Estudio de isotermas y cinética de adsorción en el proceso de remoción de metales pesados en soluciones acuosas mediante la aplicación de nanopartículas de óxido de zinc obtenidas por síntesis verde

Abstract

The objective of this research work was to study the isotherms and adsorption kinetics in the removal of heavy metals in aqueous solutions using zinc oxide nanoparticles (NPsZnO) obtained by green synthesis. For this, Aloe vera extract and zinc acetate dihydrate were used as a metal precursor, obtaining nanoparticles in size ranges between 100 and 200 nm. The characterization of the NPsZnO was carried out by Fourier transform infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM). Its efficiency in removing cadmium (Cd) and lead (Pb) was evaluated using an atomic absorption spectrophotometer. The results indicated that the concentration of the adsorbent and the pH were influential factors in the removal capacity, the optimal concentration of adsorbent was 1 g for Cd and 0.01 g for Pb, with an optimal pH of 5 for Cd and 7 for Pb. It was determined that adsorption followed a pseudo-second-order kinetic model for both metals, and that the Langmuir isotherm was the most suitable for Cd, while the Freundlich isotherm was the best fit for Pb. In addition, it was concluded that the synthesis process should continue to be studied, given that Aloe vera showed great capacity as a reducing agent, thanks to its bioactive compounds, which facilitated the formation of the desired nanoparticles. It was also determined that the NPsZnO demonstrated be effective in the removal of heavy metals, always considering the factors mentioned in the methodology. It was recommended to investigate the effectiveness of NPs in the removal of other heavy metals and perform an economic feasibility analysis for their large-scale application.