Controlling interlayer spacing of graphene oxide membrane in aqueous media using a biocompatible heterobifunctional crosslinker for Penicillin-G Procaine removal

Abstract

In the present work, amino acid crosslinked graphene oxide (GO) membranes were prepared and used to remove Penicillin-G procaine (PG-P) as a model antibiotic from water. The modification of GO nanosheets was performed by β-Alanine (βA) as a biocompatible heterobifunctional crosslinker. The GO-based membranes were prepared on dopamine treated polyethersulfone support using the pressure-assisted self-assembly method. The βA-modified GO nanosheets exhibited a higher interlayer d-spacing in the dry state compared to GO, while swelled in a lower extent (about 2.5 Å) in the aqueous media due to the βA crosslinking effect. The βA-modified GO membranes appeared to have a more ordered lamellar structure and smoother surface morphology, as a result of βA-GO nanosheets higher surface charge and the lower rate of film formation. These membranes provided considerably high water permeability of 75–732 L/m2·h, and excellent rejection of 97% for PG-P, while the unmodified GO-based membranes showed low rejection of 30% for PG-P. Results showed the prominent role of GO-based solution concentration in the separation performance of the resulting membrane; low solution concentration led to low rejection while high concentration weakened the membrane stability. In contrast to GO membranes, the βA-modified GO membranes retained their high separation performance over a wide pressure range of 1–5 bar and feed concentrations of 1–50 ppm. Furthermore, the βA-modified GO membranes provided about three times better antifouling properties due to their smoother surface morphology and higher negative surface charge.