Spray-coated graphene oxide hollow fibers for nanofiltration

Advances in process intensification in the chemical and pharmaceutical industry depends on the availability of more sustainable separation methods. For this progress, membranes with high stability in organic solvents are needed. GO-coated membranes could be advantageous in these applications, being chemically, thermally and mechanically stable. However, simple, scalable, low-cost fabrication methods, particularly for GO deposition on hollow fibers are still in an early phase. We propose here a simple spray-coating method for deposition of GO sheets on crosslinked hollow fiber supports. We first fabricated polyetherimide hollow fiber membranes and crosslinked them with hexamethylene diamine. These supports have strong tolerance to various organic solvents. The amide reaction arising between the imide groups of polyetherimide and the amine groups of hexamethylene diamine provide even higher chemical and mechanical stability. Thereafter, the spray-coating of GO dispersions led to the formation of a stable selective layer on the hollow fibers. An excellent adhesion between GO and the substrate was achieved. The chemical reasons for that were investigated by solid state NMR. Overall, this simple method enables the application of GO hollow fiber membranes in organic solvent nanofiltration, with high performance demonstrated in water and acetone.