Adding ZnO and SiO2 to scatter the agglomeration of mechanochemically prepared Zn-Al LDH precursor and promote its adsorption toward methyl orange

In this study, a mechanochemical route to promote the adsorption of the precursor of Zn-Al layered double hydroxide (LDH) was introduced, in which ZnO and SiO 2 were added to Zn basic carbonate and Al hydroxide that were first dry milled into an activated state as a precursor for a LDH phase. The samples prepared in this way were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR) and Scanning electron microscopy (SEM). The precursors showed a high adsorption rate when added with the oxides. 10% addition of ZnO gave a maximum MO removal efficiency of 96.91% (193.82 mg/g at initial MO concentration of 160 mg/L), 16.46% higher than the sample without addition. Addition of SiO 2 at 25% allowed MO removal efficiency reaching 88.90% (222.25 mg/g, at initial MO concentration of 200 mg/L), 19.26% higher than the no additive sample. The improvement in the adsorption performance could be attributed to the effective dispersion of the precursor's agglomeration phenomenon. Discussion was performed based on the characterized features of the samples and fitting results on several adsorption models.