Green Synthesis Of Nano-and Micro-Inorganic Materials

The plant and its lixivium, extract have been used to prepare nano-and micro- inorganic materials. Compared with the traditional chemical synthesis, this method has many advantages such as simple operation, mild reaction, and non-toxic by-products, and the raw materials are cheap and available. And the materials prepared by this method have biocompatibility. So it is a green synthesis method of preparing nano-and micro- inorganic materials, now the method has attracted many attentions. In this paper we use spinach, capsicum annuum L and garlic sprouts as reactants or templates to prepare nano-and micro-calcium oxalate crystal, PbS crystal, selenium and silver/protein biocomposites at room temperature under ambient pressure. The influencing factors of reaction and the possible formation mechanism of nano-and micro-inorganic materials are also studied and discussed in this paper. The main contents of this thesis are as follows:1. Oxalic acid is rich in spinach. When the roots and leaves of spinach were put into the solution of calcium ions, calcium oxalate crystals could be synthesized directly. The oxalate ions from the root spinach was confirmed by inhibitory kinetic test, and the calcium ion selective electrode was used to detect the concentration changes of calcium ions for tracking the reaction kinetics process. The reaction products were confirmed by transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), Capillary Electrophoresis (SDS-PAGE). The results indicated that spindle and the rod-like crystals of calcium oxalate monohydrate (COM) and calcium oxalate dihydrate (COD) were formed mainly when root and leaf extract of spinach reacted with calcium ions; fractal pattern of polycrystalline aggregates composed of small spherical panicles were appeared in the inner leaves of spinach. Increasing the concentration of calcium ions, the content of COM crystal increased significantly. When the broth of spinach leaf reacted with calcium ions, cube-shaped COD crystals mainly formed, which suggested that soluble and insoluble proteins, from different parts of spinach with different polar groups, might play different roles in inducing and controlling crystal growth.2. The Capsicum annuum L extract contains a lot of biomolecules such as protein/enzymes, polysaccharide, amino acids and vitamins, et al, which would be used as both reductants and templates to react with SeO₃²- and Ag+ ions to directly form cx-setenium, silver/protein biocomposites. The reaction process was monitored by ultraviolet-visble spectroscopy (UV-vis), and the reaction products were characterized by Raman spectroscopy,â…©-ray photoemission spectroscopy (XPS), selected area electron diffraction (SAED), electron spectroscopy (ED), FT-IR, XRD, TEM. differential spectrum technique. Relatively uniform size spherical silver nano-composite particles with diameter of about 12nm were formed in Ag+ ions reaction solution. With increase of reaction time, the spherical Ag nanoparticles transformed from potycrystalline to single crystal, and the size of particles gradually increased to 40 nm. Hollow spherical amorphous selenium was formed in reaction solution of SeO₃²- ions, and the size of cx-Se/protein composite particles increased with the concentration of extract, but decreased with the increase of pH value. FT-IR spectra showed that biomolecules such proteins in above solutions not only played reductant and the template roles, but also took part in the formation of cx-Se, Ag/protein biocomposites. A recognition—reduction limited nucleation and growth model was suggested to explain the possible formation mechanism of Ag/protein biocomposites. Materials prepared using this green synthetic method have good biocompatibility and show potential applications.3. Garlic sprout has the capacity of enriching Pb2+ ions in water, and its roots have refined natural holes. Nano-and micro- PbS crystals were prepared by using garlic sprout template. SEM and TEM images showed that hexagon-shaped crystals formed within garlic roots; Cone and caky crystal formed on outer surface of root; flower-like crystal formed on outer stem surface of garlic sprouts, and polyhedron crystal presented in inner of garlic sprouts. And different dendritic crystal formed in reaction solutions. The changes of FTIR spectra revealed the proteins from different parts of garlic sprouts played different inducing roles in crystal growth. XRD patterns showed that the cubic phase crystal growth mainly paralleled with (111) plane of PbS, and the crystal growth presented on the garlic sprouts mainly paralleled with (220) plane. Fluorescence spectroscopy (PL) showed PbS crystals prepared in this system also had well luminescence properties. Meanwhile, this experiment also provided a new lnethod of treating plants which were used to absorb heavy metal ions from sewage and polluted soil and changing the wastes to treasures.