Synergistic effect of pH solution and photocorrosion of ZnO particles on the photocatalytic degradation of Rhodamine B

This research aims to study the synergistic effect of pH solution and photocorrosion of ZnO particles on the photodegradation of Rhodamine B (RhB) dye. The stability of ZnO particles was investigated by zeta potential measurement. The structure, morphology and photocatalytic activity of ZnO were analysed by X-ray diffraction, scanning electron microscope and ultraviolet-visible spectrophotometer, respectively. The ZnO particles were highly crystalline with a bandgap energy of 3.23 eV. The surface charges of particles were found to be pH-sensitive, where they were more negative under alkaline condition, i.e., -11.1, -5.3 and -38.2 mV at pH 3, 7 and 11, respectively. ZnO particles that dissolved in pH 3 solution produce Zn2+ ions, while precipitation of Zn(OH)(4)(2-) was observed in pH 11 solution, resulting in morphology change of ZnO from rod shape to lamellar shape . The synergistic effect of photocorrosion and dissolution of ZnO particles in acidic solution reduced RhB dye removal efficiency from similar to 90% at pH 7 to similar to 70% at pH 3. In alkaline solution, ZnO particles displayed remarkable reusability as it still recorded a 94.8% degradation efficiency after five successive cycles.

Automated summary

This study aimed to investigate the synergistic effect of solution pH and photocorrosion on the photodegradation of Rhodamine B dye by ZnO particles. It was found that ZnO particles exhibited pH-sensitive behavior, with significant changes in morphology under different pH conditions. Despite a reduction in efficiency in acidic solutions, ZnO particles showed remarkable reusability in alkaline conditions.