Core-shell graphene oxide-polymer hollow fibers as water filters with enhanced performance and selectivity

Extraction of proteins from blood biological fluids requires the removal of large aggregates or cellsby membrane filtration. However, conventional filters, based on simple size exclusion, do not allowto remove small molecules such as antibiotics. Here, we demonstrate that a graphene oxide (GO)layer can be firmly immobilized either inside or outside polyethersulfone-polyvinylpirrolidinonehollow fibers (PES) modules and that the resulting core-shell structure inherits the microfiltrationability of PES and the adsorption selectivity of GO.GO nanosheets were deposited on fiber surface by filtration of a GO suspension through a PEScartridge (cut-off 0.1-0.2 ?m), then fixed on it by thermal annealing at 80°C, rendering theminsoluble. The filtration cut-off, retention selectivity and efficiency of the resulting inner and outermodified hollow fibers (HF-GO) were tested by performing filtration on water spiked with bovinserum albumin (BSA, 66KDa, ?15 nm sized), monodisperse polystyrene nanoparticles (52 nm and303 nm sized), water contaminated with two quinolonic antibiotics (ciprofloxacin and ofloxacin) andrhodamine B (RhB). These tests showed that microfiltration capability of PES was retained by HFGO,in addition the GO coating can capture the molecular contaminants while letting through BSAand smaller Polystyrene nanoparticles. Combined XRD, molecular modelling and adsorptionexperiments show the separation mechanism does not rely only on a physical size exclusion, but itinvolves intercalation of solute molecules between GO layers.