Highly efficient graphene oxide-based functionalized membranes for water desalination and dye separation

Abstract

Wastewater treatment is one of the most challenging problems nowadays due to the presence of different solid pollutants like dyes, salts, and organic compounds. Graphene oxide (GO)-based membrane technology is a potential method to treat wastewater. Herein, we developed a novel cGO/MSG composite membrane by functionalizing GO nanosheets with monosodium glutamate (MSG) as a cross-linker with tailored interlayer spacing. Subsequently, the cGO/MSG membranes with varying thicknesses were utilized to achieve efficient separation of diverse salts and dyes. The as-synthesized cGO/MSG membrane showed high pure water permeance of 213 ± 5 L m⁻² h⁻¹ bar⁻¹. Such a membrane also showed excellent separation efficiency for dyes with high water permeance, i.e., methylene blue (100 ± 1% and water permeance of 90 ± 5 L m⁻² h⁻¹ bar⁻¹) and even blue (99 ± 1% and permeance 130 ± 5 L m⁻² h⁻¹ bar⁻¹). Moreover, the membranes exhibited excellent salt rejection properties, with rejection rates greater than 97% achieved for Pb(NO₃)₂ and Ni(NO₃)₂. Additionally, these membranes were also stable even in harsh conditions for a long time. We believe that this approach will help to develop different membranes in the future for desalination purposes.