The superior decomposition of 2,4-Dinitrophenol under ultrasound-assisted Fe3O4@TiO2 magnetic nanocomposite: Process modeling and optimization, Effect of various oxidants and Degradation pathway studies

In the present study, the ultrasound-assisted Fe3O4@TiO2 magnetic nanocomposite was employed to catalytic oxidation of 2,4-Dinitrophenol. The catalyst features were characterised by SEM, TEM, XRD, BET, FTIR, VSM, DLS and TGA techniques. The effect of operational parameters i.e. pH, catalyst amount, 2,4-Dinitrophenol concentration and ultrasound power on DNP removal was examined and optimised in terms of sono-catalytic degradation system using RSM-based CCD approach. Over 91.45% of DNP were removed by Fe3O4@TiO2 /US system (FTU) under optimum conditions within 30 min and the mineralisation degree was found to be 73% and 64.2% based on COD and TOC, respectively. Quenching experiments confirmed that O2•- is dominant radical species in degradation process. FTU system was more successful in activation of S2O82- than IO4− and H2O2. Based on GC-MS analyses, the possible decomposition pathway was proposed. AOS and COS analyses indicated that FTU system can improve the bioavailability of DNP. The effect of CO32− on DNP degradation was more complicated than other anions. Fe3O4@TiO2 could keep its performance to at least the 5th cycle while Fe and Ti leaching was negligible. The performance of FTU system for DNP treatment under real conditions was tested and promising results were achieved.