Study On Electrochemical Detection Of Heavy Metal Ions In Water Using Manganese-based Nanomaterial

In recent decades,the modernization process has made remarkable achievements.However,due to the lack of certain environmental awareness and corresponding environmental protection measures in the development process,environmental pollution has become increasingly prominent,especially the water pollution,which not only causes serious damage to the ecosystem,but also brings great hidden dangers to people’s health.Water is the source of life.Serious water pollution makes the water in nature full of a large number of harmful substances,especially various heavy metal ions,which eventually accumulate in the human body and lead to various diseases.Therefore,it is very important to detect trace heavy metal ions in natural water quickly and effectively.Electrochemical method has been widely concerned because it can detect heavy metal ions in water quickly,accurately and sensitively.In recent years,various kinds of nano sensing materials have been reported in endlessly,but most of them are about their high sensitive detection performance,few of them are about the electrochemical sensitive mechanism in detail,and exploring the micro mechanism is particularly important for the design of new high sensitive detection nano materials to detect heavy metal ions in water.Therefore,in this paper,manganese based nanomaterials are used as electrode modification materials to further study the mechanism between the sensitive interface modified by nanomaterials and the highly sensitive electrochemical behavior.The main work of this paper includes the following:(1)Manganous oxide with octahedral morphology was synthesized by hydrothermal method,and Def-Mn3O4 with surface defects was obtained by calcination.The Def-Mn3O4 was used to modify the glassy carbon electrode to detect heavy metal ions.In addition,it showed the best detection sensitivity for Pb(Ⅱ),and Def-Mn304/GCE showed excellent detection reproducibility and stability.The high sensitive detection performance was attributed to calcination treatment.The surface defects provide a large number of adsorption sites.In addition,the conductivity of the material is improved and the electron transfer is promoted.This part provides reference for the next part.(2)Firstly manganese oxide was synthesized by hydrothermal method,and then FeOx/Mn3O4 nanocomsite was obtained by in situ growing iron oxide nanoparticles on the surface of manganese oxide.Here,the sensitivity of FeOx/Mn3O4 modified electrode to Pb(Ⅱ)was 2497.54 μA μM-1 cm-2(111.89 μA μM-1),and the limit of detection(LOD)was 0.015 μ M.In order to explore the mechanism of highly sensitive detection,the corresponding adsorption experiments and electrochemical experiments have been done.According to the corresponding XPS and FT-IR results,the highly sensitive detection of Pb(Ⅱ)is not based on the enhanced adsorption capacity of the material,but on the high-energy interface structure generated in FeOx/Mn3O4,providing a large number of active sites,promoting the electron transfer in the detection process.In addition,the Mn(Ⅱ)/Mn(Ⅲ)and Fe(Ⅱ)/Fe(Ⅲ)cycles on the surface of FeOx/Mn3O4 can promote the oxidation-reduction process of Pb in the detection process,and ultimately improve the detection sensitivity greatly.