Studies On Carbon-based Materials For The Electrochemical Detection Of Tetrabromobisphenol A

Tetrabromobisphenol A(TBBPA)is the most common used brominated flame retardants.It is widely used in many industrial manufacturings.The heavy use of TBBPA has resulted in environmental pollution problem.Its residues have been found in the samples of environment media like water,earth and dust,even in the wild animal and human beings.Some previous studies have reminded that TBBPA has toxic effect to multiple body systems,even increases the risk of tumors.Consequently,more and more attentions are focused on its environmental contamination.Various analytic methods have been studied for TBBPA detection.But the defects of time consuming,costly and complicate pretreatment hinder the application of these methods.Under this situation,electrochemical method is introduced as a candidate analytic technique with advantages of fast,simple,economy and portability.In this dissertation,With a view to providing suitable detection technology for dealing with TBBPA pollution problem,we fabricated electrochemical methods based on carbon-based materials for sensitive TBBPA detection.The main contents are as following:Chapter 1 Facile electrochemical determination of tetrabromobisphenol A based on functionalized N-doped graphene modified glassy carbon electrodeObjective:To improve the aqueous dispersibility of N-doped graphene by hydrophilic functionalization;to develop an electrochemical method for TBBPA determination with the functionalized N-doped graphene as sensing material.Methods:TPA was used to hydrophilic-functionalize the N-doped graphene.The characteristics of the functionalized materials were demonstrated with UV-vis absorption,cyclic voltammetry and so on.After the experimental parameters were optimized,an electrochemical method for TBBPA detection was developed based on the functionalized N-doped graphene.Results:Through ?-? interaction.TPA was introduced to improve the aqueous dispersibility of the N-doped graphene.The negatively charged sheets were prevented from self-aggregating by electrostatic repulsion.The well-dispersed composite with pleasurable electrochemical characteristics were more favorable to modify glassy carbon electrode than pristine N-doped graphene.Then,CTAB could be loaded on the negatively charged N-doped graphene.The hydrophobic end of CTAB was utilized to accumulate TBBPA and enhance the oxidation response.This electrochemical method was achieved to detect TBBPA in the range of 0.01 ?M to 1 ?M with a detection limit of 9 nM(S/N = 3).Moreover,this method was applied to detect TBBPA in practical water samples with a recovery of 95.3%?109.8%.Conclusions:The surface-functionalized N-doped graphene was successfully applied to develop an electrochemical method for TBBPA detection.The advantages of the method including simpleness,low cost and high efficiency might greatly facilitate its application in environmental monitoring.Chapter 2 Studies on graphitic carbon nitride as electrode sensing material for tetrabromobisphenol A's determinationObjective:To employ g-C3N4 as a sensing material for TBBPA electrochemical determination;to demonstrate the electrochemical properties of g-C3N4 and its sensitization mechanism for TBBPA detection.Methods:For the investigation,g-C3N4 was synthesized at different temperatures(723 K,773 K,823 K,873 K)and characterized by field emission scanning electron microscopy,transmission electron microscopy.Fourier transform infrared spectroscopy,thermogravimetric analysis,Raman spectroscopy,X-ray diffraction and X-ray photoelectron spectroscopy.Then,the as-prepared g-C3N4 was used to modify glassy carbon electrode.After the parameters were optimized,TBBPA was quantified with differential pulse voltammetry by this modified electrode.Results:Synthetic temperature was found to lead to the difference in morphology,structure and component of the obtained g-C3N4.The morphology and graphite-like nitrogen component of g-C3N4 were considered as the key factors to impact its electrochemical performance.Though along with the bad electrochemical activity,the results presented that g-C3N4 could increase the oxidation response of TBBPA.The pH-dependent affection was contributed to the electrostatic attraction between g-C3N4 and TBBPA.This affection could accumulate TBBPA onto the modified electrode and increase the electrochemical signal.With this method.TBBPA was quantified in the range of 0.02 ?M to 1 ?M with a detection limit of 5 nM(S/N = 3).The fabricated method was also used to detect TBBPA in real water samples with a recovery of 96%?102%.Conclusions:The low-cost and environmentally friendly material,g-C3N4,could be utilized as electrochemical sensing material for TBBPA determination.And the modified electrode showed good performance in analyzing environmental samples and potential application in water pollution analysis.Chapter 3 Sensitive electrochemical detection of tetrabromobisphenol A based on graphitic carbon nitride-ionic liquid-doped carbon paste electrodeObjective:To prepare a g-C3N4 doped carbon paste electrode for sensitive TBBPA determination in view of the advantages of simple production,comfortable renewal and good reproducibility of carbon paste electrode.Methods:Coupled with N-Butylpyridinium hexafluorophosphate,g-C3N4 was doped into carbon paste electrode and then the surface of the electrode was modified with PDDA.After the parameters were optimized,the doped electrode was used to detect TBBPA with differential pulse voltammetry.Results:Because of the similar structure of g-C3N4 and graphite,they were mixed thoroughly in the grinding process.The mixture reduced the block effect from bulk partial of g-C3N4 to electron transport.Besides,the improved electrochemical performance of the doped carbon paste electrode was also attributed to the N atoms of g-C3N4.These atoms had unshared pair electrons and provided active regions on the surface of the electrode.Furthermore,based on ?-? interaction and hydrogen bond.g-C3N4 was coupled with N-Butylpyridinium hexafluorophosphate.The composite elevated the promotional effect of the pristine g-C3N4 for TBBPA oxidation response.Furtherly,the positively charged PDDA enhanced the accumulation and the oxidation response of TBBPA.The fabricated sensor was successfully employed to determinate TBBPA in the range of 1 nM to 30 nM and 30 to 500 nM with a detection limit of 0.4 nM(S/N = 3).This method was also achieved to analysis practical water samples with a recovery of 85.9%?97.9%.Conclusions:The prepared electrode presented the advantages of fairly simpleness and pleasurable sensitivity.Finally,it showed potential application to detect TBBPA in practical samples.