Adsorption and reduction of m-nitrophenol at the dropping mercury electrode

✍ Scribed by D. Britz; H.H. Bauer

• Publisher: Elsevier Science
• Year: 1968
• Tongue: English
• Weight: 862 KB
• Volume: 13
• Category: Article
• ISSN: 0013-4686
• DOI: 10.1016/0013-4686(68)87007-0

✦ Synopsis

m-Nitrophenol is adsorbed at the dme, and lowers the double-layer capacitance, at potentials more positive than its reduction potential. At that potential, a differential-capacitance peak appears that is partly faradaic in origin and partly due to the "desorption" (through reduction) of the m-nitrophenol.

The faradaic admittance and its phase angle are anomalous, and indicate a disproportionation reaction following the tirst step in the reduction.

In the presence of surfactants, however, the anomalies disappear; moreover, at low concentrations of surfactant, the magnitude of the admittance is enhanced. The effect of the surfactants is two-fold: the disproportionation is hindered, and also the depolarizer is displaced from the surface.

Addition of the first electron is followed by a 2-electron reduction-step, which occurs at the reduction potential in the absence of surfactant and is shifted in the presence of surfactants to the desorption potential of the latter. The rate constants for these electron-transfer steps have been estimated.