in pipelines and on equipment surfaces is a serious problem in many branches of industry. Different scales are formed in cooling water systems and caused heat transfer problems. A common method for controlling scale deposition is the use of chemicals which act as antiscalants. This study focuses on the selection of antiscalant and the parameters of the process for the creation of resource-saving technologies for the use of water in industry. To inhibit the scale formation in cooling water systems, antiscalant RT-2024-4 was used, characterised and the ability of the reagent to mitigate the scale formation was tested. Artesian, tap water and water from the Desna River and model solutions with a hardness of 7.33-14.65 mg-eq/L were used as test objects. The conducted studies show that the temperature increase in the range of 80-90°С and the time of thermostating in the range of 2-5 hours have practically no effect on the stabilisation and anti-scale effects. The statistical data processing method was used to analyse the experimental data. High stability of water with respect to scale formation was established. The expediency of using the scale stabilizer RT-2024-4 for mineralised and highly mineralized waters was shown.

This paper details the synthesis of palygorskite/biochar/iron oxide composites and their utilization for the remediation of water solutions contaminated with uranium(VI). The synthesis procedure involved the combination of iron chloride, starch, and palygorskite with subsequent pH adjustment, drying of the formed precipitate, and pyrolysis at 600°C. The synthesis of mesoporous materials, primarily composed of iron oxides, including magnetite and hematite, was confirmed using various characterization techniques, including FTIR, SEM, and XRD. It was shown that the adsorption of uranium(VI) reached a maximum of 100.2 μmol/g, exhibiting the highest affinity, which is associated with significant magnetite involvement, which facilitates the reduction processes of uranium(VI) to uranium(IV). The findings demonstrated that the uranium removal process was enhanced by a rise in pH, with significant adsorption and possible precipitation occurring under neutral conditions, so using these composite materials is suitable for in situ remediation of water solutions contaminated by uranium(VI).

The modification of zeolite with activated charcoal for hydrogen adsorption was investigated. The aims of this research were to activate natural zeolite (Z), modify Z with commercial activated charcoal (AC/Z), and study the properties of these materials for hydrogen storage. The Z was prepared by the desilication method. The obtained Z was modified by activated charcoal using the wet impregnation method. The obtained materials were characterised by surface area analyser, X-ray diffraction, fourier transform infrared spectroscopy, and scanning electron microscopy with energy dispersive spectrometry. The hydrogen storage performance (at 298 K and 1 atm) was observed by Hydrogen-temperature programmed desorption (H2-TPD). The results showed that the presence of activated charcoal on the zeolite surface increased the specific surface area, reached 188.54 m2/g. However, Z exhibited the highest hydrogen storage capacity of 0.57 mmol/g.