Microwave-assisted biosynthesis and characterization of ZnO film for photocatalytic application in methylene blue degradation

Abstract

This study aims to investigate the physical characteristics and photocatalyst activity of biosynthesized ZnO with pineapple (Ananas comosus) peel extract under microwave irradiation. The ZnO powder was prepared in two different concentrations of zinc nitrate hexahydrate (ZNH) at 200mM (Z-200) and 500 mM (Z-500). The optical, structural, and morphological properties of ZnO were analyzed using UV-Vis spectroscopy, X-Ray Diffraction (XRD), and Scanning Electron Microscopy (SEM), respectively. The UV-Vis absorption spectrum showed a wide absorbance peak of ZnO at the wavelength of 300-360 nm with a bandgap energy of 3.22 and 3.25 eV. The XRD result confirmed the wurtzite structure of ZnO with high crystallinity. SEM morphology showed spherical particles with an average particle size of 190-220 nm. For photocatalytic application, ZnO film was fabricated via the doctor blade method from microwave-assisted biosynthesized ZnO powder. ZnO films were then applied under UV-irradiation to examine the photocatalytic degradation of methylene blue. It was found that the catalytic behavior of ZnO film was affected by the starting ZNH concentration with maximum effectiveness of 46% degradation after 2 h.

Degradation of Paracetamol in Distilled and Drinking Water via Ag/ZnO Photocatalysis under UV and Natural Sunlight

“…UV-vis absorbance spectroscopy is used to calculate the band gap energy (E g ) of pure and co-catalytically modified ZnO films (Figure 6a). The spectra show the presence of a /ZnO = 365 nm and λ maxZnO = 362), which is consistent with zinc oxide's properties [43]. This is explained by the zinc oxide being photoexcited from the lower valence band to the higher conduction band.…”

Influence of the Nature of Aminoalcohol on ZnO Films Formed by Sol-Gel Methods

“…ZnO-based thin films can be prepared using a variety of procedures [ 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 , 41 , 42 ], such as pulsed-laser [ 20 ], solvothermal/hydrothermal [ 21 , 22 ], electrochemical [ 23 , 24 ] and ultrasonic-mist-vapor deposition methods [ 25 ], spray pyrolysis [ 26 ], magnetron sputtering [ 27 ], microwave-assisted [ 28 ] procedures, and also the sol-gel method (SGM) [ 2 , 12 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 ], which is one of the most attractive and highly preferred, due to its low cost, simplicity, and feasibility. In general, the SGM requires a Zn(II) salt, an organic compound as stabilizer, and a solvent […”

“…In general, the SGM requires a Zn(II) salt, an organic compound as stabilizer, and a solvent [ 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 ]. Among the most common substances that are used as stabilizer are aminoalcohols, especially those having the proper orientation of the N- and O-heteroatoms as to bind to the Zn 2+ ions forming chelates, or acting as bridging ligands in the precursors and, therefore, preventing the precipitation of Zn(OH) 2 [ 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 43 , 44 , 45 , 46 ]. The world-wide long-term sol-gel ZnO precursor forms from zinc acetate dihydrate (ZAD) and ethanolamine ( Figure 1 , a ) in 2-methoxyethanol (ME) [ 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 38 , 39 , 40 ].…”

“…Among the most common substances that are used as stabilizer are aminoalcohols, especially those having the proper orientation of the N- and O-heteroatoms as to bind to the Zn 2+ ions forming chelates, or acting as bridging ligands in the precursors and, therefore, preventing the precipitation of Zn(OH) 2 [ 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 43 , 44 , 45 , 46 ]. The world-wide long-term sol-gel ZnO precursor forms from zinc acetate dihydrate (ZAD) and ethanolamine ( Figure 1 , a ) in 2-methoxyethanol (ME) [ 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 38 , 39 , 40 ]. It is well known that its transformation to ZnO is a complex multi-step process that involves in situ formation of alkoxide or alkoxy complexes, the subsequent hydrolysis, polymerization, and thermal treatment to yield the final ZnO [ 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 ].…”

“…The world-wide long-term sol-gel ZnO precursor forms from zinc acetate dihydrate (ZAD) and ethanolamine ( Figure 1 , a ) in 2-methoxyethanol (ME) [ 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 38 , 39 , 40 ]. It is well known that its transformation to ZnO is a complex multi-step process that involves in situ formation of alkoxide or alkoxy complexes, the subsequent hydrolysis, polymerization, and thermal treatment to yield the final ZnO [ 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 ].…”