Microstructure optimization of bioderived polyester nanofilms for antibiotic desalination via nanofiltration

The successful implementation of thin-film composite membranes (TFCM) for challenging solute-solute sepa-rations in the pharmaceutical industry requires a fine control over the microstructure (size, distribution, and connectivity of the free-volume elements) and thickness of the selective layer. For example, desalinating anti-biotic streams requires highly interconnected free-volume elements of the right size to block antibiotics but allow the passage of salt ions and water. Here, we introduce stevioside, a plant-derived contorted glycoside, as a promising aqueous phase monomer for optimizing the microstructure of TFCM made via interfacial poly-merization. The low diffusion rate and moderate reactivity of stevioside, together with its nonplanar and dis-torted conformation, produced thin selective layers with an ideal microporosity for antibiotic desalination. For example, an optimized 18-nm membrane exhibited an unprecedented combination of high water permeance (81.2 liter m-2 hour-1 bar-1), antibiotic desalination efficiency (NaCl/tetracycline separation factor of 11.4), an-tifouling performance, and chlorine resistance.

Automated summary

The successful implementation of thin-film composite membranes (TFCM) for challenging solute-solute separations in the pharmaceutical industry requires fine control over the microstructure and thickness of the selective layer. In this study, stevioside, a contorted glycoside derived from plants, was introduced as a promising monomer for optimizing the microstructure of TFCM. The use of stevioside produced thin selective layers with ideal microporosity for antibiotic desalination, exhibiting high water permeance, antibiotic desalination efficiency, antifouling performance, and chlorine resistance.