Effect And Mechanism Of Degradation Of Nitrobenzene Compounds In Water By Ultrasound/Zero Zinc

Due to industrial growth, large numbers of nitrobenzene compounds have beendischarged into water. Nitrobenzene compounds are known as an stable, toxic and unbiodegradable compounds, which pollute the environment seriously. Conventionalmethods for wastewater treatment may be inefficience for nitrobenzene compoundselimination. Therefore, several alternative processes have been proposed, whichadvanced oxidation processes(AOPs) belong to. The AOP induced by ultrasound hasbeen regarded as a promising manner. With the action of ultrasonic irradiation,contaminants can be transformed to substance with low toxicity, biodegradable matter,even be mineralized. But ultrasonic alone is of inefficiency for providing highdegradation efficiency to some pollutants. So it’s necessary to associate ultrasonicirradiation with other methods. Among these combined methods, the combination ofultrasound and solid catalysts is a simple and effective way.In this paper, the degradation efficiency of4-nitroaniline, nitrobenzene and4-nitrobenzoic acid by ultrasound in the presence of zero zinc was reported. Influncefactors of initial pH, zero zinc loading, ultrasonic intensity and initial concentrationwere detected in the degradation processes of three materials. At the same time, thekinetics and mechanisms that4-nitroaniline, nitrobenzene and4-nitrobenzoic acid weredegraded respectively by ultrasound cooperated with zero zinc were studied too.According to the results, all the four actors had effects on degrading effect. Thelower the value of pH and the more dosage of zero zinc, the higher rates of degradation.When the concentations of the three targete pollutants all were0.01mmol/L，takendegradating effect and consumption into consideration, the optimized treatmentcondition for4-nitroaniline was as follows: initial pH7, zero zinc loading0.4g/L,ultrasonic intensity1W/cm2, and the degradation rate reached89.12%. For nitrobenzene,the best condition was initial pH7, zero zinc loading0.4g/L, ultrasonic intensity2W/cm2, and the degradation rate was89.12%. Though the best condition for4-nitrobenzoic acid was the same as4-nitroaniline, the degradation rate was decreasedby11.20%.Besides, dagradation processes of targete pollutants, including4-nitroaniline,nitrobenzene and4-nitrobenzoic acid, followed first-order pharmacokinetic kineticsmodel. Meanwhile, the synergetic effect between ultrasound and zero zinc existed in thecoupled system for enhancing targete pollutants degradation significantly. Thecooperative factors for4-nitroaniline, nitrobenzene and4-nitrobenzoic acid were3.70,3.18and2.26respectively. And mechanism of ultrasound/zero zinc origined from the following aspects: on one hand, hydroxylation and mechanical effect of ultrasound; onthe other hand, reduction and particle effect of zero zinc, and the both aspects enhancedeach other. But for nitrobenzene, the system existed pyrolysis of ultrasound as well.