Green synthesis of active Fe₂O₃ nanoparticles using Aloe barbadensis and Camellia sinensis for efficient degradation of malachite green and Congo red dye

Abstract

The synthesis of metal oxide nanoparticles has gained much attention due to its wide range of applications in the field of industrial, chemical, and biological applications. These metallic nanoparticles have been developed for azo-dye removal, but they are limited for ecofriendly and cost-effective processes. The main objective of this study is to focus on the synthesis of Fe₂O₃-nanoparticles by green route followed by its application in the dye removal process from wastewater. In this approach, the active iron oxide nanoparticles (Fe₂O₃-NPs) were produced successfully using Camellia sinensis and Aloe barbadensis leaf extract. The prepared nanoparticles were characterized using SEM, XRD, FTIR, and UV–Vis spectroscopy, As per results, the NPs effectively degraded both the azo-dyes from the aqueous solution with 70–80% removal efficiency in 40–45 min under optimum conditions. Moreover, the color change in the solution indicated the formation of Fe₂O₃-NPs. The absorption peak was observed at 275 nm and 270 nm for Aloe barbadensis leaf extract and Camellia sinensis extract, respectively. The FTIR peak at 553.63 cm⁻¹ indicates the presence of Fe₂O₃ NPs along with other peaks at 2853.3 cm⁻¹ for O–H stretching in carboxylic acid; at 3404 cm⁻¹ due to the O–H group present in the extract, broad peak of 3406 cm⁻¹ shows –OH group of carbohydrates and phenols along with a peak at 2891 cm⁻¹ for asymmetrical and symmetrical C-H stretching. The results of XRD and SEM indicate the homogeneity, shape, and size of NPs, which were spherical and cubic. The size of the particles ranged between 80 and 100 nm for both types of NPs prepared using the extracts. The Langmuir and Elovich isotherms were used to analyze adsorption behavior. The pseudo-first-order and pseudo-second-order kinetic approaches were used and found satisfactory for both approaches. An extensive discussion has been made in light of the experimental data and results obtained.