Preparation and Adsorption Properties for Methyl Orange of Highly Dispersed Boehmite and Alumina Nanostructures

The nano boehmite (gamma-AlO(OH)) was synthesized by template-free hydrothermal method with aluminum nitrate as the aluminum source and urea as the precipitant. The final products aluminum oxide (gamma-Al2O3 and theta-Al2O3) were obtained by calcined at different temperatures. The products were characterized by X-ray diffraction (XRD), field emission scanning electron microcopy (FESEM), transmission electron microscopy (TEM), Fourier transfer infrared (FTIR), nitrogen adsorption-desorption method and UV-visible Spectrophotometer (UV-Vis). The adsorption properties of the product for methyl orange (MO) was studied, and the effect of adsorption time, pH value of the solution, methyl orange concentration and recycling on the adsorption performance of the products systematically were investigated. In addition, the adsorption theory studies on the adsorption process was conducted. The results showed that the products obtained by this method are more dispersible, uniform and complete in morphology compared to the products prepared by other methods. The products were highly dispersed nano-bundled structure. The maximum adsorption of gamma-AlO(OH) on methyl orange reached 1 492.5 mg.g(-1). The adsorption mechanism of the products includes chemical adsorption mechanism, electrostatic adsorption mechanism and so on. The adsorption of MO on the three products accord with the Langmuir monolayer adsorption model, and the adsorption process are consistent with the pseudo-second-order kinetic.