Detection Of Heavy Metal In Water Based On Nanocomposite Material

Heavy mental ions are highly toxic species which can cause long-term damage tobiological events at the cellular level, cause significant oxidative damage, and arecarcinogens.With the development of nanotechnology,nanocomposite can demonstratedifferent mechanical, optical, electrical, electrochemical and structual properties thanthose of each individual nanomaterial. The promise of nanocomposites lies in theirmultifunctionality, the possibility of realizing unique combinations of propertiesunachievable with nanomaterials. In this study, we construct three works based onnanocomposites for detection of heavy mental. Multiwalled carbon nanotube and goldnanoparticle show excellent signal enhancement effect, which hold great potential forthe further improvement modified with biomolecule. Integrating the magnetic metalnanoparticle to hybrid materials can produce a new system to detect heavy metal.1. Detection of heavy metal lead and cadmium using bi/humicacid/chitosan/multiwalled carbon nanotube composite modified electrodeA sensitive platform for the simultaneous electrochemical determination of Cd(II)and Pb(II) in aqueous solution has been developed based on the humicacid-chitosan-multiwalled carbon nanotube composite modified bismuth film glassycarbon electrode (GCE) using differential pulse anodic stripping voltammetry(DPSAV). The humic acid as well as the enlarged, activated surface and goodelectrical conductivity of multiwalled carbon nanotube contributed to the depositionof Cd(II) and Pb(II) on the electrode surface. Under the optimum conditions, a linearrelationship existed between the currents and the log concentration of Cd(II) in therange between5.0×10-8mol/L to10-5mol/L and10-8mol/L to10-5mol/L with thedetection limits of2.0×10-8mol/Lfor Cd(II) and5.0×10-9mol/L for Pb(II), respectively,based on a signal-to-noise ratio equal to3(S/N=3).In addition, the developedelectrode displayed a good repeatability and reproducibility. These studies imply thatthe humic acid-chitosan-multiwalled carbon nanotube composite might be analternative candidate for practical applications in electrochemical detection of metalions.2. Detection for copper ions with modified histidine/gold nanoparticles/carbonnanotubes modified electrodes This paper based on a histidine self-assembled monolayers functionalized goldnanoparticles/multiwalled carbon nanotube/SH/gold nanoparticles glassy carbonelectrode applied to improve the performance of detecting trace Cu(II) in differentialpulse anodic stripping voltammetry (DPASV). The AuNPs/MWCNTs nanohybrid hasporous nanostructure with large active surface area, and the histidine adapters onAuNPs/MWCNTs surface can greatly enhance the sensitivity and selectivity indetecting Cu(II). Under the optimum conditions, a linear relationship existed betweenthe currents and the log concentration of Cu(II) in the range between10-11mol/L-10-7mol/L with the detection limits of10-12mol/L, based on asignal-to-noise ratio equal to3(S/N=3). The interference experiments show that somemetal cations had little influence on the DPSAV signals of Cu(II). In addition, thedeveloped electrode displayed a good repeatability and reproducibility.The highsensitivity and excellent selectivity in contrast to the values reported previously in thearea of electrochemical Cu(II) detection, demonstrated the analytical performance ofthe as-prepared sensor toward Cu(II) was superior to the existing electrodes. Theas-prepared sensor was further applied to determine the Cu(II) in the realenvironmental water sample, and the results agreed satisfactorily with the certifiedvalues.3. Detection of mercury with magnetic iron oxide/gold nanoparticles compositeThis paper based on nanocomposite applied to improve the performance ofdetecting trace Hg(II) in fluorescence analysis.The nanocomposite,which wascomposed of magnetic iron oxide and gold nanoparticles, has excellent propertieswith large active surface area and the magnetism can greatly enhance the sensitivityand selectivity in detecting Hg(II).The A and T were unwinded due to Hg(II) formstrong and stable T-Hg-T complex,which recovered the fluorescent intensity of aDNA was rich in nucleotides T.The method showed the advantage of beingsimple,highly sensitive and selective,and rapid.Under the optimum conditions, alinear relationship existed between the currents and the concentrations of Hg(II) in therange between10-13mol/L-10-6mol/L with the detection limits of10-12mol/L, based ona signal-to-noise ratio equal to3(S/N=3). The interference experiments show thatsome metal cations had negative influence on the fluorescent intensity signals ofHg(II). These studies imply that the method might be an alternative candidate forpractical applications in detection of metal ions.