Synthetization Of Novel Adsorbents And Their Adsorptive Properties For Heavy Metal Ions

In recent years, there are many news report focus on that heavy metals are very toxic and pose a threat to man and the environment. The amount of these heavy metals（such as chromium, copper, mercury, lead and cadmium） in our environment increases as a result of industrialization, for example the speed development of mine drainage, machinofacture, chemical manufacturing and electronic instrument etc. Heavy metals not only pollute water source quality, they can also accumulate in crops and aquatic life due to non-biodegradability, finally metal ions accumulate and their amounts are increased to human body along the food chain. Therefore, the accurate determination of trace and ultra trace metals is the most important research for chemical workers. With the progress of technology, many instrument analysis methods possessing higher sensitivity and selectivity have been developed recently. But because the environmental samples are complicated and concentration of analytes is estremely low, pre-concentration of trace elements is still necessary. Currently, solid phase extraction is one of the most convenient, fast and flexible pre-concentration techniques. This paper mainly described the preparation of several adsorption materials which are high selectivity and big adsorbing capacity in order to determine the trace heavy ions in complex samples. At the same time, the adsorption selectivity characteristics for trace heavy metals have been investigated systematically. The more detailed novelty of this research can be categorized as following:1.A new solid-phase extractant, active carbon bound-Rhodamine-Diethylenetriamine（AC-Rh-6G-DETA）, has been synthetized and then it was applied for adsorbing of trace Cr（Ⅲ）, Cu（Ⅱ） and Pb（Ⅱ）. The experimental conditions were optimized with respect to different experimental parameters （pH, adsorbent amount, flow rate etc.） using column procedures in details, the elution condition has also been investigated in order to reach quantitative elution. Through the combination of solid phase extraction and ICP-AES, the proposed method has been established to analyse Cu（Ⅱ） and Pb（Ⅱ） in actual samples.2.In the present study, active carbon bound-Maleic anhydride-o-aminophenol （AC-HPMA） was used as a solid phase extractor for Cu（Ⅱ） ions which determined by ICP-AES. The influences of the experimental parameters including pH of the solutions, amounts of adsorbent, flow rate, eluent concentration and volume on the quantitative recoveries of analyte ions were investigated. The effects of matrix ions in natural waters on the adsorption were also discussed. The detection limit of this method for Cu（II） was0.27ng mL^-1. The prepared sorbent as solid-phase extractant was successfully applied for the preconcentration of trace Cu（II） in nature and certified samples with satisfactory results.3. In this work, halloysite nanotubes （HNTs） were chemically modified with N-2-Pyridylsuccinamic acid （PSA） to produce a new adsorbent （HNTs-PSA） for selective solid-phase extraction of Pb（II）. The new adsorbent was characterized by Fourier transform infrared spectroscopy （FT-IR）, transmission electron microscope （TEM）, thermogravimetric analysis （TGA）, and elemental analysis to evaluate the surface modification. Under the optimized conditions (pH5, flow rate1.5mL min^-1), Pb（II） was retained on the column packed with HNTs-PSA, and then was quantitatively eluted by1.5mL0.5mol L^-1 HC1and determined by inductively coupled plasma-optical emission spectrometry. An enrichment factor of67was obtained using30mg of HNTs-PSA. The maximum static adsorption capacity for Pb（II） is22.8mg g^-1. The detection limits of this method for Pb（II） was0.32μg L^-1. The relative standard deviation under optimum conditions was3.4%（n=11）.