Search Results (320)

This research investigates cobalt-based and iron-based coordination polymers as advanced adsorbents for removing nitrate from water, addressing the increasing demand for effective and customizable treatment materials. Both coordination polymers were synthesized through solvothermal methods using terephthalic acid as the organic linker and were characterized by scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS), which verified their crystalline, porous structures and uniform metal dispersion; Fourier-transform infrared spectroscopy (FTIR) was used to analyze surface characteristic functional groups of the samples before and after adsorption. Batch adsorption tests combined with response surface methodology (RSM), based on a Box–Behnken (BBD), were employed to optimize key operating conditions, including adsorbent dose (0.1–0.5 g/L), pH (3–7), and temperature (25–45 °C). Under optimal conditions (pH 3–5, 0.3 g/L, 30–35 °C), the Co-coordination polymer achieved a maximum nitrate removal of 54.1% and an adsorption capacity of 212.8 mg/g, while the Fe-coordination polymer reached 30.5% removal with a capacity of 35.0 mg/g. Kinetic studies were well fitted by the pseudo-second-order (PSO) model for the Co-coordination polymer (R² = 0.992–0.997), indicating chemisorption control, whereas the Fe-coordination polymer exhibited diffusion-driven behavior. The equilibrium data fit the Langmuir model well for both, confirming monolayer adsorption. The findings suggest that the Co-coordination polymer provides superior nitrate removal owing to stronger metal–anion interactions, whereas the Fe-coordination polymer offers more stable but lower adsorption capacity. Full article

Wastewater containing such inorganic contaminants, especially phosphate and nitrate ions, has to be treated thoroughly before disposal into natural environments. This is a precautionary measure to avoid adverse effects on public health, which are exacerbated when these two pollutants are present in an aqueous system. The present research investigated how the adsorption process is influenced by factors such as the effect of ion composition, contact time, temperature and competitive adsorption behavior in multi-anion systems using Ternary Biopolymer–Bentonite Beads. This study used five isotherms and four kinetic models to investigate phosphate ions removal on prepared natural Clay-Bio-polymer composite beads. The results indicate that the pseudo-second-order (PSO) kinetic model provides the most accurate description of the adsorption process. Moreover, the correlation coefficients (R²) obtained for both the Langmuir and Freundlich isotherm models are nearly equal to 1, confirming their strong reliability in fitting the experimental data. The strong fit of both the Langmuir and Freundlich models indicates that the adsorption process exhibits mixed behavior, with both monolayer adsorption on relatively homogeneous sites and multilayer adsorption on heterogeneous sites. This mixed-behavior system is typical of composite adsorbents with diverse surface properties. The Redlich-Peterson model, a hybrid of Langmuir and Freundlich, showed the best overall correlation (R² = 0.990 for H₂PO₄⁻ and 0.998 for NO₃⁻). The applicability of the Sips and Toth isotherm models, which account for both uniform and non-uniform adsorption behaviors, validated the experimental results. In the competitive binary system, the maximum adsorption capacities achieved by the composite were 121.844 mg/g for H₂PO₄⁻ and 27.979 mg/g for NO₃⁻. The results indicate strong competition between H₂PO₄⁻ and NO₃⁻ ions for the available active sites, reflecting an antagonistic adsorption. A positive value of ∆H° verifies that the adsorption process is endothermic and primarily physical, consistent with the experimental observations. The negative ∆G° values demonstrate that the adsorption occurs spontaneously, whereas the positive ∆S° indicates an increase in randomness at the solid–liquid interface during the uptake of phosphate ions. Full article

Choline-based ionic liquids (ILs) have emerged as promising candidates for application in multifaceted avenues, including electrochemistry, biomaterials, and environmental remediation technologies. However, their regulatory effects on the growth of agricultural plants have rarely been discussed. In this study, 14 choline–fatty acid ILs ([Chl][FA] ILs) containing different FA anions were synthesized, and their effects on the maize growth were investigated. Hydroponic experiments revealed that low concentrations (20 mg/L) of dicarboxylic acid-based [Chl][FA] ILs (e.g., choline pentane diacid [Chl][Pent]) significantly promoted maize root and shoot biomass, whereas higher concentrations inhibited it. Specifically, [Chl][Pent] enhanced chlorophyll content without altering Fv/F₀, upregulated nitrate reductase (NR) and glutamine synthetase (GS) activities, and stimulated the expression of key nitrogen metabolism (NR and GS) and photosynthetic (Rubisco) genes. Pathway analyses of differentially expressed genes indicated that [Chl][Pent] was associated with the upregulation of nitrogen and glycerophospholipid metabolism. [Chl][Pent] increased the average grain yield by 6.88% over two years compared to CK. Field application of [Chl][Pent] increased grain yield and protein accumulation relative to both control and choline chloride treatments. Overall, these findings demonstrate the potential of dicarboxylic acid-based [Chl][FA] ionic liquids as eco-friendly biostimulants for enhancing crop growth, yield, and quality. Full article

Pollution of rivers and large water bodies, including reservoirs, by wastewater from various sources is one of the most critical issues in the Donetsk region, requiring continuous monitoring and assessment of surface water quality. The research aims to assess the state of the Kalmius River under anthropogenic pressure, as well as to find correlations between the species composition, photosynthetic activity of phytoplankton, and the degree of water pollution. This study presents the results of biomonitoring of the Kalmius River and its tributaries within Donetsk City, which are under intense anthropogenic pressure. Pollution of the river channel by phenol, anionic surfactants, Ferrum ions, chlorides, and sulfates was identified. Based on the combinatorial pollution index, the water in the Kalmius River and its tributaries can be classified as polluted. The pigment composition of water samples was analyzed, and the species composition of river phytoplankton was determined. Dominant species include Chlorella vulgaris Beij., Dictyosphaerium pulchellum H.C.Wood, Scenedesmus quadricauda Brébisson, and Oscillatoria agardhii M.A.Gomont. Photosynthetic activity of the river’s algal flora was assessed based on chlorophyll fluorescence induction curves of natural phytoplankton. A correlation was established between surface water pollution levels and changes in the photosynthetic apparatus of microalgae cells. A strong negative correlation was found between the content of nitrate nitrogen in the aquatic environment and the photosynthetic activity, pigment composition, and abundance of the main dominant forms of phytoplankton, particularly the microalgae of the genus Cyclotella. The data obtained shows that the Kalmius River’s pollution has a significant impact on phytoplankton biodiversity, leading to the growth of cyanobacteria species. Full article

Blood collection tubes are widely used medical devices. Inaccurate citrate anticoagulant concentration can influence the results of coagulation tests. The producer’s expertise and responsibility are considered the quality safeguards. However, the tubes undergo changes during their lifecycle, partly due to storage conditions, and the end user or a third party has no comprehensive insight. A methodology is necessary to reveal the tube’s inherent characteristics. We provide insight into the anionic–cationic composition and pH of anticoagulant solutions in commercial tubes using high-performance ion exchange chromatography on a purified water model, making the anticoagulant volume accuracy assessment possible through a direct dye-dilution method. The results revealed differences between the tubes of two producers, Greiner BIO-ONE (A and A(nr)) and BD (C). Tube C has the most accurate anticoagulant amount. Both brands contain buffered citrate. The method of buffer preparation is not a source of interferant for the spectrometric method of the tubes’ quality evaluation. Acetate, formate, chloride, nitrite, sulfate, oxalate, bromide, and nitrate impurities were determined in anticoagulant solutions, all in tube A and some in the others. Tubes C exhibit the highest contamination with cations. Full article

To identify the sources and driving mechanisms of nitrate contamination in pore water around Nansi Lake, 54 pore water samples were analyzed via hydrogeochemical analysis, Gibbs diagrams, ionic ratios, and principal component analysis (PCA). The pore water is predominantly slightly alkaline, with dominant cations Ca²⁺ and Na⁺, and anions HCO₃⁻ and SO₄²⁻. Nitrate-nitrogen (NO₃⁻-N) concentrations range from 0.82 to 54.31 mg·L⁻¹, with a coefficient of variation of 1.41 and an exceedance rate of 18.52%, indicating significant external inputs. A positive correlation between NO₂⁻ and NO₃⁻ suggests denitrification in some areas. Nitrate concentrations exhibit distinct spatial heterogeneity: high concentrations occur in agricultural/aquaculture lakeside plains and urban areas, low concentrations near coal mining subsidence zones, and transitional zones showing outward diffusion. Nitrate sources are predominantly anthropogenic. High Cl⁻ and low NO₃⁻/Cl⁻ ratios indicate domestic and aquaculture wastewater infiltration, whereas low Cl⁻ and high NO₃⁻/Cl⁻ ratios indicate agricultural fertilizer input. Industrial and natural sources are minor. PCA identified three controlling factors (cumulative variance 69.81%): coal mining and industrial/domestic pollution (39.82%), carbonate rock weathering (19.44%), and agricultural activities (10.55%). Health risk assessment shows no significant risk for adults (hazard quotient (HQ) < 1), but children face localized risks at nine sites (HQs of 1.25–2.26) in intensive farming, urban, and transitional zones. Excessive fertilizer application and sewage leakage are the primary causes, posing methemoglobinemia risks to infants. This study provides a scientific basis for nitrate pollution control and sustainable water management in the Nansi Lake Basin and offers methodological insights for similar lacustrine plain regions. Full article

Chitosan-coated sand has been developed as a sustainable, environmentally friendly, and cost-effective water treatment method for removing nitrate anions, leveraging the adsorption properties of chitosan. When applied to sand using glutaraldehyde as a cross-linking agent, this adsorbent removes nitrate anions with an adsorption capacity (q_e) of 154.41 mg g⁻¹. This approach is particularly advantageous due to its low cost, high adsorption capacity, and effectiveness over a wide range of pH and temperatures, although its performance is optimal under slightly acidic to neutral conditions (pH = 6) due to electrostatic attraction and ion exchange, as the positively charged amino groups of chitosan bind to the negatively charged nitrate ions. Nitrate adsorption is also described by the Langmuir isotherm and follows the pseudo-second-order model. Furthermore, the adsorbent remains highly stable even after five regeneration cycles, demonstrating its long-term effectiveness and durability, while offering a cost-effective and environmentally friendly solution in accordance with the principles of sustainable development. Full article

Groundwater is a strategic resource for maintaining ecological balance and supporting human development in arid inland basins. However, under the dual pressures of climate change and human activities, it faces threats in both quantity and quality. This study selects the Chahan Usu River watershed in the eastern Qaidam Basin, a typical arid inland basin on the Tibetan Plateau, to assess the current quality of groundwater resources and reveal the formation mechanisms and material sources of its hydrochemistry. The results show that the groundwater in the watershed is generally weakly alkaline, with some areas exhibiting high salinity. The dominant cations and anions are Na⁺ and Cl⁻, respectively. The hydrochemical type is mainly Cl-Na, with a minority being mixed Cl-Mg·Ca. Overall, the groundwater in the watershed is suitable for domestic use. However, in the middle and lower reaches of the Chahan Usu River, nitrate and ammonia nitrogen contamination reduce its suitability. Meanwhile, although long-term use of this groundwater would not lead to soil degradation, its widespread high salinity and high sodium content make it unsuitable for irrigation. Water–rock interactions with evaporites and silicate rocks are the main mechanisms controlling groundwater chemistry in the watershed. Among them, halite minerals contribute most of the Na⁺ and Cl⁻, while sulfate minerals provide Ca²⁺ and SO₄²⁻. In addition, cation exchange is widespread. This study provides a reference for ensuring the security and sustainable development of groundwater resources on the plateau. Full article

Artemisia maritima holds potential applications in the rehabilitation of degraded environments, particularly in salt-affected areas, for biosaline agriculture aimed at biomass production for further valorization and green biotechnology. The aim of the present study was to investigate the response of A. maritima to alterations in soil chemical composition, including differences in mineral supply, the addition of various sodium salts, and contamination with several heavy metals (cadmium, lead, copper, manganese, zinc), in order to establish a scientific basis for further applied research. Under standard fertilization conditions, the growth of A. maritima plants was restrained by nitrogen deficiency. Surplus nitrogen enhanced mineral uptake and growth, especially for shoots, and stimulated clonal development. Low to moderate (50 and 100 mmol L⁻¹) NaNO₃ treatment significantly stimulated shoot growth, while Na₂HPO₄ and NaHCO₃ treatments exhibited the most adverse effects at 200 and 400 mmol L⁻¹, resulting in reduced growth and biomass, and even the deterioration of the aboveground parts. Chlorophyll fluorescence parameters served as reliable early indicators of the detrimental effects of salinity associated with individual anions. Shoot macronutrient levels remained unchanged for phosphorus and calcium, while nitrogen increased in nitrate treatments. Root mineral nutrient content was more susceptible to salinity, with significant changes observed for all macro- and micronutrients, varying depending on the specific element and anion type. The alterations in mineral nutrition observed for each anion treatment exhibited distinct characteristics. A. maritima plants demonstrated high tolerance to all heavy metals, with roots being more susceptible compared to shoots. At the shoot level, statistically significant growth inhibition was evident only for 1000 mg L⁻¹ lead and 1000 mg L⁻¹ zinc treatments. A. maritima plants can be characterized as high accumulators of cadmium, lead, manganese, and zinc, and as extreme accumulators of copper in shoots. Nitrophily, clonal expansion with a help of bud-bearing roots, and the ability to accumulate relatively high concentrations of mineral elements in shoots are among the important physiological characteristics of A. maritima plants, enabling them to exhibit high resilience in environmentally heterogeneous habitats. Full article

Nitrates and nitrites are inorganic anions which, beyond specific concentration threshold, are classified as water pollutants. Nitrate compounds are commonly used as fertilizers; however, their high concentration in soil and in wastewater, as well as their reduction to nitrites, pose serious environmental and human health risks. Therefore, detecting these ions in water intended for human consumption, zootechnical use, and agricultural applications is essential. This work presents a proof of concept for a spectroscopic prototype setup enabling simple, direct, and simultaneous detection of nitrates and nitrites in water. The device employs solid-state sensor technology and requires no sample pretreatment or chemicals. Ultimately, this apparatus will allow real-time, in-line process analysis. UV absorption bands centered at approximately 302 nm and 355 nm were selected for detecting nitrates and nitrites, respectively. Because nitrite exhibits a slight absorption at 302 nm as well, a straightforward method for simultaneous nitrate and nitrite detection is proposed. The proposed system incorporates a UV deuterium lamp, a 10 cm path length optical cuvette, and a custom home-built silicon carbide detector. This configuration enables testing various concentrations, achieving detection limits of 2.2 mg/L for nitrates and 0.5 mg/L for nitrites. Potential interferences from substances commonly found in drinking and treated agricultural wastewaters, including sodium bicarbonate, sodium sulfate, ammonium chloride, hydrogen peroxide, and sodium hypochlorite, were also investigated. Finally, a compact on-site and online monitoring future device is illustrated. Full article

Millions of people across rural and peri-urban regions worldwide remain exposed to unsafe concentrations of naturally occurring fluoride in groundwater. In West Bengal, India, community-level water purification plants (CWPPs) have been widely installed to remove excess fluoride, yet their long-term operational performance remains minimally documented. This study assessed the pre-filter and post-filter water quality of 58 such groundwater-based CWPPs across the fluoride-affected districts of Bankura and Purulia in West Bengal, to evaluate in-field fluoride removal performance and potential hydrogeochemical, operational, and management drivers. Evaluation included fluoride concentration and key physicochemical parameters such as pH, temperature, electrical conductivity (EC), oxidation-reduction potential (ORP), total dissolved solids (TDS), and other anions including bromide, chloride, bicarbonate, nitrite, nitrate, phosphate, and sulphate. Fluoride concentration ranged from 1.7 mg/L to 8.2 mg/L and 1.6 mg/L to 3.9 mg/L in the sampled source water of Bankura and Purulia respectively, with both pre- and post-filter water of all the observed treatment units exceeding the WHO guideline of 1.5 mg/L. Potential contributors to underperformance may include inappropriate filter media selection, insufficient backwashing and regeneration, limited operational oversight and/or non-tailored treatment approaches. However, details on the adsorbent media and operational details were not available, and thus findings reflect observed field performance rather than necessarily causal relationships. These operational insights will contribute to the global discussion on improving decentralized groundwater treatment systems in resource-constrained settings. Full article

Safe drinking water and microbial inactivation from surfaces and devices are among the World Health Organization’s priorities. Plasma-activated water (PAW) inactivates microorganisms mainly by producing radicals (hydroxyl radicals, superoxide, nitrogen oxide, etc.), which form secondary reactive species like nitrates, nitrites, hydrogen peroxide, etc., from the air–liquid interface, where the plasma interacts with the water. A plasma arc device for water treatment with enhanced arc length was constructed at the Andronikashvili Institute of Physics (TSU) and used in the study. PAW’s antibacterial efficacy has been evaluated against Gram-negative E. coli and remarkably stress-resistant Gram-positive B. pumilus. This study identifies reactive oxygen (hydrogen peroxide and superoxide anions) and nitrogen species (total nitrate and nitrite ions) in plasma-activated water, analyzing their potential impact on antioxidant enzyme activity and their relationships with bacterial cell viability. B. pumilus exhibits greater resistance to plasma-activated water as a disinfectant compared to E. coli. Catalase is more effective than superoxide dismutase in protecting cells from external oxidative stress, based on the two antioxidant enzymes studied. Full article

2,9-Bis(1,2,4-triazin-3-yl)-1,10-phenanthroline (BTPhen)-based ligands show great promise in the separation of trivalent lanthanides and actinides. Experimental studies have shown that americium forms stronger complexes with the BTPhen ligands than europium; most theoretical studies have so far failed to reproduce these results. In the current study, three different metal forms (the naked cation, its nitrate or perchlorate salts and tetraaqua solvated salts) were used to study different complexation reactions. It was shown that in the case of naked cations and salts, europium forms the most stable complex with the 2,9-bis(1,2-triazin-3-yl)-1,10-phenanthroline ligand in all of the reactions compared. However, europium is also more strongly interacting (compared to americium) with anions and water molecules in the tetraaquatrinitrato or tetraaquatriperchlorato complexes. That shifts the energies of reactions like Am(NO₃)₃·4H₂O + [Eu(H₂O)₄BTPhen]³⁺ = [Am(H₂O)₄BTPhen]³⁺ + Eu(NO₃)₃·4H₂O in favor of the americium being complexed with BTPhen and europium with anions and water. Therefore, the americium complexes with BTPhen become the more stable form, in an agreement with the experimental studies. Comparison of counterion influence (nitrate vs. perchlorate) indicates that bigger preference for americium over europium complexation corresponds to the nitrate complexes and stems mainly from the fact that in M(NO₃)₃(H₂O)₄ europium is stabilized more than in M(ClO₄)₃(H₂O)₄. Full article

This study focuses on the synthesis and characterization of buckwheat husk-derived activated carbon, chemically activated with potassium hydroxide (KOH) and subsequently modified with urea and Prussian Blue (PB). The obtained carbons were evaluated in terms of particle-size distribution, surface morphology, structural features, and electrokinetic properties using scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM–EDS), Fourier-transform infrared spectroscopy (FTIR), Raman spectroscopy, and electrophoresis, as well as N₂ adsorption–desorption (BET surface area and porosity analysis). The results confirmed that both pyrolysis conditions and the type of modifier significantly affect the physicochemical properties of the activated carbon and its behavior in electrolyte solutions. Colloidal stability and particle size were strongly dependent on pH and the type of anions present in solution, with sodium nitrate (NaNO₃) systems showing higher stability than sodium chloride (NaCl). Modification with KOH and urea imparted a more basic surface character, whereas PB introduced more acidic properties. All samples exhibited predominantly negative surface charges and mesoporous structures, which are favorable for adsorption processes and enhance affinity for heavy-metal cations. Among the tested materials, BH-KOH-Fe (Fe-modified KOH-activated carbon) showed the most favorable performance for the targeted application, while BH-KOH (KOH-activated buckwheat husk-derived carbon) exhibited high surface area and good colloidal stability. The prepared materials show promising applicability for water purification, including the removal of organic pollutants and radionuclides (e.g., ¹³⁷Cs and ⁹⁰Sr), as well as metal cations (K⁺, Na⁺, and Li⁺). Full article