Synergistic advance Fenton oxidation and hydrodynamic cavitation treatment of persistent organic dyes in textile wastewater

This is an investigation into the treatment of simulated Orange II sodium salt (OR2) contaminant in wastewater using jet-loop hydrodynamic cavitation in hybrid combination with hydrogen peroxide (H2O2) and nano zero valent iron (nZVI). A 69.8 % degradation of OR2 (10 mg/L) was achieved per hour in the jet-loop hydrodynamic cavitation system by itself (inlet pressure = 400 kPa, pH = 2, volume = 10 L). The combination of H2O2 and iron (II) sulfate in the jet loop hydrodynamic cavitation was not very effective. This is due to the possible scavenging effect of the iron (II) sulfate and H2O2 on the hydroxyl radical. However, the combinational treatment using an optimum amount of H2O2 and nZVI in the jet loop hydrodynamic cavitation resulted in 99 % decolouration of the OR2 solution within an hour treatment. 74 % mineralisation was also achieved as a function of % TOC reduction (400 kPa, pH 2, 1 mg/L H2O2, 1 mg/L nZVI, 1 h). The enhancement of the degradation with hydrogen peroxide, iron sulfate or nano zero valent iron led to the generation of nitrate ions and sulfate ion as evident by the UV spectrometer, TOC, FT-IR and GC–MS analysis. This result shows the synergistic enhancement in the mineralization of azo dye containing industrial wastewater during the combinational treatment with advanced Fenton oxidation (H2O2 and nZVI) in the jet loop hydrodynamic cavitation system.