Modifying aluminum–water reaction to generate nano-sized aluminum hydroxide particles beside hydrogen

• Reaction of Al with water can be promoted by wet milling of Al powder
• The produced aluminum hydroxide includes nanorods with aspect ratio of up to 100, nanoparticles and spindles
• Calcination of aluminum hydroxide by either conventional or microwave furnace results in production of nano alumina powder.

Al–water reaction is used to produce nanoparticles of aluminum hydroxide. Ball-milling of aluminum powder in water was examined for promoting this reaction. Scanning electron microscopy and X-ray diffraction assisted by Rietveld refinement were used to study the by-products of the reaction. Results showed that the activated Al powder completely reacted with water at room temperature. Hydrogen, gibbsite and bayerite were formed at the end of the reaction. A mechanism is proposed to explain how wet milling of Al powder can promote the reaction. The morphology of the by-products changed with the milling time. Notably the samples milled for 7 and 12 h had the shapes of nanospheres, nanospindles and nanorods. The calcination process made in conventional furnace and microwave oven changed the morphology of the produced alumina phases.

Hydrogen and nano-sized aluminum hydroxide were produced by wet milling of an aluminum powder in water. Rietveld refinement of X-ray diffraction patterns shows the presence of gibbsite and byerite phases. Microwave calcination transforms the produced hydroxide phases to alpha and gamma alumina phases. A longer ball milling time results in a faster kinetics of the reactions and finer by products.Figure optionsDownload as PowerPoint slide