Mercury Ions In Aqueous Solution Research Articles

Optimization of Plasmonic U-Shaped Optical Fiber Sensor for Mercury Ions Detection Using Glucose Capped Silver Nanoparticles

Heavy metal contamination of water bodies has an adverse effect on human health and the environment even at very low concentrations. In this paper, we report U-shaped fiber optic probe coated with glucose capped silver nanoparticles (AgNPs) for label-free detection of mercury ions in aqueous solution. The reaction between glucose capped AgNPs and mercury ions resulted in a reduction in the plasmonic absorbance. The developed sensor probe was able to detect mercury ions concentration as low as 2 ppb, which is less than the World Health Organization acceptable limit for mercury ions in drinking water. The sensor probes displayed excellent selectivity towards mercury ions over other metal ions. Furthermore, the developed sensor probe was able to detect mercury ions down to 5 ppb in domestic tap water, i.e., selective detection of mercury even in real matrix having high concentration mixtures of various essential ions. The response of AgNPs coated sensor probe was found to be better than glucose capped gold nanoparticles and hollow gold-silver nanostructures coated fiber-optic probes.

Fluorescence-sensitive adsorbent based on cellulose using for mercury detection and removal from aqueous solution with selective "on-off" response.

A new fluorogenic bio-adsorbent was successfully synthesized for detection and adsorption of mercury ions in aqueous solution. It showed high sensitivity in removing Hg (II) at low concentration with a detection limit of 84 ppb which was below the maximum discharge standard in enterprise drain off water in China, besides, the adsorbent had good selectivity towards Hg (II) among numerous kinds of cations in water that it showed fluorescent quenching properties for Hg (II) ions due to photo-induced electron transfer. In addition, batch adsorption experiments were investigated to study the influence of initial concentration of metal ions, contact time, pH of the solution on the adsorption capacity. Equilibrium adsorption isotherms demonstrated the Hg (II) removing process fitted well with Langmuir isotherm model, and the maximum adsorption capacity for mercury was measured to be 143.88 mg/g. Furthermore, the adsorption kinetics was found to follow pseudo-second-order model. FTIR spectra and SEM-elemental mapping clearly confirmed the adsorbed heavy metal ions.

Simultaneous Voltammetric Determination of Cd2+, Pb2+, and Hg2+ Ions Using Aminosepiolite-Coated Glassy Carbon Electrode: Optimization of Detection Parameters via Response Surface Methodology

Adsorptive stripping voltammetry using a glassy carbon electrode modified by a film of aminosepiolite was utilized for simultaneous pre-concentration and trace detection of cadmium, lead, and mercury ions in aqueous solution. The modified sepiolite exploited as electrode material was obtained by grafting on its surface of [(3-(2-aminoethylamino)propyl)]trimethoxysilane (AEPTMS). The results demonstrated that the amine groups on sepiolite efficiently affected the voltammetric detection of heavy metals. The full factorial design matrix and response surface methodology were applied in designing experiments, to determine the optimal conditions and to evaluate their mutual interactions. The high values of adjusted R2 obtained of the fitted model show that the experiments data were well explained by the model, which then allowed to acquire optimum parameters for the electroanalysis and detection of the analytes by differential pulse voltammetry. At pH 6.5 of accumulating medium, with an electrolysis potential of –0.9 V and in the concentration range of 10−8 M to 10−9 M, calibration plots were obtained. The limits of detection (3Sd/m) were 8.689 × 10−10 M, 8.197 × 10−10 M, and 8.099 × 10−10 M, respectively, for Cd2+, Pb2+, and Hg2+ ions. The interference effect of several cations and anions on the response of the analytes was also evaluated, and finally, the sensor was applied to the simultaneous detection of metal ions in tap water with satisfactory recovery rates.

A reversible biocompatible silver nanoconstracts for selective sensing of mercury ions combined with antimicrobial activity studies

In this manuscript we have reported an easy, eco-friendly and green chemical process for the synthesis of silver nanoparticles (AgNPs) by taking silver nitrate as the metal precursor and aqueous extract of fruits of phyllanthus acidus: phyllanthus family as both the reducing agent as well as capping agent. The formation of AgNPs has been investigated using UV–Vis spectroscopy where gradual generation of an intense surface plasmon resonance band at 425 nm clearly indicates the formation of silver nanoparticles. The optimum condition for the formation of AgNPs has also been established using UV–Vis spectroscopy. AgNPs have further been characterized by powder X-ray diffraction method, Fourier transform infrared spectroscopy, Scanning Electron Microscope and Transmission Electron Microscope. Interestingly, the synthesized AgNPs is used successfully for the detection of environmentally hazardous mercury ions in aqueous solution by colorimetric method. Furthermore, it has been found that the silver nanoparticles show reversible response towards mercury ion. Again, these AgNPs shows observable antibacterial activity against A. hydrophila.

Dichlororesorufin-Based Colorimetric and Fluorescent Probe for Ultrasensitive Detection of Mercury Ions in Living Cells and Zebrafish

In this work, a simple dichlororesorufin-based colorimetric and fluorescent probe R-Hg with the recognition receptor of carbonothioate was designed, synthesized, and exploited to determine mercury ions in aqueous solution and living cells as well as in zebrafish. After a series of analytical tests, probe R-Hg showed some excellent characteristics, such as ultrasensitivity, high selectivity, and good water solubility. The probe solution exhibited a very large fluorescence enhancement (about 150-fold) upon addition of Hg2+. Additionally, probe R-Hg exhibited excellent sensitivity, which could quantificationally detect Hg2+ at the nanomolar level, and the detection limit was 0.49 nM. Moreover, probe R-Hg could be used as a “naked-eye” probe for monitoring Hg2+, because the color of its solution transformed remarkably from yellow into pink with the participation of Hg2+. Importantly, probe R-Hg has potential application value and has been successfully applied to the determination of Hg2+ in practical water sa...

A Highly Stable Framework of Crystalline Zinc Phosphite with Selective Removal, Recovery, and Turn-On Sensing Abilities for Mercury Cations in Aqueous Solutions.

A highly stable framework of organic-inorganic hybrid zinc phosphite (NTOU-4) and its cobalt analogue (NTOU-4a) were synthesized under the hydro(solvo)thermal conditions and structurally characterized by single-crystal X-ray diffraction. Their frameworks consisted of inorganic metallophosphite chains, in which the metal atoms were interlinked through 1H-1,2,4-triazole-3,5-diamine and 1,4-benzenedicarboxylate linkers to form new crystalline materials. It is extremely difficult to achieve the consolidation of three distinct coordinations of metal-carboxylate, metal-triazolate, and metal-phosphite bonds into one crystal, resulting in the synthesis of the first mixed-ligand terephthalate-metallophosphite solids in the absence of organic molecules as templates or space-filling counters in their structures. Interestingly, the zinc compound not only exhibits high thermal stability (up to 400 °C in air) and chemical resistance to seawater, aqueous solutions (pH 3-11), and organic solvents at boiling conditions, but also shows selective removal, recovery, and "turn-on" sensing abilities of toxic mercury ions in aqueous solutions. Furthermore, the synthesis, characterization, and the difference of the framework stabilities between isostructural zinc and cobalt compounds are also reported.

Laccase Inhibition by Mercury: Kinetics, Inhibition Mechanism, and Preliminary Application in the Spectrophotometric Quantification of Mercury Ions

The noncompetitive inhibition of laccase by mercury ions is reported, in particular focusing their effect over the enzyme catalytic activity. The enzymatic kinetics were obtained for different substrates (caffeic acid, gallic acid, and catechol), where caffeic acid displayed the greatest enzymatic activity. The laccase inhibition by mercury ions permitted to establish the inhibition effect through a mixed model (that actually displayed a behavior closer to that of the noncompetitive inhibitors) when evaluated by means of UV-Vis spectrophotometry, using caffeic acid as an electron donor. A mercury concentration of 2 mM led to 35% enzymatic inhibition after only a 2-minute incubation period. This method was used for quantification of mercury ions in aqueous solution, showing a detection limit of 15 ± 1 ppm. Therefore, this work presented a novel perspective for the determination of the toxic Hg(II) ions that can be readily implemented into environmental remediation methods.

Photosynthesis of silver nanoparticles using Durio zibethinus aqueous extract and its application in catalytic reduction of nitroaromatics, degradation of hazardous dyes and selective colorimetric sensing of mercury ions

A simple green route was reported to prepare highly stable silver nanoparticles. The aqueous leaf extract of Durio zibethinus reduces Ag+ to Ag0 in the presence of natural sunlight. The capping and stabilization of dAgNPs by the phytoconstituents of Durio zibethinus was confirmed by FTIR. TEM confirms that the dAgNPs are spherical in shape with a size range between 10–25 nm. XRD pattern confirmed that the dAgNPs are arranged in the face-centred cubic structure. The catalytic activity of the dAgNPs was proved by sodium borohydride mediated reduction of nitro aromatic compounds and degradation hazardous organic dyes. The reaction kinetics was analysed by pseudo-first order equation. Regardless of the efficacy of degrading organic dyes, we showed by zebrafish mortality assay that the toxicity of the dye degraded water reduced drastically. Besides catalysis, the dAgNPs has the potential to selective colorimetric sensing of hazardous mercury ion in aqueous solution.

Synthesis of lanthanum doped carbon dots for detection of mercury ion, multi-color imaging of cells and tissue, and bacteriostasis

This work describes a hydrothermal method for the preparation of multi-functional carbon quantum dots of the type La-CQDs. The La-CQDs are 4.3±0.3nm in diameter and have a good dispersion and exhibit excellent emission property and high stability, as well as excitation-dependent emission behavior with typical excitation/emission peaks at 350/460nm. They can also be used as an effective fluorescent probe for the quenchometric determination of mercury ion in aqueous solution with a detection limit of 0.1µM. The particles are readily internalized by liver epithelial HepG2 cells and enable multi-color fluorescence imaging by displaying green and red emission if excited with 488 and 543nm light, respectively. Intravenous injection of the quantum dots in nude mice, in turn, enabled tissue imaging. The La-CQDs possess abundant phosphate, hydroxyl, pyridinic, pyridine-like and pyrrole-like nitrogen groups. Therefore, they can exhibit strong fluorescence, improve the accuracy as an optical monitoring code both in vitro and in vivo, and enhance blood compatibility. In vitro investigations show that La-CQDs do not exhibit significant apoptotic effects on NIH3T3 cells even at a high concentration (2.5mg/mL) while they exhibit improved antibactericidal capacity of the La-CQDs against gram-positive S. aureus and gram-negative E. coli bacteria was also observed. No apparent pathological damages are observed in all organs during the 30-day period, which suggests that La-CQDs do not produce detectable long-term toxicological responses.

Microcantilever array instrument based on optical fiber and performance analysis.

We developed a microcantilever array biosensor instrument based on optical readout from a microcantilever array in fluid environment. The microcantilever signals were read out sequentially by laser beams emitted from eight optical fibers. The optical fibers were coupled to lasers, while the other ends of the fibers were embedded in eight V-grooves with 250 μm pitch microfabricated from a Si wafer. Aspherical lens was used to keep the distance between lasers. A programmable logic controller was used to make the system work stably. To make sure that the output of lasers was stable, a temperature controller was set up for each laser. When the deflection signal was collected, lasers used here were set to be on for at least 400 ms in each scanning cycle to get high signal-to-noise ratio deflection curves. A test was performed by changing the temperature of the liquid cell holding a microcantilever array to verify the consistent response of the instrument to the cantilever deflections. The stability and conformance of the instrument were demonstrated by quantitative detection of mercury ions in aqueous solution and comparison detection of clenbuterol by setting test and reference cantilevers. This microcantilever array detection instrument can be applied to highly sensitive detection of chemical and biological molecules in fluid environment.

Green synthesis of silver nanoparticles using Carica Papaya fruit extract under sunlight irradiation and their colorimetric detection of mercury ions

We have successfully synthesized silver nanoparticles (AgNPs) by using aqueous extract of papaya (Carica papaya) fruit as bioreductant under sunlight irradiation without additional capping agent. Characterizations were done using UV-Visible spectrophotometry and Fourier Transform Infrared Spectroscopy (FTIR). The synthesized AgNPs have yellowish-brown color with surface plasmon resonance peak at 410 nm. Good selectivity of the AgNPs towards hazardous heavy metal of mercury ions in aqueous solution has been developed as a green environmental sensor. The presence of Hg(II) ions in the mixture changed the yellowish-brown color of AgNPs to colorless due to oxidation of Ag(O) in AgNPs to Ag(I) ions. Effect of samples matrix such as alkali metal, alkaline earth metal and transition metal ions were evaluated.

Hg selective adsorption on polypropylene-based hollow fiber grafted with polyacrylamide

A novel polypropylene hollow fiber membrane with a new function of selective adsorption of mercury ions in aqueous solutions was successfully prepared. The surface of the polypropylene hollow fiber membrane was initially modified with polydopamine by surface polymerization, and subsequently grafted with polyacrylamide (PAM) polymer brush via the surface initiated atom transfer radical polymerization (SI-ATRP) technique (thereafter named as PP-PAM). This study investigated the adsorption performance of Hg(II) ions by PP-PAM and the effect of various influencing factors on Hg(II) ion adsorption. The experiment indicated that the Hg(II) adsorption capacity of the PP-PAM increased with the increase of the pH, and the Hg(II) adsorption kinetics was consistent with the pseudo-second-order kinetic model. The adsorption isotherm followed the Langmuir model, with the maximum adsorption capacity calculated to be 0.854 mmol/g for Hg(II) ions. The adsorption study in multi-component system indicated that PP-PAM preferentially adsorbs Hg(II) over Pb(II) ions, with significant adsorption capacity difference of the two heavy metal ions. This study provided an efficient method for the preparation of the adsorptive polypropylene hollow fiber membrane, which expands its application for the selective removal of heavy metal ions.

Colorimetric Sensing of Mercury Ions in Aqueous Solutions by Zinc Core–Shell Nanoparticles

Colorimetric Sensing of Mercury Ions in Aqueous Solutions by Zinc Core–Shell Nanoparticles

L-Tryptophan-capped carbon quantum dots for the sensitive and selective fluorescence detection of mercury ion in aqueous solution

l-Tryptophan-capped carbon quantum dots (l-CQDs) were facilely synthesized through “green” methodology, and the obtained material was utilized as a sensitive and selective fluorescence sensor for mercury ion (Hg2+) in pure aqueous solutions. Carboxyl-functionalized CQDs were first green synthesized by a one-step hydrothermal route, and l-tryptophan was then attached to CQDs via direct surface condensation reaction in aqueous solution at room temperature. The as-synthesized l-CQDs had an average size of ca. 5 nm with a good dispersity in water, and exhibited a favorable selectivity for Hg2+ ions over a range of other common metal cations in aqueous solution (10 mM PBS buffer, pH 6.0). Upon the addition of Hg2+, a complete fluorescence quenching (ON–OFF switching) of l-CQDs was evident from the fluorescence titration experiment, and the fluorescence detection limit of Hg2+ was calculated to be 11 nM, which indicated that the obtained environmentally friendly l-CQDs had sensitive detection capacity for Hg2+ in aqueous solution.

Removal of mercury(II) ions in aqueous solution using the peel biomass of Pachira aquatica Aubl: kinetics and adsorption equilibrium studies.

Mercury is a highly toxic substance that is a health hazard to humans. This study aims to investigate powders obtained from the peel of the fruit of Pachira aquatica Aubl, in its in natura and/or acidified form, as an adsorbent for the removal of mercury ions in aqueous solution. The materials were characterized by Fourier transform infrared spectroscopy and thermogravimetric analysis. The infrared spectra showed bands corresponding to the axial deformation of carbonyls from carboxylic acids, the most important functional group responsible for fixing the metal species to the adsorbent material. The thermograms displayed mass losses related to the decomposition of three major components, i.e., hemicellulose, cellulose, and lignin. The adsorption process was evaluated using cold-vapor atomic fluorescence spectrometry (CV AFS) and cold-vapor atomic absorption spectrometry (CV AAS). Three isotherm models were employed. The adsorption isotherm model, Langmuir-Freundlich, best represented the adsorption process, and the maximum adsorption capacity was predicted to be 0.71 and 0.58 mg g(-1) at 25 °C in nature and acidified, respectively. Adsorption efficiencies were further tested on real aqueous wastewater samples, and removal of Hg(II) was recorded as 69.6 % for biomass acidified and 76.3 % for biomass in nature. Results obtained from sorption experiments on real aqueous wastewater samples revealed that recovery of the target metal ions was very satisfactory. The pseudo-second-order model showed the best correlation to the experimental data. The current findings showed that the investigated materials are potential adsorbents for mercury(II) ion removal in aqueous solution, with acidified P. aquatica Aubl being the most efficient adsorbent.

Sensing of bisphenol A and mercury ions in aqueous solutions using a functionalized porous gold electrode

Endocrine disrupting compounds (EDCs) such as bisphenol A (BPA) and mercury ions can accumulate in living tissue, causing many health problems. Therefore, to prevent contaminated water and products reaching consumers, it is necessary to develop a sensitive and efficient sensing system for these compounds. However, common analytical techniques for EDCs are based on mass spectrometry, which is both costly and requires an expert analyst. Herein, we describe the preparation of a functionalized, porous gold electrode for electrochemical sensing of BPA and mercury ions in aqueous solutions that is formed via a templating method and simple pressing. The prepared porous gold electrode was characterized by SEM-EDS, N2 adsorption-desorptions, and FTIR spectroscopy. The prepared porous gold has a very large surface area (8.1 m2/g) and comparable electrical conductivity (1.33 × 104 S/cm) to pure gold. To prevent electrode poisoning by oxidation byproducts of the target analytes, an indirect sensing method was used: the ferricyanide oxidation reaction. For hexyl and thiol-functionalized porous gold electrodes (C6–PAu and SH-PAu), a linear relationship between the current responses and the concentrations of BPA and mercury ions with high correlation coefficients (≥0.9998) at very low aqueous concentrations (≤0.7 μM) was found using differential pulse voltammetry measurements. Also, the C6–PAu electrode could be regenerated easily by washing with ethanol, and was reused five times consecutively.

D-penicillamine-templated copper nanoparticles via ascorbic acid reduction as a mercury ion sensor

Mercury ion is one of the most hazardous metal pollutants that can cause deleterious effects on human health and the environment even at low concentrations. It is necessary to develop new mercury detection methods with high sensitivity, specificity and rapidity. In this study, a novel and green strategy for synthesizing D-penicillamine-capped copper nanoparticles (DPA-CuNPs) was successfully established by a chemical reduction method, in which D-penicillamine and ascorbic acid were used as stabilizing agent and reducing agent, respectively. The as-prepared DPA-CuNPs showed strong red fluorescence and had a large Stoke's shift (270nm). Scanning electron microscopy, transmission electron microscopy, Fourier-transform infrared spectroscopy, fluorescence spectroscopy, and ultraviolet-visible spectrophotometry were utilized to elucidate the possible fluorescence mechanism, which could be aggregation-induced emission effect. Based on the phenomenon that trace mercury ion can disperse the aggregated DPA-CuNPs, resulting in great fluorescence quench of the system, a sensitive and selective assay for mercury ion in aqueous solution with the DPA-CuNPs was developed. Under optimum conditions, this assay can be applied to the quantification of Hg2+ in the 1.0–30μM concentration range and the detection limit (3σ/slope) is 32nM. The method was successfully applied to determine Hg2+ in real water samples.

A highly sensitive fluorescent sensor with aggregation-induced emission characteristics for the detection of iodide and mercury ions in aqueous solution

A highly sensitive fluorescent sensor with aggregation-induced emission characteristics was developed for the detection of iodide and mercury ions.

Recyclable Hypersensitive Fluorescent Dipeptidyl Chemosensor Based on Silica Nanoparticles Using Signal Amplification for the Detection of Hg(II) and Cu(II) in Aqueous Solutions

Silica nanoparticles (SiNPs) were synthesized for the detection of heavy metal ions by conjugating a dipeptidyl fluorescent chemosensor (DPN) into the SiNPs using a click reaction. Among the 14 metal ions tested, SiNPs conjugated with DPN (DPNSi) showed sensitive responses toward Hg(II) and Cu(II) ions in aqueous solutions. The detection limits of DPNSi were determined to be 3.8 and 16.5 nM for Hg(II) and Cu(II) ions, respectively, in aqueous solutions. Moreover, the sensitivity of DPNSi to Hg(II) ions was significantly higher than that of DPN. DPNSi was sufficiently sensitive for monitoring the maximum allowable level of Hg(II) and Cu(II) ions in drinking water demanded by the Environmental Protection Agency (EPA). DPNSi could be recycled for the detection and removal of toxic mercury ions in aqueous solutions by regeneration with glutathione.

A highly sensitive fluorescent chemosensor for simultaneous determination of Ag(I), Hg(II), and Cu(II) ions: Design, synthesis, characterization and application

A fluorescent chemosensor based on dimethylaminocinnamaldehyde-aminothiourea (DA) has been designed, synthesized, and applied with a combined theoretical and experimental study. The synthetic path, optimized molecular structure and characteristics of DA were carried out using the calculations at the B3LYP/LanL2DZ level of theory. The experimental investigations have a good agreement with the theoretical results. DA can be used as a chemosensor for simultaneous quantification of silver, copper, and mercury ions in aqueous solution at the ppb level. The stable geometric structures of the complexes between DA and Ag+, Hg2+, Cu2+ with stoichiometry of 1:1, 2:1, and 2:1, have been found and investigated for electronic properties and fluorescence quenching phenomena by using Atoms in Molecules (AIM) and Natural Bond Orbitals (NBO) analyses.