Mineralization of aniline in aqueous solution by electro-activated persulfate oxidation enhanced with ultrasound

Abstract

Mineralization of aniline in wastewater was performed using electro-activated persulfate oxidation assisted with ultrasonic irradiation. Experiments were carried out under batch-wise mode to investigate the influence of various operation variables on the sonoelectrolytic behavior, such as ultrasonic power intensity, electrode potential employed, sonoelectrolytic temperature, persulfate anion concentration, acidity of wastewater and nitrogen gas dosage. It is notable that the aniline contaminants could be almost entirely eliminated by means of sonoelectro-activated persulfate oxidation, in which sulfate radicals served as principal oxidizing agents, of which amounts were significantly elevated with assistance of acoustic streams. Ethanol and tert-butyl alcohol were used as scavengers to clarify the reactive radicals. Based on the results given by gas chromatograph–mass spectrometer (GC–MS), it was postulated that aniline preliminarily underwent oxidation to form iminobenzene radicals, followed to convert into azobenzene, nitrobenzene and nitrosobenzene respectively. Hydroquinone and p-benzoquinone were also detected as reaction intermediates. Generally, the sonoelectro-activated persulfate process is a potential method for treatment of aniline in wastewater.