Voltammetric Determination of o-Phenylenediamine in Industrial Wastewater by An Electrode Modified with Nanocomposite Film of TiO_2/Hydroxyapatite/MWCNT
A nanocomposite film modified electrode was successfully prepared by dispersing titanium dioxide nanoparticles(TiO2),hydroxyapatite nanofibers(HAP) and multi-wall carbon nanotube(MWCNT) into chitosan solution.Based on this modified electrode,a mercury-free and highly sensitive method for the determination of o-phenylenediamine(o-PDA) was established.The prepared electrode was characterized by scanning electron microscope(SEM),cyclic voltammetry(CV) and alternating current impedance(EIS),and the electrochemical behaviors and kinetic properties of o-PDA on the modified electrode were investigated.The experimental results showed that a sensitive oxidation peak of o-PDA appeared at TiO2/HAP/MWCNT modified electrode(Epa=0.538 V),which illuminated the nanocomposite film had a good synergistic catalytic effect on the oxidation of o-PDA.Further experiments showed that the oxidation process was an irreversible process containing a two-electron and two-proton reaction.This electrode process was controlled by the diffusion step,and the standard rate constant was 1701/s.Trace level of o-PDA can be determined with this oxidation peak.The peak currents were linearly dependent on the o-PDA concentrations in the range of 5.0×10-5-1.0×10-3 mol/L with correlation coefficient of 0.9976 and detection limit of 1.0 ×10-5 mol/L.This nanocomposite modified electrode had favorable stability and had been applied to the quick determination of o-PDAin industrial wastewater,and the recovery was from 98.6% to 104.6%.