Carbon-silica mesoporous composite in situ prepared from coal gasification fine slag by acid leaching method and its application in nitrate removing

Dandan Zhu; Jing Zuo; Yinshan Jiang; Jinyi Zhang; Jiupeng Zhang; Cundi Wei

doi:10.1016/j.scitotenv.2019.136102

Carbon-silica mesoporous composite in situ prepared from coal gasification fine slag by acid leaching method and its application in nitrate removing

Sci Total Environ. 2020 Mar 10:707:136102. doi: 10.1016/j.scitotenv.2019.136102. Epub 2019 Dec 13.

Authors

Dandan Zhu¹, Jing Zuo¹, Yinshan Jiang¹, Jinyi Zhang¹, Jiupeng Zhang¹, Cundi Wei²

Affiliations

¹ Key Laboratory of Automobile Materials (Ministry of Education), College of Materials Science and Engineering, Jilin University, Changchun 130025, People's Republic of China.
² Key Laboratory of Automobile Materials (Ministry of Education), College of Materials Science and Engineering, Jilin University, Changchun 130025, People's Republic of China. Electronic address: weicundi_jlu@163.com.

PMID: 31863988
DOI: 10.1016/j.scitotenv.2019.136102

Abstract

Coal gasification fine slag (CGFS) was produced in the coal gasification process which was classified as an industrial solid waste. It was featured with naturally formed amorphous structures and an abundance of silicon, carbon and metal oxides. In this study, on the basis of the composition and structure characteristics of CGFS, a simple hydrochloric acid (HCl) leaching technology was applied to in situ prepare carbon-silica mesoporous composites (CSMCs) from CGFS by fully considering the value of the residual carbon. Special focus was put on the novel mechanism of pore formation in amorphous silica glass microspheres (SGM) during acid leaching. Experimental evidences showed that the metal oxides were uniformly distributed in SGM thus the dissolution of the metal oxides were starting from the surface of SGM, then gradually extending to the interior, and finally leading to form "tree branch" mesoporous channels. In addition, a response surface method was used to predict the optimal reaction conditions and the optimal sample (named as CGFS-O) was successfully prepared. CGFS-O possessed a prominent specific surface area (SSA) (337.51 m²/g) as well as an excellent pore volume (0.341 cm³/g). CGFS-O also exhibited a desirable capacity for NO₃^- removing and the adsorption process was studied detailed by changing different adsorption conditions. Adsorption results proved that CSMCs have the potential to purify wastewater in an economically and environmentally way. Therefore, combined with a proof-of-concept adsorption performance experiment, our study has not only provided a cost-effective strategy to industrially prepare CSMCs, reutilizing CGFS in an environmentally friendly way, but also contributed to the future applications of CSMCs with valuable insights into the pore formation mechanism in SGM during acid leaching process.

Keywords: Carbon-silica mesoporous composite; Coal gasification fine slag; Environmental protection; Nitrate adsorption; Pore formation mechanism; Solid waste utilization.