LiAlO₂-Melamine for efficient and rapid iodine capture

The search for efficient material to capture iodine from off-gas streams continues. Herein, a novel composite of lithium aluminate and melamine, abbreviated as LiAlO2-Mel, was synthesized and exhibited high vapor iodine capture capacity accompanied by good regeneration ability. The LiAlO2-Mel showed an enormous capture capacity of 1281 mg/g within 4 h towards I2 (g) at 150 °C. The kinetics study showed that the dominant process (at 150 °C) was chemisorption via NI and C-NHI bonding mechanisms. Additionally, LiAlO2-Mel has a low surface area (14.6157 m2/g) yet produced high capacity, suggesting chemisorption played a critical role. However, physisorption was the dominant process at lower temperature values, as proved by kinetics fittings and activation energy (Ea = 23.19 KJ/mol) studies. The kinetics models were validated by statistical error validity models (sum of square error, Chi-square test, and normalized standard deviation). Thermogravimetric analysis and adsorption-desorption experiments showed that the LiAlO2-Mel can be recovered by heat treatment (25-800 °C) in N2 atmosphere and ethanol washout (24 h, 25 °C) of the LiAlO2-Mel-I. The high capture capacity, along with eco-friendly and cost-effectiveness, highlights the promising potential of LiAlO2-Mel for iodine capture.