Efficacy of Electrically-Polarized 3D Printed Graphene-blended Spacers on the Flux Enhancement and Scaling Resistance of Water Filtration Membranes

TL;DR

This study introduces an electrically-polarized 3D printed graphene-polylactic acid spacer that significantly enhances water flux and reduces scaling in water filtration membranes through novel fabrication and polarization techniques.

Contribution

First demonstration of electrically-polarized 3D printed graphene-polylactic acid spacers for improved membrane performance in water filtration.

Findings

Water flux increased by over 50% with E-GRP spacer.

E-GRP spacer reduced gypsum scaling on membranes.

Polarization effect maintained for over 100 hours.

Abstract

In this research, an electrically-polarized graphene-polylactic acid (E-GRP) spacer is introduced for the first time by a novel fabrication method, which consists of 3D printing followed by electrical polarization under a high voltage electric field (1.5 kV/cm). The fabricated E-GRP was tested in an osmotic-driven process (forward osmosis system) to evaluate its performance in terms of water flux, reverse solute flux, and ion attraction compared to a 3D printed non-polarized graphene-polylactic acid (GRP) spacer and a polylactic acid (PLA) spacer. The use of the developed E-GRP spacer showed > 50% water flux enhancement (32.4 +- 2 LMH) compared to the system employing the GRP (20.5 +- 2.3 LMH) or PLA (20.8 +- 2.1 LMH) spacer. This increased water flux was attributed to the increased osmotic pressure across the membrane due to the ions adsorbed on the polarized (E-GRP) spacer. The E-GRP spacer also retarded the gypsum scaling on the membrane compared to the GRP spacer due to the dispersion effect of electrostatic forces between the gypsum aggregation and negatively charged surfaces. The electric polarization of the E-GRP spacer was shown to be maintained for > 100 h by observing its salt adsorption properties (in a 3 M NaCl solution).