2D-layered Mg(OH)2 material adsorbing cellobiose via interfacial chemical coupling and its applications in handling toxic Cd2+ and UO22+ ions.

ABSTRACT

The interfacial chemistry of nanocomposite materials is of overarching importance in the separation and purification science; moreover, its understanding helps to guide synthesis, clarify structure-property relationship and unearth novel applications. However, the composites feature rather complicated local structures and hydrogen bonds are often involved in the interface and the vicinity of active sites. In this regard, density functional theory first-principle calculations associated with experimental study have synergistically examined two-dimensional (2D) magnesium hydroxide material with different layers and their adsorption toward cellobiose. Hydrogen bonds are found responsible for the interfacial coupling, which make it vital to cover the dispersion correction in the calculation. The average adsorption energy ranges from -0.29 to -0.35 eV, falling well within the range of reported hydrogen-bonding strength. On the basis of calculated structural/interfacial properties and experimental findings, the 2D Mg(OH)2 in terms of three-layer model was unraveled to substitute toxic Cd2+ ion and sorb radioactive UO22+ that is coordinated by water and hydroxyl groups. These reactions are thermodynamically feasible. The ion-exchanging mechanism was proposed for cadmium removal and the outer-sphere adsorption one for uranium extraction.