Electrocatalytic oxidation and differential pulse voltammetric determination of hydroxylamine using a 4-hydroxy-2-(triphenylphosphonio)phenolatecarbon nanotubes modified electrode

Abstract

The electrocatalytic oxidation of hydroxylamine was studied at the surface of a carbon paste electrode (CPE) spiked with multi-wall carbon nanotubes (MWCNT) and 4-hydroxy-2-(triphenylphosphonio)phenolate (HTP). The modified electrode (HTP-MWCNT-CPE) exhibits an excellent electrochemical catalytic activity toward hydroxylamine oxidation. The results show that there is a dramatic enhancement on the anodic peak current of hydroxylamine oxidation at the HTP-MWCNT-CPE in comparison the value obtained at HTP-CPE and MWCNT-CPE. The kinetic parameters of the electron transfer coefficient, α, the heterogeneous electron transfer rate constant, k', and the exchange current density, j0, for oxidation of hydroxylamine at the HTP-MWCNT-CPE were determined using cyclic voltammetry. Differential pulse voltammetry exhibits three dynamic linear ranges of 2.0-10.0 μM, 10.0-1000.0 μM and 1000.0-8000.0 μM, and a lower detection limit of 0.16 μM for hydroxylamine. Finally, the modified electrode activity was studied for hydroxylamine determination in two water samples and satisfactory results were obtained.