Study On The Structure And Composition Of Zn-Al-Ce-LDHs And Its Adsorption To Selenium

Due to its unique structure(porosity, specific surface area and uniform composition) and wide usages, hydrotalcite material has been used as catalyst or catalyst carrier, drug delivery, adsorption agent(ion exchange agent). As adsorbent, hydrotalcite has good absorption effect for many non-metal elements. The high content of selenium in water is harmful to human body, so it is important to study the adsorption of selenium in water. The main work and conclusions of this paper are as follows.Zn-Al-Ce-NO3--LDHs(precursor) was prepared, and the preparation conditions, its structure and composition were analyzed. XRD analysis showed that when the p H value was 10, the Al molar ratio of Ce was 0.05, the reaction temperature was 40, and the aging temperature was 100, the crystallinity of Zn-Al-Ce-NO3--LDHs was highest. NO3- in Zn-Al-Ce-NO3--LDHs interlayer could be saw using infrared spectroscopy; The chemical formula of Zn-Al-Ce-NO3--LDHs could be calculate combined thermogravimetry mass differential thermal analysis and ICP-AES analysis, it is [Zn40Al18Ce(OH)120](NO3-)18·50H2O.The prepared Zn-Al-Ce-NO3--LDHs were intercalated with laurate, acrylic acid, carbonate, stearic. Structure analysis by XRD and infrared spectra, showed that different anions in the Zn-Al-Ce-LDHs have complete the hydrotalcite structure and anions were successfully inserted hydrotalcite like compound interlayer. Combined with hydrotalcite precursor layer elements data and the hydrotalcite thermogravimetric and differential thermal analysis, chemical formula of a series of LDHs could be calculated as follows: [Zn40Al18Ce(OH)120](CO32-)9·60H2O; [Zn40Al18Ce(OH)120](laurate)18400H2O;[Zn40Al18Ce(OH)120](stearate)18·60H2O; [Zn40Al18Ce(OH)120](acrylate)18100H2O.The effect of different modifiers on the Zn-Al-Ce-CO32--LDHs was studied. The modification effect of the super dispersant was best, the optimum modification conditions as follows: the dosage of the modifier was 2.5%, the modified temperature was 80℃, and the modified time was 2h. The results of the modified LDHs showed that the structure of LDHs not changed, and the dispersion was better after modification. The adsorption of selenium with modified Zn-Al-Ce-CO32--LDHs was studied, and the effect of adsorption for selenium of LDHs was studied. selenium in residual liquid after adsorption by hydrotalcite was determinated of by Hydride Generation-Atomic Fluorescence Spectrometry, isothermal adsorption equation could be figured out by detecting selenium content in a series of residual liquid,the results showed that the hydrotalcite on selenium adsorption model is consistent to Freundlich model.