Preparation Of Mg/Al Layered Double Hydroxides And Study On Its Capability Of Color Removal From Dyes Aqueous Solution

For the first time, Mg/AI layered double hydroxides is prepared hydrothermal by perfect mixed spraying reactor using industrialization equipment and the stuff is industrial magnesium sulfate, aluminum sulfate, sodium hydroxide, sodium carbonate. It finds that this new function material of magnesium family can remove color efficiently.Results show that it is possible to prepare Mg/AI layered double hydroxides with perfect crystal, little impurities and symmetrical particle size, by perfect mixed spraying reactor utilizing cheap industrial stuff if the stuff is taken at appropriate ratio, the pH value controlled between 8 and 9 and the crystal grains are thermally crystallized for 24 hours at 130℃ in a large-scale retort.Different instruments such as XRD, TG-DTA, IR et al are used to characterize . the chemical component, crystal structure, thermal decomposition, specific surface area and particle distribution of the prepared sample. Results indicate that the sample's crystal structure and character accord with Mg/AI layered double hydroxides, formula is Mg6Al2(OH)16CO3·4H2O, specific surface area is 81.4 m2/g, pore volume is 0.47mL/g, average particle diameter is 11.1 μm. The molar proportion of magnesium and aluminum in prepared sample is the same as that of taken stuff. After the sample is calcined at 500℃, the specific surface area is 113 m2/g and the pore volume is 0.85 mL/g, they are large than before it is calcined. There are two stages in the process of thermal decomposition. The crystal water is lost on the first stage with the weight decreeing 11.6%. On the second stage, Mg/AI layered double hydroxides' hydroxyls and carbonate are eliminated, the weight reduces 29.8%, at the same while, magnesia and spinel are formed. The lost weight is consistent with the theoretic value.After studying the color removal capability of Mg/AI layered double hydroxidesand the calcined one, it find that they can remove the reactive dye Cibacron Blue P-TS and the acid dye TECTILON Red F-2G ef(?)iently, the color removal efficiency exceeds 99% for the two dyes. In the same condition, the color removal efficiency of Mg/Al layered double hydroxides is lower than the calcined one.The experiment results indicate that time, solid amount taken, temperature and initial concentration of dyes solution have an effect on the color removal efficiency to different degree. What's more, both Mg/Al layered double hydroxides and the calcined one have a good pH buffer action to reactive and acid dyes.The adsorption isotherms are identical with Langmuir adsorption model, when Mg/Al layered double hydroxides remove Cibacron Blue P-TS and TECTILON Red F-2G dyes. The saturated adsorption amounts of Cibacron Blue P-TS and TECTILON Red F-2G are 109.89mg/g and 208.33mg/g respectively.Furthermore, Mg/Al layered double hydroxides having removed color from the dyes solution can decolour again after it is calcined at 500 ℃ for three hours, the color removal efficiency exceed 95% to the Cibacron Blue and P-TSTECTILON Red F-2G aqueous solution.