Two-phase Solvothermal Method For Synthesis Of Magnesium-based And Aluminum-based Nanomaterials And Application Of Dye Water Treatment

Magnesium-based and aluminum-based nanomaterials, as important functional nanomaterials, have extensive applications in paint, ceramics, and catalyst and water treatment. Compared to other nanomaterials, the magnesium-based and aluminumbased nanomterials are extensive sources, environmentally friendly and its raw materials much cheaper. Furthermore, magnesium and aluminum elements may form a variety of different uses functional nanomaterials, which makes the magnesiumbased and aluminum-based nanomaterials have a big advantage in practical applications. In recent years, many efforts have been made to prepare different shape and size of the magnesium-based and aluminum-based nanomaterials nanomaterials, and also researched the application in various areas in the future. Previous studies indicated that the property of the nanomaterials can be development by the controlling the morphologies, nanoparticle size and special surface area. Thus,development of different methods to control magnesium-based and aluminum-based nanomaterials of the morphologies, size, composition, surface area can improve material in various aspects of performance. In this paper, firstly, we synthesized of Mg(OH)2 nanosheets and lamellar MgO nanostructures a two-phase solovthermal method and followed by an adsorption-calcination process. The Mg(OH)2 nanosheets and lamellar MgO nanostructures showed a super adsorption capacity for Congo red. Secondly, we have synthesized AlOOH with various morphologies including nanofragments, nanorods, nanoflakes and multiply stacked nanostructures by two-phase solvothermal. The corresponding morphology-preserved Al2O3 products were obtained after calcinations. What’s more, the adsorption properties of the as-prepared Al2O3 products were also investigated. Furthermore, the Mg/Al-LDH nanosheets were obtained by two-phase solvothermal method. At the same time, we also successfully prepared Ti O2/Mg/AlLDH nanocomposites through two-phase solvothermal method and coating method, and also investigated its photocatalytic properties.Firstly, monodisperse Mg(OH)2 nanosheets have been prepared through a twophase solvothermal method with the aid of magnesium nitrate, sodium oleate and sodium hydroxide. The as-prepared Mg(OH)2 nanosheets exhibited high adsorption properties for Congo red(CR) and the maximum adsorption capacity was estimated to be 1820 mg g-1 at the CR concentration of 1000 mg L-1. Moreover, the lamellar MgO nanostructure was obtained by using a subsequent adsorption-calcinations process. The as-prepared MgO nanosheets also showed a superior adsorption property of CR. And the maximum adsorption capacity is as high as 2650 mg g-1 at the CR concentration of 1600 mg L-1. The high adsorption capacity might be related to the particle geometry and large surface area(87.97 m2 g-1 for Mg(OH)2 and 132.31 m2 g-1 for MgO). The adsorbents can be easily regenerated for five times without any significant loss in their adsorption property.Secondly, phase transfer method was developed to prepare boehmite(γ-AlOOH) nanostructures with various morphologies including nanofragments, nanorods, nanoflakes and multiply stacked nanostructures. After calcination, the corresponding aluminum oxide(γ-Al2O3) nanostructures were obtained from the as-prepared γ-AlOOH products and preserving the same morphology. The obtained samples were characterized by several techniques, such as X-ray diffraction(XRD), transmission electron microscopy(TEM) and N2 adsorption-desorption technique. The possible formation mechanism of the precursors has also been proposed. Adsorption experiments indicated that γ-Al2O3 nanorods exhibited better adsorption capacity for Congo red(CR) in contrast to other as-prepared γ-Al2O3 nanostructures and commercial alumina(Al2O3), and the adsorption obeyed well to Langmuir isotherm model. Besides, the adsorption kinetics followed pseudo-second-order rate equation.Last, the Mg/Al-LDH nanomaterials with various morphologies have been synthesized by two-phase solvothermal method, and subsequent the hydrothermal method and coating method was followed to obtain TiO2/Mg/Al-LDH nanomaterials. The morphology and structure of the as-prepared products were characterized by Xray diffraction(XRD) and transmission electron microscopy(TEM). At the same time, the factor in synthetic process of reaction temperature, reaction time, reaction pH and Mg/Al ratio were investigated to reveal the influence on the morphology and structure of the products. And then, the photocatalytic performance of the as-prepared TiO2/Mg/Al-LDH naomaterials was carried out by the degradation of the methylene blue. The results indicated that the TiO2/Mg/Al-LDH naomaterials exhibited the superior photocatalytic performance.