| As well as heavy metals, high residue in the environment of precious metals will harm the health of human body, whether from the perspective of resource sustainability or environmental protection, the detection and reclamationof precious metal is very significant. The residue of precious metals in environment is very low, it is difficult to directly determine by general analysis instrument, but the analytical instruments which can detect directly with low detection limit is too expensive to popularize used for the daily determination of precious metals, so it is necessary to separate and enrich the actual samples before detection. Solid phase extraction is one of the most commonly used methods of separation and enrichment. The key of this method is the selection of solid phase extraction material. On the basis of a large number of scientific research achievements of predecessors, this article synthesized novel materials for solid phase extraction of modified chitosan, and apply them to the separation and enrichment various trace silver、palladium of real samples successfully,by the detection instrument-flame atomic absorption spectroscopy(FAAS). The paper mainly includes the following content:1. The introduction mainly summarized and the present situation of resources of silver and palladium, then it listed the common detection methods、separation and enrichment method and the separation and enrichment of precious metal in recent years. It focus on the analysis of the advantages and disadvantages of the chitosan as the solid-phase extraction material, then introduce modified methods of chitosan and it’s classification, finally put forward our own ideas and solutions.2. In this paper, we use a one step method with ethylene glycol as reducing agent to prepared magnetic chitosan microspheres, then optimized the adsorption and elution conditions of separation and enrichment trace silver by the static method.Established a new method to measure trace silver in the Chinese herbal medicine that magnetic chitosan microspheres enrich and separate and flame atomic absorption detects, the result shows that the method detection limit(3 sigma, n = 11) 7.46 mg/L,the static saturated adsorption capacity is 78.59 mg/g, the results is satisfactory.3. In this study, a novel separation and enrichment material-magnetic rhodanine chitosan was successfully prepared by one-step magnetization of chitosan which wasmodified by rhodanine, and was characterized by Fourier transform infrared spectrometer(FT-IR). The adsorption properties of the magnetic rhodanine chitosan for Ag+ were investigated by static method, and the flame atomic absorption spectrometry(FAAS) was used as the detection method. The results showed that when the solution adjusted to p H 5.6 and then shocked at room temperature for 25 min, Ag+ can be fully adsorbed by the adsorption materials, the adsorbed Ag+ could be eluted with 0.1 mol/L thiourea. The static saturated adsorption capacity for Ag+ was121.8 mg/g. Under the optimum conditions, the obtained linear response of Ag+ in the range from 0.01 to 5.0 mg/L with detection limit(3σ,n=11) of 8.50 ng/m L, the relative standard deviation(RSD) was 0.72% and the recoveries were 97.8%~102.7%. The proposed method was applied for the determination of trace Ag+ in actual water sample with satisfactory results.4. The paper inspected adsorption of trace palladium used rhodanine magnetic chitosan as solid-phase extraction material by dynamic method, explored the effects of the adsorption and elution of palladium by influence factors such as acidity,temperature, flow rate in detail, and found the best conditions of adsorption and elution. The dynamic saturated adsorption capacity is 51.38 mg/g, the obtained linear response of Pd2+ in the range from 0.2 to 8.0 μg/m L with detection limit(3σ,n=11) of0.073 μg/m L, relative standard deviation(RSD)was 4.74%. The methods can be used to detect the trace palladium in ore samples. |
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