Efficient photodegradation of phenol in wastewater using ZnAl–Bi photocatalysts analysing the effect of Bi content on ZnAl LDH synthesized in one step

The layered double hydroxide (LDH) zinc–aluminum (ZA) catalysts with different percentages of bismuth (6, 8, 10 and 12.5%) were synthesized using the chemical co-precipitation method at pH 10. The materials were characterized using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), UV–Vis spectroscopy, scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HR-TEM). Furthermore, the influence of bismuth content on the catalysts was evaluated in the photodegradation of phenol, studying its impact. X-ray diffraction confirmed the formation of hydrotalcite in the ZA solid, and the hydrotalcite phase was predominant in the catalysts with different bismuth content. The solid with 10% bismuth (ZABt-10) exhibited the highest capacity for phenol degradation, achieving a degradation of 97.31% and mineralization of 83.30% using these materials without activation or calcination processes. The photocatalytic mechanism involved in the photodegradation of phenol on the ZABt-10 material occurs via ^•O₂⁻, h⁺ and ^•OOH contributing 38, 34 and 25%, respectively, resulting in a 97% degradation of the phenol molecule. Furthermore, this material completely degrades the intermediate products (hydroquinone, benzoquinone and catechol).