Nitrogen Doped Carbon Nanopores-facilitated Reduction Of Nitrobenzene By Sodium Sulfide

As a common，nitrobenzene is a high toxicity environmental organic pollutant,and has been listed as the environmental priority pollutant by our country. Nitrobenzenein environment would result in the damage of aquatic organisms, destruction ofgroundwater resources, and cause human diseases through food chain or drinking water.Based on these reasons, it is significant to remediate the nitrobenzene pollutioneffectively. In this study, chemical reduction method was taken to remediate thenitrobenzene pollution using sodium sulfide (Na2S) as reductant catalyzed by nitrogendoped carbon nanopores which is compunded independently.First of all, phosphoric acid, sucrose, and hexamethylenetetramine was used ascarbon source and nitrogen source to compund the nitrogen doped carbon nanopores.Then, various measures were conducted to definite the apparent and internal structuresof the material. The results show that N element was doped in the carbon structuresucessfully, and the mass fraction of N element is about10.2%. The mass fraction ofPyridinic N was also been determined.In the next step, batch experiments were proceed to make sure wheather thenitrogen doped carbon nanopores can mediate the redox reaction of nitrobenzene byNa2S in aqueous solutions. With the presence of nitrogen doped carbon nanopores(typically250mg/L) and Na2S (8mM) simultaneously, the relationship between theconcentration of nitrobenzene（mg/L） and time（h） is：Y=80.68e-0.2826X，R2=0.9966（X and Y represents for the time and concentration of nitrobenzene，respectively），while the observed pseudofirst-order rate constant (kobs) for the reductionof nitrobenzene is0.2826h-1. After reaction with Na2S for16h under the catalysis ofnitrogen doped carbon nanopores， the system gave nearly complete removals ofnitrobenzene. No significant reduction of nitrobenzene was found in controlled trials,which clearly illustrates the conspicuous reaction facilitation by nitrogen doped carbon nanopores.The study has also found that the nitrogen doped carbon nanopores cancatalyze the reduction of nitrobenzene to aniline in spite of been in the aerobic oranaerobic environments, which implies that the materials not only can be used toremove nitroaromatics in the industrial wastewater, and can also be used to assist theattenuation and remediation of these chemicals in an anaerobic environment. Inaddition, the materials can be well adapted to a large range of pH (pH:4.55-10.38).Furthermore, the materials show up a good reusability. All the results mean that thematerial can be served as a superior and high-efficiency catalyst with the widespreadapplication.Finally, on the basis of literature and observations made above, the catalyticmechanism of the nitrogen doped carbon nanopores mediated nitrobeneze reductionmay be the function of enhancing electron transfer and activation of nitrobenezemolecules. To make sure the effect of nitrogen-containing functional groups, high-temperature processing (800℃) was taken to decrease the relative amount of O elementand increase the relative amount the N element. Contrastive analysis of shows that thematerial after high temperature treatment has better catalytic effect. The result suggeststhat it is the nitrogen-containing functional groups do favor to the catalytic activity ofthe material, rather than the oxygen-containing functional groups, actually. What’smore, the study figures that Pyridinic N and Graphitic Nmay serve the the catalyticactivity of the nitrogen doped carbon nanopores.