ZnO Semiconductor Nanoparticles and Their Application in Photocatalytic Degradation of Various Organic Dyes.

Priscy Alfredo Luque-Morales,Alejandra Lopez-Peraza,Victor Manuel Orozco-Carmona,Yolanda Angelica Baez-Lopez,Horacio Edgardo Garrafa-Galvez,Osvaldo Jesus Nava-Olivas,Guillermo Amaya-Parra,Manuel De Jesus Chinchillas-Chinchillas

doi:10.3390/ma14247537

Abstract

The biosynthesis of oxide semiconductor nanoparticles (NPs) using materials found in nature opens a wide field of study focused on sustainability and environmental protection. Biosynthesized NPs have the capacity to eliminate organic dyes, which pollute water and cause severe damage to the environment. In the present work, the green synthesis of zinc oxide (ZnO) NPs was carried out using Capsicum annuum var. Anaheim extract. The photocatalytic elimination of methylene blue (MB), methyl orange (MO), and Rhodamine B (RhB) in UV radiation was evaluated. The materials were characterized by scanning and transmission electron microscopy (SEM and TEM) and SEM-coupled energy dispersive spectroscopy (EDS), attenuated total reflectance-infrared (ATR-IR), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), Photoluminescence (PL), and ultraviolet-visible spectroscopy (UV-Vis). The TEM analysis showed the NPs have an average size of 40 nm and quasi-spherical shape. ATR-IR showed the ZnO NPs contained functional groups from the extract. The analysis through XRD indicated that the NPs have a hexagonal zincite crystal structure with an average crystallite size of approximately 17 nm. The photoluminescence spectrum (PL) presented an emission band at 402 nm. From the UV-Vis spectra and TAUC model, the band-gap value was found to be 2.93 eV. Finally, the photocatalytic assessment proved the ZnO NPs achieved 100% elimination of MB at 60 min exposure, and 85 and 92% degradation of MO and RhB, respectively, at 180 min. This indicates that ZnO NPs, in addition to using a friendly method for their synthesis, manage to have excellent photocatalytic activity in the degradation of various organic pollutants.

Highlights

Environmental pollution is a topic of interest to the scientific community, as the increase in damage caused to ecosystems is becoming more noticeable
The morphology of zinc oxide (ZnO) NPs biosynthesized with Capsicum annuum var
As observed in the results, the only elements found in the material were C, O, and Zn, which correspond to elements present in the organic molecules of the extract and to the zinc oxide NPs [38]

Summary

Introduction

Environmental pollution is a topic of interest to the scientific community, as the increase in damage caused to ecosystems is becoming more noticeable. Some techniques used for the elimination of organic dyes, pollutants, and non-biodegradable residues in water are ion exchange, adsorption, ozonation, Fenton reaction, reductive degradation, and microbial processes, among others [8]. Some of these techniques are expensive, use dangerous reagents, generate toxic by-products, and do not eliminate the source of the problem [9]. Photocatalysis is a simple, lowcost process that does not cause toxic by-products This technique has been shown to be highly effective in degrading pollutants in water using solar energy or UV energy

Methods

Results

Conclusion