Molecule transfer mechanism in 2D heterostructured lamellar membranes:
The effects of dissolution and diffusion
Abstract
Two-dimensional (2D) lamellar membranes are promising for efficient
molecule transfer, while the underlying molecule transfer mechanism is
rarely elucidated. Herein, heterostructured nanosheets are prepared by
self-assembling small-sized hydrophilic cyanuric acid melamine (CMN) and
hydrophobic g-C3N4 nanosheets. The resultant lamellar membranes show
comparable affinity to both polar and nonpolar solvents, allowing them
to dissolve on membrane surface and diffuse through membrane channels.
Permeance results demonstrate that the transfer of polar solvents is
controlled by dissolution and diffusion processes, while that of
nonpolar solvents is governed by dissolution process. And the
corresponding equations are established. Importantly, polar solvents are
induced to form ordered arrangement in hydrophilic nanodomains and then
maintain this state in hydrophobic nanodomains, affording low-resistance
transfer thus high permeance: 1025 L m-2 h-1 bar-1 for acetonitrile. In
contrast, nonpolar solvents with disordered arrangement acquire lower
permeance than that of polar ones, but with comparable diffusion ability
in these membranes.