Preparation of 2D Materials and Their Application in Oil–Water Separation

Abstract

The problems of environmental pollution are increasingly severe. Among them, industrial wastewater is one of the primary sources of pollution, so it is essential to deal with wastewater, especially oil and water mixtures. At present, biomimetic materials with special wettability have been proven to be effective in oil-water separation. Compared with three-dimensional (3D) materials, two-dimensional (2D) materials show unique advantages in the preparation of special wettable materials due to their high specific surface area, high porosity, controlled structure, and rich functional group rich on the surface. In this review, we first introduce oil–water mixtures and the common oil–water separation mechanism. Then, the research progress of 2D materials in oil–water separation is presented, including but not limited to their structure, types, preparation principles, and methods. In addition, it is still impossible to prepare 2D materials with large sizes because they are powder-like, which greatly limits the application in oil–water separation. Therefore, we provide here a review of several ways to transform 2D materials into 3D materials. In the end, the challenges encountered by 2D materials in separating oil–water are also clarified to promote future applications.

Expanding the horizons of covalent organic frameworks: sub-stoichiometric synthesis as an emerging toolkit for functional COFs

“…A large number of as-synthesized and membrane-immobilized COFs have shown wide applications in micropollutant removal, oil water separation, decontamination of metal ions and biological applications. [154][155][156][157][158][159][160][161][162] Carbon allotropes containing COF hybrids are also known to improve their physicochemical properties for energy and environmental applications. [163][164][165] In this context, the rst report on a hybrid material comprising of a COF synthesized via a sub-stoichiometric approach (TT-COF) and graphene oxide (GO) appeared in 2022.…”

Hybrid Two-Dimensional Porous Materials

“…Among 2D materials such as graphene derivatives, MXene, LDHs, and TMDs possess desirable mechanical, thermal, and wetting properties and show potential for oil−water separation. 85 However, they have limitations such as surface oxygen functional groups, hydrolysis, insufficient interlayer spacing, and oxidation in open atmosphere, which hinder their practical application. Hybridizing MOFs with suitable 2D materials can address these limitations and improve their properties, such as increasing stability, hydrophobicity, and creating hierarchical pores, resulting in advanced materials for oil−water separation applications.…”

“…However, pure MOFs are prone to moisture-induced degradation in open environments due to their microporous nature. Among 2D materials such as graphene derivatives, MXene, LDHs, and TMDs possess desirable mechanical, thermal, and wetting properties and show potential for oil–water separation . However, they have limitations such as surface oxygen functional groups, hydrolysis, insufficient interlayer spacing, and oxidation in open atmosphere, which hinder their practical application.…”

Two-Dimensional Nanomaterial (2D-NMs)-Based Polymeric Composite for Oil–Water Separation: Strategies to Improve Oil–Water Separation

“…Recently, two-dimensional (2D) materials such as graphene, graphene oxide (GO), carbon nitride (C 3 N 4 ), boron nitride (BN), and transition metal dichalcogenides (TMDs) (WS 2 , MoS 2 , MXene,), layered double hydroxides (LDHs), and black phosphorus (BP) etc. have drawn a key interest among the researchers in this field due to the unique properties of 2D-NMs such as high surface area, amenability to surface modifications, high mechanical strength, facile synthesis, and cost-effectiveness that provide a chance for scaling up the process, thereby effectively using various applications including oil-water separation [30][31][32][33][34][35][36][37][38][39]. 2D-NMs provide fast diffusion (sorption-desorption) rate and enhance water transportation.…”