A novel approach towards multivariate optimization of graphite/PbO2 anode synthesis conditions: Insight into its enhanced oxidation ability and physicochemical characteristics

Abstract

Electrochemical oxidation has drawn great interest for its potential application in degrading persistent organic pollutants (POPs) through electrogenerated hydroxyl radical at the surface of anode. This study aims at the preparation of an inexpensive graphite/PbO2 anode. For enhancing oxidation performance, preparation process parameters viz. Pb(NO3)2 concentration, potential, and time of electrodeposition of a graphite/PbO2 anode, electrodeposited from acidic electrolyte bath, were optimized targeting a POP, 2,4-dinitrophenol removal. The changes in morphological properties of the developed oxide films were analyzed using scanning electron microscopy (SEM) which manifested significant impacts of selected anode preparation process parameters. Furthermore, PbO2 film prepared at optimum conditions were characterized using SEM, atomic force microscopy (AFM), energy dispersive X-ray spectroscope (ESD) elemental mapping, and X-ray diffraction (XRD) for thorough investigation of crystal structures, elemental distribution over surface, and phase of PbO2. Angular structures in both SEM and AFM analysis and appearance of β-PbO2 characteristic peaks in XRD analysis confirmed formation of electrocatalytically active phase of PbO2. For further enhancing the oxidation ability, influencing experimental parameters viz. current intensity, pH, and NaCl concentration were optimized. After 2 h of electrolysis at optimum experimental conditions, COD and total organic carbon removal efficiency of 93.6 ± 0.63% and 71.7 ± 1.52% were obtained respectively.