Zn–Al layered double hydroxides intercalated with carbonate, nitrate, chloride and sulfate ions: Synthesis, characterization and dyes removal properties

Publication date: Available online 11 November 2015 Source:Journal of Taibah University for Science Author(s): Fatima Zahra Mahjoubi, Abderrahim Khalidi, Mohamed Abdennouri, Noureddine Barka In this work, Zn-Al layered double hydroxides intercalated with carbonate, nitrate, chloride and sulfate ions were synthesized by co-precipitation method at constant solution pH. The as-synthesized samples were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM) and simultaneous thermogravimetric/differential thermal analysis (TGA-DTA). XRD patterns showed that Zn-Al-SO4 had the greatest interlayer spacing, followed by Zn-Al-Cl, Zn-Al-NO3 and Zn-Al-CO3. FTIR spectra confirmed clearly the presence of intercalated anions in the structure of LDHs. Batch experiments for methyl orange (MO) adsorption onto synthesized samples were investigated under various conditions such as contact time, initial dye concentration and solution pH. Experimental results showed that pH is the most influencing factor. The effective pH range for MO removal was found to be 3.5-4.5. Kinetics data can be well described by the pseudo-second-order kinetic model instead of pseudo-first-order. Equilibrium data were analyzed using Langmuir, Freundlich and Dubinin-Radushkevich models. Results showed that Langmuir and Dubinin-Radushkevich isotherm models fit well the experimental data. The Zn-Al-LDH samples exhibit an exceptional Langmui...

Source: Journal of Taibah University for Science - November 11, 2015 Category: Science Source Type: research