Adsorption and photocatalytic performance of ZnAl layered double hydroxide nanoparticles in removal of methyl orange dye

The textile industries generate huge amounts of highly toxic color wastewater. A potential solution to this global environmental pollution demands the appropriate design and synthesis of artificial photocatalysts with high activities. The presence of methyl orange (MO) dye causes distinct acute impact on health therefore the removal of this dye from aqueous solution is highly desirable. The aim of this study was to assess the efficiency of photo-degradation of methyl orange dye with application of ZnAl layered double hydroxides (LDHs) as a photocatalyst. For this purpose, ZnAl LDHs were synthesized by simple and cost-effective coprecipitation method with varying Zn/Al molar ratios 2:1, 3:1 and 4:1. Samples were characterized by XRD, TG–DTA and UV–visible techniques to achieve information in aspects of phase transformation, thermal stability and their dye absorption capacity. Crystallinity and bandgap of catalyst play an important role in dye degradation mechanism & it is observed that the crystallinity of LDHs increases on calcination (at 600°C) and Zn/Al molar ratio. The investigation also reveals that an increase in Zn/Al molar ratio and calcination influences the dye degradation capacity of catalyst. It was found that the photocatalytic activity of calcined ZnAl LDHs depends on its intermediate products ZnO and ZnAl2O4 composites which can be regulated by changing Zn/Al molar ratio and heat treatment. The highest degradation of MO dye was found to be 95.21% within a time period of 1 h. Also, the reusability and stability of ZnAl photocatalyst were found to be steady up to 5 successive cycles. © 2021, The Author(s), under exclusive licence to Springer Nature Switzerland AG.