Thermoelectrochemistry of Paracetamol – Studied at Directly Heated Micro‐wire and Rotating Disk Electrodes

Abstract

We compare the thermoelectrochemical behavior of paracetamol (acetaminophen) at both directly heated gold micro‐wire electrodes (1–115 °C) and rotating disk electrodes (100–8000 rpm). Koutecky‐Levich plots were recorded at various temperatures between 23 and 60 °C. The calculated Ik values (representing reaction rate at infinite mass transport) were plotted as Arrhenius‐type graphs, and the obtained energy values of 20–30 kJ/mol depended on the potential chosen for the corresponding Koutecky‐Levich plots. This led to the conclusion that these energy values are not activation energies, but rather an energy difference due to overvoltage as described in the Butler‐Volmer equation. Accordingly, Koutecky‐Levich plots recorded at various temperatures allowed to determine the Butler‐Volmer kinetics including transfer coefficients even at low concentrations. Arrhenius plots obtained at heated micro‐wire electrodes revealed two linear regions corresponding to diffusion control with 16 kJ/mol at high temperature and 20–30 kJ/mol at very low temperature. The latter activation energy values were found in a very narrow temperature range and probably belong to a transition region towards a kinetic activation energy.

Scanning Electrochemical Microscopy of Electrically Heated Wire Substrates

“…The effects of convection and temperature on the hybridization of DNA and RNA have been investigated as well [17]. Recently, the oxidation kinetics of acetaminophen (paracetamol) was studied, comparing the results obtained using a heated microwire in a cooled electrolyte versus using a rotating disk electrode in heated solution [18]. Further improvements to the hot-wire setup have been achieved by modifying the surface of gold microwires depositing carbon nanotubes, which resulted in increased reversibility of voltammetric experiments [19].…”