Molten salt synthesis of gadolinium boride nanocrystals suitable for methyl blue removal

Abstract

Efficient removal of cationic dyes such as methyl blue (MB) is of great importance from the environmental perspective. Although adsorption methods have been employed for this purpose, it is not easy to find inorganic materials featuring both high adsorption capacity and ratio. Herein, a comprehensive study on the MB removal performance by GdB6 nanoparticles was provided. GdB6 was conveniently synthesized via the reaction of GdF3 and NaBH4 at 900 °C in molten LiCl-KCl, and the resulting nanoparticles exhibit cubic-shaped structures with an average size of 100 nm and BET surface area of 51.5 m2/g. During the evaluation of MB removal performance, reduction of MB to colorless leucomethylene (LMB) on the surface of GdB6 was observed for the first time, which makes it more reliable to determine the capability of GdB6 in the treatment of MB. In addition to reduction, MB decolorization mainly results from adsorption on the surface of GdB6 based on the adsorption-desorption tests. The adsorption behavior follows the pseudo-second-order kinetics and Freundlich isotherm model. An adsorption capacity of 3108.8 mg/g with an adsorption ratio of 77.7% was obtained, and the performance remained unchanged after six adsorption-desorption cycles, which demonstrate the excellent MB removal performance of GdB6 in comparison to other inorganic materials.

Keywords

• Gadolinium boride
• Molten salt synthesis
• Methylene blue
• Adsorption
• Wastewater treatment