| Water pollution problems, especially the determination and treatment of pollutants have received more attention. Because of the several advantages such as high efficiency, sensitivity, simple operation, low cost and so on, electrochemical method have got more favors of researchers. But the electrochemical detections of persistent organic pollutants still got nowhere for the chemical inertness and dielectric property of these substances. Therefore, it is of great significance to achieve the determination of persistent organic compounds. Since nano functional materials have been used in many fields, the combination of nano functional materials with biological adsorption has great merits for sewage treatment.This paper mainly studied the electrochemical quantitative analysis of persistent organic pollutants and some of the most common toxic heavy metal ions at mercapto-β-cyclodextrin modified Au microelectrode. In addition, we also studied the influence of the electrode dimension on detection sensitivity. At last, magnetic nanoparticles γ-Fe2O3were packaged into the biosorbent chitosan and the synthetized magnetic biosorbent used for Cr(VI) removal was studied.The first chapter mainly introduces the origin and the harm of persistent organic pollutants in the environment as well as the conventional detection methods and some common prevention measures for these substances. Then the sources and hazards of heavy metal ions in water were introduced and some commonly used methods for determination and treatment of these inorganic pollutants was recommended.The second chapter mainly introduced a method for quantitative analysis of chemical inert persistent organic pollutants based on electrochemical impedance spectra (EIS) using mercapto-β-cyclodextrin modified microelectrode. Electrochemical impedance spectra at nanoelectrode were firstly reported. Compared with the conventional electrode, microelectrode and nanoelectrode have lots of difference in cyclic voltammetry and electrochemical impedance spectra, which could be attributed to different ways of mass transfer to the electrode surface. Using electrochemical impedance spectroscopy, very tiny changes in the micro-and nanoelectrode surface can be detected. At micro-and nanoelectrode the determination of PCB-77can get higher sensitivity and lower detection limit than at conventional electrode. The ultratrace determination of eight persistent organic pollutants in the range of2-32pM was investigated which could be comparable to standard methods. Through density functional theory calculations, it was found that only organic molecules with appropriate dimension can be selected on the modified electrode.In chapter3, heavy metal ions were detected through special bonding affect at mercapto-(3-cyclodextrin modified microelectrodes by electrochemical impedance spectra. The EIS analysis of toxic Cr(Ⅵ) and As(Ⅲ) in mild electrolyte was superior to the conventional voltammetry. Due to the special bindings between cyclodextrins and bivalent metal ions, a quantitative detection of these heavy metal ions was accomplished, and electrochemical impedance spectra was used to track the pH-switchable effect between cyclodextrins and Cu(Ⅱ).In chapter4, magnetic nanoparticles γ-Fe2O3was successfully packaged to biosorbent chitosan to realize the recovery and reuse of biosorbent. γ-Fe2O3-chitosan beads can be effectively used to removal of Cr(Ⅵ) in aqueous solution. Through the adsorption kinetics and adsorption thermodynamics analysis, a detailed understanding of the adsorption process was achieved. Anti-jamming ability of γ-Fe2O3-chitosan beads was very strong, and the performance of regeneration and reuse was very predominant. Through the FTIR and XPS characterization of γ-Fe2O3-chitosan beads, a detailed explanation for Cr(Ⅵ) removal mechanism was introduced.In the chapter5, all the work in this thesis was summarized and the next research work was shortly prospected. |
PDF Full Text Request