Petaloid-array hierarchically structured carbon Dots/Mg(OH)2 composite: Design, characterization and removal/recovery of cadmium via slowly releasing

The ever-growing contamination of water resources generated by heavy metals is posing significant threat to sustainable development, and urging the necessity of safe disposal. In this work, we designed a facile method to prepare carbon dots/Mg(OH) 2 (marked as CDs/Mg(OH) 2 ) composite, which enables to remove and recover potentially toxic metal of Cd 2+ from water. The newly-prepared CDs/Mg(OH) 2 features a hierarchical petaloid-array structure and has large specific surface area of 96.2 m 2 g −1 . It is evident that the composite is composed of Mg(OH) 2 slices, to which CDs are attached. Density functional theory calculation recognized the composite microstructure at the atomic level. Weak chemical coupling between sub-units were borne out by optimized structures, energetics, infrared vibrations, and electronic structures. The CDs/Mg(OH) 2 composite shows high removal capacity and long durability while treating Cd(II)-contaminated water. The incorporation of CDs could regulate and control the up-taking rate of Cd 2+ ions and consequently fabricate well-dispersed 1D nanowires of Cd(OH) 2 . The corresponding mechanism was proposed. Specifically, the sample CDs/Mg(OH) 2 -60 reaches 1015.4 mg g −1 removal capacity; it can be used for 12 cycles and still keep removal efficiency as high as 98.6%.