Studies On The Electrochemical Enhancement Of Carbon Nanocomposite Materials And Their Applications For Tetrabromobisphenol A Sensing

Tetrabromobisphenol A(TBBPA)is one kind of the most widely used brominated flame retardant.Studies have shown that TBBPA could be detected extensively in the environment,as well as in bodies of human at the trace level(μg L-1).As a potential persistent organic pollutant,TBBPA was reported for its endocine disrupting effectct,immunotoxicity,neurotoxicity and developmental toxicity.Therefore,development of rapid and reliable methods for the trace-level TBBPA determination is greatly sigmificant in exploring the main exposure way of TBBPA and protecting the health of the population.Electrochemical methods were widely applied in the environmental and health fields owing to their high sensitivity,rapid response,low production cost,and easy operation.With the rapid development of nanotechnologies,the manufacture of functional nanomaterial-modified electrodes and their interface sensitization effect is key issue of detecting trace-level TBBPA with the electrochemical method.Notably,the carbon nanomaterials has already shown the excellent electrocatalytic activity,the further development of multi-functional carbon nanocomposites would achieve the synergetic effect of different components and improve the sensitivity and accuracy of the sensor.This may provide the resolution for the critical problem of trace-level TBBPA detection.In this paper,three kinds of carbon nanocomposites were prepared,and the nanocomposites were further applied to establish new methods for the highly sensitive electrochemical analysis of TBBPA in environmental samples.The interfacial sensitization effect of carbon nanocomposites were investigated and demonstrated.The research work of this the paper mainly contains the following parts:Chapter 1 Study on the Synergetic Enhancement of Multi-walled Carbon Nanotubes-Fe304 Hybrid/trimethyloctadecylammonium and its Application for the Electrochemical Sensing of Tetrabromobisphenol AObjective:Based on the catalytic performance of multi-walled carbon nanotubes-Fe3O4 hybrid(MWCNTs-Fe3O4)and the enrichment ability of trimethyloctadecylammonium(TOAB)towards TBBPA,a new electrochemical sensor was developed and further applied to detect the trace-level TBBPA in water samples.Methods:The MWCNTs-Fe3O4 hybrid was prepared by the hydrothermal method.The hybrid was cast onto the surface of the electrode along with the TOAB to fabricate the sensor.The material properties of MWCNTs-Fe3O4 were verified by various characterization techniques.The electrochemical behavior of TBBPA on the surface of modified electrode was studied by cyclic voltammetry and chronocoulometry method.The oxidation process and the catalytic mechanism of TBBPA were further studied.Finally,the developed sensor was applied to detect the TBBPA in real water samples.Results:MWCNTs-Fe3O4 hybrid and TOAB composite could effectively enhanced the electrochemical performance and the enrichment ability of electrode.So that the composite could realized the sensitization of the electrode and further improved the detection sensitivity.The mechanisms of TBBPA oxidation process on the modified electrode surface were involved two electrons and two protons.This fabricated sensor displayed excellent analytical performance for TBBPA detection over a range from 3 to 1000 nM,and the detection limit is 0.73 nM(S/N = 3).Moreover,the proposed electrochemical sensor exhibited good reproducibility and stability,and could be successfully applied to detect TBBPA in water samples with satisfactory results.The new sensor was used to detect TBBPA in water samples,the analytical results were consistent with the results of high-performance liquid chromatography.And the values of recovery were over the range from 95.5%to 106.5%.Conclusion:This study successfully developed the TOAB/MWCNTs-Fe3O4 based electrochemical sensor.The sensor showed excellent detection performanc and could be used for trace-level TBBPA determination in the water samples.Chapter 2 Study on the Synergetic Enhancement of Graphene/Ag nanowires and its Application for Electrochemical Sensing of Tetrabromobisphenol AObjective:As a two-dimensional carbon nanomaterial,graphene(Gr)is widely known for its good electrical conductivity,high chemical stability and easy modification.Ag nanowires(AgNW),an one-dimensional nanomaterial,can further improve the electron transfer rate of Gr.Both types of materials were used for electrode modification to enhance the electrochemical response of TBBPA.Method:The chemical reduction method and one-step polyol method were adopted to prepare Gr and AgNW,respectively.The X-ray diffraction,scanning and transmission electron microscopy,and Raman spectroscopy were used to characterize the two types of nanomaterial.The two types of materials were modified on the glass carbon electrode(GCE),and their synergistic enhancement effect was investigated by the differential pulse voltammetry.The study had also systematic optimized the fabrication and detecting conditions of electrode.After its methodological evaluation,the newly-built electrochemical sensor were applied for TBBPA detection in real water samples.Results:The Mn2+ served as the control agent and it could effectively regulate the nucleation and growth of AgNW.As demonstrated in the electron microscopy,the prepared AgNW showed a good morphological uniformity with raletively large diameter length ratio.Moreover,by overlapping with the crystal boundary and wrinkles of Gr,the AgNW could further improved the electrical performance of Gr with its one-dimensional electron path.This could further speed up the electron transfer rate of sensing interface and improve the performance of the electrode.The electrochemical active area of AgNW/Gr/GCE surface reached up to 0.137 cm2,nearly 2.85 times higher than a bare GCE.The linear range of the sensor was from 1 to 500 nM,and the detection limit was 0.45 nM(S/N = 3).The sensor could be used for the analysis of water samples with accurate results,the values of recovery were over the range from 95.5%to 106.5%.Conclusion:This study had successfully developed the AgNW/Gr-based electrochemical sensor.The sensor is featured by its high detection capacity,offering a new method for detection of trace-level TBBPA in water.Chapter 3 Study on the Synergetic Enhancement of MoS2 and Au@Gr and its Application for the Electrochemical Sensing of Tetrabromobisphenol AObjective:The nanocomposite consisted of MoS2 and Au nanoparticle modified graphene(Au@Gr)was exquisitely prepared.And the nanocomposite(MoS2-Au@Gr)was further used to develope a sensitive electrochemical sensor.This sensor would provide an effective technical support for the evaluation of TBBPA exposure via indoor dust.Method:This study developed a new sensor for the TBBPA electrochemical detection based on the synergistic enhancement effect of two-dimentional MoS2 and Au@Gr.The electrochemical impedance spectroscopy(EIS)and chronocoulometry were applied to explore the electrical conductivity and adsorption capacity of the sensor.The cyclic voltammetry and differential pulse voltammetry were used to investigate the electrochemical behavior of TBBPA on the surface of composite-modified electrode.A novel electrochemical method based on the the newly built sensor could be used for TBBPA sensitive detection in the indoor dust samples.Results:According to the characterization results,the synthesized MoS2-Au@Gr nanocomposites showed a porous and layered structure,which could effectively increase the superficial area of electrode.The double layer charge reached up to 1.315μC,about 4 times greater than GCE,indicating that the nanocomposite could effective improve the enrichment capacity of electrode.Synergistic effect of the nanocomposite also enhanced the electrochmical signal of TBBPA,and the oxidation current value became 16 times higher than GCE,which indicated the prepared nanocomposite could effectively boosting the sensitivity of the analytical method.The linear range of the sensor was from 0.5 to 500 nM,and the detection limit was 0.13 nM(S/N = 3).The sensor was accurate in its detection capabilities with the standard addition recovery between 97.2%～103.6%.Hence,the sensor could be successfully used for the detection of TBBPA in the indoor dust samples.Conclusion:This study successfully fabricated the MoS2-Au@Gr nanocomposite and further developed a sensitive electrochemical sensor based on the synergistic effect of the nanocomposite.The new sensor would provide a new method for sensitive and rapid detection of TBBPA in the indoor dust samples.