Study On Interaction Of Electron Shuttle And Aniline-Iron Biological Reduction Process

Iron ore is commonly found in surface layers and is the most common oxidationreduction active mineral in nature.Microbial mediated biogeochemistry cycle of iron widely acts in anaerobic environments such as sediments and aquifers deep in the earth,and is one of the main ways of iron metabolism in nature.Organic matter containing quinone groups can act as electron shuttles to transfer electrons between microorganisms and Fe(Ⅲ)oxides,promoting the biological migration and transformation of iron;This process also affects the migration and transformation of pollutants.The migration and transformation of iron under the coexistence of electron shuttle and pollutants were systematically explored,and the solid minerals after reduction were characterized.The results of the study are helpful for us to fully understand the biogeochemistry cycle of iron in multi-component reactions.The main research conclusions of this thesis are as follows:1.The reduction effect of typical substances on Fe(Ⅲ)oxide goethiteExploring the effects of several typical substances on the reduction of Fe(Ⅲ)oxide goethite by setting up biological and non biological systems.Through experiments,it was found that the reduction of Fe(Ⅲ)is mainly influenced by microorganisms.In the absence of microbial participation,other biological reducing substances that affect iron are basically unable to play a promoting role.And through SEM observation,the reduction of goethite by microorganisms is mainly achieved through direct contact.2.The Effect of Sodium Lactate and AQS Concentrations on the Reduction of Fe(Ⅲ)Oxide GoethiteWhen Fe(Ⅲ)oxide is used as the only electron acceptor,sodium lactate is used as the only electron donor to study the biological reduction effect of different concentrations of lactic acid Fe(Ⅲ).In batch experiments,it was found that the amount of Fe(II)produced by adding 15 m M of sodium lactate is 6.39 times that of no added lactic acid.Therefore,sufficient electron donor are needed to maintain the biological reduction of Fe(Ⅲ).When the electron donor is sufficient,the addition of 0.1～0.5m MAQS increases the kinetic parameters of Fe(II)production by 1.66,1.92 and 2.28 times,respectively,and also increases the consumption of sodium lactate to improve microbial metabolism,significantly promoting the biological reduction of Fe(Ⅲ),thus accelerating the biological reduction process of iron.3.The Effect of Aniline on the Reduction of Fe(Ⅲ)Oxide Goethite Mediated by AQSBy setting the initial addition of aniline and adding aniline 12 hours later,two reaction systems were formed: "MR-1+goethite+AQS+aniline" and "MR-1+goethite+AQS" with aniline.Add different concentrations of aniline to the reaction system to investigate the impact of pollutants on the biological reduction of iron.In batch experiments,it was found that the addition of aniline promoted the biological reduction of iron,but there were significant differences in the biological reduction of iron between different concentrations of aniline and the addition at different times.The addition of 3 μm aniline at the initial and 12 h after the reaction has the greatest effect on the bioreduction of iron.Aniline,as a toxic and harmful substance,has an inhibitory effect on the bioavailability of iron when its concentration is too high.Add 3 initially and after 12 hours of reaction The production of aniline Fe(II)in m is 1.06 and 1.12 times higher than that in the presence of only microorganisms,respectively.At the same time,a control experiment was conducted without the addition of AQS.The study found that in a reaction system containing aniline,the addition of AQS generated 1.27 times more Fe(II)within 72 hours of the reaction compared to the absence of AQS.This indicates that the electron shuttle containing pollutants can stimulate the biological reduction of iron and improve the bioavailability of aniline,allowing aniline to be utilized as a carbon source in the reaction system and thus degraded.When characterizing the reduced Fe(Ⅲ)oxide,the reaction system with aniline added after12 hours showed more stable crystallization of goethite after reduction compared to before the reaction.