Preparation Of Novel Functionalized Materials As Solid-phase Extractant And Application For Preconcetration And Separation Of Trace Metal Lons In Environmental Samples

The wide application of information technology and continuous introduction of the new achievements of mathematics, physics, life science and material science, greatly enriched the content of modern analytical chemistry. Modern analytical chemistry is a science far more than an analysis method to make the determination of the chemical composition and concentration of substances. It has also extended to chemical information science, and to interdisciplinary science of biochemical, physical chemistry, environmental chemistry. The industry development and continuing population growth brought enormous pressure to the environment, the ecosystem was badly destroyed. In this paper, an idea of "green", as well as dependent content and a concept of "green chemistry" will be integrated into this topic, mainly aiming at soil and water environmental pollution problems of heavy metals, we prepared and synthesized several novel functionalized materials as solid-phase extractants, and made systematic investigation on the preconcentration and separation property of trace heavy metal ions from environmental samples. We hope it can provide certain theory basis and direction for design to solve the problem of heavy metals pollution.1. A new nanometer silicon dioxide (SiO2) modified with5-Methylbenzotriazole (MBTA) as a solid phase extractant was used for simultaneous preconcentration and separation of trace lead(II) and mercury(Ⅱ) in aqueous solution prior to the measurement by inductively coupled plasma optical emission spectrometry (ICP-OES). Static and dynamic procedures were used to carry on the investigation of adsorption and desorption behavior for lead(Ⅱ) and mercury(Ⅱ), including the pH value, time of kinetic equilibrium and flow rate, the sample volume and enrichment factor, the elution conditions and the interfering ions. The maximum static adsorption capacity of the sorbent for lead(Ⅱ) and mercury(Ⅱ) at optimum conditions has been found to be37.6μg mg-1and30.3μg mg-1, respectively. The detection limit (3σ) of this method for lead(Ⅱ) and mercury(Ⅱ) was0.28 ng mL-1and0.19ng mL-1, respectively. The relative standard deviations (R.S.D.s) of the method under optimum conditions were lower than3.0%. The proposed method achieved satisfied results when it was applied to the determination of trace lead(II) and mercury(II) in certified reference material, biological and water samples.2. A new sorbent4-(8-hydroxyquinoline azo)benzamidine-modified activated carbon was synthesized. The sorbent was used for preconcentration and separation of trace amounts of Pb(Ⅱ) in environmental samples by solid-phase extraction prior to the measurement by ICP-OES. The effects of pH, shaking time, eluent concentration and volume, sample flow rate and potential interfering ions were studied. Under the optimum conditions, the enrichment factor was100, the detection limits (3σ) is0.43ng mL'', and the relative standard deviation (R.S.D.) was1.7%(n=8). The adsorption capacity of the sorbent is53.58mg of lead(Ⅱ) per gram of the material. The prepared sorbent was successfully applied for the preconcentration of trace Pb(Ⅱ) in the reference materials GBW08301(river sediment) and GBW08302(Tibet soil) with satisfactory results. The determined recovery of lead(II) from Yellow river water, Huangshui water, and tap water is in range of99.3-101.6%.3. Preconcentration and separation of erbium ions onto activated carbon functionalized with o-Methoxy benzoic acid diethylenediamine from environmental samples has been investigated. Optimal conditions have been established, including value, adsorbent mass, shaking time, flow rate and conditions of complete elution. The adsorption of other rare earth ions has been measured under specified conditions to evaluate the selectivity. The maximum adsorption capacity was47.27mg g-1for Er(III). The adsorption of erbium ions complied with both Langmuir and Freundlich isothermal equations well in the concentration range studied. The effect of different anions and cations on the adsorption of erbium ions has also been examined. The detection limit (3σ) of method for Er(Ⅲ) was0.35ng mL-1. The relative standard deviation (R.S.D.) of the method was2.1%. The adsorbent possessed high analytical potential for preconcentration of trace Er(III) from standard reference materials and real samples.4. Two solid-phase adsorbents (phase Ⅰ and phase Ⅱ) were synthesized successfully that o-Anisic acid derivatives were evenly modified on the surface of activated carbon. It was certified that two adsorbents were applied to preconcentrate and separate trace levels of Pb(Ⅱ) and Fe(Ⅲ) from natural liquid samples with satisfactory results. It can be found that the adsorption capacity of the ions adsorbed on phase I and phase II was48.3and85.7mg g'for Pb(II),39.5and72.5mg g-1for Fe(Ⅲ), respectively. The detection limit (3a) of the method separated on phase Ⅰ and phase Ⅱ was0.12and0.09ng mL-1for Pb(II),0.23and0.17ng mL-1for Fe(Ⅲ), respectively. The relative standard deviations (R.S.D.s) of the method were lower than3.0%.The adsorption and desorption property of two kinds of adsorbents was comparatively studied, respectively. The adsorption selectivity of heavy metal ions at certain pH, the adsorption kinetics, the condition of complete elution, the effect of coexisting ions, the adsorption capacity and adsorption isotherm modes were examined. Based on the experimental datum determined by inductively coupled plasma optical emission spectrometry (ICP-OES), it was certified that the adsorption on the surface of adsorbents was in strict accordance with the monolayer adsorption principle. The structural features of series of multi dentate ligand modified on adsorption matrix had been obtained. These conclusions can provide reference for synthesizing an efficient adsorbent which is specific to remove a particular kind of contaminant.5. Ferrite magnetic particles were synthesized in the best condition, of which the surface was successfully modified by zincon after coated with SiO2, and the new prepared adsorbent was applied to preconcentration and separation of trace Cr(Ⅲ). The adsorption capacity was15.2μg mg-1, the detection limit (3σ) of method for Cr(III) was0.09ng mL-1, and the relative standard deviation (R.S.D.) of the method was2.6%. Using magnetic particles as adsorbent matrix, it was obvious that the advantages were prominent, such as, fast and simple separation process, quick dynamic equilibrium, etc. Compared with other related reports, this new adsorbent could adsorb metal ions in lower pH value solution, which increased the extent of practical application range. The higher selectivity and adsorption capacity also highlighted its excellent adsorption performance and greatly improved its application value.