The Preparation Of Nano Sulfur In Liquid Phase And Its Bioactivity In Ionic Liquid

Sulfur is a nonmetallic element necessary for life. Sulfur nanoparticles display unique physical and chemical features because of effects such as the quantum size effect, mini size effect, surface effect and macro-quantum tunnel effect. So sulfur naoparticles would present higher efficacies such as removal of heavy metals, radical-scavenging, antimicrobial activity, antioxidant and antitumor activities。In this thesis, two methods were employed in the synthesis of sulfur nanoparticles in aqueous phase. One is the acid reduction of sodium thiosulfate, the other is the decomposition of sodium polysulfide. The amino acids were used to modify nano sulfur produced. The morphologies, particle sizes and stability of nano sulfur in liquid phase were characterized and discussed. To study the bioactivity of nano sulfur, the ionic liquid was used as the medium, and the interaction of sulfur with copper(Ⅱ) ion was studied. Finally, the antimicrobial activity of the S-Cu complex in ionic liquid was studied. The results are as following:1. Preparation of sulfur nanoparticles by the decomposition of sodium thiosulfate.With the sodium thiosulfate as the sulfur source, the amino acids as the surface modifier, and the ascorbic acid as the acid reagent, the sulfur nanoparticles were prepared. The resonance rayleigh scattering (RRS) was used to study the stability of sulfur nanoparticles in liquid phase. The laser light scattering (LLS) and the transmission electron microscope (TEM) were used to characterize the size distribution and morphology of the product. The results show that, the acidic amino acids acted better in the preparation of nano sulfur. It served as the surface modifier and the acid reagent. The produced nano sulfur had a spherical morphology with uniform particle size(50-100 nm).2. Preparation of sulfur nanoparticles with the decomposition of polysulfide.The sulfur nanoparticles were prepared by using sulfur powder as original material, acetic acid as precipitating agent, and the amino acids as the surface modifier. The modulation and stabilization effect of amino acids on the nano S0 was studied. The laser light scattering (LLS), resonance rayleigh scattering (RRS), and transmission electron microscope (TEM) were used to characterize Nano S0. The results showed that amino acids could modulate and modify the surface of nano S0.The sulf-amino acids (methionine and cytine) modified nano-S0 better. The sulf-amino acids-nano-S0 kept stable in one month and the diameters were smaller than 250 nm. The morphology was spherical.3. Interaction of sulfur with copper(II) ion in ionic liquid.At 200℃, the interaction of sulfur with copper(II) ion was studied. The ionic liquid [bmim]BF4 was used as the medium. FTIR, Raman spectroscopy, and UV-Vis spectra were used in the characterization of the product. Under high temperature conditions, the sulfur atomized and activated, which made the chemical adsorption of copper(Ⅱ) ion possible in ionic liquid.4. The antimicrobial activity of the S-Cu complex in ionic liquid.A typical gram-negative bacteria(Escherichia coli) and a typical gram-positive bacteria(Staphyloccocus aureus Rosenbach) were selected as the test strains. The Inhibition zone method was used to test the antibacterial activity of the product. The results showed that the the S-Cu(Ⅱ) complex in ionic liquid had better antimicrobial activity against Staphylococcus aureus.