| Silica gel has good thermal stability, high mechanical strength and pore structure.The surface area of silica gel is relatively easy to control because of containing a large amount of active silicon hydroxyl, and it’s easy chemical bonding or modification to the surface. Also, silica gel is widely used in the filed of adsorption of copper, lead,cadmium and other heavy metal ions. By consulting a large number of Chinese and foreign literature, in this paper, three adsorbents were prepared. At first, silica gel was activated, and then the activated silica gel was modified with diethylenetriamine,dithizone respectively. Finally, we got two modified silica gel adsorbents DETA-SG and DT-SG. The two adsorption materials were used as the adsorbent and the flame atomic absorption spectrometry(FAAS) was using as detection means for the detection means, a new rapid sensitive detection method was build. Influence factors of modified silica gel adsorption properties for heavy metals copper, cadmium, lead were investigated. The thesis consists of five chapters:In the first chapter, we give an overview of the significance and progress of heavy metal detection and analysis, a brief overview of the commonly used detection methods of heavy metal ions, adsorption separation and enrichment methods and materials. The modification of silica gel and its application in the separation of heavy metal ions on the preconcentration was introduced.In the second chapter, with 3-chloropropyl trimethoxy silane(CPTS) as coupling agent, diethylenetriamine(DETA) as the functional groups, amino bonded silica gel adsorption material DETA-SG were prepared, which was characterized by infrared spectroscopy. Using DETA-SG as adsorbent, FAAS as the detection means, and the adsorption of trace Cu2+was investigated by static method. Results showed that, when pH 5, temperature 35 C, shock absorption at 50 min, Cu2+ can be quantitatively adsorbed by DETA-SG. The method for the determination of the detection limit for Cu2+(3, n=11) is 5.90 g/L, the static saturated adsorption capacity is 16.63 mg/g, the relative standard deviation is 3.3%. This method was applied to the determination of trace Copper in real sample, and the results were satisfactory.In the third chapter, diethylenetriamine bonded silica(DETA-SG) as the solidadsorbent, using FAAS as a means of detection, a new method was established for separation and enrichment of trace Cadmium in dynamic conditions. The method for the determination of Cd2+with a detection limit of 0.83 g/L, the linear range is 0.02~4.2μg/L, the relative standard deviation RSD is 1.84%. This method was successfully applied to the determination of trace amounts of cadmium separation enrichment and determination in rice.In the fourth chapter, the modification of silica with dithizone, dithizone modified silica gel was synthesized(DT-SG) adsorption material, and its structure was characterized by IR. In the static condition, the adsorption properties of Ag+were studied, such as pH value, temperature, adsorption time and elution agent. The method was applied to the determination of Ag+ in the standard sample, and the results were satisfactory.In the fifth chapter, DT-SG was used as the solid adsorbent, with the means of FAAS, under the dynamic method; this paper discussed the DT-SG effect on the adsorption of trace concentrations of lead. The linear equation of this method was A=0.0164c-0.0006, the linear range is 0.06~3.5 g/m L, the detection limit is 0.69 g/mL,RSD is 2.1%. The method was applied to the detection of Pb2+ in water which is collected from the Xiangjiang River, the pond in the Rain lake park and the laboratory,and the results were satisfactory. |
PDF Full Text Request