Enhanced electrocatalytic degradation of 2,4-Dinitrophenol (2,4-DNP) in three-dimensional sono-electrochemical (3D/SEC) process equipped with Fe/SBA-15 nanocomposite particle electrodes: Degradation pathway and application for real wastewater

Abstract

2,4-dinitrophenol (2,4-DNP), which is a nitrophenol compound, is a carcinogenic and non-biodegradable pollutant, which is found at high concentrations in industrial wastewater. Degradation of 2,4-DNP using a three-dimensional sono-electrochemical (3D/SEC) process equipped with G/β-PbO2 anode and Fe/SBA-15 nanocomposite particle electrodes was evaluated in the present study. Investigating the effect of parameters including pH, electrolysis time, current density, and 2,4-DNP concentration on the performance of the 3D/SEC-Fe-SBA-15 process in 2,4-DNP degradation was considered, and optimization of these parameters was done using the Taguchi design technique. Field emission scanning electron microscopy (FESEM), X-ray diffraction analysis (XRD), energy-dispersive X-ray spectroscopy mapping (EDX-mapping), transmission electron microscopy (TEM), and Fourier Transform Infrared Spectroscopy (FTIR)) were the analyses techniques used to support the successful synthesis of Fe-SBA-15 and G/β-PbO2 anode. The optimum values obtained for pH, electrolysis time, current density, and 2,4-DNP concentration were 5.0, 60.0 min, 5.0 mA/cm2, and 50.0 mg/L, respectively. The experimental removal efficiencies of 2,4-DNP, COD, and TOC using 3D/SEC-Fe-SBA-15 process, under the mentioned conditions, were obtained to be 96.3%, 88.28%, and 83.82%, respectively. In addition, the AOS value was developed from −0.29 to + 0.88; this indicates the high mineralization of 2,4-DNP and improvement of the solution biodegradability. Detecting the intermediates produced during the degradation process was done by LC-MS analysis, and pathways for its degradation was proposed. Results were indicative of the high potential of the 3D/SEC-Fe-SBA-15 process for treating wastewater containing phenolic compounds, e.g., 2,4-DNP, and can provide acceptable efficiency.