Development and challenge of coal-based nanocarbon materials and their application in water treatment: a review

Discover Nano Review Development and challenge of coal‑based nanocarbon materials and their application in water treatment: a review MingShuai Xie1 · HongChao Luo2 · XinJuan Liu1 · ChaoChuang Yin2 Received: 21 July 2024 / Accepted: 23 September 2024 © The Author(s) 2024  OPEN Abstract Under the dual pressures of environmental protection and energy security, the development and application of coalbased nanocarbon materials, supported by the technical concepts of molecular chemical engineering and nanomaterial science, is of significant importance for achieving the high-value clean utilization of coal. Furthermore, it serves as an effective means to assist in the realization of dual carbon goals. Coal, with its abundant reserves, high carbon content, and aromatic and hydrogenated aromatic groups, exhibits great advantages and potential in the synthesis of nanocarbon materials. In addition to its applications in traditional power and chemical industries, coal-based nanocarbon materials also demonstrate significant value in the field of environmental pollution control. This article succinctly summarizes the preparation methods and properties of coal-based carbon nanotubes, coal-based carbon quantum dots, and coalbased graphene, elucidates their current applications in water pollution control and governance, and anticipates their development trends in water pollution control, aiming to provide support for the clean and efficient utilization of coal and water pollution control. Keywords Coal · Coal-based nanocarbon materials · Design and preparation · Carbon quantum dots · Carbon nanotubes · Graphene · Water treatment 1 Introduction Coal, as a widely distributed, abundantly available, and cost-effective natural resource, is a crucial asset for the advancement of human society. Presently, coal is primarily utilized in sectors such as power generation, coking, gasification, liquefaction, pyrolysis, and coal chemical industries. Beyond its efficient and clean use as fuel and non-energy applications in coal chemical industries, an innovative method of efficient and clean utilization of coal is through coal-based nano-carbon materials. Microscopically, coal can be divided into organic and inorganic components. The inorganic portion is mainly comprised of various minerals, including metal oxides, metal sulfides, and carbonates. Conversely, the organic constituents are rich in carbon elements, followed by hydrogen, oxygen, nitrogen, and sulfur. These elements predominantly exist in coal as various functional groups, forming the macromolecular structure of coal, which includes aromatic cores with aromatic layered structures, surrounded by various functional groups and alkyl side chains [1–3]. Additionally, coal exhibits natural similarities to carbon materials, containing crystalline intermediates that lie between amorphous carbon and graphite states [4, 5]. Therefore, coal is an excellent precursor for the preparation of nanoscale carbon materials [6]. Common nano-carbon materials include fullerenes [7], carbon * HongChao Luo, | 1School of Environmental and Chemical Engineering, Dalian University, Dalian 116622, China. 2School of Chemistry and Materials Engineering, Liupanshui Normal University, Liupanshui 553004, China. Discover Nano (2024) 19:162 | https://doi.org/10.1186/s11671-024-04115-4 Vol.:(0123456789) Review Discover Nano (2024) 19:162 | https://doi.org/10.1186/s11671-024-04115-4 nanotubes [8], carbon quantum dots [9, 10], graphene [11], graphene oxide, and carbon fibers [12]. Due to its outstanding material performance parameters [13–15], coal-based nanocarbon materials have extensive applications not only in traditional fields such as electricity and chemical industry, but also in medical [16–18], energy [19–21], and water treatment sectors [22–24]. In the realm of water treatment, these materials are utilized for adsorbing pollutants like heavy metal ions [25–27], nitrobenzenes, antibiotics, bisphenol A, organic dyes, polycyclic aromatic hydrocarbons, and their oxygenated derivatives, owing to their significant specific surface area, abundant pore structure, high mechanical strength, and strong hydrophobic properties [28]. Moreover, their ease of functionalization renders coal-based nanocarbon materials suitable as catalyst supports for catalyzing the degradation of organic pollutants, demonstrating immense utility in the field of water treatment. The application and development time curve of coal-based nano-carbon materials in water treatment are shown in Figs. 1 and 2. The diagram illustrates the progress of research, from the initial exploration of its potential in water treatment to the development of various preparation and modification techniques. At present, the preparation technology of coal-based nano-carbon materials has made certain progress, yet several challenges remain during the process, such as: (1) Environmental pollution issues during preparation. The pretreatment of raw coal involves the use of strong acids, strong bases, high temperatures, high-pressure environments, and special protective atmospheres, resulting in waste liquid, waste gas, and solid waste that not only pose significant environmental hazards but also increase the difficulty of separating and purifying the products. (2) The technology for the large-scale preparation of coal-based nano-carbon materials remains to be refined, primarily due to the diverse types of coal, their complex compositions, and varying contents of impurities. The current preparation technologies are not universally applicable to all types of coal, greatly limiting the commercial application of coal-based nano-carbon materials. (3) The complex composition and structure of coal and its derivatives mean that the relationship between material performance and coal structure composition is still unclear. Therefore, further clarification of the structureperformance relationship between the properties of coal-based nano-carbon materials and their microstructures is required to achieve performance regulation of these materials at the molecular level. (4) The widespread application of carbon nano-materials necessitates modification, functionalization, and structural regulation. Transforming coal and its derivatives into various nano-carbon materials requires multiple operational steps. These four points currently constrain the large-scale preparation and application of coal-based nano-carbon materials in water treatment. Hence, there is a need to develop a process technology and route that couple various modifications, structural regulation, and green efficiency to lower synthesis costs, thereby highlighting the significant raw material and cost advantages in preparing nano-carbon materials based on coal and its derivatives. This paper primarily elucidates the preparation Fig. 1  Application of coalbased nano-carbon materials Vol:.(1234567890) Discover Nano (2024) 19:162 | https://doi.org/10.1186/s11671-0 (...truncated)