Catalytic Oxidation Of Aniline In The Persulfate And H₂O₂ Systems

Aniline is an important chemical which has been widely used in military and pesticides domains.With the development of the chemical engineering,the amount of discharged aniline is gradually increased,leading to serious environment issues.In the recent years,more attentions are paied on AOPs?advanced oxidation progresses?based on PS?persulfate?.However,since PS is stable and inactive to produce SO₄^·-,the transition metals are usually employed to activate PS to increase the oxidation.In this work,?-MnOOH is used to catalyze PS to remove aniline under various conditions and its removal effects and reaction mechanisms are studied.The results show that the remove rate of 1.1 mM aniline can reach 99%in 360 minutes under the condition of pH 10.0,1.0 g L^-1?-MnOOH and 7.4 mM PS,with the pseudo-first order rate constant of 2.38×10^-2 min^-1.After 10 times of repeat use,the catalysts can still remove 95%of the aniline in the?-MnOOH/PS system.TOC analysis indicates the aniline is turned to other organism rather than decomposition.The FTIR and the flight mass spectrometry suggest that aniline has been turned into polyaniline polymerized with six aniline molecules and with the max molecular weight of 563.The quenching experiments and the XPS analysis further reveal the reaction mechanism is non-oxidizing free radical mechanism.In aqueous solution,HCO₄^-which is the product of HCO₃^-and H₂O₂,can degrade organic pollutants.When the transition metal ion is added to the solution,the organic matters removal rate can be accelerated.In this chapter,we used Mn²⁺/HCO₃^-/H₂O₂ to degrade the aniline contaminanta.The results show that in Mn²⁺/HCO₃^-/H₂O₂ system,98%of the 1.1 mM aniline can be removed in 120 mins under the condition of pH 8.5,0.2 M HCO₃^-,20 mM H₂O₂ and 0.1mM Mn²⁺,with the pseudo-first order rate constant of 8.53×10^-2 min^-1.HPLC-MS analysis indicates that aniline was oxidized to azobenzene.The quenching experiment and the cyclic voltammetry analysis further reveal Mn=O is produced in the solution and cooperate with·OH,O₂^·-and ¹O₂ to oxidize aniline into azobenzene.This study provides new insights for removing aniline from wastewater and remediating aniline contaminated groundwater.