Wettability-Regulated Synthesis of Metal-Organic Framework Array with Subnanochannels Enables Efficient Separation of Mono-/Multivalent Metal Ions.

Achieving efficient separation of mono-/multivalent metal ions is essential in various fields, yet it remains a significant challenge. In this work, a metal-organic framework (MOF) array with subnanochannels that exhibit high selectivity and ion permeability in the sieving of mono-/multivalent metal ion was developed. Specifically, we used confined interfacial reaction at room temperature to synthesis the MOF array inside the micrometer through-pores of a polyethylene terephthalate (PET) membrane. The location of the oil/water interface was regulated by adjusting the surface wettability of the PET membrane. By taking advantage of size sieving effect of the subnanochannels of MOF crystals, we were able to effectively separate monovalent metal ions from multivalent metal ions with selectivity reaching up to 3930±373 (e.g., Li + /Zr 4+ ). The fluxes of Li + ions were observed to be as high as 1.97 mol h -1  m -2 . The MOF array-based membrane with subnanochannels that we have developed exhibits great promise for applications in wastewater treatment, lithium extraction from salt-lake brines, and other related fields.