Search

The scalable production of high grade activated carbon from abundant coal for supercapacitors application is an efficient way to achieve high value-added utilization of coal sources. However, this technology is challenging due to lack of comprehensive understanding on the mechanism of activation process and effect of external factors. In this paper, the effect of activating temperature and time on the specific capacitance of coal-based activated carbon prepared by H2O steam activation was studied using the response surface method. Under optimal conditions, coal-based activated carbon exhibits the largest specific capacitance of 194.35 F·g−1, thanks to the appropriate pore/surface structure and defect degree. Density functional theory calculations explain in detail the mechanism of contraction of aromatic rings and overflow of H2 and CO during the activation. Meanwhile, oxygen-containing functional groups are introduced, contributing to the pseudocapacitance property of coal-based activated carbon. This mechanism of reactions between aromatic carbon and H2O vapor provides understanding on the role of water during coal processing at the molecular level, offering great potential to regulate product distribution and predict rate of pore generation. This insight would contribute to the advancement of other coal processing technology such as gasification. [ABSTRACT FROM AUTHOR]

With the widespread promotion of coal gasification technology, the mass-produced solid waste coal gasification slag has caused serious threat to the environment. Coal gasification fine slag (CGFS) is rich in aluminosilicates, which can be used as a source of aluminum (Al). In this study, a hydrothermal method with enhanced mass and heat transfer was used to extract Al from CGFS. The Al3+-rich acid leaching solution was polymerized with calcium aluminate powder to obtain polyaluminum chloride (PAC). Orthogonal test results show that when the extraction rate of Al ions from CGFS reaches 78.9%, the Al2O3 content and basicity of PAC are 30.95% and 58.09%, respectively. When the prepared PAC is added to domestic sewage at 100 mg/L, the turbidity of the sewage drops from 68 to 12 NTU, and the removal rates of chemical oxygen demand and ammonia nitrogen reach 60% and 52.5%, respectively. It is a promising approach for environmental protection and high value-added utilization of CGFS. [ABSTRACT FROM AUTHOR]

Coal gasification fine slag (CGFS) is one of the by-products of coal gasification process, which is mainly composed of inorganic minerals and residual carbon. The key to realize the high-value utilization of CGFS is separating the residual carbon and mineral in CGS effectively. Owing to irregular distribution of carbon in different size of CGFS, which could not be enriched by simple grinding and screening for component enrichment. In this paper, the enrichment of CGFS was carried out by the float-sink method, which is low-cost and does not result in the loss of raw materials. The carbon-rich particles (CRP, ash: 27.89%) and mineral-rich particles (MRP, ash: 78.01%) were obtained, where CRP contains a large amount of amorphous carbon with rich porous structure, while MRP is a heterogeneous material containing not only inorganic minerals but also organic carbon with low porosity. The mineral particles exist as aluminosilicates with a high degree of polymerization. The results of this paper will provide theoretical and technical support for the high-value utilization of CGFS. [ABSTRACT FROM AUTHOR]