Experimental Study On Remediation Of Nitrobenzene Contaminated Soil With Zero-valent Iron And Sodium Perulfate

With the continuous development of the modern chemical industry,the demand for nitrobenzene is increasing day by day,and the total amount of nitrobenzene emissions increases rapidly at a rate of tens of thousands of tons every year.Nitrobenzene-contaminated soil has become one of the urgently needed soil problems.Nitrobenzene is used to produce dyes,spices,explosives and other organic synthesis industries.The nitrobenzene could change the soil properties,reduce soil microorganisms,decrease the soil utilization,and even do harms to the health throuth biological enrichment.The current research on remediation of nitrobenzene-contaminated soil mainly focuses on the degradation of nitrobenzene into aniline,but little attention is paid to the generated aniline.A large amount of aniline will still affect the soil ecological environment.Therefore,the development of an economical and efficient remediation scheme to remove nitrobenzene from the soil,and improve soil health is a great significance for alleviating the current situation of soil resource tension in China.In this study,the soil contaminated with high concentration of nitrobenzene was used as the research object.The combined technology of zero-valent iron reduction and sodium persulfate oxidation was used.Zero-valent iron reduced nitrobenzene to aniline in advance and produced divalent iron,and then zero-valent Iron and ferrous iron activate sodium persulfate to produce sulfate radicals.Finally,sulfate radicals oxidize aniline.In-depth study of the efficiency and influencing factors of zero-valent iron-sodium persulfate combined remediation of nitrobenzene contaminated soil.Based on the above considerations,this paper designed a total of three related experiments,respectively analyzed and discussed the influencing factors of combined technology to degrade nitrobenzene in water,research on the influencing factors of the technology to degrade nitrobenzene in soil and the soil column remediation of nitrobenzene contaminated soil.The conclusions of this study are as follows:(1)The experiment of degrading nitrobenzene in water with zero-valent iron-sodium persulfate can be concluded that the nitrobenzene in water can be removed by adding zero-valent iron and sodium persulfate in sequence,and delaying the time of adding sodium persulfate agent can improve nitrate.The degradation rate of basic benzene,under the best experimental conditions,the degradation of nitrobenzene can reach 92%.When zero-valent iron,sodium persulfate and nitrobenzene are present at the same time,the reduction rate of nitrobenzene is only 17%.Sodium persulfate will compete with nitrobenzene for zero-valent iron and cause the reduction rate of nitrobenzene to decrease.(2)The beaker experiment of zero-valent iron-sodium persulfate combined degradation of nitrobenzene in soil shows that when reducing the pre-adsorbed nitrobenzene on the soil,the zero-valent iron added can degrade 85%at a dose of 8g/L The residual nitrobenzene in the soil is only 0.13 mg/g.When the optimal sodium persulfate dosage is added,the oxidation rate of aniline reaches 79%.Therefore zero-valent iron and sodium persulfate can effectively degrade nitrobenzene in soil.(3)Experimental study on soil column remediation of nitrobenzene contaminated soil shows that the optimal flow rate of water in the soil column is 1 mL/min,the optimal degradation rate of nitrobenzene is 87.8%,and then sodium persulfate is loaded into the soil column The maximum oxidation rate of aniline is 82.03%.The adsorption of nitrobenzene in the soil is mainly affected by organic matter,so the organic matter in the soil has a great influence on the reduction of nitrobenzene.As the content of organic matter decreases,the degradation rate of nitrobenzene increases.It is concluded from experiments that zero-valent iron and sodium persulfate have the potential to repair nitrobenzene pollution.Through subject research,the research results of this article provide theoretical basis for the actual remediation of nitrobenzene-contaminated soil.