| Pollution of heavy metal is mainly caused by the environmental contamination of the heavy metal and its compounds, resulting from the poured wasted gas or water, and compounds containing heavy metal ions. With the continuous development of economy, specific industries such as metal finishing, electroplating, metal smelting, chemical engineering, papermaking, and mining were more and more, the problems of the illegal mining and over-standard pollutant discharged are in a serious situation that many contamination accidents of heavy metal have been reported. Heavy metal pollutants are not only non-degradable, but also cumulative and reduplicative in the natural environment which can be the main threats to human health. The heavy metal can inactivate the proteins or enzymes in the human body by destroying the structure of their proteins, what is more, the heavy metal can be enrich in the human body through food chain and do harm to the health of people. Thus, how to detect and treat the heavy metal pollutant effectively is the important issue of the present environmental protection work. In this thesis, the thiol-modified carbon materials were used as the matrix, the new materials for adsorbing or detecting the heavy metal ions were prepared by some modified methods such as composite material and heteroatom doping and the optimization condition and mechanism were also discussed. The results obtained include the following three aspects:(1) Graphene oxide (GO) has been fabricated by using modified hummers method. Then a facile diazonium chemical process was developed to fabricate thiol-modified graphene oxide (GO-SH) by introducing thiol group compound to the GO by 4-aminothiophenol. The prepared GO-SH was used as the adsorbent for removal of heavy metal ions Cu(?), Cd(?) and Pb(?). The parameters such as pH value, contact time, metal ions concentration and adsorbent dosage were optimized. Isothermal adsorption model was established, the result showed that the Freundlich isothermal adsorption model fitted the experimental data better than the Langmuir model.(2) The GO-SH was used to self-assemble with chitosan via an electrostatic interaction. The chemical structure and morphology of the CS/GO-SH composite were characterized by Fourier transformed infrared, Raman spectroscopy, scanning electron microscopy, X-ray powder diffraction and thermogravimetric examination. The results indicated that the CS/GO-SH contains multifunctional groups such as-OH,-COOH,-SH and-NH2. The resulting CS/GO-SH was used as an adsorbent material for removal of Cu (?), Pb (?) and Cd (?) in single-and multi-metal ions system, and the optimal experimental conditions were studied. It was found that the CS/GO-SH has potential application in the field of adsorptive materials due to its superiority of the chemical structure and the specific surface area.(3) An engineered multi-walled carbon nanotubes (MWCNTs) material was successfully synthesized via doping the nitrogen atoms and grafting the thiol groups into the activated MWCNTs matrix for detecting lead ions and cadmium ions by square wave voltammetry (SWASV). The morphology structure and the composition of the engineered MWCNTs were characterized by Fourier transformed infrared, Raman spectroscopy, scanning electron microscopy and X-ray photoelectron spectroscopy. The results indicated that the engineered MWCNTs exhibited improved dispersibility, and selectivity for metal ions detection due to the introduction of the nitrogen atoms and thiol groups. In addition, the developed electrode material displayed a good repeatability and reproducibility. These studies implied that the engineered MWCNTs may possess a potential application in heavy metal ions detection, and the design idea is worth using for reference to improve the performance of metal ions detection sensor. |
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