Effect of combined microwave-ultrasound irradiation in the structure and morphology of hidrotalcite like compounds Al/Mg-CH₃COO and its evaluation in the sorption of a reactive dye

Textile effluents contain a great variety of dye residues, their presence in the environment is undesirable since they cause a severe contamination in the aquifers. Different technologies are commonly used in the removal of these kind of dyes, which are often recalcitrant due to their anionic character, such as the sorption with activated carbon, zeolites and recently anionic clays (hydrotalcite-like compounds Al/Mg (HT-Al/Mg)) with relatively good results. The HT-Al/Mg can be synthesized by various methods assisted by treatments in the crystallization stage such as microwave and/or ultrasound irradiation, which allow the control of textural and morphological properties, in addition to reducing the synthesis times. The effects on the texture and morphology properties of HT-Al/Mg with an organic interlaminar anion (CH3COO-) synthesized by coprecipitation assisted with microwave irradiation, ultrasound and microwave-ultrasound in combined mode are studied. The synthesized materials were evaluated in the sorption of the reactive dye BEZAKTIV Red S-LF with reference to activated carbon. The solids were characterized before and after evaluation by known techniques described below. It was found that the HT-Al/Mg-CH3COO irradiated by the combined mode had the highest capacity of removal of the dyes compared to the reference material and when the materials were irradiated separately by microwaves or ultrasound.

Keywords: hydrotalcite-like compounds, hydrotalcites morphology, hydrotalcites texture, microwave and/or ultrasound irradiation synthesis.