Controlled microwave-assisted and pH-affected growth of ZnO structures and their photocatalytic performance

Abstract

A fast microwave-assisted method was used to grow zinc oxide. The synthesis was carried out under three different pH conditions (8, 10 and 12) with the precipitation agent triethylamine. The obtained materials were comprehensively characterised using X-ray diffraction (XRD), scanning and transmission electron microscopy (SEM and TEM), low-temperature N2 sorption (BET model), and analysis of electrokinetic potential and thermal stability (TGA). It was established that the pH value had a significant impact on the crystallinity, morphology and thermal stability of the final products. The primary purpose of this study was to use the synthesised materials in a process of photodegradation (in the UV light range) of the model organic pollutant – 4-chlorophenol (20 mg/dm3). The photo-oxidation tests showed that the obtained zinc oxide materials exhibit good photodegradation and mineralisation efficiency. Moreover, the kinetics of the photocatalytic degradation of 4-chlorophenol were determined based on the pseudo-first-order model, assuming the Langmuir–Hinshelwood mechanism.