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The individually and simultaneously detection of heavy metal ions have been widely reported. However, little analyzed the difference and relationship between the two such as sensitivities and limit of detection (LOD) using irradiated natural materials. Based on the electrochemical detection of Pb(II), Cd(II), Hg(II) and Cu(II) ions, their stripping behaviors, through combining an irradiated attapulgite (IAP) at a fluence of 30 kGy (IAP30) with room temperature ionic liquid (RTIL) composites coated electrodes, were compared and analyzed by square wave stripping voltammetry. The characteristic of sensitivities and LOD of IAP30/RTIL electrode towards metal ions were markedly improved in comparison with IAP electrode. The LOD of the simultaneous detection towards Pb(II), Cd(II), Cu(II) and Hg(II) using IAP30/RTIL electrode were 0.8, 0.5, 0.2 and 0.06 nM, respectively. The sensitivities and LOD of Pb(II), Cd(II) in simultaneous detection were lower and higher than these in individual detection, while those of Hg(II) and Cu(II) increased and decreased in comparison with the individual detection at IAP30/RTIL or IAP30 modified electrode. An enhanced sensitivity of Hg(II) in the simultaneous detection reached 242.4 μA/μM, and was the largest among four metal ions. Analysis of six groups of solutions including Pb(II)-Cd(II)-Hg(II), Cd(II)-Cu(II)-Hg(II), Pb(II)-Cu(II)-Hg(II), Cu(II)-Hg(II), Pb(II)-Hg(II), Cd(II)-Hg(II) were further performed, respectively. This study provided a novel method for the construction of sensitive electrochemical sensors of heavy metal by natural materials, and an effective reference that meet the needs of environmental control for analysis of different metal ions. [ABSTRACT FROM AUTHOR]

The polyethylenimine (PEI) or ethanediamine (EDA) has been employed to adsorb metal ions. However, both the combination of CoFe 2 O 4 -reduced graphene oxide (rGO) with PEI or EDA for the analysis of Cu(II) determination and interaction mechanism towards copper ion by electrochemical method and X-ray photoelectron spectroscopy (XPS) are, to the best of our knowledge, unexplored. The amine functionalized rGO/CoFe 2 O 4 composite were synthesized through a one-pot method, and characterized by electrochemical method and different spectra such as FT-IR, XRD, XPS, etc. The lowest detection limit with 20 pM (3δ method) and sensitivity with 0.39 μA/nM towards Cu(II) was obtained at PEI/rGO/CoFe 2 O 4 modified electrode under optimized condition. The characteristics of Cu(II) on the amine-group functionalized CoFe 2 O 4 /rGO composite were investigated by cyclic voltammetry and XPS. The shifts of O and N peaks of PEI (or EDA)/CoFe 2 O 4 /rGO preconcentrating Cu(II) showed the synergistic effect of CoFe 2 O 4 /rGO and PEI (or EDA) to Cu(II). The analysis indicated that the interaction between the composite and Cu(II) was adsorption control process. The proposed electrode was also employed to the analysis of real soil sample. Thus, the proposed method and interaction mechanism analysis based on adsorption interaction could provide a reference for further investigate the pollution of metal ions. [ABSTRACT FROM AUTHOR]

This study attempts to understand the stripping behaviors and mutual impact of different metal ions in electrochemical detection. A reduced graphene oxide-Fe 3 O 4 (rGO-Fe 3 O 4 ) nanocomposites with small-sized Fe 3 O 4 is prepared by a simple and one-pot synthesis method. The morphology and structure of the nanocomposites are investigated by scanning electron microscopy, energy dispersive X-ray spectroscopy, Fourier transform infrared spectrometer and X-ray diffraction. The electrochemical behaviors of nanocomposite electrode are characterized by cyclic voltammetry and electrochemical impedance spectroscopy. The individual and simultaneous stripping analysis of Cd 2+ , Pb 2+ and Hg 2+ using rGO-Fe 3 O 4 electrode are performed by square wave anodic stripping voltammetry (SWASV) under optimized condition, and experimental data show that there are differences in some parameters such as sensitivities and detection limits, etc. To further understand phenomena, a series of interference tests are systematically evaluated by SWASV in detail. The experimental results demonstrate that determination of Cd 2+ is easy to be influenced by Pb 2+ and Hg 2+ . At last, the proposed electrode is used to analyze content of Pb 2+ in soil sample. The result obtained at the nanocomposite electrode is comparable to that obtained by inductively coupled plasma atomic emission spectroscopy, indicating a good accuracy. The sensor could provide an effective detection and analysis method for heavy metal ions. [ABSTRACT FROM AUTHOR]

Abstract It is rather important to not only obtain the better detection efficiency for metal ions, but also investigate the change of sensitivity and detection limit in the simultaneous detection. Herein, a novel type of room temperature ion liquid (RTIL)/γ-AlOOH/Fe(OH) 3 composite was prepared. Both the individual and simultaneous determination of Hg(II) and Cu(II) were examined by the composite electrode. The electrode exhibited the lowest limits of detection (LODs) of 0.5 and 0.3 nM for Hg(II) and Cu(II) in simultaneous determination, the highest sensitivities of 64.5 and 65.9 μA/μM, respectively, and the shortest response time. Both Hg(II) and Cu(II) films electroplated on the surface of composite were used to further analyze change of sensitivity and LOD, respectively. The thickness of films influenced the sensitivity and LOD. The proposed electrode was also performed the analysis of soil sample. The analytic method in this study could open up an avenue for the analysis and detection of metal ions, and provide a reference of electrochemical sensor based on metal films. [ABSTRACT FROM AUTHOR]