An Ultrasonically Facilitated Boron-Doped Diamond Voltammetric Sensor for Analysis of the Priority Pollutant 4-Chlorophenol

Abstract

Electroanalysis of the ‘priority pollutant’, 4-chlorophenol, is largely unreported in the scientific literature, due mainly to the electrode passivation observed from oxidative by-products. Work is presented which details the combination of high-intensity ultrasound with a mechanically and chemically robust boron-doped diamond electrode allowing successful development of an aqueous 4-chlorophenol voltammetric sensor. The surface regeneration abilities of power ultrasound, through cavitational erosion of electrodeposited 4-chlorophenol by-products, facilitates a reproducible, insonated limiting-current oxidative signal in dilute acid conditions, with increased mass-transport offering enhanced sensitivity. A lower limit of detection of 1 μM and a linear range of 1–300 μM are reported; the technique being analytically useful over a concentration range where aquatic 4-chlorophenol pollution is known to occur. The use of power ultrasound during the electrooxidation of 4-chlorophenol at boron-doped diamond has also been shown to be advantageous in the electrochemical degradation of the substance, potentially offering further waste-water clean-up applications of this dual technology.