Synthesis and adsorption property of zeolite FAU/LTA from lithium slag with utilization of mother liquid

Co-crystalline zeolite FAU/LTA-0 was synthesized by hydrothermal method from lithium slag. To make the most of excess silicon and alkali sources in mother liquid derived from FAU/LTA-0, zeolite FAU/LTA-1b was synthesized in the same method with the use of mother liquid by adding a certain amount of aluminum source. Influences of different adding ways of aluminum source and recycling dosages of mother liquid on synthesis of zeolites FAU/LTA with mother liquid were investigated. The phase, microstructure and thermostability of FAU/LTA-0 and FAU/LTA-1b were characterized by XRD, SEM and TG-DTA. The calcium and magnesium cation exchange capacities (CECs) of the zeolites were determined. The results have shown that co-crystalline zeolite can be synthesized with the use of mother liquid by adding aluminum source after 2 h of reaction. Compared with FAU/LTA-0, the crystal twinning structure of FAU/LTA-1b became weaker, the grain size was smaller, and the thermostability was better. With a lower dosage of mother liquid, the content of P-type impurity in product decreased significantly, and the content of LTA phase increased. The reuse rate of mother liquid can reach 48%. The CECs of FAU/LTA-1b-150 can reach 343 mg CaCO3.g(-1) and 180 mg MgCO3.g(-1), showing more excellent adsorption capacities than FAU/LTA-0 and commercial zeolite 4A. The full recycling use of mother liquid to synthesize zeolite FAU/LTA which can be applied for detergent not only improves resource utilization but also reduces production cost. (C) 2015 The Chemical Industry and Engineering Society of China, and Chemical Industry Press. All rights reserved.