Electrocatalytic degradation of 2,4-dichlorophenol by granular graphite electrodes

Abstract

A reactor using granular graphite as an electrode material was used to electrochemically degrade 2,4-dichlorophenol. The degradation efficiency reached more than 95% after 24 h at all experimental conditions. Adsorption of 2,4-dichlorophenol by the granular graphite can be described with the Freundlich isotherm. The degradation kinetics are pseudo-first-order. The degradation rate increased linearly with both applied current density and flow rate. The pseudo-first-order surface reaction rate constants, ka, at a flow rate of 5 mL/min increased from 0.0015 L/h m 2 at an applied current density of 0.41 mA/m 2 to 0.0028 L/h m 2 at an applied current density of 2.21 mA/m 2. The ka values at a current density of 1.14 mA/m 2 increased from 0.0021 L/h m 2 at a flow rate of 5 mL/min to 0.0068 L/h m 2 at a flow rate of 50 mL/min. Charge efficiency, ranging from less than 1 to 60 μg/C, increased with the concentration of 2,4-dichlorophenol and decreased with the applied current density. Hence, using a low applied current density could be more economical than a high applied current density when applying this technique.