The Influences Of Cathodic Polariziton On BDD Electrodes And The Application On Electroanalysis Of Lead Ions

Boron-doped diamond electrode possesses a series of technologically important characteristics: extremely wide potential window, very low background current, excellent chemical and electrochemical stability and remarkable corrosion stability, which made it has a broad application prospect in electrosynthesis, electroanalysis, electrochemically sensor and so on. In order to explore the application of BDD electrodes in water treatment, we have studied the influence of electrochemical polarization on the surface properties of BDD, and applied it to the analysis of lead ions in aqueous solution.In order to make use of boron-doped diamond (BDD) electrodes better in analyzing heavy metal ions in aqueous solution, we performed cathodic polarization on three boron doping level BDD electrodes (700,2500,8000ppm) in a constant potential (-3V vs SCE) and different lengths of polarization time (5-50min) in0.5mol/L H2SO4solution. Electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) were employed to investigate the effects of cathodic polarization, which were carried out in an electrolyte of0.2mol/L KCl blended in1.0mmol/L Fe(CN)63-/4-redox couple. Linear sweeping anodic stripping voltammetry (LSSV) was served for the investigation on the determination limit and sensitivity of lead ions analysis in O.lmol/L HCl. The results showed that the redox peak difference (Δ Ep) of CV curve, the charge transfer resistance(Rct) of BDD and the determination limit of Pb2+analysis decrease rapidly and then reach a stationary value with cathodic polarization time extending, respectively, while the determination sensitivity of lead analysis showed a reverse regularity. A BDD with higher boron doping level, e.g.8000ppm is a better candidate for Pb2+analysis. It could reach the determination limit of0.96μg/L and the determination sensitivity of185μA/ppm with LSSV after30min cathodic polarization.In order to make use of boron doped diamond (BDD) electrodes well in analyzing heavy ions in industrial waste water, the influences of supporting electrolytes, which were nitric acid, sulfuric acid, perchloric acid and hydrochloric acid and blended in different salts on lead ions analysis in aqueous solution were investigated. The work electrode was8000 ppm BDD electrodes for30minutes electrochemical polarization. Different supporting electrolytes of acid and blended salts selected will lead to different determination sensitivities in analyzing lead ions in aqueous solution. The acid concentration or the pH of the aqueous solution system made up of electrolyte and samples will also influence the determination sensitivity of lead ions. By our investigation, we found that the best supporting electrolyte system to analyze lead ions is0.01mol/L H2SO4and NaCl blended solution system, the best pH value of the solution was2.