Zinc Titanate Nanopowders. Synthesis and Characterization

Zinc titanates nanopowders viz.; Zn2TiO4, ZnTi3O8 and ZnTiO3 were synthesized through the thermal decomposition course of ZnC2O4.2H2O-TiO2 precursor (1:1 mole ratio), prepared via a new co-precipitation method up to 900oC. Thermogravimetric measurement (TG) was utilized to characterize the precursor decomposition while X-ray diffraction (XRD), Fourier transform infra-red (FT-IR) were used to characterize the decomposition products as well as the phase transitions at different temperatures. XRD revealed the starting of titanates formation at 700oC via detecting Zn2TiO4 along with ZnO and TiO2 (anatase) diffraction peaks. By increasing the calcination temperature to 800oC, the ZnO content vanished with the appearing of Zn2Ti3O8 besides ZnTi2O4 and impurities of TiO2 (anatase). Finally at 900oC, the Zn2Ti3O8 content was decomposed into ZnTiO3. Nitrogen adsorption-desorption isotherm of the calcined precursor at 900oC indicated low specific surface area of 7.1 m2 g-1 in accordance with the agglomeration nature estimated via transmission electron microscopy (TEM) study. The conductivity measurements showed semiconducting behavior of the prepared titanates with ferroelectric transition in the range 200-308oC.The obtained low dielectric value suggests the uses of present titanates as a co-fired ceramic or resonator ceramics.

Perovskite Zinc Titanate Photocatalysts Synthesized by the Sol–Gel Method and Their Application in the Photocatalytic Degradation of Emerging Contaminants

In this study, perovskite ZnTiO3 photocatalysts were fabricated by the sol–gel method. The photocatalytic capability was verified by the degradation of the emerging contaminant, the antibiotic amoxicillin (AMX). For the preparation, the parameters of the calcination temperature and the additional amount of polyvinylpyrrolidone (PVP) and ammonia are discussed, including the calcining temperature (500, 600, 700, 800 °C), the volume of ammonia (750, 1500, 3000 μL), and the weight of PVP (3 g and 5 g). The prepared perovskite ZnTiO3 was characterized by XRD, FESEM, BET, and UV-Vis. It is shown that the perovskite ZnTiO3 photocatalysts are structurally rod-like and ultraviolet light-responsive. Consequently, the synthesis conditions for fabricating the perovskite ZnTiO3 photocatalysts with the highest photocatalytic performance were a calcining temperature of 700 °C, an additional ammonia amount of 1500 μL, and added PVP of 5 g. Moreover, the photocatalytic degradation of perovskite ZnTiO3 photocatalysts on other pollutants, including the antibiotic tetracycline (TC), methyl orange (MO), and methylene blue (MB) dyes, was also examined. This provides the basis for the application of perovskite ZnTiO3 as a photocatalyst to decompose emerging contaminants and organic pollutants in wastewater treatment.

Effect of Calcination Temperature on the Photocatalytic Activity of Zn2Ti3O8 Materials for Phenol Photodegradation

Zinc titanate (Zn2Ti3O8) is a bimetal oxide material that is especially attractive as a photocatalyst. In the preparation of the Zn2Ti3O8, the calcination temperature is a crucial parameter. Hence, in the present work, we aimed to synthesize the Zn2Ti3O8 materials from zinc(II) nitrate and titanium(IV) isopropoxide as precursors by using a sol-gel method and followed by calcination at 700, 900, and 1100 °C to give ZT-700, ZT-900, and ZT-100 materials, respectively. The ZT materials were characterized using Fourier transform infrared (FTIR), diffuse reflectance ultraviolet-visible (DR UV-vis), and fluorescence spectroscopies. It was confirmed that the ZT materials contained O−Ti−O, Zn−O−Ti, Zn−O, Ti−O−Ti, and Ti−O functional groups as shown from their FTIR spectra. Similar fluorescence properties were only observed on the ZT-700 and ZT-900. From the bandgap energy analysis, ZT-700 and ZT-900 contained spinel and cubic Zn2Ti3O8 (spl-Zn2Ti3O8 and c-Zn2Ti3O8) crystal phases), while ZT-1100 contained c-Zn2TiO4 and TiO2 rutile crystal phases. The kinetic analysis of photocatalytic phenol degradation showed that both ZT-700 and ZT-900 materials exhibited high photocatalytic activity with the reaction rate constants of 0.0353 and 0.0355 h−1, respectively. These values were higher than that of the ZT-1100 (0.0206 h−1). This study demonstrated that calcination at 700 and 900 °C resulted in the formation of the spl-Zn2Ti3O8 and c-Zn2Ti3O8 phases, which were effective as the photocatalyst, but the formation of c-Zn2TiO4 and rutile TiO2 at calcination of 1100 °C deteriorated the photocatalytic activity. Copyright © 2021 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).