Aromatic Nitro Compounds Based On Electrochemical Detection Of Functional Carbon Material

As an important raw material and intermediate of chemical products such as dyes and pesticides,nitroaromatic compounds can pollute the surrounding environment during the process of production and transportation.It is also an important component of explosives which often used by terrorists.It is an important risk of security.It is particularly important to be fast and real-time monitoring so that many countries classify them as "priority" pollutants.It is urgent to find a quick,sensitive and simple method for the detection of nitroaromatic compounds to satisfy the needs of social development.Compared with mass spectrometry,spectrum and other traditional detection methods of large-scale and need to be based on laboratory research,electrochemical equipment with light equipment,real-time monitoring of the scene,high sensitivity has become a hot research.The electrode material is the core of electrochemical detection of NACs.This paper focuses on the design and preparation of electrode materials with high sensitivity,high selectivity and wide linear range for aryl nitro compounds.To explore the electrochemical detection mechanism of NACs,optimize the electrochemical test conditions and according them to design suitable electrode material.Compared with the precious metal catalyst modified electrode material,this paper mainly studies?1?hydrothermal preparation of functional carbon materials;?2?pyrolysis of porous carbon materials.For the first type of material,this paper first uses glucose as raw material to synthesize hydroxyl-rich carbon microspheres in one step by hydrothermal method.Through the optimization of the time and temperature of hydrothermal synthesis,the prepared hydroxyl-rich carbon microsphere material exhibits high sensitivity?477.5 ?A·ppm-1·cm-2?for representative TNB,low background current?-7.8 ?A?,low detection limit?LOD = 0.85 ppb?.Its electrochemical indicators relative to the commercial carbon material BP 1000 and nitric acid oxidation after the BP 1000 has greatly improved.The results of IR and XPS combined with electrochemical detection show that the surface hydroxyl groups played an important role in the electrochemical reaction,that is,the ?-? conjugation between the electron donor O and the electron deficient system of NACs,and hydrogen bonds between the H in the-OH group and O in the-NO₂ group enhanced the adsorption of NACs in the pre-stationary process,which was beneficial to the subsequent electrochemical signal enhancement.In addition,we introduce acrylic acid in the hydrothermal synthesis of glucose precursors to prepare carboxyl-containing carbon microspheres to examine whether the common oxygen-containing functional groups-COOH also play a role in the detection of NACs.In this part,we mainly explored the influence of the mass fraction of acrylic acid.Finally to determine when the amount is 5 wt%acrylic acid,NACs detection signal in the same type of carboxyl-containing carbon microspheres in response to the maximum sensitivity of 263.5 ?A·ppm-1·cm-2 and 160.4 ?A·ppm-1·cm-2.But the sensitivity is only 1/2 to the hydroxyl-rich carbon microspheres,which indicates that the carboxyl group does not achieve our desired effect when detecting NACs,but can still be optimized at hydrothermal temperature and time.The second aspect is pyrolytic carbon,still use glucose as precursors,adding KOH as pore-forming agent,Fe?N03?3·9H20 and Co?N03?2·6H20 to promote graphitization.Mixing the above ingredients uniformly,.calcined at a high temperature within nitrogen atmosphere,hydrochloric acid pickling to remove metal and impurities,preparing the final carbon material which is prussian blue carbon composite material to carry on electrochemical testing.It has a high sensitivity?>3000 ?A·ppm-1·cm-2?,is 100 times to glassy carbon electrode.And it also has low background,LOD=0.03 ppb,and can be detecting to low-concentration which is 2 ppb NACs and maintain the good responsiveness and linearity,this is due to the dual effect of the strong catalytic activity of Prussian blue and the strong adsorption capacity of carbon.Finally,we selected the pyrolytic carbon material KOH-glucose-CoFe-HCl-800 to use in the actual water sample detection,and it still able to maintain good sensitivity and linearity.