Graphene membranes with tuneable nanochannels by intercalating self-assembled porphyrin molecules for organic solvent nanofiltration

Organic solvent nanofiltration (OSN) membranes with excellent and tuneable molecular separation performances are important in pharmaceutical industry. Here, we report reduced graphene oxide (rGO) membranes intercalated with self-assembled 5, 10, 15, 20-tetrakis (1-methyl-4-pyridinio) porphyrin (TMPyP) molecules for this purpose. These membranes showed strong tolerances to water and various organic solvents and their OSN performances can be easily tuned by controlling the amount of intercalated porphyrin molecules. The methanol permeance of an rGO membrane (mass loading = 44 mg m−2) was increased by 2 times upon intercalating 60% TMPyP relative to its own weight. This composite membrane also exhibited high rejection (>92%) for negatively charged organic dyes with molecular dimensions larger than 1.7 nm in methanol. As a demonstration, it was used to separate vitamin B12 from its aqueous or methanol solution, exhibiting a solvent permeance of 5.76 or 4.40 L m−2 h−1 bar−1 and a rejection of 98.4% or 91.0%.

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