Incorporation of Cellulose Nanocrystals into Graphene Oxide Membranes for Efficient Antibiotic Removal at High Nutrient Recovery

Abstract

Two-dimensional (2D) material-based membranes hold great promise in wastewater treatment. However, it remains challenging to achieve highly efficient and precise small molecule/ion separation with pure 2D material-fabricated lamellar membranes. In this work, laminated graphene oxide (GO)–cellulose nanocrystal (CNC) hybrid membranes (GO/CNC) were fabricated by taking advantages of the unique structures and synergistic effects generated from these two materials. The characterization results in physiochemical properties, and the structure of the as-synthesized hybrid membranes displayed enhanced membrane surface hydrophilicity, enhanced crumpling surface structure, and slightly enlarged interlayer-spacing with the incorporation of CNCs. Water permeability increases by two to four times with the addition of different CNC weight ratios in comparison to a pristine GO membrane. The optimal GO/CNC membrane achieved efficient rejection toward three typical antibiotics at 74.8, 90.9, and 97.2% for sulfamethoxazole (SMX), levofloxacin (Levo), and norfloxacin (Nor), respectively, while allowing a high passage of desirable nutrients such as NO3 – and H2PO4 –. It was found that SMX removal is primarily governed by electrostatic repulsion, while adsorption plays a crucial role in removing Levo and Nor. Moreover, the density functional theory calculations confirmed the increased antibiotic removal in the presence of an organic foulant, humic acid. Such a 2D material-based hybrid membrane offers a new strategy to develop fit-for purpose membranes for resource recovery and water separation.

Cross-Linked and Doped Graphene Oxide Membranes with Excellent Antifouling Capacity for Rejection of Antibiotics and Salts

“…For the pristine GO membrane, the peaks at 1724, 1642, 1404, 1234, and 1070 cm –1 corresponded to the CO stretching vibration over the −COOH group, the sp 2 -hybridized CC stretching vibration, the C–OH stretching vibration over the −COOH group, the C–O–C stretching vibration, and the C–O stretching vibration over the alkoxyl group. These adsorption bands could be ascribed to the presence of carboxyl, aromatic, epoxy, and alkoxy groups on the GO nanosheets. ,, Compared with the GO-MPD membrane, the adsorption peak intensities of the CO stretching vibration (1728 cm –1 ), the C–OH stretching vibration (1404 cm –1 ), and the C–O–C stretching vibration (1233 cm –1 ) were decreased, which showed that MPD consumed part of the oxygen-containing groups on GO nanosheets through the covalent cross-linking reaction. At the same time, the adsorption band of the CO stretching vibration slightly blue-shifted from 1724 to 1728 cm –1 .…”

“…In addition, the composite membranes prepared by doping are also a way to improve the performance of nanofiltration. Gao et al prepared the hybrid membrane by mixing GO with cellulose nanocrystal (CNC) and loading it on a poly­(vinylidene fluoride) (PVDF) substrate, which had a unique structure and synergistic effect, and showed high water permeability and antibiotic rejection rate . Zhang et al prepared a partially reduced graphene oxide (prGO)-doped sulfonated graphene oxide (S-GO) composite membrane and carried out thermal deoxidation treatment .…”

Organic–Inorganic Hybrid Near-Infrared Emitting Porous Polymer for Detection and Photodegradation of Antibiotics

“…Recently, fluorescence detection has been widely applied to detection of antibiotics because of its facile operation and high sensitivity . In addition, various techniques for removing antibiotics from water involve catalysis, adsorption, membrane separation, etc. − In water pollution control, catalysis treatment has also been recognized as a convenient and efficient method . Among the various reactions, photocatalytic water purification has attracted a lot of attention because of its high efficiency, low cost, and easy operation .…”

Machine Learning of Microscopic Ingredients for Graphene Oxide/Cellulose Interaction

“…Recently, nCL/GO composites were applied to develop sensors, capacitors, , water treatment membranes, , biomaterials, and environmental remediation materials . The GO functional groups (i.e., hydroxyl, epoxy, carbonyl, and carboxyl) favor the electrostatic attraction and hydrogen bonding with cellulose chains .…”