Influence of the synthesis method of layered double hydroxides on the textural properties and nitrate removal

Layered double hydroxides were prepared by co-precipitating Mg2+ and Al3+ ions at constant pH. Three different methods of solution additions and two temperatures for synthesis and aging were tested in each method. Through X-ray diffraction, it was confirmed that all the synthesized solids have a hydrotalcite-type structure, obtaining more crystalline compounds when one solution of Mg/Al is added to another whit CO3- /OH- and compounds with greater interlaminar spacing when three different solutions are added (Mg/Al, CO3- and OH-). In addition, the solids obtained by this last method have a higher specific surface area and total pore volume, as confirmed by the N2 adsorption-desorption. A similar trend occurs with synthesis and aging temperatures where better textural properties are obtained at a higher temperature, reaching surface area values of 242 m2/g and pore volume of 0,93 cm3/g. All the synthesized solids were active for removing nitrates in water, obtaining the best results with the samples prepared by dripping three different solutions at 60 degrees C (26 mgNO3-/g.) This fact demonstrates the correlation between the synthesis method and the textural properties of the material with its potential appli-cation in removing contaminants.

Automated summary

Layered double hydroxides were synthesized by co-precipitation of Mg2+ and Al3+ ions at constant pH. Different methods of solution additions and temperatures were tested, resulting in varied crystallinity and interlaminar spacing. The solids obtained at higher temperatures showed better textural properties and exhibited higher efficiency in nitrate removal. This study demonstrates the correlation between synthesis method, textural properties, and the application of removing contaminants.