Preparation and characterisation of montmorillonite-Fe3+ (MMT-Fe3+) nanoclay mineral for crystal violet (CV) removal from aqueous solutions

Abstract

Montmorillonite-Fe3+ (MMT-Fe3+) nanoclay mineral was successfully prepared using a ferric chloride precursor. The prepared sample was characterized using IR, XRD, BET and SEM-EDX. We have explored the highly efficient and environmentally benign MMT-Fe3+ for adsorption of Crystal Violet (CV) dye from aqueous solution under ambient conditions. The MMT-Fe3+ was interacted with CV dye solution at different pH, temperature and solid-to-liquid ratio. The concentration of CV dye removal was estimated from its optical density at λmax = 590 nm using UV–Vis spectrophotometer. The CV dye removal was rapid at basic pH and increases with temperature up to 40 °C. A complete reduction (100%) was occurred in about 7 min at pH 7 and 10 while at pH 3 in about 10 min. The time taken for complete reduction at 0, 30 and 40 °C are 10, 7 and 5 min respectively. The removal followed by adsorption of dye molecules on the spent nanoclay mineral was evident from SEM/EDX analysis. More importantly, MMT-Fe3+ could be separated and retrieved easily after the reaction by centrifugation from the degraded CV dye solution. The experimental results of CV dye removal from MMT-Fe3+ follows the pseudo first order kinetics. This study reveals that MMT-Fe3+ has the potential to be used as reductant/adsorbant to remove cationic pollutants effectively and rapidly from drinking water and large scale of industrial wastewater.