Micro-structural analysis of aqueous uranyl ions (UO22+) during the course of forward and back extraction in A biphasic system using all atom atomistic simulations.

N-propyl nitrate (NPN, CH3CH2CH2ONO2), a prevalent atmospheric alkyl nitrate (RONO2), is a key component of secondary organic aerosol (SOA) and a critical NOx reservoir. To support atmospheric pollution control, its •OH-initiated degradation mechanism, kinetics, atmospheric lifetime, and subsequent reactions were systematically investigated using density functional theory (DFT) and multistructural canonical variational transition state theory with small curvature tunneling (MS-CVT/SCT). Conformational searches identified the most stable conformers of NPN and the transition states for α-, β-, and γ-C-H H-abstraction, with α- and β-C-H abstractions as dominant pathways. Rate constants and branching ratios were calculated with multistructural torsional (MS-T) anharmonicity correction. The total rate constants show minimal variation (±2%) at 200-263 K, with an average value of ∼7.03 × 10-13 cm3 molecule-1 s-1; at 263-1000 K, they agree well with experimental values and display weak positive temperature dependence, with a calculated value of 7.59 × 10-13 cm3 molecule-1 s-1 at 298 K. The atmospheric lifetime of NPN is 1.02-18.56 days at 217-298 K. Given the scarcity of experimental data on •OH-initiated oxidation of NPN, the comprehensive kinetic and mechanistic results presented herein provide valuable supplementary data for atmospheric chemistry databases and offer guidance for future experimental investigations.

Rapid advances in materials chemistry and data-driven approaches have accelerated the development of aquatic chemical sensors, yet accurate, real long-term nutrient monitoring remains a significant challenge. Reliable real-time detection of nitrate (NO3-), nitrite (NO2-), and ammonium (NH4+) ions is essential for understanding aquatic biogeochemistry, mitigating eutrophication, ensuring precision fertigation, and ensuring sustainable water resource and crop management. Conventional electrochemical sensors can achieve low detection limits, but issues of accuracy, reproducibility, and stability under variable conditions hinder their broader application. In this preliminary study, electrochemical impedance spectroscopy (EIS) was employed in a three-electrode system to capture impedance responses over a wide frequency range, where the electrode-electrolyte interface was modelled using an equivalent circuit comprising resistive, capacitive and impedance elements. Impedance features including the real part, imaginary part, amplitude, and phase were analyzed as functions of concentration and frequency for the three target ions. To address the inherent nonlinearities of EIS data, advanced machine learning models were applied, with extreme gradient boosting (XGBoost) used for feature extraction, principal component analysis (PCA) for dimensionality reduction and a stacked ensemble (SVR-MLP-ridge regression) yielding the highest overall predictive accuracy (R2 = 0.99, RMSE < 0.921 ppm, MAE < 0.808 ppm, EV = 0.99) across all analytes. The developed hybrid tree-PCA-ML framework enables interpretable frequency-based analysis consistent with the physicochemical interpretations from the equivalent electrical circuit models. This combined EIS-ML approach not only enhances predictive accuracy for nutrient concentrations but also identifies critical frequency regions governing the sensing mechanisms, offering a pathway toward high-precision, real-time water quality monitoring.

Surface modification of colloidal semiconductor nanocrystals (NC) with inorganic ligands is known to enhance charge transport in NC-based optoelectronic devices. We have adapted this strategy to the emerging field of quantum dot (QD) photocatalysis to boost ammonia synthesis under visible light irradiation. Herein, a positively charged inorganic Lewis acid metal-solvent complex is used as a surface ligand on indium phosphide (InP) QD to facilitate photoinduced charge transfer from QD photocatalyst to nitrate ions. Additionally, the cationic surface of metal-solvent complex-capped InP QDs assists the electrostatic channeling of nitrate ions toward the QD surface, thereby further enhancing the charge extraction. The nitrate-to-ammonia conversion approaches near completion within 30 min of visible light illumination, with ammonia as the sole product detected in both aqueous and gaseous phases. The use of inorganic ligands results in 16-fold and 4-fold enhancements in reaction rate and apparent quantum efficiency, respectively, compared to conventional organic alkyl ligands. The apparent quantum yield reached a maximum of ∼6%, which is one of the highest values reported to date for the visible light-driven reduction of nitrate to ammonia. Water is identified as the proton source. We further demonstrate the broader applicability of other Lewis acid metal halide complexes as surface ligands for InP QDs in photocatalytic ammonia synthesis. Overall, our study shows the significance of the "ligand of choice" approach and catalyst-reactant interactions in regulating the photocatalytic performance of QDs for multielectron reactions that demand efficient and directional electron flow.

We highlight recent advances in nitration chemistry with emphasis on the development of sustainable and selective methodologies. A comprehensive overview of nitrating reagents is provided, classified by origin (organic or inorganic) and activation mode (photochemical, electrochemical, thermal, and others). Each reagent is critically analyzed with respect to its performance across different nitration processes, that is, aromatic, ipso-, olefinic, alkyne, and heteroatom nitration. This analysis scrutinizes yield, substrate scope, functional group tolerance, versatility, resource and hazard, key features that comprise an efficiency score. A comparative analysis of activation strategies underscores the evolution of nitration from classical mixed-acid approaches to modern photocatalytic, electrochemical, and cross-coupling methodologies. The insights gathered here provide a practical framework for identifying the most suitable nitrating reagents and highlight future directions toward safer, greener, and more versatile nitration chemistry.

ABSTRACT Concentrated solar power (CSP) systems commonly use solar salt as a high temperature heat transfer and storage medium. This study examines the effect of oxygen (O 2 ) and nitrogen oxide (NO) gas concentrations on solar salt thermal stability and 310N stainless steel corrosion at 600°C up to 1224 h. The impact of the gas atmosphere (5–80 vol% O 2 , 400–600 ppm NO) on salt chemistry, including nitrate, nitrite, oxide, and chromate ions, was analyzed, and corrosion behavior was evaluated through weight change, corrosion rate, and microstructural analysis. The results show that introducing NO gas concentrations ≥ 400 ppm with at least 5 vol% O 2 stabilizes salt decomposition by controlling nitrite and oxide ion formation and promotes the development of a protective corrosion layer on the steel surface. Once this protective layer is formed, variations in oxygen concentration (5–80 vol%) in the presence of ≥ 400 ppm NO gas have a minimal long‐term effect on the corrosion behavior of stainless steel in solar salt. These findings underscore the importance of maintaining minimum O 2 and NO levels to optimize salt chemistry that effectively mitigates steel corrosion in solar salt systems.

Nitroanilines are versatile building blocks for the synthesis of miscellaneous compounds such as dyes, pharmaceuticals, perfumes and many other targets. To answer the chemical limitations of the well‐developed “mixed acids” conditions (such as harsh conditions, poor regioselectivity, and poor functional group tolerance), several alternatives nitration conditions have been developed specifically for aniline derivatives. In this review, we offer an overview of the miscellaneous existing methodologies to provide nitroanilines through aromatic nitration of pre‐functionalized anilines. The development of more sustainable approaches using enabling technologies is also presented and their sustainability is discussed through a comparative study of E‐factors.

Methanotrophic bacteria are the primary organisms that consume atmospheric methane (CH4) and have potential to mitigate climate-active gases. However, a limited understanding of the genetic determinants of methanotrophy hinders the development of biotechnologies leveraging these unique microbes. Here, we developed and optimized a CRISPR interference (CRISPRi) system to enable functional genomic screening in methanotrophic bacteria. We built a genome-wide single guide RNA (sgRNA) library in the industrial methanotroph, Methylococcus capsulatus, consisting of ~45,000 unique sgRNAs mediating inducible, CRISPRi-dependent transcriptional repression. A selective screen during growth on CH4 identified genes associated with essential methanotrophic bacterial processes and previously unidentified essential gene candidates, highlighting the utility of CRISPRi for functional genetic screening in methanotrophs. The CRISPRi screen also led to nitrate mineral salts medium optimization to improve methanotroph biomass productivity from CH4. Collectively, our results show that the CRISPRi system and sgRNA library developed here can be used for facile gene-function analyses and genomic screening to identify genetic determinants of methanotrophy and isolation of improved methanotroph biocatalysts.

This research successfully converted spent coffee grounds (SCG) into powdered activated carbon (AC) through carbonization at 400°C. The surface functional groups of this carbon were subsequently modified using hydrochloric acid as an activating agent to enhance its adsorption properties. The purpose of this research was to evaluate the performance of this modified activated carbon (MAC) as an adsorbent for reducing nitrate content in tofu industry wastewater, which is characterized by high concentrations of nitrate ions. The MAC was characterized using SEM and FTIR analysis to determine its surface morphology and functional groups, which are critical for adsorption process of capturing atoms, ions, and molecules on a materials surface. The batch adsorption experiments using AC and MAC as adsorbent were then performed for reducing nitrate content in tofu industry wastewater. Batch adsorption experiments were conducted under optimal conditions: a pH of 7±0.2, room temperature, a stirring rate of 150 rpm, and an adsorbent dose of 1 g/L. The results demonstrated a significant decrease in nitrate concentration from 28.6 mg/L to 1.2 mg/L, achieving a 95.80% removal efficiency at an equilibrium contact time of 180 minutes. The performance of the MAC was comparable to, and even more favorable than, that of unmodified activated carbon (UAC) used as a control that only achieved 58.74% percentage removal of nitrate. This remarkable nitrate removal efficiency is attributed to the distinct morphology and enhanced surface properties imparted by the hydrochloric acid modification. Therefore, modified activated carbon from coffee grounds shows high potential as an effective adsorbent for wastewater treatment.

BackgroundCallitriche cophocarpa Sendtn. (water starwort; Plantaginaceae) is an aquatic higher plant common in natural environments worldwide. The plant is used in folk medicine due to its ability to synthesize large amounts of secondary metabolites with a broad range of biological activity. This study used various types of tissue culture to produce safe plant material for medical purposes. The plants were subjected to elicitation through nitrogen deficiency, and their extracts were examined for biological activity.ResultsQualitative phytochemical analysis of shoots in vitro showed the presence of phenolic acids and phenylethanoid and iridoid glycosides. Based on the results, cultures (stationary and agitated) grown in liquid medium were selected due to their greater effectiveness, i.e., plant growth and higher production of secondary metabolites, compared to a temporary immersion bioreactor. In the second part of the research, tissue cultures (stationary and agitated) were subjected to elicitation, where the stressor was a decreased level (¼N) or lack (0 N) of available nitrogen in the form of nitrate and ammonium ions. Compared to unelicited tissues, a greater accumulation of phenolic acids and phenylethanoid and iridoid glycosides was observed. However, when individual secondary metabolites within these classes were considered, some compounds showed reduced accumulation under elicitation with a medium containing a reduced concentration of N ions, which also resulted in decreased fresh weight growth.The antioxidant and antibacterial properties of extracts from both control and elicited plants were evaluated. The induction of synthesis of the phenolic acids and phenylethanoid and iridoid glycosides resulted in an increased reducing capacity and antibacterial properties against reference, antibiotic-resistant, and antibiotic-sensitive strains of Staphylococcus aureus.ConclusionsCallitriche cophocarpa grown in vitro is a rich source of valuable secondary metabolites. Elicitation by nitrogen deficiency activates biochemical pathways connected with phenolic compounds and phenylethanoid glycosides. The strong bactericidal properties of C. cophocarpa relate to a high level of accumulation of verbascoside and phenolic acidsSupplementary InformationThe online version contains supplementary material available at 10.1186/s12870-026-08807-0.

Alpine lakes exhibit a distinct physicochemical character compared to other aquatic systems shaped by rugged terrain and extreme environmental conditions. The nival summits of upper Bhaderwah, known as the Kailash landscape, are dotted with a group of alpine lakes yet to be examined for water quality, thus prompting the current investigation. The water sampling and analysis were performed for nineteen major water quality parameters in six alpine lakes, comprising three primary (Kali Kund, Kailash Kund, and Shiv Kund) and their associated lakes (Mahakal Kund, Rishi Sar, and Vishi Sar) during September 2021, 2023, and 2024. All the major physicochemical parameters, including water temperature, electrical conductivity, total dissolved solids, turbidity, pH, dissolved oxygen, carbonates, bicarbonates, total alkalinity, chloride, nitrate, sulphate, phosphate, fluoride, calcium, magnesium, total hardness, sodium, and potassium ions, exhibited low to very low values with slight deviations among the water bodies. The Gibbs plot suggested that the lakes are regulated by precipitation, while the Piper diagram indicated a Calcium-bicarbonate water type. The results indicate the pristine water quality of the alpine lakes, however, the increased anthropogenic activities may impair the water quality if appropriate management measures are not adopted. The findings call for long-term ecological monitoring of these high-altitude lakes.

In this study, we investigated the intermolecular vibrational dynamics of five deep eutectic solvents (DESs) composed of a 4:1 molar ratio mixture of acetamide and lithium salts, namely, lithium nitrate, perchlorate, trifluoromethanesulfonate, bis(fluorosulfonyl)amide, and bis(trifluoromethylsulfonyl)amide, using femtosecond Raman-induced Kerr effect spectroscopy. The low-frequency spectra below ∼200cm-1 revealed that the peak position and first moment of the intermolecular vibrational band depended on the anion species, while acetamide molecules mainly determined the spectral intensity in most cases. However, the librational motion associated with the planar nitrate ion resulted in an intense low-frequency spectrum. The first-moment value was larger for the nitrate DES than for the other four DESs, indicating stronger intermolecular interactions in the former. A similar trend was observed for surface tension values. Comparison with previous results for lithium bis(trifluoromethylsulfonyl)amide-organic amide DESs showed that variation in the first moment of the intermolecular vibrational band and in the bulk parameter (square root of surface tension divided by liquid density) is larger upon changing the anion species than upon changing the organic amide species. Accordingly, the microscopic intermolecular interactions probed by the intermolecular vibrational band are significantly influenced by the anion species. Furthermore, a plot of the first moment of the intermolecular vibrational band vs the bulk parameter displayed a linear correlation, indicating a strong relationship between microscopic intermolecular interactions and macroscopic properties in the DES systems.

In this study, the effects of current density, electrolysis time, pH value, and sodium chloride (NaCl) electrolyte dosage on fluoride removal efficiency were systematically investigated. The results showed that the optimal operating parameters were determined as follows: current density of 10 mA/cm², electrolysis time of 30 min, pH value of 6, and NaCl dosage of 1 g/L. Under these optimal conditions, the fluoride removal efficiency could stably exceed 85%. Calcium, magnesium, and sulfate ions at an appropriate concentration of 50 mg/L significantly enhanced the fluoride removal efficiency, whereas nitrate ions exhibited a pronounced inhibitory effect. In the current density range of 5–15 mA/cm2, the advanced fluoride removal process via electrocoagulation was better fitted to the pseudo-first-order adsorption kinetics model, indicating that the adsorption process was dominated by physical adsorption. The Zeta potential showed a trend of initial increase followed by a gradual decrease. The generated flocs had an average particle size of 146.4 μm and underwent significant directional aggregation, forming a large number of irregular dendritic and star-shaped flocculent aggregates.

The wing scale chemical spectra of two nymphalid species, Parantica aglea and Acrea terpsicore was investigated using Fourier Transform Infrared Spectroscopy (FTIR) to determine characteristic functional groups. Comparative analysis of the functional groups revealed the presence of several major groups, including alcohols, phenols, aldehydes, alkanes, alkenes, alkyl halides, alkynes, methylene, acids, nitro compounds, primary, secondary, and tertiary amines, esters, ethers, polysulfides, aryl disulfides, cyanide and thiocyanate ions, carbonate ions, organic sulphates, organic nitrates, nitrate ions, aromatic ethers, aromatic phosphates, phosphate ions, ammonium ions, silicate ions, transition metal carbonyls, and organic siloxanes or silicones. Common functional groups between the two species include alcohols and phenols, alkanes, alkenes, alkyl halides, methylene, acids, esters, ethers, aryl disulfides, cyanide and thiocyanate ions, carbonate ions, organic nitrates, nitrate ions, phosphate ions, and silicate ions. However, certain elements are specific to particular regions, such as alkynes. This study represents the first FTIR analysis conducted on the wing scales of P. aglea and A. terpsicore providing valuable insights into their chemical compositions.

The river ecosystems of the Qinghai–Tibet Plateau, recognized as a vital component of the “Asian Water Tower,” possess unique hydrological conditions and extreme environments that have shaped key indicator groups, most notably zooplankton. The community dynamics and structural characteristics of these zooplankton exhibit regular spatio-temporal distribution patterns across elevational gradients and seasonal successions. However, the intrinsic mechanisms underlying community succession and their correlations with environmental factors remain poorly understood, and the primary environmental drivers influencing community structure require further elucidation. Based on systematic zooplankton surveys and environmental data collection conducted across the Lhasa River basin from 2019 to 2021, this study established a comprehensive species inventory comprising 113 taxa across four major groups, alongside a multi-dimensional environmental dataset. We analyzed the spatio-temporal heterogeneities of zooplankton community structures—including abundance, biomass, and diversity indices—across different seasons and river reaches. The results revealed the composition and seasonal turnover of dominant taxa, with rotifers accounting for 39.82% of the total taxonomic richness. Mean zooplankton abundance and biomass across the basin were 1.18 ind./L and 343.60 × 10−5 mg/L, respectively, with peak values observed during autumn and within the Chabalang Wetland. The zooplankton community structure in the upstream, midstream, and downstream reaches, as well as associated wetlands, was significantly correlated with specific environmental factors (p &lt; 0.05), including ammoniacal nitrogen (NH4+-N), magnesium (Mg2+), total hardness (TH), potassium (K+), iron (Fe2+), sodium (Na+), sulfite (SO32−), nitrate ion (NO3−), chloride ion (Cl−), total phosphorus (TP), and sulfide (S2−). Cl−, TH, Mg2+, SO32−, and elevation (Ele) were the key environmental drivers significantly influencing zooplankton abundance across seasons (p &lt; 0.05). Furthermore, zooplankton abundance decreased significantly with increasing elevation during the winter. This research deepens our understanding of community assembly mechanisms in plateau river ecosystems and provides a scientific foundation for aquatic biodiversity conservation and ecological management in the Lhasa River basin.

This study successfully fabricated a freestanding ZnO@(NiFe)OOH nano-heterostructure array electrocatalyst with high hydrophilicity for efficient electrocatalytic nitrate reduction to ammonia (NO3RR) in neutral media. The material integrates the large specific surface area of one-dimensional ZnO nanoarrays with the electronic modulation capability of heterogeneous interfaces, which significantly enhances nitrate adsorption and activation, promotes proton supply, and effectively suppresses the hydrogen evolution side reaction. The highly hydrophilic surface further accelerates electrolyte diffusion, nitrate ion transport, and product desorption. In a neutral electrolyte of 0.1M PBS containing 0.15M KNO3 at a potential of -1.0V (vs. RHE), the catalyst achieves an ammonia production rate of 4.86 mg·h-1·cm-2 with a Faradaic efficiency of 85.58%, while generating minimal byproducts, demonstrating excellent catalytic selectivity and stability. This work provides a new strategy for the structural design and performance enhancement of NO3RR electrocatalysts, which holds significance for advancing green ammonia synthesis and enabling efficient conversion of nitrate in water pollution control.

This article presents a study of wastewater treatment at a tannery using a developed process flow diagram that combines an adsorber, a floating bed bioreactor, and an aeration tank. The study was conducted on real wastewater from the tannery of PO SHEVRET LLC, located in the city of Volgograd. The average physicochemical composition of this water was: COD – 5850±433 mg/l, BOD5 – 1525±249 mg/l, suspended solids – 1205.7±33 mg/l, mass concentration of nitrites (by nitrogen) – 0.045±2 mg/l, ammonium ion – 40±6 mg/l, nitrate ion – 81±16 mg/l and total chromium – 42±24 mg/l. The results of the studies of the developed technological scheme for the treatment of wastewater from tanneries show that the use of this technology allows achieving deep purification. The reduction in BOD5, COD, chromium, nitrates, nitrites, ammonium nitrogen and suspended solids in wastewater amounted to 85.04 %, 94.78 %, 100 %, 96.29 %, 100 %, 97.75 % and 99.75 % respectively. The results confirm that this integrated technology provides effective treatment, significantly reducing the pollution level and contributing to more sustainable wastewater management in the tannery industry.

Background: Irrigation water quality is a fundamental determinant of soil health, crop productivity, and the synthesis of health-promoting bioactive compounds in functional foods. This study evaluates the hydrochemical status of the Berqaber (Joghas) Reservoir and its inflowing rivers (Aghstev and Joghas) in the Tavush region of Armenia, a strategic water resource for regional agriculture, to assess their suitability for sustainable functional crop production. Objective: This study aims to evaluate the hydrochemical status of the Berqaber Reservoir and its inflowing rivers (Aghstev and Joghas) in northern Armenia, assess their suitability for irrigation using established water quality indices, and examine the implications of irrigation water quality for the safety, nutritional content, and bioactive compound accumulation in functional crops. Methods: Water samples were collected in April and July 2024. Analyses included physicochemical parameters, such as pH, total dissolved solids (TDS), and major ions: calcium (Ca²⁺), magnesium (Mg²⁺), sodium (Na⁺), bicarbonate (HCO₃⁻), and chloride (Cl⁻). Heavy metals analyzed included lead (Pb), copper (Cu), zinc (Zn), manganese (Mn), and nickel (Ni). Irrigation suitability indices were calculated: Sodium Adsorption Ratio (SAR), Magnesium Hazard (MH), and Stabler’s coefficient (k). To validate irrigation safety, nitrate ion (NO₃⁻) concentrations, heavy metal accumulation, and nutritional indicators (vitamin C and starch) were assessed in irrigated potatoes, tomatoes, and eggplants. Results: The irrigation waters exhibited a slightly alkaline reaction (pH 7.4–7.5) with low salinity (TDS 480–570 mg/L). The ionic composition was dominated by Ca²⁺, Mg²⁺, Na⁺, HCO₃⁻, and Cl⁻. SAR values (2.22–2.26) and Stabler’s coefficients (≈10) classified the water as satisfactory for irrigation with low sodicity risk (United States Salinity Laboratory (USSL C2–S1 category). MH values (48.78–49.46%) approached the 50% threshold associated with potential soil structural sensitivity. NO₃⁻ concentrations (12.4–13.0 mg/L) exceeded the Armenian regulatory limit of 10 mg/L (Class 3, Moderate Quality), yet nitrate and heavy metal concentrations in edible crop tissues remained well below Maximum Permissible Concentrations (MPC), and nutritional parameters were unaffected. Conclusion: The Berqaber Reservoir system provides irrigation water with low sodicity risk; however, borderline MH and elevated nitrate levels indicate moderate anthropogenic pressure. Despite this, nitrate and heavy metal concentrations in crops remain within permissible limits, ensuring their safety and functional quality. Effective institutional oversight and compliance with water quality regulations are essential to maintain long-term, sustainable, functional crop production. Novelty of the Study: This study is the first to integrate hydrochemical assessment of irrigation water with empirical validation of functional crop safety in the Tavush agroecosystem of northern Armenia. By linking irrigation water chemistry with crop nitrate accumulation, heavy metal transfer, and nutritional quality indicators, the research establishes a comprehensive “water-to-table” evaluation framework for sustainable functional food production in mountainous agricultural systems. Keywords: irrigation water, water quality, heavy metals, sodium adsorption ratio, nitrates, magnesium hazard, Berqaber Reservoir, functional foods, water regulation

Methyl 2-hydroxybenzoate, also known as methyl salicylate (MeSa), is a volatile organic compound emitted from green leaves into the atmosphere. The emission of MeSa into the atmosphere is comparable to that of benzene; however, information on its oxidation in the air is limited. Here, the atmospheric oxidation mechanism of MeSa, initiated by its reaction with the OH radical, is investigated using theoretical calculations. The oxidation mechanism of methyl benzoate (MeBz), a homologue to MeSa, is also studied. Oxidation of both MeSa and MeBz with OH starts with OH additions to the aromatic ring, forming MeSa/MeBz-nOH adducts (n denotes the addition site), and by hydrogen-atom abstraction (HAA) from the methyl group. MeSa-3OH, MeSa-5OH, and MeBz-3OH react with O2 similarly to substituted benzene-OH adducts, forming dicarbonyls through bicyclic and bicyclic peroxy radical intermediates, while MeSa-2OH reacts in a similar way as phenol-2OH, forming a substituted cyclohexadienone compound. For MeSa-6OH, MeBz-2OH, and MeBz-4OH, they react with O2 mainly by direct HAA, forming methyl 2,6-dihydroxybenzoate, methyl 2-hydroxybenzoate (MeSa), and methyl 4-hydroxybenzoate, respectively. Under atmospheric conditions, MeSa-6OH and MeBz-4OH react with O2 slowly at pseudo-first-order rate coefficients of ∼102 s–1, allowing their reactions with NO2 in polluted regions and forming the notorious aromatic nitrate compounds.

Phosphate contamination in water bodies is a major environmental concern due to its role in eutrophication, necessitating the development of low-cost, efficient, and sustainable removal technologies. In this study, an eco-friendly biosorbent was prepared from waste banana peels through saponification followed by Fe(III) loading (Fe(III)-SBP) for effective phosphate ion removal from aqueous solutions. The prepared biosorbent was characterized using FTIR and SEM to confirm functional group modification and surface morphology, while the point of zero charge (pHPZC) was determined to be 6.8. Batch biosorption experiments revealed that phosphate uptake was highly pH-dependent, with a maximum biosorption capacity of 18.51 mg/g at pH 5.34. Equilibrium and kinetic data were best described by the Langmuir isotherm and pseudo-second-order kinetic model, indicating monolayer chemisorption. Competitive ion studies showed negligible interference from chloride and nitrate ions, whereas sulphate and bicarbonate ions significantly inhibited phosphate removal. The adsorbed phosphate was efficiently desorbed using 0.5 M NaOH, demonstrating good regeneration potential of the biosorbent. Overall, the results confirm that Fe(III)-loaded saponified banana peels are an effective, low-cost, and sustainable biosorbent for phosphate removal, highlighting their potential application in wastewater treatment and nutrient pollution control.