Adsorption Mechanism Of Copper (â…¡) On Sulfur Micro/nano Particles And Their Antibacterial Activity

The sulfur and sulfur-containing compounds have the unique biological activity. 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 nanoparticles would present higher efficacies such as removal of heavy metals, radical-scavenging, antimicrobial activity, antioxidant and antitumor activities. In this thesis, the interaction of sulfur with Cu(â…¡) was studied in two systems:ethanol-water solution and PEG400-water solution. The modification and modulation of amino acids on elemental sulfur (S0) nanoparticles in liquid phase were studied. Finally, the antimicrobial activity of the S and S-Cu complex was studied. The results are as following:Sulfur was dissolved in ethanol and employed as an adsorbent for Cu(â…¡) under ultrasonic. The results showed that the sulfur microparticles adsorbed Cu(â…¡) by weak complexing action and attained equilibrium at 25 min; the diffusion rate at the interface between solid and liquid phases determined the overall adsorption rate. The adsorption rate was determined by the concentration gradient(c0-ce). Increasing initial metal concentration resulted in an increase in adsorption capacity of the sulfur microparticles. Freundlich isothermal model could be used to describe the adsorption behavior.The sulfur was dissolved in PEG400 and employed as an adsorbent for removing Cu(â…¡) from aqueous solution. The results show that the adsorption behavior conforms to the pseudo-second-order dynamics equation, confirming that the adsorption process is controlled mainly by chemical sorption. The adsorption isotherms of the Cu(II) on the sulfur microparticles indicate that Langmuir isotherm equation gives better fit than Freundlich isotherm, confirming that the adsorption for the Cu(â…¡) is monomolecular layer form.The modulation and stabilization effect of amino acids(cystine, cysteine, methionine, glycine, serine, aspartic acid, phenylalanine, arginine, histidine, proline) on S0 nanopartilces has been studied, and eleven amino acids modified nanosulfur sols (Amino Acid-nanoS0) were prepared. The results show that the amino acids play a key role in determining the morphology of sulfur nanostuctures. The sulfur-containing amino acids were found to be useful for nanoS0 to show stable dispersion in liquid phase.The antibacterial activity of the nanoS0 and S-Cu complex was studied by the agar diffusion method. A typical gram-negative bacterium (Escherichia coli) and a typical gram-positive bacterium (Staphylococcus aureus) were selected as the test strains. The results demonstrated that Met-nanoS0 and S-Cu complex could evidently inhibit the growth of Escherichia Coli, but they couldn't inhibit that of Staphylococcus Aureus.