Molecule transfer mechanism in two-dimensional heterostructured lamellar membranes: The effects of dissolution and diffusion

Two-dimensional lamellar membranes are promising for efficient molecule transfer, while the underlying transfer mechanism is rarely elucidated. Herein, heterostructured nanosheets are prepared by self-assembling small-sized hydrophilic cyanuric acid melamine and hydrophobic g-C3N4 nanosheets. Resultant lamellar membranes show comparable affinity to polar and nonpolar solvents, allowing them to dissolve on membrane surface and diffuse through membrane channels. Results demonstrate that for lamellar membranes with distinct wettability, the permeance difference for polar solvents is originated from dissolution and diffusion processes, while that for nonpolar solvents is stemmed from dissolution process. Accordingly, corresponding equations which are suitable for heterostructured lamellar membranes are established. Importantly, polar solvents are induced to form ordered arrangement in hydrophilic nanodomains and then maintain the ordered state in hydrophobic nanodomains, affording a low-resistance transfer and high acetonitrile permeance of 1025 L m(-2) h(-1) bar(-1). In contrast, nonpolar solvents with disordered arrangement exhibit lower permeance than that of polar ones.