Synthesis And Application Of A Class Of Non-Quinone Redox Mediators

Nitrates have been widely used in industrial and agricultural production and have become a widespread pollutant in natural waters.Although microorganisms are one of the more effective methods for removing nitrate nitrogen,they suffer from long reaction times and low removal efficiencies.This paper reports the synthesis a series of carbamate compounds as non-quinone redox mediators and using sodium nitrate as a model pollutant,investigated the effect of carbamate compounds on the catalytic anaerobic reduction of NO3-N by Paracoccus versutus（strain GW1）.The purpose was to accelerate the microbial anaerobic reduction rate of NO₃-N and provide technical support for the rapid removal of NO₃-N in wastewater.Firstly,4-[（propyloxycarbonyl）amino]benzenesulfonic acid was synthesized by chemical reaction in aqueous solution using propyl chloroformate and sulfanilic acid starting materials.The effects of material ratio,reaction temperature,solvent and the acid-binding agent on the product yield were investigated;the optimum reaction conditions based on varying these parameters were obtained.Based on these optimal conditions,other carbamate compounds were also synthesized.The products obtained were characterized by FTIR spectroscopy and ¹H-NMR spectroscopy.The carbamate compounds were then used as redox mediators and their effects on the removal of NO3-N in wastewater under anaerobic conditions by Paracoccus versutus.GW1 were systematically studied.The results showed that 2-[（methoxycarbonyl）amino]ethanesulfonic acid had the most significant effect in accelerating the anaerobic reduction of NO3-N by Paracoccus versutus GW1;the removal rate of NO3-N was approximately2.12 times higher than the controls.The influence of the medium dosage,the initial concentration of NO₃-N and the p H value of wastewater on anaerobic reduction of NO3-N in the Paracoccus versutus.GW1was studied;2-[（methoxycarbonyl）amino]ethanesulfonic acid was used as the redox mediator.The experimental results showed that as the concentration of2-[methoxycarbonyl)amino]ethanesulfonic acid increased（within a certain range）,the removal rate of NO₃-N also increased.As the initial concentration of wastewater increased,the removal rate of NO₃-N is decreased;the p H of the waste water had little effect on the processofbacterialreductionofNO₃-Nbyaccelerated N-（2-aminoethanesulfonyl）carbamate.Microbial microorganisms could reduce NO₃-N under both weak acid and weak base conditions.