Study On Surface Enhanced Raman Detection And Removal Technology Of Mercury Ions In Environmental Water

The exposure of mercury ions(Hg²⁺)poses a serious threat to human health,therefore,high requirements are promoted for the detection of trace Hg²⁺.In this study,an Au-DNA film-forming substrate was synthesized based on the T-Hg²⁺-T protocol,and surface enhanced Raman scattering?SERS?technique was used to achieve the purpose of detecting the trace amount of Hg²⁺in water.The results showed that when the concentration of Au was 3×10^-3 mol·L^-1 and the film-forming agent Nafion was0.0004%,Au-DNA had the highest intensity Raman signal,the lower limit of SERS detection was 1×10^-12 mol·L^-1,which was more sensitive than the previous report and could meet the national drinking water monitoring standard.The substrate was desirable for the detection of Hg²⁺and the influence of other metal ions could be negligible.The as-prepared substrate showed good stability and sensitivity even immersed in water for1 h.With the high sensitivity,selectivity,stability,and recyclability,this Au-DNA SERS platform provides a promising tool for field monitoring of Hg²⁺ions.Among all kinds of adsorbent materials,large specific surface area is conducive to improving the adsorption removal capacity of the material,and graphene oxide?GO?has become one of the research hotspots.When GO is magnetic,it not only improves the adsorption of GO,but also facilitates the recycling of materials.In this paper,Fe₃O₄@GO magnetic composite material was synthesized for Hg adsorption and characterized by SEM,TEM,XRD and BET.The synthesized Fe₃O₄@GO has a lamellar structure,and the attached particles are aggregates of iron oxides with a diameter of about 20 nm;the specific surface area of Fe₃O₄@GO is 144.32 m²·g^-1,and the pore size is concentratedly distributed between0?5 nm,the maximum pore size is 5.51 nm,and the maximum pore volume is 0.15cm3·g-¹.The results of adsorption kinetics showed that the adsorption of Hg²⁺by Fe₃O₄@GO was a quasi-first-order kinetic model,and adsorption equilibrium could be completed within 60 minutes.The theoretical equilibrium adsorption capacity of Fe₃O₄@GO for Hg²⁺was 1.13 mg·g^-1,and the coefficient of determination R² was0.9920 when the adsorption equilibrium was fitted by a quasi-first-order kinetic model.The adsorption isotherm data indicated that the Langmuir adsorption isotherm model could relatively well described the adsorption isotherm of Fe₃O₄@GO on Hg²⁺,the maximum adsorption capacity of Hg²⁺by Fe₃O₄@GO was 24.15 mg·g^-1,and the coefficient of determination R² was 0.9875.The retrievable results of Fe₃O₄@GO showed that the composite had good magnetic properties and could be recycled in practical applications.