The Effect of Aging Time on the Properties of Mg-Al-CO3 Layered Double Hydroxides and Its Application as a Catalyst Support for TiO2

By using chloride salts as the raw materials, Mg-Al-CO3 layered double hydroxides (Mg-Al-CO3 LDHs) with Mg/Al molar ratio 2: 1 were prepared via a coprecipitation method. The effect of the aging time on the crystallinity, particle size, chemical composition, morphology, specific surface area, and pore size distribution of Mg-Al-CO3 LDHs were studied in details. The effect of aging time during LDHs preparation process on adsorption capacity of LDHs and their calcined products (mixed metal oxide, MMO) were investigated by removing the pollutant acid red 1 (AR1) from aqueous solution. The results showed that LDHs prepared at 90 degrees C for 4 h (LDH-4) had a higher specific area of 103.7 m(2)/g and LDHs prepared at 90 degrees C for 8 h (LDH-8) exhibited well-formed hexagonal crystals with a relative smooth surface. The LDH-4 and its calcined product are more effective in removing AR1 than LDH-8, which is related to the differences in their specific surface area. Meanwhile, anatase TiO2-coated MMO with MMO/TiO2 mass ratios at 1: 1 and 2: 1 were prepared via a chemical precipitation route in the presence of LDH, the composites showed an efficiently photocatalytic activity in the removal of AR1.