Research And Application Of Electrochemical Properties Of Several Kinds Of Dyes

Solution components that occured oxidation or reduction on the electrode can be reseached and tested by voltammetry with a certain concentration range,which was a very effective method to study the electrode process kinetics and chemical reaction mechanism of the experiments.At the same time,it was a very sensitive analytical technique,and had quickly analysis technology.In this thesis,the carbon paste electrode modified by some kinds of dyes were detected by voltammetry.Moreover,their electrocatalysis on energy source,some pharmic were studied and conclusions were drawn as follows.(1)The voltammetric behavior of fluorescein has been investigated at a carbon paste electrode.In the phosphate buffer solution with a p H value of 3,fluorescein produced an oxidation peak at 1.0 V,and the oxidation of fluorescein was an irreversible one-electron and one-proton process with diffused character.Based on the anodic voltammetric behavior of fluorescein,a square wave voltammetric method was proposed for the determination of fluorescein.The oxidation peak current of fluorescein was linearly with its concentration in the range from 8.0×10-8 to 3.0×10-6 mol/L,and the detection limit was 2.0×10-8 mol/L.Meanwhile the proposed method was employed to determine fluorescein in water tables.(2)The voltammetric behavior and electrochemical reaction mechanism of YBesmarck brown has been investigated at a carbon electrode using cyclic and square wave voltammetry.In the phosphate buffer solution with a p H value of 11,the YBesmarck brown produced two oxidation peaks at + 0.37 V and + 0.72 V.But the peak at + 0.37 V was a sensitive oxidation peak.The oxidation of YBesmarck brown was a diffused-controlled irreversible process.The peak current varied linearly with the concentration of YBesmarck brown in the range from4.0 × 10-9 mol/L to 4.0 × 10-8 mol/L,and in the range from 4.0 × 10-8 mol/L to 2.0 × 10-6mol/L,respectively.The detection limit was 2.6 × 10-10 mol/L.The relative standard deviation(R.S.D.)was 2.8% after six times measurement.The proposed method was employed in determining basic brown in water tables.(3)The voltammetric behavior of rhodizonic acid sodium salt on carbon paste electrode(CPE)was studied.In phosphate buffer(p H 7),rhodizonic acid sodium salt yields two oxidation peaks with the peak potention 0.64 V and 0.74 V on the carbon paste electrode,andone of the more sentive oxidation peak was discussed.The oxidation peak current of rhodizonic acid sodium salt was linearly with its concentration in the range from 1.0 × 10-7 to5.0 × 10-5 mol/L with the detection of 7.5 × 10-8 mol/L.The proposed method can be used to determine the content of rhodizonic acid sodium salt in water tables.(4)The electrode modified by Ni(?)-Rh-CPE has been fabricated by the elecyrochemical polymerization on carbon paste electrode(CPE)through cyclic voltammetry(CV).A couple of redox current peaks are appeared at 0.448 V and 0.361 V after scanning in0.1 mol·L-1 Na OH solution.The experimental results indicate that Ni(?)-Rh-CPE showed a strong electrocatalytic ability towards the oxidation of tannic acid in alkaline solutions.The oxidation peak current with concentration from 1.0 × 10-7 mol/L to 1.0 × 10-6mol/L low concentration and 1 × 10-6 mol/L to 1.2 × 10-5 mol/L showed a good linear relationship with a detection limit of 1.2 × 10-7 mol·L-1.Futhermore the preparation process of Ni(?)-Rh-CPE was simple,which had high sensitivity and good stability.It can be applied to the quantitative determination of tannic acid in practical samples.(5)The electrode modified by Ni(?)-Rh-CPE had been fabricated by elecyrochemical polymerixation Ni(?)-Rh at the surface of carbon paste electrode.It showed good electrocatalytic activity toward the oxidation of hydrazine at a reduced overpotential as well as an increased peak current compared with carbon paste electrode.The calibration curve for hydrazine determination was linear from 4.0 × 10-6 mol/L to 2.4 × 10-5 mol/L in sodium hydroxide solution by amperometry.The detection limit was 1.7 × 10-6 mol/L.The modified electrode was simple in preparation,and is of chatater of fast response,high sensitivity and good reproducibility for hydrazine determination.(6)Based on the results of study on the electrochemical behavior of James green B at the carbon paste electrode and its reaction mechanism,an electrochemical method for determination of James green B was proposed.Under the optimum experimental condition,in a PBS buffer medium with a p H value of 3,linear relationship between values of reductive peak current and concentration of James green B in the range of 5.0 × 10-7~1.0 × 10-5 mol/L was obtained,with a detection limit of 3.1 × 10-7 mol/L.It was shown that the reaction of James green B was an irreversible process,controlled mainly by diffusion.