Evans Blue dye removal from contaminated water on calcined and uncalcined Cu-Al-CO3 layered double hydroxide materials prepared by coprecipitation

This work focuses on studying the removal of Evans Blue dye, which is a water pollutant, using Cu-Al-CO3 anionic clay known also as layered double hydroxide (LDH) and its phase calcined at 500 degrees C (Cu-Al-500). LDH is easy to synthesize by a coprecipitation method at a constant pH; it is non-toxic and non-expensive, constituted of plane sheets containing alternating octahedral stack M(OH)6 formed by divalent (Cu2+) and trivalent (Al3+) cations and carbonate anions (CO32-) in the interfoliar space. The X-ray diffraction (XRD) pattern of the formed solids shows that the synthesized phase is the LDH type, and was confirmed by infrared spectroscopy (FT-IR). Thermogravimetric analysis (TGA) shows that the decarbonation of LDH begins at 500 degrees C, thus this temperature is chosen for the calcination of this clay. XRD and FT-IR of the calcined phase confirm the obtaining of copper and aluminium oxides. The UV-visible study of the adsorption of Evans Blue is performed by varying different parameters such as the weight of LDH and its calcined phase, the concentration of the dye and the pH of the solution. The obtained isotherms from this kinetic study show that the adsorption of Evans Blue dye is more efficient in the calcined phase compared with the as-synthesized LDH.