2.2. Synthesis of Aluminum Hydroxide Nanoparticles

Aluminum hydroxide nanoparticles were synthesized by following the proposed procedure with a minor modification [32]. Firstly, to prepare the 4 M NaOH and 1 M Al(NO₃)₃ solutions, the appropriate amounts of NaOH pellets and Al(NO₃)₃ were dissolved in ultrapure water. Aluminum hydroxide was received by titrating 1 M Al(NO₃)₃ with 4 M NaOH in a plastic barker with continuing magnetic stirring. The stirring speed of 500 rpm was kept constant during the titration. When the white wet precipitation was obtained, it was centrifuged at 6000 rpm (Digisytem, Taiwan) to separate the solid and liquid. Then, the material was dried at 80 °C for 24 h. The white powders were then heated at 600 °C for 12 h (sample A) and at 800 °C for 6 h (sample B) in a Nabertherm furnace before reducing the temperature to 40 °C in a desiccator. Finally, the aluminum hydroxide nanoparticles were kept in a PE bottle.