Electrochemical Detection Of Heavy Metals Research Articles

Electrochemical detection of heavy metals in rice, milk and tap water using free-standing carbon felt electrodes

In this work, a carbon felt (CF) was utilized to fabricate electrochemical sensors for the simultaneous detection of Cd2+, Pb2+ and Hg2+. The working conditions of CF sensors including thermal activation, electrolytes, and enrichment potentials and times were systematically investigated. Under the optimal detection conditions, the resulting sensors showed good linearity in the concentration ranges of 3–10,000, 2–10,000 and 5–10,000 μg/L for the detection of Cd2+, Pb2+ and Hg2+, corresponding to the detection limits of 1, 0.5, and 1 μg/L, respectively. Meanwhile, the resulting electrochemical sensor demonstrates excellent reproducibility and anti-interference. In addition, the CF electrodes maintain good stability even after 180 days of storage at room temperature. In real water, rice and milk samples, the CF electrodes have been successfully utilized for the detection of Cd2+, Pb2+ and Hg2+ and the results were in agreement with those obtained from the inductively coupled plasma mass spectrometry.

Waste-derived carbon nanodots for fluorimetric and simultaneous electrochemical detection of heavy metals in water

Sustainable synthesis of carbon nanodots (CNDs) through a green route – converting beer bagasse, a by-product of the beer industry, into hydrochar via eco-friendly hydrothermal carbonization, and their application for the selective detection of harmful heavy metal ions.

Zinc oxide nanostructured platform for electrochemical detection of heavy metals

AbstractZnO nanoparticles (ZnO‐NP) were prepared by a facile precipitation technique using di‐isopropyl amine as precipitating agent. The morpho‐structure and porosity of the as‐prepared nano‐powder were investigated by FT‐IR analysis, X‐ray diffraction (XRD), scanning electron microscopy (SEM), and BET analysis. By drop‐casting, a composite film was deposited to obtain ZnO‐NP‐Nafion/GCE modified electrode. The modified electrode was investigated by cyclic voltammetry, electrochemical impedance spectroscopy, and square wave anodic stripping voltammetry (SWASV) for the detection of Pb2+, Cd2+, Cu2+, and Fe3+, and it was successfully applied for the detection of Pb2+ and Cu2+ in real water samples.

Recent Progress in Morphology-Tuned Nanomaterials for the Electrochemical Detection of Heavy Metals.

Heavy metals are one of the most important classes of environmental pollutants which are toxic to living beings. Many efforts are made by scientists to fabricate better sensors for the identification and quantification of heavy metal ions (HMI) in water and food samples to ensure good health. Electrocatalysts have been demonstrated to play an important role in enhancing the sensitivity and selectivity of HMI detection in electrochemical sensors. In this review, we presented morphologically well-tuned nanomaterials used as efficient sensor materials. Based on the molecular dimensions, shapes, and orientation, nanomaterials can be classified into 0-D, 1-D, 2-D, and 3-D nanomaterials. Active surface areas with significant exposure of active sites and adsorption-desorption abilities are extensively varied with dimensionality, which in turn ultimately influence the sensing performance for HMI.

Highly sensitive electrochemical detection of Hg(II) promoted by oxygen vacancies of plasma-treated ZnO: XPS and DFT calculation analysis

Even though there have been a variety of electrochemical sensors, it is of great importance to search for a nanomaterial with efficient active sites and explain its mechanism in the electrochemical detection of heavy metals. In the present research work, flower-like oxygen vacancy-rich zinc oxide (OV-ZnO) is prepared by processing flower-like ZnO (ZnO) with plasma. The presence of oxygen vacancies is validated using X-ray photoelectron spectroscopy (XPS), electron spin resonance (ESR), and Raman spectroscopy. The prepared OV-ZnO is then used to modify the glassy carbon electrode (GCE) surface to construct an electrochemically sensitive interface for detecting Hg(II). According to the obtained results, oxygen vacancies can significantly improve the sensing performance of the electrode for Hg(II) detection, achieving a detection sensitivity of up to about 1323.91 μA·μM−1·cm−2 and a detection limit of approximately 0.023 μM. In addition, OV-ZnO revealed good anti-interference performance against common heavy metal ions and showed excellent stability and reproducibility. XPS and density-functional theory calculations suggest that its good electrochemical sensing performance could possibly be due to the activation of oxygen vacancies, the low adsorption energy, and the appropriate Hg-Zn bond length. Moreover, the OV-ZnO-modified GCE exhibits high sensitivity to Hg(II) in actual water samples, which offers theoretical guidance for constructing electrochemical sensors for practical applications in the future.

WITHDRAWN: Electrochemical detection of heavy metals using carbon quantum dots modified with metal oxides

Abstract The high toxicity of chemical pollutants and its detrimental effects to the living organisms has led to significant public concern. Hence it is very much necessary to monitor the level of these toxic ions in the environment using an appropriate sensor. In order to detect the heavy metal such as lead, mercury, cadmium etc. in water, there exist a need to develop a novel sensing technology for more sensitivity and rapid detection. The use of classical methods for the detection of the toxic ions in water is both tedious and time consuming. Nanomaterial of carbon serve as a powerful tool in analyzing these heavy metal ions due to their selectivity and sensitivity to one cation, owing to their excellent photoluminescence and photophysical properties.In this present work ,green synthesis of carbon quantum dots was carried out using lemon juice and onion juice. These CQD’s were then doped with metal oxides such as bismuth oxide and zinc oxide. These metal oxide doped CQD’s improves the sensitivity and electrical conductivity of electrodes and hence increases the rate of electrochemical reaction. The carbon dots and metal oxide doped carbon dots were characterized using IR technique, UV –Visble spectroscopy and SEM. The sensing property of electrode towards heavy metal was investigated by modifying the electrode with CQD’s, CQD’s doped with metal oxide and anionic polymer (nafion).The cyclic voltammetric studies were carried out with glassy carbon electrode modified with CQD/Bi203/Nafion. The cyclic voltammograms obtained showed that glassy carbon electrode modified with CQD/Bi203/Nafion showed excellent sensing property towards lead.

Polypyrrole: a reactive and functional conductive polymer for the selective electrochemical detection of heavy metals in water

The last two decades have witnessed attractive, innovative aspects of conductive polymers (CPs) in monitoring environmental pollution. In this regard, CP-based electrode materials were designed for the selective recognition of heavy metal ions in the environment (e.g. waste, river or tap water) or in simulated polluted environmental samples. In this review, the emphasis is on polypyrrole (PPy), an interesting electrosensing electrode material for heavy metals due to its facile preparation, versatile chemistry and physicochemical features. Indeed, health issues raised by metal ion pollutants require an urgent holistic approach for environmental problem solving. In this review, we will summarize the existing knowledge on the use of PPy as electrode material for the detection of heavy metals. We will report strategies of preparation of polypyrrole that exhibit selectivity towards heavy metal ions: (i) choice of dopant, (ii) functionalization of polymer backbone by chelatant groups, and (iii) preparation of ion imprinted polypyrrole. It is clear from this review that dopants could act as chelatant of metal ions and increase the selectivity. Such improvement could also be achieved by copolymerization of pyrrole with pyrrole-bearing chelatant groups (e.g. EDTA-like) or finally by the imprinting technique. The latter imparts artificial receptor sites for the recognition of metal ions combining the shape of the receptor site within the polypyrrole matrix that fit in well with the size of the metal ion, on the one hand, and the receptor site–ion interactions, on the other hand. Regardless, the method employed to design polypyrrole sensing layers for heavy metal nanostructuration seems to definitely improve the sensitivity of polypyrrole-based sensor devices. The review finishes by concluding remarks and indication of possible challenging new directions exploring polypyrrole in tracking occurrence of heavy metal ions in the environment.

Oxygen Plasma/Bismuth Modified Inkjet Printed Graphene Electrode for the Sensitive Simultaneous Detection of Lead and Cadmium

In this work, a simple procedure for the preparation of an inkjet printed disposable graphene electrode is reported. Commercial graphene ink was printed on a kapton substrate and the resulting electrode was 30 min treated by oxygen plasma, then modified by a bismuth salt. The as prepared electrode was characterized by Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), laser scanning microscopy (LSM) and scanning electron microscopy (SEM) coupled to energy-dispersive X-ray spectroscopy (EDX). The sensing properties of the characterized electrodes were then investigated using cyclic voltammetry and Electrochemical Impedance Spectroscopy (EIS). Afterwards, these electrodes were exploited in a comparative way for the electroanalysis of Cadmium(II) and Lead(II) ions. An increase in the electrode sensitivity due to its modification and to the presence of bismuth was observed. Some preliminary experiments based on stripping square wave voltammetry highlighted the interest of using the proposed disposable inkjet printed electrodes for the electrochemical detection of heavy metals in tap water.

Review—Application of Deficient Apatites Materials in Electrochemical Detection of Heavy Metals: Case of Mercury (II) in Seawater and Fish Samples

Contamination by metallic trace elements is considered a serious problem considering their toxicity and their cumulative power in the food chain. These heavy metals such as mercury (II) are thus monitored and recognized today as pollutants dangerous for humans and their environment. In this review, we look back at 10 years of our dedicated research, and summarize the main advances made in terms of exploitation of apatitic materials for the detection of heavy metals. Recent trends in the application of apatite compounds for electrochemical detection of heavy metals are shown. In this perspective, the present work focuses on the development of electrochemical sensors based on new deficient apatites materials. The proposed sensors revealed a high efficiency for the analysis of mercury ions with a stable and amplified signal. This latter has been optimized by varying the nature and content of the substituents in the gap apatite structure. The adsorption characteristics of these materials serve to trap inorganic micropollutant like mercury. Moreover, the modification of the surface properties of graphite carbon electrodes by newly lacunar apatites has served to control the quality of seawater and fish samples with satisfactory results.

Graphene Oxide-Poly(dimethylsiloxane)-Based Lab-on-a-Chip Platform for Heavy-Metals Preconcentration and Electrochemical Detection.

Herein, we present the application of a novel graphene oxide-poly(dimethylsiloxane) (GO-PDMS) composite in reversible adsorption/desorption, including detection of heavy metals. GO-PDMS was fabricated by simple blending of GO with silicon monomer in the presence of tetrahydrofuran, followed by polymerization initiated upon the addition of curing agent. We found GO concentration, curing agent concentration, pH, and contact time among the most important factors affecting the adsorption of Pb(II) used as a model heavy metal. The mechanism of adsorption is based on surface complexation, where oxygen active groups of negative charge can bind with bivalent metal ions Me(II). To demonstrate a practical application of this material, we fabricated microfluidic lab-on-a-chip platform for heavy-metals preconcentration and detection. This device consists of a screen-printed carbon electrode, a PDMS chip, and a GO-PDMS chip. The use of GO-PDMS preconcentration platform significantly improves the sensitivity of electrochemical detection of heavy metals (an increase of current up to 30× was observed), without the need of modifying electrodes or special reagents addition. Therefore, samples being so far below the limit of detection (0.5 ppb) were successfully detected. This approach is compatible also with real samples (seawater) as ionic strength was found as indifferent for the adsorption process. To the best of our knowledge, GO-PDMS was used for the first time in sensing application. Moreover, due to mechanical resistance and outstanding durability, it can be used multiple times unlike other GO-based platforms for heavy-metals adsorption.

A Fully Inkjet-Printed Sensor for Electrochemical Detection of Heavy Metals

Heavy metals are present in soil and water as a non-degradable element in environment usually in their cationic form. Some of these metals, such as iron, copper, etc. are crucial for life. On the other hand, some of them are toxic such as lead (Pb) that could cause a detrimental effect on the human nervous system and cadmium (Cd) that could cause damage to kidney [1]. Various detection methods have been employed to determine Pb(II) and Cd(II) concentration including atomic absorption, emission spectroscopy, inductively-coupled plasma mass spectrometry, cold vapor atomic fluorescence spectrometry, and electrochemical analysis. Among them, electrochemical analysis has gained more attention due to its high selectivity, high sensitivity, low cost, and simple determination process [2]. Stripping voltammetry in conjunction with mercury-based electrodes was initially used in heavy metal electrochemical sensing platforms, but due to the toxicity of mercury, bismuth-based electrodes has become a good alternative for electrochemical detection of heavy metals. Bismuth (Bi), an environmentally-friendly element, offers a wide electrochemical window, low background current, and clear separation between neighboring peaks [3, 4]. Employing paper to develop sensing platforms has become popular in recent years due to, porous structure and extremely low cost. Paper-based electrochemical sensors can be good candidate for environmental analysis especially in the resource limited areas due to their extremely low cost [5]. In this work, we present a fully inkjet-printed electrochemical sensor for determination of Pb(II) and Cd(II). Inkjet-printed sensors offer many advantages including mass automated printing process, uniform deposition and low waste of the materials, and scalable manufacturing comparing to the conventional screen printing approach. The sensor basic design structure is illustrated in the figure. The inkjet printing process was based on our previously development described in [6, 7]. In situ plating of the Bi on the carbon nanotube electrode occurred at the preconcentration step of the anodic stripping voltammetry by applying negative voltage to the working electrode. Acetate buffer solution containing various amount of Pb(II) and Cd(II) was then introduced to the presented paper-based sensing platform, and the anodic stripping analysis has been performed to determine the Pb(II) and Cd(II) concentration.

Comparison of various bismuth film electrodes in simultaneous electrochemical detection of heavy metals for application in quantum dot-linked immunoassays

Various electrode materials commonly used in electroanalysis were tested in preparation of respective bismuth film electrodes and compared in simultaneous electrochemical detection of heavy metals, simulating dissolved quantum dots used as labels of antibodies in quantum dot-linked immunosorbent assays. According to results obtained during voltammetric measurements, it can be concluded that selected commercial screen-printed electrodes showed many significant drawbacks which are described in detail. Contrary to the gold disk electrode, conventional glassy carbon electrode coated with thin bismuth film was applicable up to −1.5 V without the need to use very high content of bismuth in supporting electrolyte. Moreover, significant interactions among present metals were observed during their electrochemical stripping analysis, especially in presence of copper and silver.

Nanocarbon‐based Electrochemical Detection of Heavy Metals

AbstractHeavy metal species are toxic, non‐decomposable molecules which exist in our ecological systems and food chains, eventually exposing us to serious health hazards and economic damage. In this context, various attempts have been made for sensitive detection of heavy metal ions through electrochemical sensor. Carbon nanomaterials endowed with unique physiochemical properties were found to be most suitable for electrochemical detection of heavy metal due to their ease to modify, high sensitivity, good selectivity and high reproducibility. Here, we present a critical review about detection of heavy metals using nanocarbon with focus on graphene and carbon nanotubes in various sources of water, soil, and foods for fast and sensitive detection of heavy metal ions. We have evaluated the current trends and discussed the major challenges associated with electrode modification and electrochemical analysis with the aim to achieve the best sensing performance.

Pre-treatment technology for electrochemical detection of heavy metal lead and cadmium in food

Wet digestion is used as the pre-treatment technology for the electrochemical detection of heavy metals in food,and the complete wet digestion condition of food sample is optimized by electrochemical experiments. The results show that the experimental samples can be digested completely using the Nitric acid-hydrogen peroxide system and is not pre-digested after adding 10 m L nitric acid at 120 ~ 140 ℃ and adding 10 ~ 15 m L of hydrogen peroxide during the heating process. The correlation coefficient of electrochemical detect is 0. 99 for digestion solution of the samples,and the recovery of standard addition is 82% ~ 115%. Wet digestion as a pre-treatment technology of food samples,It can digest sample fully and meet the requirements of electrochemical detection.

Heavy metal complexation on hybrid mesoporous silicas: an approach to analytical applications

Recent advances in the development of new materials are having a major impact on Analytical Chemistry. For example, the unique properties of ordered mesoporous silicas have been shown to enhance the analytical performance of many existing techniques or allow new, exciting ones to be developed. Likewise, the introduction of organo-functional groups makes mesoporous silicas highly versatile and enables them to perform specialized tasks, such as the adsorption of toxic heavy metals from aqueous solutions. In this tutorial review, we present readers with a brief introduction to the most relevant achievements in the preparation of hybrid mesoporous silicas functionalized with chelating ligands for the complexation of heavy metals. We also provide some recent examples from the last ten years regarding the analytical applications of such hybrid silicas. Two topics of great current interest in environmental water analysis for heavy metal detection, namely the use of hybrid mesoporous silicas as sorbents for solid-phase extraction and the use of these materials to develop new strategies for electrochemical detection of heavy metals by stripping voltammetry, are addressed.

Nanomaterials application in electrochemical detection of heavy metals

Recent trends in the application of nanomaterials for electrochemical detection of heavy metals are shown. Various nanomaterials such as nanoparticles, nanowires, nanotubes, nanochannels, graphene, etc. have been explored either as modifiers of electrodes or as new electrode materials with interest to be applied in electrochemical stripping analysis, ion-selective detection, field-effect transistors or other indirect heavy metals (bio)detection alternatives. The developed devices have shown increased sensitivity and decreased detection limits between other improvements of analytical performance data. The phenomena behind nanomaterials responses are also discussed and some typical responses data of the developed systems either in standard solutions or in real samples are given. The developed nanomaterials based electrochemical systems are giving new inputs to the existing devices or leading to the development of novel heavy metal detection tools with interest for applications in field such as diagnostics, environmental and safety and security controls or other industries.

Upstream microelectrodialysis for heavy metals detection on boron doped diamond

Paper shows the development of a microelectrodialyser with a 6μL active volume with the aim to miniaturized a total analysis system (μTAS) using microfluidic chips for heavy metals analysis. Microsystem was fabricated with ion-exchange membranes to define concentration and dilution compartments and platinum wires as electrodes in order to pre-concentrate and pre-treat heavy metals in water solution. After 200min electrodialysis at 15μLmin−1, a concentration factor up to 120 has been obtained in the case of the treatment of a Pb(NO3)2 solution. With the aim to combine a microelectrodialyser with a mercury free electrochemical detection of heavy metals, boron doped diamond (BDD) film performances as working electrode were studied for Pb2+ analysis by SWASV. A linear detection from 20ppb to 100ppb of lead has proved the stability of the BDD electrode. Concentration range is compatible with the electrodialyser channel outlet allowing in associated both presented systems to built an innovative lab-on-a chip microsystem to environmental analysis.

ChemInform Abstract: Carbon Nanotube‐Based Extraction and Electrochemical Detection of Heavy Metals

AbstractReview: 75 refs.

Carbon nanotube-based extraction and electrochemical detection of heavy metals

In this mini review, recent trends and challenges in developing carbon nanotube-based extraction and electrochemical detection of heavy metals in water are reviewed. Carbon nanotubes (CNT) have electrical, mechanical, chemical, and structural properties superior to those of conventional materials, for example graphite and activated carbon. CNT-based procedures are also more efficient than traditional techniques and methods, for example liquid–liquid extraction, atomic-absorption spectroscopy, flame photometry, and inductively coupled plasma, because they can enable rapid, sensitive, simple, and low-cost on-site detection. Different forms of CNT, including as-grown, oxidised, and functionalised CNT, can be well suited to metal adsorption. The measurement procedure relies on adsorbing the metal on the CNT surface after reasonable contact time, either by applying an electrical potential or under open-circuit conditions, and subsequent quantification. Different types of CNT-based electrode, including composite, paste, and binder-free, can be fabricated and used for metal detection. Application of CNT and their novel properties to the adsorption and detection of heavy metals is discussed in detail.

Enhanced electrochemical detection of heavy metals at heated graphite nanoparticle-based screen-printed electrodes

The effect of temperature upon the electrochemical stripping performance of a heavy metal sensor based on carbon nanoparticles is studied. The morphological changes of the sensing surface during the multidetection of Cd2+, Pb2+, Cu2+ and Hg2+ ions are studied by TEM and SEM. The effect of the temperature on the heavy metal deposition using carbon nanoparticle-based SPEs is also compared to a sensor that does not contain carbon nanoparticles. The effect of temperature seems to be more pronounced for the nanoparticle-based sensor. This phenomenon is clarified by the electrochemical response as well as the TEM and SEM images of the sensing materials used. In addition, the response performance of the nanoparticle-based sensors for increasing concentrations of heavy metals from 5–100 μg L−1 for Cd2+, Pb2+ and Cu2+ and from 1 to 10 μg L−1 for Hg2+, in both single and multiple detections with potential for real applications, is presented. The nanoparticle-based sensor seems to be stable for up to one month while being used in continuous monitoring of heavy metals in seawater.