Real Water Research Articles

3D-printed carbon black/polylactic acid electrode modified with silver particles: a powerful alternative and cost-effective sensor for nitrate sensing in real water samples

3D-printed carbon black/polylactic acid electrode modified with silver particles: a powerful alternative and cost-effective sensor for nitrate sensing in real water samples

Navigating an unpredictable environment: the moderating role of perceived environmental unpredictability in the effectiveness of ecological resource scarcity information on pro-environmental behavior

BackgroundThe global issue of ecological resource scarcity, worsened by climate change, necessitates effective methods to promote resource conservation. One commonly used approach is presenting ecological resource scarcity information. However, the effectiveness of this method remains uncertain, particularly in an unpredictable world. This research aims to examine the role of perceived environmental unpredictability in moderating the impact of ecological resource scarcity information on pro-environmental behavior (PEB).MethodsWe conducted three studies to test our hypothesis on moderation. Study 1 (N = 256) measured perceived general environmental unpredictability, perceived resource scarcity and daily PEB frequencies in a cross-sectional survey. Study 2 (N = 107) took it a step further by manipulating resource scarcity. Importantly, to increase ecological validity, Study 3 (N = 135) manipulated the information on both ecological resource scarcity and nature-related environmental unpredictability, and measured real water and paper consumption using a newly developed washing-hands paradigm.ResultsIn Study 1, we discovered that perceived resource scarcity positively predicted PEB, but only when individuals perceive the environment as less unpredictable (interaction effect: 95% CI = [-0.09, -0.01], ΔR2 = 0.018). Furthermore, by manipulating scarcity information, Study 2 revealed that only for individuals with lower levels of environmental unpredictability presenting ecological resource scarcity information could decrease forest resource consumption intention (interaction effect: 95%CI = [-0.025, -0.031], ΔR2 = .04). Moreover, Study 3 found that the negative effect of water resource scarcity information on actual water and (interaction effect: 95%CI = [3.037, 22.097], ηp2 = .050) paper saving behaviors (interaction effect: 95%CI = [0.021, 0.275], ηp2 = .040), as well as hypothetical forest resource consumption (interaction effect: 95%CI = [-0.053, 0.849], ηp2 = .023) emerged only for people who receiving weaker environmental unpredictability information.ConclusionAcross three studies, we provide evidence to support the moderation hypothesis that environmental unpredictability weakens the positive effect of ecological resource scarcity information on PEB, offering important theoretical and practical implications on the optimal use of resource scarcity to enhance PEB.

Modeling approach for Ti3C2 MXene-based fluorescent aptasensor for amoxicillin biosensing in water matrices

Amoxicillin, a member of the penicillin family, is primarily utilized for the treatment of various bacterial infections affecting ears, nose, throat, urinary tract, and skin. Given its widespread application in medicine, agriculture, environment, and food industry, the precise and sensitive detection of amoxicillin is important. This study introduces a novel approach to developing a sensitive and selective fluorescent aptasensor relying on fluorescence resonance energy transfer (FRET) for the specific detection of amoxicillin. The carboxyfluorescein-labeled aptamer serves as a energy donor, while MXene functions as an energy acceptor, and acting as a quencher. To achieve optimal detection efficiency, a dual optimization strategy utilizing RSM-CCD and ANN-GA was used to fine-tune experimental conditions. The fluorescence measurements revealed an expansive linear range extending from 100 to 2400 ng mL−1, accompanied by an exceptionally low detection limit of 1.53 ng mL−1. Additionally, it shows an excellent selectivity towards amoxicillin over other antibiotics commonly found in water matrices. The aptasensor demonstrates good stability and reproducibility; effectiveness of the aptasensor was validated by testing in real water samples. This remarkable sensitivity and broad dynamic range affirm the efficacy aptasensor in accurately detecting varying concentrations of amoxicillin in wastewater bodies.

A Ratiometric Green Fluorescent Carbazole-bis(hydrazinobenzothiazole) Probe for the Selective Detection of Toxic Hg2+ Ions in Real Water Samples.

A dyad Carbazolyl-bis(hydrazinobenzothiazole) was designed to form a symmetrical structure that containing two-arm active binding sites facilitates coordination with Hg2+ ion. This sensor has imparted a colorimetric and fluorometric changes in presence of Hg2+ ions. The ligand showed a selective blue shift in presence of Hg2+even in co-existence with heavy metal ions with luminescence change from colorless to blue and colorless to green under day light. Enhanced Intramolecular charge transfer process is responsible for fluorescence transformation when ligand interacts with Hg2+ ion. The emission spectra showed a ratiometric response to increasing addition of Hg2+ ions. The sensor is capable of detecting above the lower concentration of 6.8025 × 10-8 M. The fluorescence efficiency of CBT-2 with Hg2+ ion is quite stable under different co-metal ions and wide range of pH 6 to 9. The sensor CBT-2 forms a 1:1 stoichiometric complex with Hg2+ ions and the binding nature is confirmed from the 1H-NMR, FTIR, and mass spectroscopic studies. The sensor CBT-2 and its Hg2+ complex possess good binding nature to protein in Bovine Serum Albumin which could be good in biological applications. Additionally, wedevelop a practical application in real water sample analysis and electrochemical detection viaoxidation potential discrimination.

A Zn/Cd/Ni Metal-Organic Framework-Based Solid and Flexible Fluoroprobes for Highly Selective Detection of 4-Nitroaniline in Real Water Samples.

The combination of diazabicyclic compound i.e. 1,4-diazabicyclo[2.2.2]octane (DABCO) and dicarboxylate linker 1,4-dicarboxylic acid are employed to self-assemble with three divalent metal ions such as Zn2+, Cd2+, Ni2+ led to the formation of highly stable pillar layered luminescent metal-organic frameworks. The emissive response of as-synthesized MOFs was studied in organic solvents with different functionalities resulting in the development of fluoroprobes having excellent recognition ability for 4-nitroaniline with detection limit upto micromolar. All the MOFs display a good linear relation between the fluorescence intensity and concentration of 4-NA in the range of 10-90µmol L-1. The values of Ksv for Zn-MOF, Cd-MOF, and Ni-MOF are found to be 1.75 × 104mol-1L, 1.25 × 104mol-1L, and 28.0 × 104mol-1L, respectively. The calculated detection limit values are 19.7µmol L-1, 27.6µmol L-1, and 1.19µmol L-1 respectively. Moreover, the study was further extended to fabricate the solid membrane-based fluoroprobe using a linear chitosan polysaccharide and act as an efficient solid fluoroprobe for the detection of 4-NA. This proposed synthesis of polymeric membrane facilitates the MOF@chitosan fluorophore to transfer its fluorescence-emissive nature to a solid state.

MOF-on-MOF-derived Fe[sbnd]Zr bimetal oxides supported on hierarchically porous carbonized wood to promote photo-Fenton degradation of ciprofloxacin

MOF-on-MOF derivatives have served as promising heterogeneous Photo-Fenton (hetero-PF) catalysts, but its self-aggregation instability and limited photocatalytic activity inhibit the effective ciprofloxacin (CIP) removal. In this study, a novel hetero-PF catalyst, dual MOF-derived FeZr bimetal oxide embedded in a wood-converted porous carbon skeleton (ZrO2@Fe3O4/WPC), was successfully synthesized via a straightforward in-situ growth strategy combined with co-pyrolysis. The as-prepared hybrid photocatalysts, featuring a large surface area, effective porous structures, efficient light absorption and a narrow band gap demonstrated superior photo-Fenton activity, accomplishing approximately 99.1 % degradation of CIP within 120 min under neutral conditions. Furthermore, the ZrO2@Fe3O4/WPC hetero-PF system showed satisfactory performance in treating real water matrices. It can be inferred that the abundant heterojunctions, resulting from the synergistic effect of FeZr mixed oxide and the porous carbonized wood substrate, contributed to the rapid separation and migration of photogenerated electron-hole pairs. Meanwhile, the FeZr site in the graphitized carbon framework activates H2O2 to accelerate the generation of the OH and O2− radicals, leading to a heightened degradation efficiency of CIP. Besides, the photodegradation pathway of CIP is obtained by liquid chromatography-mass spectrometry (LC-MS). This study indicates that combining porous carbonized wood and heterometallic MOF derived materials provides a promising method for realizing high-efficiency photo-Fenton degradation of antibiotic water pollutions.

Rational design of peptide-based fluorescent probe for sequential recognitions of Cu(II) ions and glyphosate: Smartphone, test strip, real sample and living cells applications

A new peptide-based fluorescent probe named DMDH with easy-to-synthesize, excellent stability, good water solubility and large Stokes shift (225 nm) was synthesized for highly selective sequential detections of copper ions (Cu2+) and glyphosate (Glyp). DMDH demonstrated great detection performance towards Cu2+via strong fluorescence quenching, and forming non-fluorescence DMDH-Cu2+ ensemble. As a new promising cascade probe, the fluorescence of DMDH-Cu2+ ensemble was significantly recovered based on displacement approach after glyphosate was added. Interestingly, the limit of detections (LODs) for Cu2+ and glyphosate were 40.6 nM and 10.6 nM, respectively, which were far lower than those recommended by the WHO guidelines for drinking water. More importantly, DMDH was utilized to evaluate Cu2+ and glyphosate content in three real water samples, demonstrating that its effectiveness in water quality monitoring. Additionally, it is worth noting that DMDH was also applied to analyze Cu2+ and glyphosate in living cells in view of significant cells permeability and low cytotoxicity. Moreover, DMDH soaked in filter paper was used to create qualitative test strips and visually identify Cu2+ and glyphosate through significant color changes. Furthermore, smartphone RGB color recognition provided a new method for semi-quantitative testing of Cu2+ and glyphosate in the absence of expensive instruments.

Transformation of polyester fibre microplastics by sulfate based advanced oxidation processes

Advanced oxidation processes (AOPs) are a potential solution to microplastics (MPs) polluted wastewater but incomplete degradation can result in the formation of smaller fragments with altered surface chemistry. In this work, the impact of sulfate based oxidation on polyester MPs was investigated. Light, heat and ultrasound activation of persulfate resulted in varied degrees of mass loss and surface degradation, as probed by scanning electron microscopy (SEM), atomic force microscopy (AFM) and Fourier transform infrared spectroscopy (FTIR). Ultrasonic activation of persulfate resulted in significantly increased fragmentation and formation of smaller microplastic fibrils. Optimised UVC/peroxydisulfate (UVC/PDS) treatment (31.8 mW cm−2, 500 mg L−1) resulted in an 18.5% mass loss over 9 h with clear surface pitting and cracking. Extended treatment under these conditions for 24 h did not result in significantly increased mass loss but did cause an increased degree of surface degradation and increased roughness, indicating that incomplete mineralisation is likely in wastewater systems accompanied by MP transformation. The influence of a real laundry wastewater matrix was also studied and a decreased rate of mass loss was observed due to competing radical reactions with the organic content of the wastewater. Results advance understanding and therefore contribute to mitigating water pollution by MPs, since their physical and chemical transformation in real water treatment systems substantially affects the interaction with organic contaminants and changes the potential environmental risk of MPs.

Eco-friendly fabrication of silver nanoparticle-decorated electrodes for aqueous bisphenol A sensing

This work fabricated an electrochemical sensor for detecting bisphenol A (BPA) by employing silver nanoparticles (AgNPs) synthesized through an eco-friendly approach. The AgNPs were produced using parsley leaf extract, which acted as a reducing and stabilizing agent in the synthesis process. The AgNPs synthesized using the green approach exhibited an average size of 15.2 ± 2.1 nm. The AgNP-modified screen-printed electrode (SPE) exhibited excellent electrocatalytic activity towards BPA oxidation, with an enhanced peak current of 28.6 μA compared to 5.2 μA for the bare SPE. The optimized sensor exhibited impressive analytical performance, boasting a broad linear range spanning 0.05–5 μM for BPA detection. Remarkably, it achieved a low limit of detection of 0.02 μM, coupled with high sensitivity. Furthermore, the sensor demonstrated commendable reproducibility, with a RSD of 3.6%, and exceptional repeatability, evidenced by an RSD of 2.4%. Upon evaluating the sensor's performance in analyzing real water specimens, the recoveries oscillated between 95.8% and 103.5%, accompanied by RSDs not exceeding 4.2%, thereby demonstrating its successful application for BPA detection. The eco-friendly synthesis approach and superior analytical performance make the AgNP-modified SPE a promising tool for on-site environmental monitoring and drinking water analysis.

Online sequential analysis of volatile and semivolatile organic compounds in water matrices by double robotic sample preparations and dual-channel mono and comprehensive two-dimensional gas chromatography coupled with time-of-flight mass spectrometry system

The monitoring of organic compounds in aquatic matrices poses challenges due to its complexity and time-intensive nature. To address these challenges, we introduce a novel approach utilizing a dual-channel mono (1D) and comprehensive two-dimensional (2D) gas chromatography coupled with time-of-flight mass spectrometry (GC × GC–TOFMS) system, integrated with a robotic pretreatment platform, for online monitoring of both volatile organic compounds (VOCs) and semivolatile organic compounds (SVOCs) in water matrices. Employing the robotic platform, we establish a suite of online liquid–liquid extraction (LLE) pretreatment processes for water samples, marking the first instance of such procedures. Leveraging the automatic headspace (HS) module, dual robotic preparations of HS and LLE are sequentially executed to extract VOCs and SVOCs from water matrices. The GC × GC–TOFMS system is distinguished by its dual-channel analytical column configuration, facilitating sequential analysis of VOCs in GC–TOFMS mode and SVOCs in GC × GC–TOFMS mode. Quantitative detection of 55 target VOCs and 104 SVOCs is achieved in a water sample using the instrument system. Our method demonstrates excellent correlation coefficients ranging from 0.990 to 1.000, method detection limits ranging from 0.08 to 4.78 μg L–1, relative standard deviations below 19.3 %, and recovery rates ranging from 50.0 % to 124.0 %. To validate the online monitoring capabilities of our system, we assess target SVOCs at three different concentration levels over a 3-day period. Most compounds exhibit recovery rates ranging from 70.0 % to 130.0 %. Furthermore, we apply our method to analyze a real water sample, successfully identifying over 100 target and nontarget VOCs/SVOCs, including alcohols, aldehydes, ketones, acids, esters, and phenols. These results highlight the efficacy of the proposed analysis system, capable of conducting two distinct analyses in automatic sequence, thereby enhancing the efficiency and accuracy of organic compound analysis in water matrices.

Pyrite/biochar-activated peroxymonosulfate strengthens tetracycline degradation: Important roles of surface functional groups and Fe(Ⅱ)/Fe(Ⅲ) redox cycling

Nonradical species with high anti-interfering properties have shown significant advantages in complex wastewater treatment. Herein, a pyrite/biochar catalyst (FBC) was prepared using pine sawdust biochar (BC) as a support material loaded with pyrite (FeS2). It exhibited high activity and stability in the FBC/PMS system for effective activation of peroxymonosulfate (PMS) to degrade tetracycline (TC) over a wide pH range (3.0–9.0). According to the characterization and analysis data, a variety of oxygen-containing functional groups (CO, -OH) and Fe and S active sites on the FBC surface assisted in PMS decomposition to produce reactive oxygen species (ROS). The mechanism study showed that the redox cycling of Fe(Ⅱ)/Fe(Ⅲ) and the electron-transfer medium of the BC oxygen functional groups contributed to the formation of SO4•-, •OH, O2•-, 1O2 and FeⅣ=O, but 1O2 was the main active oxidant. The potential pathways for TC degradation were suggested, and the toxicity of by-products was predicted by toxicity evaluation. Furthermore, FBC/PMS system exhibited minimal sensitivity to interference of concomitant materials. Overall, this study provided a reference for the application of green advanced oxidation technology of iron-based mineral composites to treat pharmaceutical contaminants in real water.

D-limonene-based polymeric adsorbent for effective Pb(II) ion removal: A comprehensive study on sorption behaviour and environmental applicability

In response to the pressing global health concern posed by lead contamination in water systems, we introduce a novel green synthesis polymer, LIM-co-DVB-co-VIM, derived from D-Limonene, a natural terpene. This polymer offers high surface area and tenability making it a promising solution for Pb(II) ion removal. Our study involves a thorough characterization of the adsorbent and optimization of operational parameters for selective Pb(II) ion removal. Adsorption follows Langmuir isotherm and pseudo-second-order kinetics, with an adsorption capacity of 31.8 mg g⁻¹ and rapid removal efficiency. Thermodynamic analysis reveals the exothermic and spontaneous nature of the adsorption process. Selectivity studies confirm the polymer's ability to selectively adsorb Pb(II) ions. Desorption experiments with 0.1 M HCl achieve a quantitative recovery of 95.7%, demonstrating efficient regeneration. Application to real water samples validates the method's effectiveness, highlighting the importance of environmentally friendly solutions in addressing water contamination challenges.

Portable and Flexible Hydrogel Sensor for On-Site Atrazine Assay on Agricultural Products.

There is growing attention focused toward the problems of ecological sustainability and food safety raised from the abuse of herbicides, which underscores the need for the development of a portable and reliable sensor for simple, rapid, and user-friendly on-site analysis of herbicide residues. Herein, a novel multifunctional hydrogel composite is explored to serve as a portable and flexible sensor for the facile and efficient analysis of atrazine (ATZ) residues. The hydrogel electrode is fabricated by doping graphite-phase carbon nitride (g-C3N4) into the aramid nanofiber reinforced poly(vinyl alcohol) hydrogel via a simple solution-casting procedure. Benefiting from the excellent electroactivity and large specific surface area of the solid nanoscale component, the prepared hydrogel sensor is capable of simple, rapid, and sensitive detection of ATZ with a detection limit down to 0.002 ng/mL and per test time less than 1 min. After combination with a smartphone-controlled portable electrochemical analyzer, the flexible sensor exhibited satisfactory analytical performance for the ATZ assay. We further demonstrated the applications of the sensor in the evaluation of the ATZ residues in real water and soil samples as well as the user-friendly on-site point-of-need detection of ATZ residues on various agricultural products. We envision that this flexible and portable sensor will open a new avenue on the development of next-generation analytical tools for herbicide monitoring in the environment and agricultural products.

CTAB modified metakaolin-based geopolymer microspheres for the selective adsorption and recovery of TcO4−/ReO4−

With the increase of radioactive wastewater, it is a major challenge to efficient removal of TcO4− from radioactive wastewater. So far, cationic metal organic frameworks (MOFs), cationic covalent organic frameworks (COFs), cationic polymeric networks (CPNs) and porous organic polymer materials (POPs) can remove TcO4− efficiently, but the cumbersome preparation process and high cost limit their practical applications. Herein, an efficient and low-cost CTAB-modified metakaolin-based geopolymer microspheres (CTAB@MGMs) with excellent adsorption properties for ReO4− is simply and rapidly synthesized by dispersion-pelletizing-solidification and vacuum infusion methods. CTAB@MGMs has fast adsorption kinetics (equilibrium in 10 min), a wide pH application range (2–10) and high selectivity in competing ions (PO43−, SO42−, NO3−, Cl−) and real waters (tap water, surface water, seawater). Importantly, complete desorption of the adsorbed sample can be realized by ethanol and MGMs can be recycled without performance decay. Meanwhile, ethanol recycling was achieved by spin-evaporation of desorption solution and a novel compound CTA-ReO4 was generated. We have analyzed and reported the crystal structure of CTA-ReO4 (CCDC Numbers: 2282273) for the first time and revealed the mechanism that ReO4− is removed by electrostatic and coordination synergism with quaternary ammonium salts after ion exchange. CTAB@MGMs is a low-cost, novel and reusable adsorbent with potential use for the removal of TcO4− from radioactive wastewater.

Cnts with nano-confined TiO2 and surface loading Co3O4: The analysis of its performance and mechanism of PMS activation for ECs degradation under visible light

The efficient activation of peroxymonosulfate for degrading emerging contaminants has become a focal point in recent decades, emphasizing the development of novel materials and efficient strategies for high-performance degradation. This study explores a spatial confinement strategy, where TiO2 is confined inside carbon nanotubes with Co3O4 loading outside, is performed to prepare the nano-confined composite TiO2-in-CNT/Co3O4. Norfloxacin is chosen as the primary target pollutant, revealing a degradation rate exceeding 97 % within 30 min. The non-radical 1O2 species were confirmed to be generated in nano-confined catalyst, but not observed in the control non-confined catalyst. Additionally, the quantity of original radical active species significantly increases in nano-confined catalyst compared to non-confined catalyst. TiO2-in-CNT/Co3O4 has excellent reusability and application universality. Wonderful stability is observed in real water and anti-ion interference experiments, highlighting its robust stability. Experimental and DFT calculation results also demonstrate that the spatial confinement strategy prevents nanoparticle aggregation, accelerates electron transfer efficiency, and promotes the cycling of Co2+/Co3+ electron pairs. This work provides insights into the regulation of confined effects in activating PMS and offers a feasible strategy for the synergistic activation of PMS for water environment remediation through a radical and non-radical mixed mechanism.

Tetracycline degradation through selective activation of molecular oxygen by a fluidic sequential photoelectro-Fenton system

The heterogeneous Fenton-like process is regarded as a promising strategy for reactive oxygen species (ROS) production by driving a two-electron oxygen reduction reaction toward H2O2 and stepping activating the as-generated H2O2 to ROS. Therefore, a fluidic sequential photoelectro-Fenton (PEF) system was developed for the selective activation of molecular oxygen to generate ROS. The system comprises a hydrogen peroxide (H2O2) electrolyzer and a photocatalytic membrane reactor (PCMR). The H2O2 electrolyzer employed a PEI-O/CNT air self-diffusion electrode to achieve high selectivity for H2O2 production without aeration. In the subsequent stage, within the PCMR, two-dimensional Fe/C3N4 with a nanoconfinement structure selectively converted H2O2 into ROS. The exceptional tetracycline (TC) degradation efficiency (96.0 %) was attributable to the synergistic effects of radical and non-radical pathways. The fluidic sequential PEF system achieved efficient and energy-saving H2O2 production (0.134 kWh/g of H2O2) and TC degradation (1.7 kWh/kg of TC). In addition, the PEF system not only has a good effect on removing tetracycline in real water but also can effectively remove a variety of antibiotic pollutants, which has a good prospect for practical application. This research contributed new insights into the development of the fluidic sequential PEF process.

Electrochemical detection of sulfanilamide using tannic acid exfoliated MoS2 nanosheets combined with reduced graphene oxide/graphite

Sulfonamides are a family of synthetic drugs with a broad-spectrum of antimicrobial activity. Like other antimicrobials, they have been found in aquatic environments, making their detection important. Herein, an electrochemical sensor was designed using tannic acid exfoliated few-layered MoS2 sheets, which were combined with a mixture of reduced graphene oxide (rGO) and graphite flakes (G). The rGO/G was formed using electrodeposition, by cycling from −0.5 to −1.5 V in an acidified sulfate solution with well dispersed GO and G. The exfoliated MoS2 sheets were drop cast over the wrinkled rGO/G surface to form the final sensor, GCE/rGO/G/ta-MoS2. The mixture of rGO/G was superior to pure rGO in formulating the sensor. The fabricated sensor exhibited an extended linear range from 0.1 to 566 μM, with a LOD of 86 nM, with good selectivity in the presence of various salts found in water and structurally related drugs from the sulfonamide family. The sensor showed very good reproducibility with the RSD at 0.48 %, repeatability and acceptable long term stability over a 10-day period. Good recovery from both tap and river water was achieved, with recovery ranging from 90.4 to 98.9 % for tap water and from 83.5 to 94.4 % for real river water samples.

Nonradical-dominated pathway toward selective catalytic ozonation of NH4+-N to N2 in drinking water over birnessite

Ammonia nitrogen (NH4+-N), which exists in the dominant form of ammonium ion (NH4+) under the pH of 6.5–8.5, is one of the regular indexes and the most important pollutants in drinking water. The selective conversion of NH4+-N into harmless substances is urgently needed and also a great challenge. Herein we propose a new NH4+-N conversion pathway based on a catalytic ozonation process with birnessite-type MnO2 (δ-MnO2) catalysts. The δ-MnO2 exhibits a superior performance for NH4+-N (1.0 mg/L) removal in adsorption (8.26 %) and oxidation (44.6 %) as well as up to 95.2 % of N2 selectivity, surpassing almost all the reported O3-based catalysts. Unlike the traditional radical oxidation, a singlet oxygen (1O2)-dominated nonradical oxidation pathway is confirmed for the efficiently selective conversion of NH4+-N to N2 through the successive dehydrogenation, leading to a 15.0-fold enhancement in NH4+-N oxidation rate compared with ozone oxidation. The Mn(III)/Mn(IV) redox sites and surface lattice oxygen in δ-MnO2 act as the active sites promoting the decomposition of O3 into •O2− and then 1O2 via electrons transfer. In application, δ-MnO2 catalytic ozonation effectively removes NH4+-N in real drinking water and presents excellent stability. This work finds a nonradical reaction mechanism in catalytic ozonation for NH4+-N selective conversion to N2, and solidly solves the problem of low-concentration NH4+-N removal from drinking water under the limited pH of 6.5–8.5 condition.

Formation and toxicity alteration of halonitromethanes from Chlorella vulgaris during UV/chloramination process involving bromide ion

Frequent algal blooms cause algal cells and their algal organic matter (AOM) to become critical precursors of disinfection by-products (DBPs) during water treatment. The presence of bromide ion (Br−) in water has been demonstrated to affect the formation laws and species distribution of DBPs. However, few researchers have addressed the formation and toxicity alteration of halonitromethanes (HNMs) from algae during disinfection in the presence of Br−. Therefore, in this work, Chlorella vulgaris was selected as a representative algal precursor to investigate the formation and toxicity alteration of HNMs during UV/chloramination involving Br−. The results showed that the formation concentration of HNMs increased and then decreased during UV/chloramination. The intracellular organic matter of Chlorella vulgaris was more susceptible to form HNMs than the extracellular organic matter. When the Br−: Cl2 mass ratio was raised from 0.004 to 0.08, the peak of HNMs total concentration increased 33.99%, and the cytotoxicity index and genotoxicity index of HNMs increased 67.94% and 22.80%. Besides, the formation concentration and toxicity of HNMs increased with increasing Chlorella vulgaris concentration but decreased with increasing solution pH. Possible formation pathways of HNMs from Chlorella vulgaris during UV/chloramination involving Br− were proposed based on the alteration of nitrogen form and fluorescence spectrum analysis. Furthermore, the formation laws of HNMs from Chlorella vulgaris in real water samples were similar to those in deionized water samples. This study contributes to a better comprehension of HNMs formation from Chlorella vulgaris and provides valuable information for water managers to reduce hazards associated with the formation of HNMs.

Novel fluorescent sensor based on triazole-pyridine derivative for selective detection of mercury (II) ions in different real water samples: Experimental and DFT calculations

Toxic heavy metals, particularly mercury II ions, must be selectively detected in industrial effluent to restrict their percentage and thereby aid in environmental protection. The present study describes the synthesis of 6-(4-(4-(5-cyano-6-oxo-4-styryl)-1,6-dihydropyridin-2-yl)-5-methyl-1H-1,2,3-triazol-1-yl)phenyl)-2-oxo-4-styryl)-1,2-dihydropyridine-3-carbonitrile (TOHC) and its ability as a novel selective fluorescent probe for the detection of mercury II ions in different real water samples. The structure of the prepared TOHC was confirmed by both FTIR and 1HNMR analysis, while crystal structure and thermal stability was investigated using XRD and TGA techniques. The optical properties of TOHC were investigated using both UV–vis and fluorescence spectroscopy at different pH values. Its luminescent properties obtained when TOHC is excited by a wavelength equal to 424 nm, where a maximum emission peak has observed at a wavelength equal to 466.6 nm. Moreover, using Stern-Volmer equation indicate that there is a good correlation between the concentration of Hg2+ ions and the fluorescence intensity of TOHC accompanied with high quenching rate equal to 2.24 x 104 mol−1.L. Selectivity of TOHC toward Hg2+ ions was confirmed by the assistance of fifteen different metal cations. In addition, Job’s Plot method and UV–vis spectroscopy were used to estimate the stoichiometry as well as understand the quenching mechanism between TOHC sensor and Hg2+ ions. The applicability of TOHC sensor for the detection of Hg2+ ions in real samples was further validated using five different real water samples and exhibited excellent results. Lastly, DFT calculations were conducted to provide atomistic insights into the chemical interaction between Hg(II) and TOHC.