Large-scale production of 4MoO3·2NH3·H2O nanosheets through antisolvent crystallization for highly efficient removal of cationic dyes

A facile method for the large-scale production of 4MoO 3 ·2NH 3 ·H 2 O (MAH) nanocrystal with tunable size and morphology is developed through an antisolvent crystallization approach. The introduction of hydroxyl groups during crystallization promotes the formation of oxygen vacancies on the MAH. Due to the high concentration of Mo 5+ centres, small nanosheet thickness, and sandwich-like crystal structure, MAH-20 exhibits an outstanding adsorption capability toward cationic dyes, with the maximum adsorption capacities up to 1169.2 mg·g −1 for methylene blue (MB) and 1452.8 mg·g −1 for rhodamine B (RhB), which are almost 10 times as that of MAH-0. An electrostatic adsorption mechanism is proposed to interpret the highly selective adsorption activity toward cationic dyes. Moreover, a fast and recyclable treatment and adsorbent regeneration are realized based on a continuous flow filtration device.