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In this study, core-shell Fe0@polyaniline (PANI) nanoparticles were synthesized to remove Rhodamine B (RhB) in aqueous solution. The Fe0/PANI composites were characterized by X-ray diffraction, Fourier transform infrared spectra, and transmission electron microscopy. The performances of Fe0/PANI on the activation of molecular oxygen for the removal of RhB were investigated, and the effects of operating parameters, such as Fe0/PANI dosage, RhB initial concentration, and pH value on RhB removal were also discussed. The results indicated that the Fe0@PANI/O2 process exhibited significantly higher reactivity than did the Fe0/O2 process for the degradation of RhB. The oxidative degradation of RhB was further promoted by the presence of anthraquinone-2-sulfonic acid sodium salt working as an electron shuttle. In addition, the reaction mechanism was discussed by measuring the concentrations of Fe(II), and total Fe formed in the system and examining scavenging effect by tert-butyl alcohol and copper chlor...

In this study, the PANI-supported nanoscale zero-valent iron (PANI/nZVI) composites have been successfully synthesized to remove Rhodamine B (RhB) from aqueous solutions using a heterogeneous Fenton-like system. The synthetic PANI/nZVI composites were characterized using X-ray diffraction (XRD), Transmission electron microscope (TEM) and Fourier transform infrared (FTIR). The results showed that they were lamellar structures and nZVI nanoparticles were introduced into their structures. The performances of PANI/nZVI composites on the activation of molecular oxygen for removal of RhB were investigated and the effects of operating parameters, such as PANI/nZVI dosage, PANI and nZVI mass ratio, RhB initial concentration, and pH value on RhB removal were also discussed. The results indicate that PANI/nZVI was proved to be the most efficient in that more than 83.31% of RhB was removed, whereas only 11.15% when using nZVI after reacting for 120 min with an initial RhB concentration of 0.02 mmol L−1 (pH = 6.50). Furthermore, the reaction mechanism was discussed by measuring the concentrations of Fe(II), total Fe and H2O2 formed in the system and examining scavenging effects using copper chloride and methanol. Finally, the stability of PANI/nZVI nanocatalyst was studied. © 2015 American Institute of Chemical Engineers Environ Prog, 35: 48–55, 2016

Degradation of azo dye Acid Orange 7 (AO7) by zero-valent aluminum (ZVAl) in combination with ultrasonic irradiation was investigated. The preliminary studies of optimal degradation methodology were conducted with sole ultrasonic, sole ZVAl/air system, ultrasonication + ZVAl/air system (US-ZVAl). In ZVAl/air system, the degradation of AO7 could almost not be observed within 30 min. The degradation of AO7 by ZVAl/air system was obviously enhanced under ultrasound irradiation, and the enhancement is mainly attributed to that the production of hydroxyl radicals in ultrasound-ZVAl process was much higher than that in sole ultrasonic or in sole ZVAl/air system. The variables considered for the effect of degradation were the power of ultrasound, the initial concentration of AO7, as well as the initial pH value and the dosage of zero-valent aluminum. The results showed that the decolorization rate increased with the increase of power density and the dosage of ZVAl, but decreased with the increase of initial pH value and initial concentration of AO7. More than 96% of AO7 removal was achieved within 30 min under optimum operational conditions (AO7: 20 mg/L, ZVAl: 2 g/L, pH: 2.5, ultrasound: 20 kHz, 300 W). This study demonstrates that ultrasound-ZVAl process can effectively decolorize the azo dye AO7 in wastewater.

Ammonium perfluorooctanoate (APFO) is an emerging environmental pollutant attracting significant attention due to its global distribution, high persistence, and bioaccumulation properties. The decomposition of APFO in aqueous solution with a combination of persulfate oxidant and ultrasonic irradiation was investigated. The effects of operating parameters, such as ultrasonic power, persulfate concentration, APFO concentration, and initial media pH on APFO degradation were discussed. In the absence of persulfate, 35.5% of initial APFO in 46.4 μmol/L solution under ultrasound irradiation, was decomposed rapidly after 120 min with the defluorination ratio reaching 6.73%. In contrast, when 10 mmol/L persulfate was used, 51.2% of initial APFO (46.4 μmol/L) was decomposed and the defluorination ratio reached 11.15% within 120 min reaction time. Enhancement of the decomposition of APFO can be explained by acceleration of substrate decarboxylation, induced by sulfate radical anions formed from the persulfate during ultrasonic irradiation. The SO4(-•)/APFO reactions at the bubble-water interface appear to be the primary pathway for the sonochemical degradation of the perfluorinated surfactants.