Tap Water Samples Research Articles

Spatial and temporal distribution of arsenic concentration in rural drinking water and health risk assessment in Northern China from 2013 to 2022: a case study of Inner Mongolia Autonomous Region

BackgroundBy monitoring arsenic levels in rural drinking water in Inner Mongolia Autonomous Region from 2013 to 2022 and evaluating their health risks, this study provides a basis for further developing strategies to promote public health.MethodsOne stable centralized water supply point was randomly selected in each township of Inner Mongolia Autonomous Region. One finished water sample and 1–3 tap water samples were collected at each supply point. Water samples were collected once during the dry season (May) and once during the rainy season (August-September). Mann-Whitney U test was used to compare arsenic concentrations in drinking water from different types of water sources, and Kruskal-Wallis test was used to compare arsenic concentrations in drinking water across different years. Environmental health risk assessment was conducted using the health risk assessment model recommended by the US Environmental Protection Agency (USEPA).ResultsOverall, arsenic concentrations in rural drinking water were higher in the central-western part of Inner Mongolia Autonomous Region compared to the eastern part. From 2013 to 2022, there was a notable decreasing trend in arsenic concentrations in rural drinking water, with over 98% of water samples meeting arsenic standards by 2022. During 2013–2019, arsenic concentrations in drinking water sourced from groundwater were consistently higher than those from surface water sources (P < 0.05). Hazard quotient (HQ) values for the entire population were below 1, and lifetime cancer risk (LCR) values exceeded 1 × 10− 6. Sensitivity analysis indicated that drinking water arsenic concentration contributed the most to health risks for the population.ConclusionDuring 2013–2022, through concerted efforts by the government and the people, excessive arsenic levels in rural drinking water have been significantly reduced, resulting in decreased health risks for the population. However, some carcinogenic risks still exist.Therefore, the next critical step in improving water quality in the region involves further optimizing methods such as coagulation, adsorption, or ion exchange to remove arsenic from drinking water.

A Selective Electrochemical Sensor for Bisphenol A Detection Based on Cadmium (II) (bromophenyl)porphyrin and Gold Nanoparticles

Bisphenol A (BPA) is a commonly synthetic chemical mainly used in producing plastic items. It is an endocrine-disrupting compound that causes irreversible health and environmental damage. Developing a simple method for BPA effective quantitative monitoring is emergently necessary. Herein, a novel electrochemical sensor for BPA detection based on [(5,10,15,20-tetrakis(p-bromophenyl) porphyrinato] cadmium (II) [(CdTBrPP)] and gold nanoparticle (AuNPs)-modified screen-printed carbon electrode (SPCE) was elaborated. CdTBrPP was synthesized and then characterized with Ultraviolet–Visible Spectroscopy (UV/vis), Infrared Spectroscopy (IR), and Proton Nuclear Magnetic Resonance Spectroscopy (1H NMR) to confirm its successful synthesis. After drop-coating AuNPs and CdTBrPP on the SPCE, the sensor performance was evaluated using square wave voltammetry (SWV), a linear response in a concentration range from 10−11 M to 10−2 M, with a low detection limit (LOD) of 9.5 pM. The CdTBrPP/AuNPs/SPCE sensor demonstrates a high selectivity and reproducibility, making it a promising candidate for developing a low-cost water-monitoring system for detecting BPA. Additionally, the proposed sensor effectively detected BPA in both tap and mineral water samples.

Assessing PFAS in Drinking Water: Insights from the Czech Republic's Risk-Based Monitoring Approach.

This study investigates the presence of perfluoroalkyl substances (PFAS) in the drinking water supplies in the Czech Republic using a risk-based monitoring approach. Tap water samples (n=27) from sources close to areas potentially contaminated with PFAS were analysed. A total of 28 PFAS were measured using ultra-performance liquid chromatography with tandem mass spectrometry after solid phase extraction. Total PFAS concentrations (∑PFAS) varied from undetectable to 90.8 ng/L, with perfluoropentanoic acid (PFPeA), perfluorohexanoic acid (PFHxA), perfluoroheptanoic acid (PFHpA) and perfluorobutane sulfonic acid (PFBS) being the most abundant, detected in over 70% of samples. Risk-based monitoring in drinking water showed that commercial wells had higher PFAS levels compared to tap water, particularly C4-C9 perfluorocarboxylic acids (PFCAs), possibly due to proximity to industrial areas. However, the hypothesis that risk-based monitoring is more effective than random monitoring was not confirmed, possibly because specific sources did not produce the target PFAS or because of the wide range and less obvious sources of potential contamination. The study also assessed exposure risks and compliance with regulatory thresholds. Weekly intake estimates for adults and children indicated that regular consumption of most contaminated water sample would exceed the tolerable weekly intake. Compared to EU regulations, none of the tap water samples exceeded the 'Sum of PFAS' parametric value of 100 ng/L, though one sample approached this limit. In addition, surface water samples from the Jizera River (n=21) showed a wider range of PFAS, with C7-C10 PFCAs, PFBS, and perfluorooctane sulfonic acid (PFOS) in every sample, with higher PFOS concentrations at a median of 2.56 ng/L. ∑PFAS concentrations increased downstream, rising from 1.08 ng/L near the spring to 26 ng/L downstream. This comprehensive analysis highlights the need for detailed/areal monitoring to also address hidden or non-obvious sources of PFAS contamination.

Electrochemical detection of catechol with a disposable carbon nanotube paste electrode modified with CTAB

Abstract The accurate and rapid detection of catechol which is a class of highly toxic organic phenolic compounds, is of great importance for the protection of environment and human health. In this work, a novel electrochemical sensor for catechol was constructed by modifying multi-walled carbon nanotube paste microelectrode with a cationic surfactant of cetyltrimethylammonium bromide (CTAB) through a simple and controllable adsorption method. Electrochemical experiment results show that the modified electrode has good electrocatalytic effect to the electrochemical response of catechol. The electrochemical response mechanism of the sensor to catechol were investigated through using many analytical methods, including scanning electron microscopy, energy-dispersive spectroscopy, Fourier-transform infrared spectroscopy, Raman spectroscopy, and electrochemical techniques. Under the optimal fabrication and application conditions, the response current of catechol on the sensor exhibits a good linear relationship with its concentration from 1.0 μmol/L ~ 7.0 mmol/L with a sensitivity of 1.33 nA/(μmol/L) and a low detection limit of 15 nmol/L (S/N = 3). Applying the sensor in the detection of catechol in tap water samples and urine samples, the results were satisfactory, indicating its good application prospect.

Synthesis and nanoparticle formation of pyrazine, benzodithiophene (BDT) and fluorene containing conjugated polymer (P-PBF) and its biosensing performance toward catechol

The development of laccase-based biosensors, in particular, have attracted much interest due to their ability to detect highly toxic molecules in the environment. This article reports a novel biosensor for catechol detection that can be used to determine toxic molecules in the environment. For this purpose, a novel conjugated polymer (P-PBF) and conjugated polymer nanoparticles (P-PBFNPs) were synthesized and characterized, respectively. To our knowledge, research has yet to be done on conjugated polymer nanoparticle-based electrochemical biosensing platforms for catechol determination. The biosensor comprises a GE/P-PBF NPs/Lac electrode, constructed with P-PBF NPs deposited onto a bare graphite electrode followed by laccase (Lac) enzyme immobilization. While electrochemical characterization was performed by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS), surface characterization was performed by field emission scanning electron microscopy (FE-SEM). The biosensor exhibited high sensitivity (1.229 μA/μM.cm2), a good linear range (0.5–25 μM) and a low limit of detection (LOD) (0.49 μM). Moreover, the developed biosensor exhibited high selectivity in the presence of interfering analytes without any memory effects. The potential of the GE/P-PBF NPs/Lac electrode in tap water, green tea, synthetic urine and serum samples indicates the inspiring biosensing applications for monitoring environmental pollution.

Development of a green-synthesized molecularly imprinted polymer-based electrochemical nanosensor for the determination of N-nitrosodimethylamine (NDMA) in serum and tap water.

N-nitrosodimethylamine (NDMA) was determined using a molecularly imprinted polymer (MIP)-based electrochemical sensor.Green-synthesized silver nanoparticles were functionalized with cysteamine to enhance their integration into the electrode surface, which was used to modify a glassy carbon electrode (GCE). Furthermore, a MIP-based electrochemical sensor was constructed via electropolymerization of 3-aminophenyl boronic acid (3-APBA) as a conjugated functional monomer in the presence of lithium perchlorate (LiClO4) solution as a dopant, chitosan as a carrier natural polymer, and NDMA as a template/target molecule. The polymer film was characterized by scanning electron microscopy (SEM) and electrochemical impedance spectroscopy (EIS). The analytical performance of the silver nanomaterial-based MIP-based electrochemical (AgNPs@Chitosan/3-APBA@MIP-GCE) sensor was evaluated under optimized conditions. The linear range of NDMA was 1.0 × 10-13-1.0 × 10-12M (0.1-1.0pM), with a limit of detection (LOD) of 3.63 × 10-15M (3.63 fM) using differential pulse voltammetry (DPV). Method validation figured out that the developed MIP-based electrochemical nanosensor exhibited excellent selectivity, accuracy, and precision, which was shown by the analysis of synthetic serum samples and tap water. The LOD and LOQ in serum samples were 17.8 fM and 59.5 fM,respectively,which were in agreement with the developed method. Good recovery results confirm the successful application of the method in serum and tap water samples. The selectivity of the developed AgNPs@Chitosan/3-APBA@MIP-GCE sensor for NDMA was demonstrated in the presence of NDEA, sartans (valsartan, losartan, irbesartan, candesartan, telmisartan), and potential interferents that arepossibly present in biological fluids (dopamine, ascorbic acid, uric acid) besides ionic species (sodium, chloride, potassium, nitrate, magnesium, sulfate) and common analgesic paracetamol.

High fluorescence quantum yield of methionine-doped carbon quantum dots for achieving rapid assay of tetracyclines in foodstuffs

The trace-level detection of tetracyclines (TCs) in food products is essential to ensure food safety and public health. Herein, we prepared the methionine-doped carbon quantum dots (Met-CQDs) using citric acid as the precursor. Met-CQDs exhibited a Gaussian unimodal peak centered at 440 nm in the fluorescent excitation spectrum, along with a remarkable greenish-blue emission and a fluorescent quantum yield of 33.5 %. Furthermore, the presence of TC (the quencher) caused a rapid quenching of the fluorescence of Met-CQDs, accompanying with a color transition from light blue to dark bule as TC concentrations increased. The coloring variation was also detected by the images captured by smartphones and RGB analysis software, facilitating portable detection of TC utilizing Met-CQDs as a fluoroprobe. The findings indicate that the Met-CQDs based fluoroprobe exhibits high selectivity, rapid response (only ∼1 min) according to an “ON-OFF” sensing model. This fluorescence sensing method gave a low detection limit (LOD) of 0.032 μM and excellent linearity for TC in the concentration range of 0.1–500 μM. Also, the smartphone-based fluorescence-visualizing approach displayed good linearity with a LOD of 0.33 μM. The interactions between this fluoroprobe and TC occurred by virtue of both inner filter effect (IFE) and static-quenching principle. The average recovery for TC in the milk, honey, and tap water samples was determined to be 98.46 ± 1.71 % by a fluorometric method. Overall, both fluorometric and RGB approaches demonstrate strong correlation with conventional LC-MS/MS, and thus the as-fabricated Met-CQDs are promising for the preliminary screening of TCs’ residues in food products.

Highly sensitive colorimetric method for the detection of organophosphorus pesticides based on H2O2 etching of silver-coated gold nanostars

The residues of organophosphorus pesticides in agricultural production and soil constitute a significant threat to both human health and ecosystems, underscoring the critical importance of developing effective detection methods for these pesticides. Here, we introduce an innovative method for detecting trichlorfon that integrates hydrogen peroxide (H2O2)-induced etching of silver-coated gold nanostars (AuNS@Ag) with an enzymatic reaction cascade. By precisely controlling the thickness of the silver layer and the morphology of the gold nanoparticle core, we enhance the sensitivity of the H2O2 etching process. In this detection system, acetylcholinesterase (AChE) catalyzes the hydrolysis of acetylcholine chloride (ACh) into choline, which is then oxidized by choline oxidase (ChOx) to produce H2O2. The generated H2O2 subsequently etches the silver layer of AuNS@Ag, leading to a pronounced red-shift in the localized surface plasmon resonance (LSPR) wavelength, from 590 nm to 735 nm. However, the presence of trichlorfon inhibits the activity of AChE, resulting in a reduced production of H2O2 and a subsequent attenuation of the LSPR wavelength shift. Under optimized experimental conditions, this method enables the linear detection of trichlorfon within a concentration range of 0.1–5.0 μg mL−1 and has been successfully applied to detect trichlorfon in cabbage and tap water samples, showcasing its promising potential in food safety and environmental monitoring.

A bionic palladium metal-organic framework based on a fluorescence sensing enhancement mechanism for sensitive detection of phorate.

We have developed a biomimetic fluorescent nanoprobe (Pd-MOF) that can accurately identify phorate at a fixed wavelength for rapid, sensitive and selective detection. Pd-MOF was a nanoparticle (260.00 ± 27.83 nm) based on the linkage of Pd metal and a TCPP organic framework. It could detect phorate according to the fluorescence principles similar to that of the bioluminescence of Chrysaora pacifica (substance interaction and chromophore fluorescence enhancement). When phorate molecules enter the pores of Pd-MOF and interact with each other, the energy transfer process is stimulated, and the fluorescence signal is significantly enhanced, thereby improving the detection sensitivity. According to shift of the white line in the XANES energy spectrum and the DFT results, phorate increased the energy gap of Pd-MOF from 0.025 eV to 0.046 eV, enhanced the stability of the system, and thus achieved fluorescence enhancement. The sensitivity of Pd-MOF was due to its much smaller energy gap (<80 times) than other metal MOFs and thus it was easier to get excited. The linear detection range for the phorate of the nanoprobe in the water system was 0.01-100 ppb, and the detection limit was 0.0017 ppb. The response time of the Pd-MOF nanoprobe to phorate was 45 seconds. The detection of phorate in tap water, pear and cabbage samples showed that the recovery rates were in the range of 87.69-106.12%, and the relative standard deviation (RSD) was less than 11.16%, which verified the possibility of Pd-MOF nanoprobe in practical application. The sensitive and specific recognition of phorate by Pd-MOF nanoprobe and the development of a phorate test strip (Pd-MOF@paper) confirmed its potential application in pesticide residue detection.

Green chemistry: magnetic dispersive solid phase extraction for simultaneous enrichment and determination of V, Ni, Ti and Ga in water samples by HR-CS ETAAS.

This work presents a straightforward, highly sensitive, and cost-effective method for the simultaneous determination of V, Ti, Ni and Ga by high resolution-continuum source electrothermal atomic absorption spectrometer (HR-CS ETAAS) in aqueous environmental samples (tap and seawater samples). The system is based on retention of the analyte onto a novel magnetic nanomaterial (M@GO magnetic graphene oxide) functionalised with methylthiosalicilate (MTS). The formed complexes between the M@GO-MTS and the target analytes were broken, adding 1 mL of nitric acid (6%) and sonication for 5 min. The optimized method achieved detection limits of 0.71 μg L-1 for Ti, 0.20 μg L-1 for V, 0.04 μg L-1 for Ga, 0.66 μg L-1 for Ni. The accuracy of the proposed method was demonstrated by analysing two certified reference materials and by determining the analyte content in spiked environmental water samples. The results obtained using this method were in good agreement with the certified values of the standard reference materials, and the recoveries for the spiked tap water and seawater samples ranged from 94% to 120%.

Modifying metal ion ratios in nickel-aluminum layered double hydroxide/reduced graphene oxide composites for selective electrochemical detection of antibiotics

Antimicrobial resistance (AMR) is a global threat that occurs as microorganisms evolve to resist antibiotic (ATB) overuse. To monitor this overuse, inexpensive, affordable, and adaptable sensors are required. While electrochemical sensors are promising, they cannot often distinguish between overlapping electrochemical interactions from multiple ATBs, resulting in poor analyte selectivity. To overcome this challenge, we design electrocatalysts consisting of nickel aluminum layered double hydroxides (NiAl-LDH) and their composites by altering the metal ion ratio to adjust the surface properties and selectivity of sensors. Synthesis of LDH and its graphene oxide (GO) composites is conducted using a low-temperature hydrothermal method. The prepared materials are characterized using various morphological and structural characterization techniques. Electrochemical characterization confirms that tuning the metal ion ratio allows sensors to differentiate between electrochemical reactions, improving the selective detection of amoxicillin and tetracycline from their mixtures. Addition of graphene oxide also enhances sensing capabilities. The optimized sensor has sensitivities of 137.6 nA µM−1 cm−2 and 161.4 nA µM−1 cm−2, and lower detection limits of 4.3 nM and 3.6 nM, respectively, for amoxicillin (Amx) and tetracycline (TC). Interferents have no significant effect on the detection of relatively low concentrations (10 µM) of the two ATBs. The electrodes can also detect the two analytes in tap water samples. This sensor methodology can potentially improve environmental antibiotic detection to mitigate the risk of antimicrobial resistance.

Monitoring of tritium concentrations in tap water and rainwater collected in Thailand.

This study aimed to measure tritium (3H) concentrations in Thailand. Nationwide tap water samples were collected in July 2021. Rainwater samples were collected monthly during May-October 2020, April-October 2021, and February-March 2022 in Chonburi province and in Chiang Mai province during July-November 2021, January 2022, and March-June 2022. The measurements of 3H activity concentrations were conducted by Osaka Sangyo University (OSU) and were compared with measurements by the Thailand Institute of Nuclear Technology (TINT). The results from OSU and TINT showed that 3H concentrations in tap water were matched in the ranged from 0.08±0.03 to 0.28±0.04BqL-1, while those in rainwater samples collected from Chonburi province and Chiang Mai province are also matched in the ranged from 0.11±0.02 to 0.21±0.03BqL-1 and 0.19±0.02 to 0.57±0.04BqL-1, respectively. Our measured result suggests that 3H concentration in tap water and rainwater shows a similar relation depending on latitude.

Transforming Food Biowaste into Selective and Reusable Adsorbents for Pesticide Removal from Water.

With growing concerns regarding environmental pollution and the need for sustainable waste management practices, this study investigates the potential of utilizing spent coffee grounds (SCG) as a precursor for producing functional carbon materials aimed at organophosphorus pesticide remediation under environmentally relevant conditions. Carbonization of SCG is followed by various activation methods, including treatment with potassium hydroxide, phosphoric acid, and carbon dioxide, individually or in combination. The resulting biochars are systematically analyzed for their adsorption performance towards malathion and chlorpyrifos. Screening tests revealed a selective adsorption preference towards aromatic chlorpyrifos over aliphatic malathion. Activation processes significantly influence adsorption kinetics and efficiency, with physical activation showing notable adsorption rates and capacity enhancements. Moreover, the SCG-derived biochars exhibit a pronounced dependency on adsorption temperature. Adsorption, regeneration, and reuse of the most promising material are tested in a real, spiked tap water sample, proving that the presence of ions in tap water did not affect the adsorption and that the material has the potential to be reused more than ten times. This work proposes a straightforward approach for recycling SCG by converting it into functional carbon materials, underscoring the importance of selecting the appropriate activation processes and conditions for practical applications in pesticide remediation.

Highly efficient Z-scheme CeO2/Bi2MoO6 heterojunction strengthened by redox mediator for photoelectrochemical detection of tetracycline with enhanced sensitivity

Accurate monitoring of antibiotics that pose risks to the environment and human health is essential. The photoelectrochemical system has emerged as a rapid and precise method for detecting environmental pollutants. However, current photoelectrochemical materials made of semiconductors face challenges due to poor photoelectric conversion efficiency. In this study, a Z-scheme CeO2/Bi2MoO6 heterojunction structure was successfully prepared by a cost-effective hydrothermal method. By leveraging built-in electric field and the Ce3+/Ce4+ redox mediator, this heterojunction achieved high photoelectrochemical conversion efficiency and functioned effectively as a sensor for tetracycline (TCH). The designed sensor demonstrated two linear ranges of 0.05–100 nM and 100–300 nM with an ultra-low detection limit of 15.4 pM for TCH. Additionally, the sensor exhibited excellent selectivity and high stability, demonstrating its potential for TCH detection in tap-water and milk samples. This study presents a simple and reliable method for the practical detection of antibiotic residues in environmental and food samples.

The effect of water filter pitchers on the mineral concentration of tap water.

To investigate the effect of water filter pitchers on the concentration of different minerals in tap water. Nine water filter pitchers (A-I) were chosen based on consumer preferences and Amazon reviews. Each filter was tested for its ability to modify the concentrations of fluoride, calcium, magnesium, potassium, and sodium in tap water. Tap water samples were collected before and after filtration, at various intervals (1, 5, 10, 30, 50, 75, and 100 L) during filtration, and analyzed using an ion-specific electrode (fluoride) and atomic absorption spectrometry (other minerals). Statistical analyses were conducted to compare filtered and unfiltered water mineral concentrations. Water filter pitcher effect: Filters F (p < 0.001) and G (p = 0.030) decreased fluoride concentrations. All filters except I (p = 0.235) and H (p = 0.717) decreased calcium concentrations (p < 0.01). Filters E (p = 0.018), D (p = 0.014), and G (p = 0.010) decreased magnesium concentrations. Filters I (p = 0.028) and D (p = 0.009) increased potassium concentrations. Filter A (p = 0.002) increased sodium concentrations, while C (p = 0.034) decreased sodium concentrations. Effect of filter aging: All filters affected mineral concentrations over time but to varying extents. Filter G had the most pronounced effect on reducing mineral concentrations compared to all others. No filter was able to completely remove fluoride from tap water, contrary to the claims made by three manufacturers. The present study highlighted that water filter pitchers vary greatly in their ability to affect mineral concentrations in tap water during their use. Further research is needed to develop more effective water treatment solutions.

Novel quinoline-based chemosensor as specific fluorescence sensing of copper ions in cancer cells and for organelle-specific imaging application

This work reports a simple synthesis of a quinoline-based organic molecule, (E)-N′-((6-methoxy-2-oxo-1,2-dihydroquinolin-3-yl)methylene) picolinohydrazide (PHMQ), and its ability to distinguish Cu2+ ion. Through the use of spectroscopic and photometric titration techniques, PHMQ’s selectivity toward various cations and anions was examined. In just two minutes, PHMQ showed fast detection of Cu2+ ions, and clear spectral fluctuations proposed persistent PHMQ-Cu2+ complex formation. The calculated emission quenching constant (1.46 × 105 L/mol) and binding constant (1.25 × 104 L/mol) values suggested that strong emission quenching occurs between the PHMQ and Cu2+ ions. A linear reduction in fluorescence response was noted for Cu2+ ions concentrations between 2–26 μM, with a detection limit of 43.4 nM. Job’s plot, ESI-mass, NMR titration experiments, and density functional theory (DFT) simulations established a 1:1 stoichiometry for the PHMQ-Cu2+ complex. Additionally, PHMQ was efficaciously utilized to quantify Cu2+ ions in drinking and tap water samples and HeLa cells, illustrating durable cellular penetrability and a fluorescence ’Turn-Off’ response to Cu2+ ions. This sensor also established usefulness in mitochondrial-targeted imaging. For the detection of Cu2+ ions in biological and environmental environments, PHMQ is a promising detector due to its high sensitivity, selectivity, and quick response.

A ratiometric and colorimetric dual-mode fluorescence method for the sensitive determination of copper ion

The present work describes the fabrication of a low-cost, simple, and highly selective analytical method based on the combination of two fluorescent carbon quantum dots (CQDs) for visual or quantitative detection of copper ions at trace levels. Folium cycas and o-phenylenediamine are used as carbon precursors for the preparation of blue fluorescence CQDs (B-CQDs) and yellow fluorescence CQDs (Y-CQDs), respectively. The dual emission ratio fluorescence sensor (B@Y-CQDs), which is obtained through a physical blending method, demonstrates the dual-mode detection of copper ions, including colorimetric detection (visual detection) and ratiometric detection (quantitative detection). Our study reports a portable fluorescent paper sensing platform based on smartphones and computer software that can visually quantify Cu2+ without the need for expensive and bulky laboratory instruments. Upon addition of Cu2+, the simple B@Y-CQDs solution or B@Y-CQDs modified paper-based strip shows a visible color change from blue to yellow under 365 nm ultraviolet light, which achieves visual detection coupled with computer software and smartphones. For the accurate quantitative detection of trace Cu2+, the changes in the fluorescence intensity ratio of F450/550 are recorded, in which B@Y-CQDs exhibited remarkable selectivity and sensitivity, with a low limit of detection (0.73 μM) within the linear ranges of 7–15 μM. The applicability of the sensor is explored by the successful detection of Cu2+ in tap water and rice samples. These results provide a novel strategy for the quantitative and visual detection of various metal ions and hold significant potential for applications in food safety assurance and water pollution control.

Silver Nanoparticles Formed Directly on a Screen-Printed Electrode/Graphene Oxide: A One-Step Electrochemical Synthesis and an Effective 2,4,6-Trichlorophenol Electrochemical Sensor

Abstract A graphene oxide/silver nanoparticles (GO/AgNPs) nanocomposite was synthesized directly onto a screen-printed electrode (SPE) using a one-step electrochemical synthesis process. The obtained result is that the SPE electrode was modified by AgNPs with an average diameter of 11.5 nm which distributed evenly on GO sheets. A 0.01 M AgNO3 solution dropped onto the SPE/GO electrode and a chronoamperometry (CA) method with a potential of −1.2 V and a time period of 10 seconds were the optimal synthesis conditions. Then, the SPE/GO/AgNPs electrode was applied in developing an electrochemical sensor to detect 2,4,6-trichlorophenol (2,4,6-TCP) using a square wave voltammetry method. A reasonable cost, a wide linear range (0.05–1.0 mM), a low detection limit (0.85 μM), a high repeatability, a good selectivity, a high durability, and especially, a rapid detection time (&lt; 1 minute) thanks to the ability to directly detect 2,4,6-TCP were the outstanding advantages of the fabricated electrochemical sensor. Moreover, the electrochemical sensor based on the SPE/GO/AgNPs electrode was also applied to detect 2,4,6-TCP in a tap water sample using a standard addition method.

Ni/N/MPC Nanocomposites Synthesized via Microwave-Assisted Biomass Conversion for Efficient H2O2 Detection

In order to improve the sensitivity and stability of the material for the detection of hydrogen peroxide, Ni/N/MPC nanocomposites were synthesized by Ni-based biomass doped with nitrogen. Nickel atoms offer such advantages as good catalytic activity and low cost, while nitrogen doping facilitates the formation of stable hybrid structures and the formation of abundant functional groups on the surface of nanocomposites. The linear equation characterizing the electrode response from the Ni/N/MPC nanocomposites was derived from the relationship between the current signal I and H2O2 concentration, demonstrating a linear range of 0.05–240.15 mmol l−1, along with a detection limit of 0.84 μmol l−1 (S/N = 3). In contrast, the electrochemical signals from Ni/NGCE and Ni/N/GCE sensors were significantly lower than those obtained from the composite materials during cyclic voltammetry testing. In practical sample analysis, the recovery rate and RSD of H2O2 in tap water samples were 97.2%–98.6% and 5.5%–6.4%, respectively. The Ni/N/MPC/GCE sensing platform presents excellent stability and enhanced sensitivity.

Novel 3D plate-like g-C3N4/BiOCl heterojunction as a highly efficient photocatalyst for the degradation of carbofuran in wastewater under visible light irradiation

The g-C3N4/BiOCl (gCN-BCl) heterojunction photocatalyst was synthesized using a low-temperature precipitation method for effective photocatalytic degradation of carbofuran (CBF). All gCN-BCl composites demonstrate greater efficacy in removing CBF compared to its individual constituents. The synergistic effect of incorporating the 0D structured BiOCl onto the 2D structured g-C3N4 was comprehensively examined using various microscopic, X-ray, and spectroscopic analytical techniques. Additionally, optical and photoelectrochemical analyses were conducted. The findings validated that the interaction between the two semiconductors at the heterointerfaces enhanced remarkable physical and structural stability, promoted high charge separation and transfer properties, and improved photocatalytic degradation. Under optimal conditions, 5-gCN-BCl (0.25 g/L) achieved a CBF (5 mg/L) removal efficiency of 95.7 % under visible light irradiation of 120 min, achieving 3.1- and 5.9-times higher degradation rate than the pure BiOCl and g-C3N4, respectively. The radical trapping experiments indicated that the h+ and •O2− were the primary reactive species involved in the CBF degradation. Furthermore, the potential toxicity of CBF and its intermediates was assessed, revealing that the photocatalytic degradation process significantly lowered the ecotoxicity of pesticide wastewater. The potency of 5-gCN-BCl was also evaluated in tap water and real wastewater samples, with CBF degradation efficiencies of 85.8 %, 47.6 %, and 38.7 % in tap water, municipal, and pesticide industry wastewater, respectively. Additionally, artificial neural network (ANN) modeling was employed to predict and optimize the photocatalytic degradation process, providing further insights into the system’s performance. The outcomes of this work offer valuable insights into the development of heterojunction photocatalysts with superior stability and efficacy for eliminating pesticides from water bodies.