Reductive Efficiencies Of Nitrobenzene By Enhanced Zero Valent Iron

Zero-valent iron(ZVI)has been widely used for its easily to abtain and operate,low cost,and qucikly reductive efficiency.Using ZVI system to pretreat nitrobenzene wastewater can reduce nitrobenzene concentration evidentely, and also enhance the degradation capability of the wastewater.ZVI combine with ultrasound system was recent and potential study field of advanced oxidation technology in water treatment.In this dissertation,nitrobenzene was elected as research object.The influence factors of the ultrasound degradation effect including initial concentration of ZVI,initial pH and ultrasound intensity, have been investigated.ZVI decomposition mechnaism and kineties has been explored.Menawhile the ZVI degradation technology of using the ultrasound combine with Fe²⁺ was also investigated.The initial pH have obviously affected on ultrasound decomposition effieieney.The reductive effects of pH were examined at different pH value of 3.0,5.0,7.0,respectively,the change of pH value and nitrobenzene concentration during reaction.The results showed that,higher reductive rate was obtained at lower initial pH value.The reduction of nitrobenzene was fitted with pseudo-first-order kinetic model, and the formation of aniline fitted with zero order reaction.Nitrobenzene was selected as the pollutant,and the feand Mnions of different concentrations were added into the ZVI system. the reactive rate was enhanced due to the addition of Fe²⁺ions,and with the addition of more Fe²⁺,ultrasound decomposition ratio became larger.However,the reactive pathway was not changed.Feions were not the main reductant,and it had a buffering capacity in the ZVI system.Irradiation time and ultrasound intensity have obviously affected on ultrasound decomposition efficieney of nitrobenzene.The longer the time of irradiation and the bigger the ultrasound intensity were,the better decomposition result was.The combination of ultrasound and Fe²⁺ can increase the degradation effect of nitrobenzene efficiently.Along with more ultrasound power was added,ultrasound decomposition ratio became lagrer.Synergetic effect of ultrasound and Fe²⁺ also appeared.When ultrasound power was 100W and initial Fe²⁺ concentration was 500mg/L,at 30min,the decomposition ratio was 90.12%.Nevertheless,when only using ultrasound or Fe²⁺,the ratio was 79.44% or 47.62%.