Sustainable and environmentally friendly synthesis of ZnO semiconductor nanoparticles from Bauhinia forficata leaves extract and the study of their photocatalytic and antibacterial activity

Abstract

The growing need to obtain nanomaterials has resulted in a trend to avoid environmentally harmful methodologies involving chemicals that damage ecosystems and health by searching for natural reducers and stabilizers with zero polluting impact. In this research, zinc oxide nanoparticles were synthesized following an environmentally friendly synthesis methodology by using a natural extract of Bauhinia forficata that, thanks to its phytochemical composition rich in organic molecules such as polyphenols and flavonoids, allows the correct formation of nanoparticles by acting as stabilizers. The results of the characterizations show the proper formation of the nanoparticles and a direct relationship between the percentage used to obtain the nanoparticles and their properties. The results obtained from XRD show a hexagonal zincite shape and crystallite sizes in the range of 22.25–31.05 nm. The appearance of a signal at ∼400 cm⁻¹ obtained from FTIR confirms the formation of the Zn-O- bond. Subsequently, the removal of different organic dyes from polluted water was analyzed using zinc oxide semiconductor nanoparticles as photocatalysts under ultraviolet light. The results show outstanding degradation of the dyes, being able to remove at least 98.0 %, 84.4 %, 94.64 %, 95.5 %, and 98.2 % for methylene blue, methyl orange, rhodamine-B, Congo red, and malachite green, respectively. Additionally, the antibacterial effect of the obtained materials against multiple pathogenic bacteria was studied. All the synthesized nanoparticle samples showed an antibacterial effect, even at low concentrations for all the analyzed pathogens. The results show the feasibility of using Bauhinia forficata to obtain zinc oxide nanoparticles and its multiple applications due to its improved properties.