Preparation Of Nanoscale Zero-Valent Iron And Research On Nitrate And Nitrite Removal

Nitrate(nitrite) pollution is increasingly serious in groundwater; which seriously endangers human health, so nitrate(nitrite) disposal in groundwater has aroused great attention nowadays. It is well-known that nanoscale zero-valent iron (NZVI) has the high activity for nitrate removal, therefore, This paper carried out two different grain size NZVI prepared by hydrogen reducing goethite, and researched the characterization and the structure of NZVI with analysis methods of XRD, TEM, SEM and BET. then investigated the effect factors of nitrate(nitrite) removal, such as initial pH value, nitrate(nitrite) concentration, dissolved oxygen (DO), iron-to-nitrate(nitrite) ratio, natural goethite grain size, and compare it with ordinary zero-valent iron (OZVI) through the static experiment. And under the same level condition, researched nitrate(nitrite) removal with the different NZVI prepared by hydrogen reducing nature goethite and synthesis goethite. The results showed that:(1) NZVI can be prepared when calcining temperature maintains above 550℃, the flow rate of hydrogen maintains 150mL/min, and calcining time is 6h.(2) Under the near-neutral condition, nitrate(nitrite) removal rate reaches 90%, superior to OZVI (10%).(3) In the reduction process, three factors(iron-to-nitrate ratio, reaction time, and nitrate concentration) have great impacts on nitrate removal with a direct proportion. The nitrate removal efficiency has little relationship with factors such as pH value, initial crushing grain size and DO in water..(4) NZVI prepared by hydrogen reducing nature goethite is better than NZVI prepared by hydrogen reducing synthesis goethite.(5) This method that hydrogen reducing goethite is relatively simple and low cost, so NZVI reducing nitrate has potential application on groundwater pollution.