Proporty Of Functionalization Materials For Preconcentration And Separation Of Trace Metal Ions

With the rapid development of proceeding industrialization and economic technolog, a lot of heavy metal ions discharged into the environment, such as air, rivers and ect,. Therefore, how to measure accurately the heavy metal ions in the soil, biological and environmental samples become the major challenges for the analytical chemists. Direct determination of trace elements at low concentrations by modern atomic spectrometric techniques is often difficult, not only because of the insufficient sensitivity of the methods, but also because of matrix effects. In order to accurately measure, the preliminary separation and preconcentration of trace elements from matrix is often required. The solid-phase extraction (SPE) is today the most popular sample preparation method in the field of separation and preconcentration of trace elements. SPE presents several major advantages, including (i) simple to operate;(ii) rapid phase separation;(iii) high preconcentration factor. Our main works are focused on the synthesis of new adsorption material, and applies them in the solid phase extraction. At the same time, we explored the enrichment and separation of trace metal ions and determination of the system. The adsorption selectivity characteristics for trace heavy metals have been investigated systematically.1. A new functional monomer-3-(N-maleic acid amide) triethoxysilane was obtained by silica gel surface imprinting technique. Th (IV)-imprinted silica gel adsorbent was synthesized and used for selective solid-phase extraction (SPE) of Th (IV) prior to ICP-AES studies. The maximum static adsorption capacity of Th (IV) on the imprinted adsorbent was21.6mg g-1and the non-imprinted adsorbent was11.4mg g-1. Compared to non-imprinted sorbent, the distribution of imprinted adsorbent for Th (IV) was lager, and the relatively selectivity factor (αr) of Th(IV)/U(VI) and Th(IV)/Zr(IV) was158and14, respectively. At PH3, the adsorbent achieved quantitative adsorption under the conditions of50mg imprinted adsorbent and2mL of min-1flow rate. The adsorbed Th (IV) could be quantitatively eluted by2mL of1mol L-1HCl. The maximum volume was150mL corresponding to the maximum enrichment factor of75. The method presented high precision and lower detection limits. It was applied to determine trace Th (IV) in the actual samples with satisfactory results.2. A new sorbent N-2-Pyridine kima to amic acid-modified activated carbon (AC-MAMQ) was prepared as a solid phase extractant. Under the selected conditions, the new adsorbent was applied for efficient enrichment and separation of trace Cu(II) in aqueous solution. The separation/preconcentration conditions of analytes were investigated, including effects of pH, the shaking time, the sample flow rate and volume, the elution condition and other conditions. The results showed that the adsorbent achieved quantitative adsorption at pH4, and the maximum static adsorption capacity of Cu(II) on the AC-MAMQ was14.6mg g-1. Studies have shown that several common metal salts, such as NaCl, NaNO3, KBr, NaAc, NaH2PO4, Na2SO4, CaCl2and MgCl2did not interfere with the separation. The adsorbed Cu(II) could be quantitatively eluted by1.5mL0.5mol L-1HC1solution. The detection limit (3σ) of this method for Cu(II) was0.16μg L-1. The relative standard deviation under optimum conditions was2.6%(n=11). The new adsorbent was applied for the preconcentration of trace Cu(II) in actual samples with satisfactory results.3. Melamine loaded activated carbon (AC-MA) as a solid phase extraction adsorbent has been developed for simultaneous preconcentration of trace Cd (II), Cr (Ⅲ) and Cu (Ⅱ) prior to the measurement by ICP-AES. The results showed that the maximum adsorption capacity of the new adsorbent for Cd (Ⅱ), Cr (Ⅲ) and Cu (Ⅱ) was16.96mg g-1,31.80mg g-1and57.48mg g-1in the optimization of the acidity (pH=4), respectively. The adsorbed metal ions were quantitatively eluted by2mL of0.5mol L-1HCl. Common coexisting ions did not interfere with the separation and preconcentration of the target ions. The detection limits (3σ) of this method were Cd (Ⅱ)2.19ng mL-1, Cr (Ⅲ)1.96ng mL-1and Cu (Ⅱ)1.31ng mL-1. The relative standard deviation under optimum condition is less than3.8%. The method has been applied for the determination of trace Cd (Ⅱ), Cr (Ⅲ) and Cu (Ⅱ) in the Yellow River water and tap water with satisfactory results.