Estudio de la remoción de iones cobre en efluentes contaminados utilizando hidrotalcita Mg/Fe modificada con aminas
Authors:   , Leyva Cruz Edgar Oswaldo 
Published: April 2022

The contamination caused by Cu (II) has been documented, by detecting concentrations of this ion in water from 3.9 mg/L to 13.8 mg/L, when NOM-127- SSA1-1994 establishes limits of 2 mg/L for copper as the permissible limit for drinking water. Given this environmental problem, in the present research work, the removal of copper ions in contaminated effluents with Hydrotalcite Mg/Fe as synthesized and modified with the 3-aminopropyltrimethoxysilane compound was studied. The coprecipitation method was used in the synthesis of the double laminar hydroxide (Hydrotalcite) Mg/Fe, with a 3: 1 molar ratio, which was characterized by: X-ray diffraction, scanning electron microscopy, infrared and UV- visible spectroscopy. Hydrotalcite Mg/Fe was used to remove the Cu (II) species from contaminated water in a controlled manner at laboratory level. The removal was carried out in water with concentrations between 15 and 50 mg/L, under controlled temperature conditions. In this work it was possible to remove at least 92% of the initial concentration used, on the other hand, it was evidenced that the phenomenon of adsorption of Cu (II) on Hydrotalcite Mg/Fe can be described by the pseudo-second order kinetic model. Additionally, two models were used to analyze the adsorption equilibrium data (Langmuir and Freundlich), both of which were adequate to describe the adsorption. Through the models used, it was determined that a chemical adsorption occurs during removal. In order to carry out a comparative study, the Hydrotalcite Mg/Fe was modified with 3-aminopropyltrimethoxysilane, this modification allows to study the influence of the amine group has on the removal of Cu (II). The modified hydrotalcite Mg/Fe was also characterized by the previously mentioned techniques, this before and after being used for removal, showing copper (II) ion was adsorbed by the modified material. It was possible to increase the total removal by 7 % with this material, additionally the removal with the calcined Mg/Fe Hydrotalcite was evaluated with a 4% increase in removal, compared to the dry Hydrotalcite. The results show that; the removal kinetics of Cu (II) with these materials can be described by the pseudo second order model. Given the importance of taking the research to a level of application in a real problem, a removal evaluation was carried out using Hydrotalcite Mg/Fe in an industrial effluent donated by a company that produces copper salts, when a concentration was found in this effluent extremely high (~ 13,000 mg/L) compared to those used during this investigation, it was necessary to use a chemical precipitation method that allowed to reduce the copper concentration, later the Hydrotalcite Mg/Fe was used, to complete the removal in this effluent and the concentration detected in the water was below that established in control standards. In the final stage of this work, in order to give an application to the adsorbent material after the removal process of Cu (II), the generated material was used as a catalyst in a chemical reaction "Click" for the synthesis of triazoles, obtaining a remarkable performance under typical conditions of green chemistry, with these results it can be argued that Hydrotalcite Mg/Fe can be considered as a bifunctional and sustainable material, since it was used in two different processes, for the removal of Cu ( II) and as a catalyst, in both cases it worked satisfactorily.