The Construction Of Heavy Metal Ion Raman Probe And Its Application In Environmental Water Analysis

In recent years,heavy metal ion pollution has attracted much attentions,even low exposure of heavy metal ions in the environment can cause serious harm to human health.Therefore,it has always been an important research topic to develop on-field,rapid and highly sensitive detection techniques for heavy metal ions in complex systems,based on the innovative breakthrough of environmental chemistry science theory and methodology.Highly sensitive Surface enhanced Raman scattering based on surface enhancement effect not only can provide the fingerprint spectral information of the molecule,but also has the advantages of fast,free from water and narrow spectral band.In this paper,based on noble metal nanomaterials,three kinds physical and chemical modification on the surface of the nanomaterials,realizing high sensitivity,high selectivity and rapid detection of heavy metal ions in environmental water.Moreover,the measurement mechanisms of these Raman probes were explored by using many characterizations and theoretical calculations.This paper consists of five parts,as follows:?1?This part mainly summarizes the definition,classification,pollution status,sources,detection methods and application progress of heavy metal ions at home and abroad.The definition and principle of Raman spectroscopy and the principle along with substrates of surface enhanced Raman spectroscopy are described.The research status and development of surface enhanced Raman spectroscopy in the field of environmental water analysis,especially in the detection of heavy metal ions in environmental water are emphatic introduced.At last,the main content and the innovation points of the research are summarized.?2?IP₆modified Ag NPs as the SERS substrate,R6G as Raman beacon molecule,a new type of Fe³⁺Raman probe was prepared.The detection mechanism of the probe is as follows:the strong interaction between phytic acid molecules and Fe³⁺can reduce the distance between silver nanoparticles,and increase the“hot spot”,elevating the electromagnetic field intensity on the surface of nanoparticles,and further improve the Raman signal of the probe,thus indirectly realizing the qualitative and can form Fe-O bond,making the probe with high selectivity.The Fe³⁺Raman probe has good stability and the performance did not decrease within 3 months due to the by the standard recovery method,and the recoveries were 86.4%and 94.8%.?3?Based on glutathione?GSH?modified gold nanoparticles?Au NPs?,Cd²⁺ Raman probe named R6G/GSH/AuNPs was constructed.The detection mechanism is as follows:under the condition of certain p H,Cd?SG?₄ was easy formed by interacting environment,AuNPs were easy to aggregate after losing the protection of GSH,leading to hot spots and electromagnetic field intensity was increased,and results in the Raman signal of R6G was increased.Therefore,the indirect detection of Cd²⁺can be achieved.This probe have high sensitivity due to the strong interaction between range was 0.5?20 mg·L^-1?R²=0.9930?.The linear GS-M-SG formed by other metal ions with GSH,inducing the probe has highly selective for detection of Cd²⁺.The detection of Cd²⁺with highly reproducible,resulting the RSD is 6.3%between the 30repeated experiments.The detection of Cd²⁺in river water was carried out,and the recoveries were in the range of 85.0%and 107.1%.The rapid and accurate detection of Cd²⁺in river water was completed by using portable Raman.?4?Hg²⁺Raman probe chip?4-Mpy/AuNPs/ITO?was constructed by modifying4-Mercaptopyridines?4-Mpy?on AuNPs/ITO surface.The detection mechanism is Hg?4-Mpy?₂.Hg?4-Mpy?₂changes the electron distribution in pyridine and results in molecular reorientation of 4-Mpy to adopt the perpendicular adsorption fashion at the surface of AuNPs,which induces the enhancement of Raman signal of 4-Mpy and realizes indirect detection of Hg²⁺.The high stability of the chips was guaranteed,due to AuNPs were modified on surface of ITO,and therefore,the performance was almost constant after 40 days at room temperature.The strong specific interaction between Hg²⁺and 4-Mpy molecules enables the chip to have high sensitivity and detection of Hg²⁺is not interfered by other component in water.The quantitative method.The recoveries were in the range of 92.9%and 104%,and the detection of Hg²⁺in the river water was completed by using the portable Raman.Finally,the chip could be recycled several times by using EDTA as cleaner based on the strong interaction between EDTA and Hg²⁺.?5?The main contents of this paper are summarized.The advantages and disadvantages of several Raman probes of heavy metal ion are sorted out.Moreover,the scientific problems existed in the studies are summarized and rethink.Own views and outlook about the development direction of detection of heavy metal ions in the future is proposed,including construction of other heavy metal Raman probe,design of double or multiple heavy metal Raman probe for simultaneous detection of several metal ions,and realizing on-field,fast,and highly sensitive detection of heavy metal ions by using portable Raman system.