Preparation of Mg-Al Layered Double Hydroxides Ultrathin Nanosheets and Its Application in Adsorption of Methyl Orange

Abstract

In this paper, well-defined Mg-Al LDHs nanosheets with high yield are prepared by the following sequential procedures: hydrothermal preparation of Mg-Al-CO[Formula: see text] LDHs, followed by expanding interlayer spacing by NH4NO3 treatment. The results show that the concentration of the layer expansion agent (NH4NO[Formula: see text] and the exfoliation solvent play a key role in the exfoliation result. The basal spacing changed from 0.758[Formula: see text]nm to the range of 0.758–0.895[Formula: see text]nm when the concentration of NH4NO3 was increased up to 5 M, which infers that the increase of layer space is caused by the synergy of NH[Formula: see text] and NO[Formula: see text]. Among the three exfoliation solvents (formamide, N-methyl pyrrolidone and isopropyl alcohol), formamide showed the highest exfoliation effect. From the characteristic XRD patterns, the as-obtained colloidal aggregates of the exfoliated nanosheets do not show the characteristic diffractions of LDHs, while the typical peaks at 10.562[Formula: see text], 20.032[Formula: see text] and 21.185[Formula: see text] assigned to LDHs are observed after drying of the colloidal aggregates. Moreover, a transparent LDH film is also successfully prepared by coating colloidal aggregates of nanosheets on a glass substrate without using any adhesive. The stable film exhibits the strong adsorption ability of Methyl Orange.