Degradation Of Aniline In Waste Water With Sulfate Radical Advanced Oxidation Technology Based On Activated Persulfate

As a chemical raw material，aniline was widely used in defense, plastics, paints, printing anddyeing, pesticide and pharmaceutical industries. While aniline is a “three-induced（carcinogenic, teratogenic, mutagenic）”material, it is harm to ecological environment andhuman health. Advanced oxidation technology based on activated persulfate was widespreadconcerned as the advantages of degradation thoroughly and simple equipment. It has becomea hot issue of reasearch.In this study, the aniline degradation by advanced oxidation technology has beeninvestigated. The influences of environmental factors included different temperatures, pHconditions，persulfate concentrations and inorganic anions on the aniline degradation wereexplored. The mechanism of aniline degradation in persulfate system was identifid. The maincontents and conclusions are as follows: Aniline degradation followed pseudo first-orderreaction model. Within the experimental temperature range of10-50°C, the higher thetemperature, the faster the aniline degradation rate. Aniline degradation rate was increasedwith increasing persulfate concentration. The influence of pH on aniline degradation iscomplex. A low aniline degradation rate was obtained at strong acid system （pH3）, while ahigh degradation rate was achieved at pH11. Maximum aniline degradation occurred at pH7when the solution was in a weak level of acid and alkalinity （pH5,7and9）. The commoninorganic anions in waste water include HCO₃^-, CO₃^2-, Cl^-, NO₃^-and SO₄^2-were all shown tohave inhibition on aniline degradation. Produced intermediates during the oxidation processwere identified by using liquid chromatography–mass spectrometry technology （LC-MS） andgas chromatography–mass spectrometry technology （GC-MS）. Nitrosobenzene, nitrobenzene,1-hydroxy-1,2-diphenylhydrazine, benzoquinone, and4-4’-diaminodiphenyl have beenidentified as the major intermediates of aniline oxidation by persulfate.The aniline degradation by persulfate activated with ferrous ion(Fe²⁺) was investigatedin batch reactor at room temperature. The experimental results showed that ferrous ion canactivated persulfate effectively. The chelating agents have a key role in promoting anilinedegradation. Citric acid was more effective than EDTA and oxalic acid. The chelate/Fe²⁺molar ratio of1/1resulted in a higher degradation rate as compared to results by other ratios.