The Study Of Kinetic Characteristics Of The Biotic/Abiotic Reductions Of Iron Oxides And The 4-Nitroacetophenone Biodegradation Mediated By Geothite

The current study mainly discussed the mechanism and kinetics charactistics of the biotic/abiotic reduction of geothite and the biodegradation of 4-Nitroacetophenone mediated by goethite. The results showed that the electron shuttle, AQS, can enhance the degree and extend of goethite microbial reduction and 4-Nitroacetophenone biodegradation. After 38 days’incubation, the dissolved Fe(II) concentration was as much as 3.94 times of that in the cell-goethite reaction system with non-AQS addition. The Michaelis-Menten kinetic model fit calculations showed the significant correlation between the initial reduction rate and the substrate concentration with a correlation coefficient, R2, high enough to 0.998. The electron shuttle, AQS, can have considerable influence on Vmax and Km values. The more reduction rate raised, the more energy ( ?E ) will be needed to drive ATP synthesis. When the microbial redox reaction almost kept in balance, the ?G rvalues reached the maximum.In the study of the kinetics charactistics of the abiotic reduction of Geothite, the results showed that the electron shuttle, AQS, can enhance the degree of goethite abiotic reduction. Without AQS addition, the degree of goethite abiotic reduction was slim, with the addition of AQS, the abiotic reduction dramatically increased after a certain lag time, the time course of produced Fe(ΙΙ) concentration showed a typical characteristic of SLogistic model. The Slogistic model fit calculations showed the significant correlation between the reaction time and produced Fe(ΙΙ) concentration with a correlation coefficient, Adj. R- Square, in the range of 0.988~0.992. When the electron donor concentrationwas limited, the characteristic of SLogistic model got weak, while the electron donor concentrations were adequate, the Adj. R-Square could be high enough to 0.990. The concentration of electron donor/acceptor and presence/absence of electron shuttle could have a certain influence on the Slogistic model fitted parameters.In the study of the biodegradation of 4-Nitroacetophenone mediated by goethite, the results showed that the product of 4-Nitroacetophenone is 4-amino benyimethadone, and the natural logarithm of concentration of 4-amino benyimethadone and the reaction time fit the ExpGro1 Model. The ExpGro1 model fit calculations showed the significant correlation between the reaction time and the natural logarithm of concentration of 4-amino benyimethadone with a correlation coefficient, Adj. R- Square, in the range of 0.971~0.989. The various concentrations of AQS and the introduction of geothite influenced the lag time of the 4-Nitroacetophenone biodegradation reaction. Once more, it implied that the reduced production-Fe(??) played a key role on the reduction of 4-Nitroacetophenone.