Study On The Preparation Of Nano-SiO₂ Modified Carbon Paste Electrode And Its Applications In Pesticide

With the rapid development of industrial technology, the environment pollution is becoming more and more serious, the pollution of pesticide has become the great problem in the world. Meanwhile administrating of environmental pollution is becoming increasingly important. A fast, convenient and accurate detection of pollutants is the precondition of administrating. Electrochemical method is a green technology that has been wide used to analysis and detect pesticide.In this thesis, The working electrode was nano-silica modified carbon paste electrode (nano-SiO2/CPE). A platinum electrode and a saturated calomel electrode (SCE) were used as the the auxiliary and the reference electrodes respectively. Some pesticides' electrochemical behavior has been studied with great details. The main researches were summarized as follows:(1) In the pH 3.00 phosphate buffer solution, the amitrole electrochemical behavior has been studied with great details at the nano-SiO2/CPE. The results show that:the amitrole can generate a sensitive oxidation peak at about+0.986V(vs SCE) on the nano-SiO2/CPE. The oxidation peak current was linear to amitrole concentration over the range from 5.00×10-6 to 1.00×10-3mol/L, the linear regression equation was ip(μA)=1.2394+1.95×104c(mol/L), regression coefficient was 0.9989, the detection limit was 2.0×10-7mol/L. The oxidation of amitrole was attributed to diffusion-controlled process at the nano-SiO2/CPE. The transmitted electron number 1 was calculated by LAVIRON formula. By the linear relationship of peak potential and pH, it can be inferred that the transmitted number of electron and proton were equal. So the electron reaction contains one electron and one proton process.(2) In the pH 11.20 B-R buffer solution, the fipronil electrochemical behavior has been studied with great details at the nano-SiO2/CPE. The results show that:the fipronil can generate a sensitive oxidation peak at about+0.742V(vs SCE) on the nano-SiO2/CPE. The oxidation peak current was linear to fipronil concentration over the range from 1.00×10-8to 2.00X10-4 mol/L, the linear regression equation was ip(μA)=0.5409+9.9725×104c(mol/L), regression coefficient was 0.9968, the detection limit was 1.3×10-9mol/L. The oxidation of fipronil was attributed to adsorption-controlled process at nano-SiO2/CPE. The transmitted electron number 2 was calculated by LAVIRON formula. By the linear relationship of peak potential and pH, it can be inferred that the transmitted number of electron and proton were equal. So the electron reaction contains two electrons and two protons process.(3) In the pH 3.00 phosphate buffer solution, the Scala electrochemical behavior has been studied with great details at the nano-SiO2/CPE. The results show that:the Scala can generate a sensitive oxidation peak at about+1.032V(vs SCE) on the nano-SiO2/CPE. The oxidation peak current was linear to Scala concentration over the range from 7.00×10-7 to 1.00×10-4 mol/L, the linear regression equation was ip(μA)=0.5723+1.4219×105c(mol/L), regression coefficient was 0.9959, the detection limit was 1.O×10-8mol/L. The oxidation of Scala was attributed to diffusion-controlled process at the nano-SiO2/CPE. The transmitted electron number 1 was calculated by LAVIRON formula. By the linear relationship of peak potential and pH, it can be inferred that the transmitted number of electron and proton were equal. So the electron reaction contains one electron and one proton process.