Multiple Heavy Metal Ions Research Articles

Plasma Tailoring of NH2-MIL-53 with Enhanced Fluorescence Emission for Simultaneous Detection of Multiple Heavy Metals in Water.

Indium, copper, and mercury are important raw materials in the electronics industry and often coexist in factory wastewater. Therefore, the development of a highly sensitive and selective method for the simultaneous detection of these heavy metal ions is of great significance for water quality monitoring and environmental protection. Herein, we report a NH2-MIL-53 fluorescent probe for the simultaneous detection of trace In3+, Cu2+, and Hg2+ in water. After a low-temperature NH3 plasma tailoring treatment for grafting electron-donor amine groups, the obtained NH2-MIL-53-M exhibited enhanced fluorescence emission intensity (∼6 times) coupled with selective adsorption of In3+, Cu2+, and Hg2+. This quenched the NH2-MIL-53-M fluorescence and allowed to significantly increase the selectivity and sensitivity for detection of In3+, Cu2+, and Hg2+. The fluorescence quenching constant (Ksv) values were 2.23 × 105, 1.00 × 105, and 2.74 × 104 M-1, while the limit of detection (LODs) values were 0.06, 0.14, and 0.53 μM, for In3+, Cu2+, and Hg2+, respectively. The concentrations of In3+, Cu2+, and Hg2+ in real environmental samples could be determined by addition of appropriate masking agents, and the recoveries were within the range of 94-110%. This study not only supplied a strategy for constructing a highly sensitive and selective fluorescent probe but also established a platform for simultaneous detection of multiple heavy metal ions in water.

Modulating NFO@N‐MWCNTs/CC Interfaces to Construct Multilevel Synergistic Sites (Ni/Fe‐O‐N‐C) for Multi‐Heavy Metal Ions Sensing

AbstractA hierarchical heterogeneous composite electrode of NiFe2O4@nitrogen‐doped multi‐walled carbon nanotubes/carbon cloth (NFO@N‐MWCNTs/CC) is prepared via a dip‐coating method, followed by a hydrothermal process. The flexible carbon cloth (CC) substrate provides robust support and the cross‐linked nitrogen‐doped multi‐walled carbon nanotubes (N‐MWCNTs) on the CC form a highly porous network with a large specific area that facilitates electron‐transfer. The stable support strengthens the framework and prevents pore structure disorder within the porous network, that could lead to the structural instability of the active sites. The decorated NiFe2O4 nanoparticles offer abundant active sites for enhanced electrocatalytic activity. Benefiting from the synergistic effect of the 3D hierarchical heterogeneous microstructure and multilevel bimetallic oxide active site (Ni/Fe‐O‐N‐C) constructs, the NFO@N‐MWCNTs/CC electrode achieves stable detection of multiple heavy metal ions (HMIs) with high reproducibility. The modified electrode allowed stable detection of multiple heavy metal ions with high reproducibility. The sensitivities of the electrode for Cd(II), Pb(II), Bi(III), and Hg(II) are 344.98, 441.02, 176.484, and 371.099 µA µm−1, respectively. The assay recoveries ranged from 95.3% to 106.8%, highlighting its practical applicability. This study provides innovative composites and theoretical insights to facilitate further advances in the simultaneous high‐performance detection of heavy metal ions.

Indirect detection of lead(II), cadmium(II) and mercury(II) on a microfluidic electrophoresis chip.

Water environments contaminated by heavy metal ions present significant challenges because these pollutants do not degrade naturally, leading to their gradual bioaccumulation in animals and plants, which ultimately poses an insurmountable threat to human health. Therefore, rapid and accurate detection of heavy metal ions in water is of great significance for environmental protection and disease prevention. In this work, we developed a novel method based on microfluidic electrophoresis coupled with indirect chemiluminescence for the immediate detection of Cd(II), Pb(II) and Hg(II) heavy metal ions. The displacement of the Co(II) ions within the chemiluminescence mixture by the above migrating sample cations caused a measurable reduction in the background signal. The results showed that the detection limits of Cd(II), Pb(II) and Hg(II) ions under the best detection conditions were 5.83 × 10-8 M, 5.38 × 10-8 M and 2.09 × 10-8 M, respectively, which were 1-2 orders of magnitude lower than those of the indirect UV method and 1 order of magnitude lower than that of the indirect laser induced detection method. This method can provide a possibility for the rapid detection of multiple heavy metal ions in actual water environments.

Rapid and accurate identification of multiple metal ions using a bispyrene‐based fluorescent sensor array with aggregation‐induced enhanced emission property

AbstractMultiple metal ions are traditionally detected using inductively coupled plasma mass spectrometry (ICP‐MS) and atomic fluorescence spectrometry. Although these methods are sensitive and accurate, they depend on complex instruments and require highly trained operators, making low costly rapid detection challenging. It is urgent to develop a convenient, rapid and sensitive method to detect multiple metal ions. Herein, we designed a bispyrene derivative (BP) with aggregation‐induced enhanced emission (AIEE) property to construct a high fluorescent sensor array to realize the effective identification of four metal ions (Fe3+, Cu2+, Co2+ and Cd2+). The differential coordination capability between metal ions and BP with the aid of acetate ions resulted the possibility of array‐based sensing. The four heavy metal ions could be immediately classified in the concentration of 100 nM. The limit of detection (LOD) of Fe3+, Cu2+, Co2+, and Cd2+ were as low as 16.2, 21.8, 51.4, and 25.9 nM, respectively. Furthermore, the sensor array was applied for identification multiple heavy metal ions in environmental samples and iron ion in rat serums with identified of 100%. The sample consumption as low as 2 µL for each detection and the results could be extracted by smartphones under ultraviolet lamps. It provided a rapid, sensitive, low‐cost, and on‐site multiple metal ions detection method.

Construction of 2D zinc(II) MOFs with tricarboxylate and N-donor mixed ligands for multiresponsive luminescence sensors and CO2 adsorption.

The solvothermal reactions of ZnCl2·6H2O, benzene-1,3,5-tribenzoic acid (H3btb), and N-heterocyclic ancillary imidazole (Im) or aminopyrimidine (a mp) ligands led to the creation of two-dimensional (2D) zinc(II) based metal-organic frameworks (MOFs), (Me2NH2)2[Zn2(btb)2(Im)2]·2DMF·3MeOH (1) and (Me2NH2)2[Zn2(btb)2(amp)]·H2O·2DMF·MeOH (2). The btb3- ligands in 1 and 2 form an anionic 2D layered structure with a (63) honeycomb (hcb) topology by linking to Zn(II) centres through their carboxylate groups. The incorporation of N-heterocyclic auxiliary ligands Im and amp into the hcb nets resulted in the formation of a 2D hydrogen-bonded and covalently pillared bilayer structure featuring two-fold interpenetrating networks. Each of these networks consists of small channels that are occupied by Me2NH2 cations and solvent molecules. Both 1 and 2 emit blue luminescence emissions in the solid state at room temperature and exhibit a great selectivity and sensitivity for the detection of acetone and multiple heavy metal ions including Hg2+, Cu2+, Fe2+, Pb2+, Cr3+, and Fe3+ ions. At 1 bar, activated 1 and 2 demonstrate moderate capacities for adsorbing CO2 at room temperature, with a preference for CO2 over N2. Notably, at higher pressures (up to 20 bar), their activated samples 1 and 2 show a temperature-dependent enhancement of CO2 uptake while retaining good stability.

Effective elimination of multiple heavy metal ions from wastewater using circular liquid-liquid extraction based on trioctylammonium carboxylate ionic liquids

The widespread discharge of effluents containing heavy metal ions (HMIs) from various industries into natural water bodies has become an alarming concern due to their harmful effects. Recently, ionic liquid (IL)-assisted liquid–liquid extraction (LLE) has emerged as a rapid and facile method for treating industrial effluents, effectively reducing the risk of secondary pollution. The primary objective of this study was to design novel hydrophobic ILs for the extractive removal of toxic HMIs from aqueous media. These hydrophobic ILs were designed by incorporating cyclic carboxylic acids (thiobenzoic acid, pyridine dicarboxylic acid, and pyrimidine dicarboxylic acid) with trioctylamine. The aim was to evaluate the effect of different coordinating atoms in the cyclic carboxylic acids on HMI extraction, while the trioctylamine moiety was chosen to provide the necessary hydrophobicity. The synthesized ILs were evaluated for their efficiency in the extractive removal of toxic HMIs, including Cu(II), Cd(II), Ni(II), and Pb(II), both individually and from their mixtures, under simulated industrial conditions. Thorough optimization was performed to identify the key parameters affecting extraction efficiency. The HMI concentrations were adjusted to their reported maximum contamination limits to ensure real-time applicability, and the ILs demonstrated successful extraction under these conditions. Experimental studies showed that the ILs were able to effectively remove HMIs even from mixtures, confirming their practical relevance. A detailed comparison with literature data revealed that the extraction mechanism primarily relied on the preferential coordination of metals, following the HSAB principle. Furthermore, metal ions were stripped back using disodium EDTA solution, facilitating the regeneration of the ILs for multiple reuse cycles and supporting a sustainable, circular process.

Emerging insights into the application of metal-organic framework (MOF)-based materials for electrochemical heavy metal ion detection

Heavy metal ions are one of the main sources of water pollution, which has become a major global problem. Given the growing need for heavy metal ion detection, electrochemical sensor stands out for its high sensitivity and efficiency. Metal-organic frameworks (MOFs) have garnered much interest as electrode modifiers for electrochemical detection of heavy metal ions owing to their significant specific surface area, tailored pore size, and catalytic activity. This review summarizes the progress of MOF-based materials, including pristine MOFs and MOF composites, in the electrochemical detection of various heavy metal ions. The synthetic methods of pristine MOFs, the detection mechanisms of heavy metal ions and the modification strategies of MOFs are introduced. Besides, the diverse applications of MOF-based materials in detecting both single and multiple heavy metal ions are presented. Furthermore, we present the current challenges and prospects for MOF-based materials in electrochemical heavy metal ion detection.

Smartphone-assisted colorimetric sensor arrays based on nanozymes for high throughput identification of heavy metal ions in salmon

The rapid, precise, and high-throughput identification of multiple heavy metals ions holds immense importance in ensuring food safety and promoting public health. This study presents a novel smartphone-assisted colorimetric sensor array for the rapid and precise detection of multiple heavy metals ions. The sensor array is based on three signal recognition elements (AuPt@Fe-N-C, AuPt@N-C, and Fe-N-C) and the presence of different heavy metal ions affects the nanozymes-chromogenic substrate (TMB) catalytic color production, enabling the differentiation and quantification of various heavy metal ions. Combined with a smartphone-based RGB mode, the colorimetric sensor array can successfully identify five different heavy metal ions (Hg2+, Pb2+, Co2+, Cr6+, and Fe3+) as low as 0.5 μM and different ratios of binary and ternary mixed heavy metal ions in just 5 min. The sensor array successfully tested seawater and salmon samples with a total heavy metal content of 10 μM in the South China Sea (Haikou and Wenchang). Overall, this study highlights the potential of smartphone-assisted colorimetric sensor arrays for the rapid and precise detection of multiple heavy metal ions, which could significantly contribute to food safety and public health monitoring.

Cu(Ⅱ)-EDTA degradation and copper recovery from wastewater in wide pH ranges by an electrooxidation-capacitive deionization system

The treatment and recovery of metal resources from complex industrial wastewater has posed significant challenges due to the presence of multiple heavy metal ions, heavy metal complexes, and acidic conditions. In this study, a novel electrooxidation-capacitive deionization (EO-CDI) system was proposed, which ingeniously harnessed the unheeded Faraday side reaction in capacitive deionization for simultaneous degradation and recovery of copper complexes from wastewater through two electrode integration. Specially, the cathode CuS0.78Se0.22 synthesized through the anionic Se-substitution strategy exhibited a remarkable adsorption capacity up to 672.02 mg/g for Cu ions, outstanding selectivity and stability, particularly in acidic environments. The water oxidation process occurring at the activated carbon anode played a crucial role by generating active species that contribute to the degradation of Cu(Ⅱ)-EDTA, which leaded to the release of copper ions, facilitating their subsequent recovery. Cyclic experiments further confirmed the excellent cyclic stability of the hybrid EO-CDI system, along with its impressive performance in copper extraction when applied to real industrial wastewater. This innovative approach offered promising prospects for addressing the challenges associated with the treatment of complex industrial wastewater and the recovery of valuable metal resources.

Effects of enzyme-induced carbonate precipitation technique on multiple heavy metals immobilization and unconfined compressive strength improvement of contaminated sand

Enzyme-induced carbonate precipitation (EICP) has been studied in remediation of heavy metal contaminated water or soil in recent years. This paper aims to investigate the immobilization mechanism of Zn2+, Ni2+, and Cr(VI) in contaminated sand, as well as strength enhancement of sand specimens by using EICP method with crude sword bean urease extracts. A series of liquid batch tests and artificially contaminated sand remediation experiments were conducted to explore the heavy metal immobilization efficacy and mechanisms. Results showed that the urea hydrolysis completion efficiency decreased as the Ca2+ concentration increased and the heavy metal immobilization percentage increased with the concentration of Ca2+ and treatment cycles in contaminated sand. After four treatment cycles with 0.5 mol/L Ca2+ added, the immobilization percentage of Zn2+, Ni2+, and Cr(VI) were 99.99 %, 86.38 %, and 75.18 %, respectively. The microscale analysis results presented that carbonate precipitates and metallic oxide such as CaCO3, ZnCO3, NiCO3, Zn(OH)2, and CrO(OH) were generated in liquid batch tests and sand remediation experiments. The SEM-EDS and FTIR results also showed that organic molecules and CaCO3 may adsorb or complex heavy metal ions. Thus, the immobilization mechanism of EICP method with crude sword bean urease can be considered as biomineralization, as well as adsorption and complexation by organic matter and calcium carbonate. The unconfined compressive strength of EICP-treated contaminated sand specimens demonstrated a positive correlation with the increased generation of carbonate precipitates, being up to 306 kPa after four treatment cycles with shear failure mode. Crude sword bean urease with 0.5 mol/L Ca2+ added is recommended to immobilize multiple heavy metal ions and enhance soil strength.

Magnetic sodium titanate nanotubes for simultaneous recovery of multiple low-level heavy and radioactive metal ions

Heavy and radioactive metal ions pollutants in water are a serious environmental problem and cause various health issues which lead to fetal human diseases. Herein, magnetic sodium titanate nanotubes (Fe3O4/NaTNTs) as magnetically separable nanostructure composite material were synthesized and used as adsorbent for simultaneous removal of multiple metal ions contaminants. HRTEM, SEM, FTIR, EDX, XRF, XRD, thermal gravimetric analysis (TGA), and zeta potential analysis were used for Fe3O4/NaTNT characterization. Thirteen metal cations including Th4+ and U4+, have been tested for competitive and simultaneous sorption on Fe3O4/NaTNTs nanostructure. In the mixed metal ions system, the removal efficiency of Co2+ and Pb2+ is the highest (Co2+; 95.9 %, Pb2+; 94.2 %). The relative selectivity for the removal of Cs+ ions (32 %) is more than that of Sr2+ ions (25 %). Thus, the data indicates the potential of Fe3O4/NaTNTs to be used in wastewater treatment, especially to simultaneously remove multiple heavy metal ions. Fe3O4/NaTNTs sorbent can be used for the rapid removal of heavy elements to mitigate large quantities of water pollution in emergencies, such as nuclear accidents and leaks.

Selective capacitive removal of Pb(II) ions from industrial wastewater using NF/Mn2CoO4@MoO2 electrodes

To achieve targeted removal of Pb2+ from industrial wastewater, a NF/Mn2CoO4@MoO2 composite electrode, synthesised using the hydrothermal method combined with electrodeposition technology, was employed to construct an asymmetric capacitive deionization (CDI) system to selectively electro-adsorb and desorb Pb2+ ions. The electrode exhibited pseudocapacitive characteristics in solutions containing Pb2+, facilitating rapid and reversible redox reactions. The asymmetric CDI system, utilising graphite paper as the positive electrode and NF/Mn2CoO4@MoO2 as the negative electrode, displayed exceptional adsorption performance at 1.4 V for 1 h, decreasing the Pb2+ concentration from 50 ppm to 4 ppb, achieving an adsorption capacity of 156.24 mg g−1, and displaying outstanding cyclic stability. Moreover, the electrode demonstrated preferential adsorption of Pb2+ in mixed solutions containing multiple heavy metal ions, with relative removal coefficients of 4.48 − 19.86 compared with other ions. Analysis of the adsorption mechanism indicated that during the adsorption process, Pb2+ was embedded between MoO2 layers, disrupting the electron cloud symmetry and triggering an oxidation reaction. Octahedral MoO2 then lost electrons and transformed into tetrahedral [MoO4]2-, forming PbMoO4 with embedded Pb2+ between the layers, and achieving effective removal of Pb2+ with high selectivity. Molecular dynamics simulations and density functional theory (DFT) calculations confirmed the high selectivity of the prepared electrode for Pb2+ ions based on stronger binding of Pb2+ to MoO2 than other ions. The electrode has application potential for the capacitive removal of Pb2+ from industrial effluent through CDI technology.

Unlocking the potential of biochar: an iron-phosphorus-based composite modified adsorbent for adsorption of Pb(II) and Cd(II) in aqueous environments and response surface optimization of adsorption conditions.

In this work, iron-phosphorus based composite biochar (FPBC) was prepared by modification with potassium phosphate and iron oxides for the removal of heavy metal ions from single and mixed heavy metal (Pb and Cd) solutions. FTIR and XPS characterization experiments showed that the novel modified biochar had a greater number of surface functional groups compared to the pristine biochar. The maximum adsorption capacities of FPBC for Pb(II) and Cd(II) were 211.66mg·g-1 and 94.08mg·g-1 at 293K. The adsorption of Pb(II) and Cd(II) by FPBC followed the proposed two-step adsorption kinetic model and the Freundlich isothermal adsorption model, suggesting that the mechanism of adsorption of Pb(II) and Cd(II) by FPBC involved chemical adsorption of multiple layers. Mechanistic studies showed that the introduction of -PO4 and -PO3 chemisorbed with Pb(II) and Cd(II), and the introduction of -Fe-O increased the ion exchange with Pb(II) and Cd(II) during the adsorption process and produced precipitates such as Pb3Fe(PO4)3 and Cd5Fe2(P2O7)4. Additionally, the abundant -OH and -COOH groups also participated in the removal of Pb(II) and Cd(II). In addition, FPBC demonstrated strong selective adsorption of Pb(II) in mixed heavy metal solutions. The Response Surface Methodology(RSM) analysis determined the optimal adsorption conditions for FPBC as pH 5.31, temperature 26.01°C, and Pb(II) concentration 306.30mg·L-1 for Pb(II). Similarly, the optimal adsorption conditions for Cd(II) were found to be pH 5.66, temperature 39.34°C, and Cd(II) concentration 267.68mg·L-1. Therefore, FPBC has the potential for application as a composite-modified adsorbent for the adsorption of multiple heavy metal ions.

Utilizing synergistic effects of bifunctional polymer hydrogel PAM-PAMPS for selective capture of Pb(II) from wastewater

The preparation of hydrogel adsorbents with admirable performance for efficient selective remove Pb(II) in complex wastewater still remains a great challenge. Herein, a novel bifunctional modified polymer hydrogel PAM-PAMPS was prepared by crosslinking acrylamide (AM) and 2-acrylamido-2-methylpropanesulfonic acid (AMPS). Compared with PEG, PAA and PAMPS, PAM-PAMPS exhibited both the maximum adsorption capacity of Pb(II) (541.90 mg/g) and satisfactory selectivity for Pb(II) in multiple heavy metal ions coexistence solutions. Various characterizations indicated that SO3H and NH2 as active sites on PAM-PAMPS occur the synergistic effects of ion-exchange and coordination with Pb(II) during the adsorption process, respectively. The adsorption energy Ead(PAM-PAMPS) obtained from density functional theory (DFT) calculations was lower than the other three hydrogels, manifesting that PAM-PAMPS formed the most stable complex with Pb(II), which further demonstrated that Pb(II) preferred to combine with PAM-PAMPS to selective capture of Pb(II). The practice utilization of PAM-PAMPS was assessed by wastewater of electroplate containing Pb(II). Meanwhile, the removal ratio of PAM-PAMPS was maintained at about 89% after 4 adsorption-desorption cycles. This study establishes a new and effective idea for the design and fabrication of bifunctionalized modified polymer hydrogels.

Simply-prepared hollow covalent organic framework as a dual-function platform for detection and removal of multiple heavy metal ions

Covalent organic frameworks (COFs) show great advantage in heavy metal ions detection and removal due to their large specific surface area, high porosity, excellent stability, and abundant functional sites. While current research primarily focuses on the influence of COF composition on detection and adsorption performance, the influence of COF′s morphology is often overlooked. In this study, a hollow structured TB-HCOF was developed through simple amorphous-to-crystalline transformation strategy involving the reaction between 1,3,5-Tris (4-aminophenyl) benzene (TAPB) and 1,3,5-benzenetricarbaldehyde (BTCA). TB-HCOF combine the advantages of COFs with the unique properties of hollow structure, such as an enlarged surface area, shortened diffusion distance, and easily accessible functional sites. It exhibited exceptional adsorption performance for heavy metal ions with the maximum adsorption capacities of 766.28 mg·g−1 for Pb2+, 759.32 mg·g−1 for Cu2+, and 640.83 mg·g−1 for Hg2+. Additionally, yolk-shell Pt nanoparticles@TB-HCOF was designed as an electrochemical sensing platform for heavy metal ions detection. Thanks to the synergistic effect between TB-HCOF with exceptional adsorption capacity and Pt nanoparticles with remarkable electrical conductivity, the sensor displayed awesome detection performance toward Pb2+, Cu2+ and Hg2+ with low limits of detection of 0.11 ng·L-1. These findings highlight the potential of simply-prepared hollow COFs as a promising material for managing heavy metal ions pollution.

A ratiometric electrochemical sensor for simultaneous detection of multiple heavy metal ions in water and herbal medicines based on methylene blue-functionalized metal–organic framework

Heavy metal contamination in water and herbal medicine poses a global threat to human health. There is a pressing need for the development of a simple and rapid method for simultaneous quantification. In this study, a ratiometric electrochemical sensor was first constructed using a hybrid material composed of methylene blue functionalized metal–organic framework (MB-UiO66-NH2) and multi-walled carbon nanotubes (MWCNTs). Then, MB-UiO66-NH2/MWCNTs harnessed the large specific surface area of UiO66-NH2 and good conductivity of MWCNTs, resulting in a sensor with superior analytical performance for Cd2+, Pb2+, and Hg2+ detection. Meanwhile, the ratiometric probe uses MB as an internal reference, with the ratio signal (Imetalion/IMB) serving as output. This ratiometric electrochemical sensor was able to enhance the reproducibility and reliability and eliminate interference, particularly in complex environments. Importantly, based on this ratiometric electrochemical platform, the low detection limit were 11.08 nM for Cd2+, 5.47 nM for Pb2+, and 6.42 nM for Hg2+, which realized the simultaneous, sensitive, and reliable detection. In addition, it has been successfully applied in real water and representative herbal medicine sample analysis. Therefore, this work provides a new approach for the risk assessment of heavy metal accumulation, which is conducive to safeguarding people's lives and health.

Fluorescent multichannel sensor array based on three carbon dots derived from Tibetan medicine waste for the quantification and discrimination of multiple heavy metal ions in water.

Afluorescent multichannel sensor array has been establishedbased on three carbon dots derived from Tibetan medicine waste for rapid quantification and discrimination of six heavy metal ions. Due to the chelation between metal ions and carbon dots (CDs), this fluorescence "turn off" mode sensing array can quantify six metal ions as low as "μM" level. Moreover, the six heavy metal ions display varying quenching effects on these three CDs owing to diverse chelating abilities between each other, producing differential fluorescent signals for three sensing channels, which can be plotted as specific fingerprints and converted into intuitive identification profiles via principal component analysis (PCA) and hierarchical cluster analysis (HCA) technologies to accurately distinguish Cu2+, Fe3+, Mn2+, Ag+, Ce4+, and Ni2+ with the minimum differentiated concentration of 5μM. Valuably, this sensing array unveils good sensitivity, exceptional selectivity, ideal stability, and excellent anti-interference ability for both mixed standards and actual samples. Our contribution provides a novel approach for simultaneous determination of multiple heavy metal ions in environmental samples, and it will inspire the development of other advanced optical sensing array for simultaneous quantification and discrimination of multiple targets.

A novel electrode for simultaneous detection of multiple heavy metal ions without pre-enrichment in food samples

Integrating a pre-enrichment step into electrochemical detection methodologies has traditionally been employed to enhance the performance of heavy metal detection. However, this augmentation also introduces a degree of intricacy into the sensing process and increases energy consumption. In this work, Mo-doped WO3 is grown in situ on carbon cloth by one-step electrodeposition. The electrode detect multiple heavy metal ions simultaneously in the range of 0.1–100.0 μM with LODs ranging from 11.2 to 17.1 nM. The electrode successfully detected heavy metal ions in diverse food samples. This pioneering detection strategy realized the direct and simultaneous detection of multiple heavy metal ions by utilizing the valence property of WO3 and oxygen vacancies generated by molybdenum doping. The Mo-WO3/CC pre-enrichment-free detection electrode boasts straightforward preparation, a streamlined detection procedure, swift response kinetics, and superior performance relative to previously reported electrodes, which makes it possible to develop a portable heavy metal ion detection device.

A Sensitive Probe of Meso-Cyanophenyl Substituted BODIPY Derivative as Fluorescent Chemosensor for the Detection of Multiple Heavy Metal Ions.

A fluorescent turn-on chemosensor (BA) was constructed by attaching bis(pyridin-2-ylmethyl)-amine (DPA) unit to the BODIPY scaffold. It can give a prominent green/yellow fluorescent response selectivity with each of Zn2+/Hg2+/Cd2+/Ca2+/Mn2+/Pb2+/Al3+. The 1:1 stoichiometry of BA and metal ions was drawn from the analysis of Job's plot. The limit detection of BA in recognition of Zn2+/Hg2+/Cd2+/Ca2+/Mn2+/Pb2+/Al3+ is ranged in 50.8-146.6 nM. There exists a linear relationship between the fluorescence intensity and concentration of metal ions (Zn2+: 4-15 µM). The mechanism of fluorescence signal "turn-on" is based on the photo induced transfer (PET) in the excited state of BA. The coordinated metal ions significantly weakened the electron-donating ability nitrogen atom in DPA, thus recovering the emission character of BODIPY. The substituted group at the phenyl ring in meso-position of BODIPY scaffold determines the recognizable list of metal ions.

A novel electrochemical sensing method based on an amino-functionalized MXene for the rapid and selective detection of Hg2.

Mercury is a highly toxic element that is widely present in all types of environmental media and can accumulate in living organisms. Prolonged exposure to high levels of mercury can lead to brain damage and death, so the detection of mercury is of great importance. In this study, a cost-effective and easy-to-operate electrochemical sensing method was successfully developed based on an amino-functionalized titanium-based MXene (NH2-Ti3C2Tx) for the rapid and selective detection of Hg2+ that could have a coordination effect with the -NH2 group of NH2-Ti3C2Tx to promote the efficient accumulation of Hg2+. In this strategy, the NH2-Ti3C2Tx was first modified on glassy carbon electrodes (GCE) to fabricate the electrochemical sensor. Benefiting from the excellent electrical conductivity, abundant active sites, and strong adsorption capacity performance of the NH2-Ti3C2Tx, the NH2-Ti3C2Tx modified GCE (NH2-Ti3C2Tx/GCE) exhibited satisfactory selectivity and enhanced square wave anodic stripping voltammetry (SWASV) measurement for the rapid detection of trace amounts of Hg2+ in aqueous solutions. The electrochemical sensor was found to be capable of detecting Hg2+ with a low detection limit of 8.27 nmol L-1 and a linear range of 0.5 μmol L-1 to 50 μmol L-1. The response time of the electrochemical sensing method was 308 s. In addition, the electrochemical sensing method has good selectivity, repeatability and stability, and multiple heavy metal ions have no effect on its detection, with repeatability and stability RSDs of 1.68% and 1.43%, respectively. Furthermore, the analysis of practical water samples demonstrated that the developed method was highly practical for the actual determination of Hg2+ with recoveries in the range of 99.22-101.90%.