Effect of drying step on layered double hydroxides properties: Application in reactive dye intercalation

Abstract

Freeze-dried sulfate intercalated layered double hydroxides (LDH) phase was synthetized by coprecipitation method via direct intercalation of sulfate anion. The effect of freeze-drying process on LDH properties was investigated. The resulting phase was evaluated for its efficiency in the intercalation of the reactive azo dye, Remazol Brilliant Red F3B (RR-F3B). The freeze-dried phase exhibited a low crystallinity and narrow particle size distribution compared to conventional LDH phases. The freezing step led to highly aggregated nanoparticles with a characteristic distance d003 of 8.12 Å. The preferential arrangement of the intercalated dye species was examined by X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) analyses. The results showed that RR-F3B molecules were partially accommodated between the LDH layers as single-layer with horizontal orientation. The effect of drying on morphological and structural properties can be attributed to several stresses during freezing and drying steps.