Preconcentration Of Trace Heavy Elements Pb, Cd, Cu With Mesoporous Molecule-sieve MCM-41 Prior To Determination By Atomic Absorption Spectrometry

On the basis of numerous references, owing to the characteristic of its structure and aperture, mesoporous molecule-sieve MCM-41 had been self-made as a new adsorbent material. A new sensitive, efficient and rapid method for the determination of trace lead, cadmium and copper with atomic absorption spectrometry was proposed. The major contents described as follows:1. This paper introduced the determination method of heavy metals in recent years. And the materials and methods of separation/concentration of trace heavy metals in use and research were reviewed. The structure and characteristic of mesoporous molecule-sieve, synthetic method and its biosorption of metals were expounded. Mesoporous molecule-sieve as separation/preconcentration material on adsorption of heavy metal ion was advanced.2. A new functiontalized mesoporous material Ti-MCM-41 was prepared by self. Then the characterization of the synthesized material was performed by TEM, SEM and BJH. The adsorption property of trace lead ions on mesoporous material Ti-MCM-41 were studied under optimal the conditions. The static adsorption capacity was 5.0 mg/g. The linear range for lead was 0.5²0μg/mL, detection limit (3σ) of this method for lead was 3.3 ng/mL. The RSD was 4.05%. The recoveries of Pb²⁺ ranged from 97.1% to 99.5% in determination materia medica samples with satisfactory results.3. A new functiontalized mesoporous material Al-MCM-41 was prepared by self. Then the product was to be characterized by SEM and IR. The adsorbent material with mesoporous material Al-MCM-41 was used to determine trace lead in water. The optimal conditions of adsorbing and desorbing on mesoporous Al-MCM-41 material for Pb²⁺ were investigated. The dynamic adsorption capacity was 6.0 mg/g. The calibration curve showed that there was a good linearity in the range of 0.5³0μg/mL, and after preconcentration it was a detection limit of 0.05 ng/mL (3σ). The RSD was 1.20%. The recoveries of Pb²⁺ ranged from 98.9% to 103.9%. It is satisfied with the determination of trace lead in environment water.4. A new method for determination of trace copper in the Chinese herbal medicine based on mesoporous Al-MCM-41 separation/preconcentration with FAAS was proposed. The experiment conditions were researched, such as effect of pH, temperature, time and interfering ion. The static adsorption capacity was 5.0 mg/g.The linear range for trace copper was 0.5²0μg/mL, detection limit (3σ) of this method for lead was 0.55 ng/mL. The linear equation was A = 0.1347·c (μg/mL) + 0.0454. The RSD was 1.16%. The recoveries of Cu²⁺ ranged from 98.5% to 100.3% in determination Chinese herbal medicine.5. A micro column packed with mesoporous material Ti-MCM-41 had been developed for on-line separation and preconcentration trace of cadmium by flame atomic absorption spectrometry. The optimal conditions of adsorbing and desorbing on mesoporous Ti-MCM-41 material for Cd²⁺ were investigated. The linear range for cadmium was 0.5⁵μg/mL, detection limit (3σ) of this method for lead was 0.06 ng/mL. The RSD was 1.80%. The recoveries of Cd²⁺ ranged from 97.3% to 101.6%. It is satisfied with the testing of trace Cd²⁺ in environment water.