Studies On The Stripping Voltammetric Analysis Of Heavy Metal Ions In Water With Metal Oxides Modified Electrodes

Livelihood issues have always been of special concern to us.Comfortable clothes,safe food,economic living and convenient transportation are the basic guarantee of our life,of which food safety is particularly important.To be specific,grain and vegetable crops need water for irrigation,and we need water for drinking,therefore,the quality of water will directly affect the food safety,thus determining the quality of our lives.On the whole,water environment of China can be judged as"local is good,overall is developmental,prospect is promising".Nevertheless,the problem of water pollution still exists and must be paid more attention to.The problem of heavy metals pollution in water has always been a matter that scientific researchers pay close attention to,because of the high toxicity of heavy metal ions.Those heavy metal ions cannot biodegrade to non-toxic material,and will accumulate in organisms step by step with the natural food chain effect.Eventually,those heavy metal ions cause extremely serious threat to plants,animals,and humans in the biosphere.Up to now,there have been many incidents arose from heavy metals pollution at home and abroad,each of which has caused heavy casualties and significant loss of national property,which is distressing.Therefore,our primary task is to explore a simple,portable,fast and efficient analysis of heavy metal ions in water.Among many methods for the detection of heavy metal ions,electrochemical analysis is generally regarded as an effective method.This is mainly because electrochemical analysis has the advantages of low cost,simple operation,fast detection and high sensitivity.In recent years,metal oxide nanomaterials have attracted more and more attention in electrochemical detection of heavy metal ions because of their ability to effectively adsorb heavy metal ions.In addition,metal oxide nanomaterials also have high adsorption properties,low toxicity,excellent biocompatibility and high catalytic activity.In this paper,the application of metal oxide and metal oxide composites in electrochemical detection of heavy metal ions is discussed.1.Use NiCo₂O₄,a three-dimensional metal oxide cage derived from MOF,as electrode material to detect Hg²⁺In this work,ZIF-67 was used as the template and precursor to prepare NiCo₂O₄ by solvothermal and pyrolysis and the electrochemical behavior of NiCo₂O₄ for the detection of Hg²⁺was evaluated.The resulting NiCo₂O₄ nanocages maintain a dodecahedral shape similar to that of ZIF-67,with a rougher surface and a larger specific surface area,which can provide a large number of adsorption sites for Hg²⁺.The experimental results showed that NiCo₂O₄nanocages modified electrode had high sensitivity to the detection of Hg²⁺,wide linear range and low detection limit.In addition,the selectivity,stability,reproducibility and repeatability of the electrochemical sensing platform were studied.The results showed that the electrochemical sensing platform could be well applied to detect Hg²⁺in real water samples.2.An electrochemical sensor based on SnO₂@N-doped carbon nanotube composites was constructed for simultaneous determination of Cd²⁺and Pb²⁺In this work,SnO₂@N-doped carbon nanotube composites were synthesized in simple way by using PPy nanotubes as the template,and the composites were used as electrode modified material to detect Cd²⁺and Pb²⁺.With a large specific surface area,N-doped carbon nanotubes can provide more binding sites for SnO₂ fixation,thus effectively preventing the SnO₂ nanoparticles from aggregating.And the contained nitrogen element can be used for chelating with heavy metals.SnO₂ is an oxide that can adsorb heavy metal ions and its nanoparticles have unique electrical conductivity.Sensitive detection of Cd²⁺and Pb²⁺in water samples was realized by SnO₂@N-doped carbon nanotube composites through adsorption and chelation.The modified electrode showed good analytical performance for Cd²⁺and Pb²⁺detection:high sensitivity（14.98μA/μM and 14.91μA/μM respectively）;wide linear range（both 10 nM-2.5μM）;and low detection limit（7.2 nM and 5.6 nM respectively）.The modified electrode also showed good stability,reproducibility and anti-interference,and has a certain application prospect in practical application.