Studies Of The Separation And Preconcentration Of Trace Heavy Elements Pb,cd With Mesoporous Molecular Sieve SBA-15 And Determination By Atomic Absorption Spectrometry

Harmful elements in the environment, such as lead and arsenic, can cause great harm to the body and other organisms with the accumulation. It has practical significane and application value to analysis and detection those elements. Mesoporous molecule-sieve was chosen to be studied because its high surface area, large pore size, pore rules, and etc. Mesoporous molecule-sieve SBA-15 firstly has been synthesized and then impregnated, loaded or bonded on the carrier to prepare a new type of adsorbent material which was applied to separate/enrich harmful metal ions, such as mesoporous molecular-sieve Ti-SBA-15 and SBA-15-SH. The separation and concentration behavior of Pb and Cd ions had been studied respectively, and then new methods for analysis and determination by FAAS of trace harmful elements have been established. The methods were simple,accurate,high efficiency,high selectivity and sensitivity. At the same time, the field of mesoporous molecule-sieve applied was enlarged. Contents are as follows:1. The detemination method of harmful elements was reviewed. Meanwhile, the separation and enrichment materials that were commonly used are briefly described. Then the structure, properties, modification and research progress were introduced in detail.2. Mesoporous molecule-sieve SBA-15 was synthesized through using P123 (EO₂₀PO₇₀EO₂₀) as the template, then the product was to be determined by TEM,SEM,IR and BJH. The adsorption characteristics of trace Pb on mesoporous molecule-sieve SBA-15 under static condition were studied. The proposed method has been applied for the determination of trace Pb in mine. The recoveries of Pb ranged from 98.7%¹06.0%. The linear range was 0.05²5.00μg/mL. The detection limit was 35ng/ml, and the relative standard deviation (RSD) was 2.25%. And the method has been appled for determination Pb of 242 standard material of Hunan Province and BYG0211-1 reference material.3. Mesoporous molecular-sieve Ti-SBA-15 has been made for a separation and preconcentration material. The adsorption characteristics of Cd on mesoporous molecular-sieve Ti-SBA-15 under dynamic condition were studied by Flame atomic absorption spectrometry. The linear range was 0.02².00μg/mL.The linear regression equation was A=0.3962·c - 0.0048 (c:μg/mL, r=0.9995). The detection limit was 1.08 ng/mL. The relative standard deviation (RSD) was 2.65%. The method was applied to the determination of cadmium in tap water, lake water of Hua Mei in Xiangtan University and Xiangjiang River water. The recoveries were between 97.3%¹02.9%. The result was satisfactory.4. A new inorganic functionalized mesoporous molecular-sieve SBA-15-SH was made directly. A PTFE micro column packed with mesoporous molecular-sieve SBA-15-SH as a new separation and enrichment material in flow injection (FI) - flame atomic adsorption spectrometry (FAAS) system for the determination of trace Pb. The adsorption characteristics of Pb on mesoporous molecular-sieve SBA-15-SH under dynamic condition were studied, and the conditions for preconcentration of Pb were optimized. The method has been applied for the determination of trace Pb in the Chinese herbal medicine with satisfactory results.