Using electrochemistry-total internal reflection imaging ellipsometry to monitor biochemical oxygen demand with polyaniline modified electrode

Abstract

Biochemical oxygen demand (BOD) is an important indicator for characterizing organic pollution in water. So various BOD sensors have been developed for BOD detection. BOD sensors based on a Clark electrode have the problem of signal drift. To overcome this problem, a combined electrochemical and total internal reflection imaging ellipsometry sensor has been proposed. To improve the sensitivity, polyaniline (PAn) and PAn incorporated with Fe(III) meso-tetra (4-sulfonatophenyl) porphyrin (FeTSPP) have been introduced on the working electrode. The results show that the combination system is effective for BOD detection with PAn. By incorporating FeTSPP, the optical and electrochemical responses of a PAn modified gold chip to BOD are improved significantly. Finally, the relationship between the optical and electrochemical signals is investigated by establishing a glass/Au/PAn-based film/liquid model. The analysis reveals that both signals represent the ratio change of the oxidized state of PAn in a similar way.