Design of Graphene-based Adsorbents and Its Removal of Antibiotics in Aqueous Solution

It is a widespread concern that the extensive use of antibiotics has caused not only harm to the human body but also heavy environmental pollution. Because of its high efficiency and universal applicability, adsorption technology has significant application potential for the removal of antibiotics. The development of new adsorbents is critical for high-efficiency adsorption treatment. In recent years, the excellent physical, chemical, and adsorption properties of graphene have made it an important antibiotic adsorbent. The high specific surface area and large number of pores of graphene provide many adsorption sites for antibiotics. In addition, the conjugated structure makes graphene relatively electronegative, which also affects adsorption. Due to the limitations of graphene and the increasing requirements for efficiency and stability of graphene adsorbents, a variety of graphene-based adsorbents have been developed to solve the issues of graphene agglomeration in aqueous solutions, poor graphene dispersibility, and poor adsorption performance. Thus far, there has not been a systematic review on the design, synthesis, and adsorption mechanism of graphene-based composites for the removal of antibiotics in aqueous solutions. The design and preparation methods for magnetic graphene adsorbents, polymer/graphene adsorbents, three-dimensional graphene gels, graphene/biochar adsorbents, and graphene-based adsorbents for catalytic degradation of antibiotics are also reviewed. We show the synthesis and design concepts of various graphene-based adsorbents, as well as their different physical and chemical properties and adsorption performance, so that we can distinguish and select different graphene-based adsorbents. We also discuss the design of adsorbents for different kinds of antibiotic contaminants to provide guidance to future researchers for choosing the appropriate design methods based on the antibiotic type. These graphene-based adsorbents can also be extended to the adsorption of various pollutants, which is of great significance for environmental protection. The main adsorption mechanism of antibiotics on graphene-based adsorbents in aqueous solutions is expounded. The cyclic structure of graphene determines the interaction between graphene and antibiotics, such as p-p and cation-p interactions. The numerous oxygen-containing functional groups on the surface of graphene oxide (GO) provide more possibilities for the design of graphene composites. Finally, the future development of graphene-based adsorbents for the removal of antibiotics in aqueous solutions is discussed. We recommend the design of highly-efficient, broad-spectrum, and selective adsorbents for high adsorption performance for multiple antibiotic contaminants in the environment. We also address the regeneration and disposal of graphene-based sorbents and promote green, harmless, and resource-based disposal.