| Magnesium hydroxide and magnesium oxide are important inorganic materials owing to their widely use in medicine, energy, aerospace, food, daily chemical, catalytic, refractory, flame retardant, acid waste liquor and heavy metal removal, smoke desulfurization, and etc. Furthermore, nanoscale magnesium hydroxide and magnesium oxide products have the highest additional value. Along with our country to become the world’s second-largest economic entity, the demand for nanoscale magnesium hydroxide and magnesium oxide will increase to a great extend.In this work, the various morphologies nano-Mg(OH)2and nano-MgO have been obtained by a precipitation method using inorganic magnesium salt as raw materials, ammonia as precipitant, and PEG1000as dispersing agent. In addition, titanium and zinc doped nano-MgO with different dosages have been prepared by calcining precursor magnesium hydroxide at temperature500℃. Then, X-ray diffraction (XRD), X-ray fluorescence spectrum (XRF), X-ray photoelectron spectroscopy (XPS) and transmission electron microscope (TEM) have been applied for characterization of the structure, composition and morphology. The results are as follows:1) Based on the orthogonal experiment results, the optimal conditions for nano-Mg(OH)2preparation are that the concentration of Mg2+is0.2mol/L, reaction temperature60℃, reaction time1.5h, and the ammonia dosage is more than10ml.2) The surfactant PEG plays key role in the morphology, structure and grain size of nano-Mg (OH)2/MgO. Our studies indicate that the best addition amount of PEG1000is0.3～4.0%wt. Nano-Mg (OH)2with needle-like, flake-like and tubular-like can be obtained by controlling the amounts of PEG1000.3) The presence of ethanol has benefit to crystallization and decreasing the average grain size of nano-Mg (OH)2/MgO. But the crystallization performance of product is inferior to that from the water-phase reaction system.4) The doped titanium can inhibit the crystallization of MgO, promote the dispersibility of nano-MgO particles and induce the formation of titanium doped MgO nanotubes when the dosage of titanium is less than3mol%. The Ti4+can replace Mg2+in the channel of MgO lattice to help form the confined substitutional solid solution structure.5) With the content of zinc increases in the zinc doped nano-MgO, the grain size increase under sintering temperature500℃. The XRF, XPS and XRD results show that the Zn2+can replace Mg2+in the channel of MgO lattice to help form the confined substitutional solid solution structure.Based on the above research, the broad-spectrum antibacterial properties of nano-Mg(OH)2and nano-MgO have been studied by using the K-B paper diffusion method and suspension antibacterial experiment systematically. The experimental strains are mainly the multi-and cross-drug resistance bacterias seriously in the clinic. The results show that the nano-Mg(OH)2and nano-MgO have high antimicrobial activity to the Staphyloccocus aureus Rosenbach, Escherichia coli, P. Aeruginosa, Bacillus subtilis, Bacillus thuringiensis and Bacillus cereus. And that, nano-Mg(OH)2and nano-MgO exhibit high antibacterial effect on the gram-positive bacteria than gram-negative bacteria. The broad-specturm antibacteria properties of titanium or zinc doped nano-MgO have also been discussed.Finally, the hemolysis test of nano-Mg(OH)2and nano-MgO have been carried out in vitro for the preliminary biocompatibility evaluation. Nano-hydroxyapatite has also been synthesize and involved in nano-MgO powder to improve its hemolysis rate.The present work will provide important reference basis for the further studies of nano-Mg(OH)2and nano-MgO applications to the biomedical field. |
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