The increase of organic pollutant concentrations in drinking water sources is a global challenge, which is exacerbated by industrial growth. Membrane separation has been effectively used to remove a range of organics from wastewaters. Small-sized organic micropollutants are often removed by size exclusion across tight ultrafiltration (UF) membranes. These membranes operate at high pressures incurring high energy costs. 2-dimensional nanomaterials including reduced graphene oxide (rGO) have potential to enhance membrane performance by reducing the separation layer thickness, increasing adsorption, enabling finely tuned pore size control, and providing high chemical stability. However, rGO-thin films are structurally unstable in water due to swelling and electrostatic repulsion of rGO nanosheets. We synthesized a novel iron doped rGO nanocomposite membrane with high separation performance of organic molecules in ultrafiltration process. Polyethersulfone (PES) ultrafiltration membranes were surface-modified by polydopamine (PDA), followed by vacuum deposition of a layer of branched polyethylenimine (PEI) cross-linked iron doped rGO (rGO – Fe) nanocomposite thin film. The nanocomposite was prepared in 3 steps: 1) the activation of carbonyl groups located on the iron nanoparticles anchored on graphene oxide (GO - Fe) by N-(3-Dimethylaminopropyl)-N′-ethylcarbodiimide hydrochloride (EDC hydrochloride) and N-Hydroxysuccinimide (NHS), 2) cross-linking GO-Fe through the primary amines of PEI, and 3) thermal reduction of crosslinked GO – Fe by NaBH<sub>4</sub>. Membrane physicochemical properties were characterized by Raman, FTIR, XPS, BET, SEM, TEM and contact angle measurement. PEI cross-linking greatly improved the dimensional stability of rGO - Fe nanocomposite membranes, which could remain intact in water for over 20 days. High removal (&gt; 75.8 %, 81.6 % and 95.7 %, respectively) of <i>p</i>-nitrophenol (6.5 ppm), and azo dyes (methyl orange and methylene blue, 20 ppm) at low transmembrane pressure (4.13 bar) were obtained by dead-end ultrafiltration. This study provides an attractive alternative for micropollutants removal from water at low pressure.

Low-pressure ultrafiltration intensification by novel cross-linked reduced graphene oxide thin film nanocomposite membranes for removal of phenols and organic dyes

ACS Spring 2022

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.