Preparation and photocatalytic kinetics of nano-ZnO powders by precipitation stripping process

Abstract

Ultra-fine zinc oxalate powders were prepared through a precipitation stripping method with bis(2-ethylhexyl) phosphate (HDEHP) diluted by tetrachloride carbon as the extractant, and oxalic acid ethanol aqueous solution as the re-extractant and precipitator. Zinc oxide powders were obtained by decomposing zinc oxalate powders at 450uC. The prepared zinc oxide powders were characterized by transmission electron microscope (TEM), Scanning electron microscope (SEM), Thermogravimetric analysis (TG), X-ray diffraction (XRD) and Fourier transmission infrared (FT-IR) spectrum. The photocatalytic performance of methylene blue by zinc oxide was studied based on the Langmuir model and Photo-Layer model. The results show that some zinc oxide powders were micro-multipore materials with hexagonal crystal. The particle size was around 32 nm. The photocatalytic process was the control step in the chemical reaction. The photo catalytic process followed pseudo-first order kinetics and NOH concentration inside the photo-layer in different reaction condition were calculated according to the Photo-Layer model.

Conventional versus lattice photocatalysed reactions: Implications of the lattice oxygen participation in the liquid phase photocatalytic oxidation with nanostructured ZnO thin films on reaction products and mechanism at both 254nm and 340nm

“…These charges are usually named as valence band hole and conduction band electrons, which may participate in the formation of active oxidising species such as hydroperoxyl radicals, hydroxyl radicals, hydrogen peroxide and super oxide [1,3,10,40]. Most of the literature attributes the oxidation of stringent organic compounds to mainly the positive hole and/or hydroxyl radical [1,3,14,17,18,39,[41][42][43][44].…”

“…Furthermore, previous studies [3,[5][6][7][8] have shown that ZnO is a promising candidate among other metal oxides such as TiO 2 , SnO 2 , ZrO 2 , ␣-Fe 2 O 3 , WO 3 , CdS and ZnS. ZnO has been used as a photocatalyst as a powder [9][10][11][12] and as supported thin films [13][14][15][16]. Most studies have focused on the characterisation of the photocatalytic nature of ZnO [9][10][11][12][13][14][15][16].…”

“…ZnO has been used as a photocatalyst as a powder [9][10][11][12] and as supported thin films [13][14][15][16]. Most studies have focused on the characterisation of the photocatalytic nature of ZnO [9][10][11][12][13][14][15][16]. Fewer studies have focussed on reaction intermediate and product quantification and analysis [1,[17][18][19], with fewer still aiming to determine the impact and relationship of the photocatalyst surface and solution reactions to this reaction intermediate and product spectrum.…”

Decoloring Methyl Orange under Sunlight by a Photocatalytic Membrane Reactor Based on ZnO Nanoparticles and Polypropylene Macroporous Membrane

“…NPs. ZnO NPs were synthesized by direct precipitation with oxalic acid as the precipitator [23] with minor modification. 12.7 g Zn(NO 3 ) 2 and 10.0 g oxalic acid were dissolved in 50 mL distilled water separately.…”