Hydrogen generation by the hydrolysis of magnesium-aluminum-iron material in aqueous solutions

Highly activated Mg-Al-Fe materials are prepared from powder by mechanical ball milling method for hydrogen generation. The hydrolysis characteristics of Mg-Al-Fe materials in aqueous solutions under different experimental conditions are carefully investigated. The results show that the hydrolysis reactivity of Mg-Al-Fe material can be significantly improved by increasing the ball milling time and Fe content. The increase of NaCl solution concentration and initial temperature is also found to promote the hydrogen generation reaction. At 25 °C, the Mg60-Al30-Fe10 (wt%) material ball-milled for 4 h shows the best performance in 0.6 mol L^-1 NaCl solution, and the reaction can produce 1013.33 ml g^-1 hydrogen with a maximum hydrogen generation rate of 499.50 ml min^-1 g^-1. In comparison to NaCl solution, natural seawater is found to have an inhibiting effect on the hydrolysis of Mg-Al-Fe material. Especially, the presence of Mg²⁺ and Ca²⁺ in seawater can greatly reduce the hydrogen conversion yield, and the SO₄^2- can decrease the hydrogen generation rate.