Controlled Synthesis Of Magnesium Oxide New Materials And Its Adsorbtion Performance Study

Magnesium oxide has been widely applied in many fields including semiconductor devices,refractory,high temperature superconducting products and catalysts,due to its typical wide band gap insulator with a band gap of 7.8 e V,thermal stability and surface alkaline.In recent years,numerous studies have demonstrated that the performance of MgO is highly influenced by its morphologies.But the reports of magnesium oxide morphology and its adsorption performance relationship are very rare.In order to explore the relationship between different morphologies of magnesium oxide and its adsorption performance,in this thesis we mainly make the following work:First of all,mesocrystal magnesium oxide?MgO?parallelogram with lengths of diagonal line in the range of 7-9 ?m has been synthesized by precipitation method using Mg?NO₃?₂·6H₂O and Na₂C₂O₄ as raw material,trace amount of sodium tripolyphosphate as the morphology regulator.At the same time,the effect of reaction conditions such as the types and addition amount of phosphate species and the reaction temperature on the morphologies and components of the resulting products was studied in detail.The results demonstrated that the introduction of trace amounts of phosphate species in the reaction system played a crucial role in determining the morphologies of the obtained products,it made the morphologies of MgO changing from trapezoidal to parallelogram,in which there is a canyon resulted from the self-assembly of layerlike structures in the middle of the diagonal line of the as-synthesized product.Whereas their components have little been influenced.After systemically investigated,it has been found that the aging time and the introduced time as well as the amount of sodium tripolyphosphate have great effect on the shape evolution of magnesium oxalate dihydrate?MgC₂O₄·2H₂O?.In addition,the evolution of the surface structure and physicochemical properties of trapezoidal MgO particle with calcination temperature were systemically investigated.The results demonstrated that with the increase of calcination temperature,the surface of MgO changed from smooth to roof,at the same time its crystal structure evolved from amorphous to polycrystal and finally to cubic single crystal.On the basis of above investigation,a new method has been developed for synthesis of MgO precursor by changing the ratio of two basic precipitation reagents in the reaction system of Mg?NO₃?₂·6H₂O and Na₂C₂O₄/K₂CO₃,and found that the ratio of two basic precipitation reagents had great effect on the morphologies MgO precursor.The adsorption performance of as-synthesized MgO was evaluated by using Congo red,when the ratio between Na₂C₂O₄ and K₂CO₃ was 1:4,the resulting MgO demonstrated the superior adsorption ability to Congo red aqueous solution.Different morphologies of MgO including trapezoidal,needle-like,flower-like and nest-like structures were prepared by a facile precipitation method.The as-obtained MgO particles as the coating material and corn starch as the adhesive agent,then coated onto the surface of filter paper via vacuum filtration strategy.The coated papers with different morphologies of MgO were used as the substrates for paper spray mass spectrometry to explore the interactions between different morphologies of MgO and therapeutic drugs.Through investigating the interactions between different morphologies of MgO coated papers and therapeutic drugs,it demonstrated that in contrast to the trapezoidal,needle-like and nest-like MgO coated papers,different drugs in dried blood spots?DBS?were more favourably eluted off from the paper coated with flower-like MgO due to its weaker surface basicity.Also,the signal intensity of different drugs during paper spray was highly dependent on their elution behaviours.It illustrated that the surface adsorption of MgO closely related with its morphology.