| In the process of modernization and internationalization of traditional Chinese medicine (TCM), we have experienced a series of misrable events, in particular, many events of heavy metals excess in TCM happened since the 1990s are impressive. Although most of these events are out of technical barriers, they indeed lead to the downgrade of TCM in international medicine market, thus affecting international reputation. Therefore, how to solve the problem of heavy metals excess triggers wide attention and research by demostic scholars, wherein the technique for selectively absorbing or extracting TCM heavey metals by using coordination chemistry principle is one of the hot spots. Since TCM effective components are complicated, we must remove the harmful elements in TCM while keeping effective components not lost or lost less. To reach this goal, chelated fragment selective for harmful elements is bonded to a certain material, and this material does not absorb effective components or absorb less. Silica gel, having this property, loses its absorption capability after water content exceeds 17%, acts as carrier only (while macroporous organic resin, active carbon and etc. can't meet this requirement), and hydroxyl group on the silica surface can be modified.Chelated fragment is bonded on the surface of silica gel via chemical bond Si-O-Si-C by silanization reaction (the end of the chelated fragment includes-SH,-NH2 and nitro-containing heterocycle), and nine modified silica gels are synthesized, wherein five silica gels have known structures and others have new structures. The structures of the modified silica gels are characterized by FT-IR spectroscopy, elemental analysis, N2 adsorption/desorption measurement, and X-ray diffraction. The results show that chelated fragment is successfully introduced to the surface of silica gel, and the chemical bonding cause no obvious change of microcellular structure order of silica gel carrier.The adsorption capacities of the nine modified silica gels toward eleven metal ions are measured in buffering solution with pH 1.0,4.0 and 6.0 using batch equilibrium adsorption experiments. Results show that y-mercaptopropyl-modified silica gel (MPS) has high adsorption capacities toward heavy metals Pb2+, Cd2+, Cu2+, Hg2+ and low ones for beneficial elements Fe2+, Fe3+, Mn2+, meaning MPS is capable of selectively absorbing heavy metal ions. Partition ratio tests further show that MPS has preferable selectivity for the above four heavy metals, making it possible to use MPS as optimal adsorption material for heavy metal ions. Taking Pb2+ for example, the adsorption rate is fast and the adsorption isotherms fits to Langmuir equation, the optimal adsorption pH value is 6.0, the maximum adsorption capacity is 0.523 mmol·g-1 (108.4 mg·g-1), and the spent MPS can be regenerated using 0.1 N HC1. y-Mercaptopropyl-modified silica gel (MPS) is applied to remove plumbum ion from the extract of Lonicera japonica Flos. The static and dynamic adsorptions were used to investigate the removal efficiency of plumbum ion. The solid content and HPLC profiles of the extract were determined to evaluate the process changes. The static adsorption experiments show that MPS has fast adsorption rate and more than 80% removal efficiency toward plumbum ion. The dynamic adsorption has better plumbum ion removal effect than the static adsorption, when the concentration of plumbum ion in the extract of Lonicera japonica Flos is 1.04μg-mL-1, the optimum parameters were as follows:6 BV of sample volume, the optimum parameters were as follows:6 times of raw materials,10 times of height to diameter, and 6 BV·h-1 of flow velocity, at the temperature of 25℃. During the removal process, obvious changes of solid content and HPLC profiles were not observed. MPS can also be used for removing plumbum ion from extract of Qingcha compound. The results show that MPS can effectively remove plumbum, with the removal efficiency of 74.6%, compared with unmodified silica gel (SG). During the removal process, there were no obvious change of solid content (only 2.6% loss) and comparability of HPLC profiles (similarity is 0.976). Therefore, MPS can selevtively remove plumbum in TCM solution with the effective components being reserved, thus realizing the objective of the expriments.In order to get stable production process and controllable quality, the process optimization, quality standard and stability of MPS were studied. The result shows that the thiol group (-SH) content of MPS can reach 600μmol·g-1(2.0%). Stable production research test shows that MPS is stable under room temperature, and-SH on the surface is hard to be oxidized.Finally, based on the adsorption regularity of MPS for removing plumbum ion in Lonicera japonica Flos, and the assumption that the dynamic adsorption process can be converted into successive static adsorption process and plate adsorption process, expressions for dynamic adsorption process are deduced. Firstly, plumbum removal efficiency which not only proves that dynamic adsorption can remove heavy metal completely in theory (x goes to 100% while n is infinite), but also reflects the relations between main process parameters. Secondly, WHM=WAbs×Q0/2, which is used for evaluating the adsorption ability of modified silica gel, and provides foundation for dosage of modified silica gel.In this paper, modified silica gel is used as the adsorbent, for removing plumbum ion in extract of TCM. Effective components are reserved, and heavy metals are selectively removed. Hence, this paper provides an example of applying modified silica gel to TCM heavy metal removal, and also a novel method for developing TCM heavy metal removal technique.
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