Immobilized graphene oxide-based membranes for improved pore wetting resistance in membrane distillation

Abstract

Membrane distillation (MD) is a useful method for the purification of difficult feedwaters but it cannot be applied in a range of industries due to pore wetting. In this work, graphene oxide (GO) laminate coatings are explored to overcome the pore wetting issues. Air gap MD (AGMD) configuration was considered, using a 35 g L−1 NaCl solution with 150 mg L−1 (150 ppm) of Triton X-100 surfactant as feed material. The GO is deposited as a laminate membrane on top of a commercial porous polyvinylidene fluoride (PVDF) support and good adhesion is achieved through the use of polydopamine (PDA) to form a hydrophilic tri-layer membrane. The small pore size achieved with the laminate GO led to increased pore wetting resistance for at least 90 h compared to 20 min with pristine commercial PVDF. Additionally, the extra layers of GO and PDA did not affect the membrane flux. Overall, a tri-layer immobilized GO membrane is synthesized with superior performance when compared to current commercial membranes, meaning that MD can be used for a new range of wastewater applications.