Preparation Of Molecular Imprinting Adsorbent And Studies Of Adsorption For Heavy Metal Ions In Traditional Chinese Medicine

The event of heavy metals for Traditional Chinese Medicine(TCM) had been reported by media since the1990s.It becomes the international medical sensitive topic and seriously damaged the imaging of Chinese medicine. The harm of heavy metals in Traditional Chinese Medicine has aroused widespread concern, so the purification of heavy metals in Traditional Chinese Medicine became a hot research. The methods of removing heavy metals in Traditional Chinese Medicine have supercritical carbon dioxide extraction, membrane separation, adsorption separation and so on. But the advantages for adsorption method are cheaper materials, low cost, the high removing rate.Using the surface molecular imprinting technology, a new molecular imprinting adsorbent based on diatomite with the Pb2+as imprinted ion was prepared. The preparation technological conditions were studied. The sorbent was characterized by using scanning electron microscope (SEM) and FIIR spectrum. It could be deduced from the SEM that PbCSDE had a materially denser. FIIR spectrum indicated that PbCSDE was cross-linked by ECH.The new chitosan imprinting biosorbent using diatomite as core material (PbCSDE) could provide a higher adsorption capacity for Pb2+, which reached139.6mg/g increasing32.3%compared with chitosan adsorbent (CTS)(the initial Pb2+concentration of600mg/l). The adsorption velocity was quickly and the equilibration time of the imprinting adsorbent for Pb2+was3h that shortened about40%compared with CTS. The molecular imprinting adsorbent can be reused for up to10cycles without loss of adsorption capacity. It had a more wide pH range of5-7than that of CTS. In the kinetics study, the pseudo-second order model could represent the adsorption process. In the isotherm study, the experimental results showed that the adsorption of Pb2+onto PbCSDE could be described by Langmuir equation.Then study the adsorption properties for heavy metal ions in water-extraction liquid of Rhodiola L. The effects on adsorption ability such as adsorption time, pH value of the initial solution were investigated. Adsorption of lead and copper ions on PbCSDE was as much as2times higher than the value on732resin. PbCSDE has a certain ability of removing heavy metal ions for Rhodiola, Salvia Miltiorrhiza, Radix Astragali, Radix Glycyrrhizae, Padix Paeoniae Alba. The removal rate were about60～70%.Finally, the influence of adsorption on salidroside was analyzed by the FTIR, UV spectra and HPLC. The results revealed that the salidroside in the water-extraction liquid of Rhodiola L. did not change after adsorption.The adsorbent was a low-cost, environment friendly material and greatly reduce the cost of production with adding a certain amount of diatomite. Its spherical appearance increases the adsorption capacity and enables the practical application. PbCDE could remove of the low concertration heavy metal ions in TCM.