Effect of carbon type on the detoxification mechanism of hexavalent chromium [Cr(VI)] by carbothermal reduction. Issue 4 (August 2022)

• Record Type: Journal Article
• Authors: Xie, Junlin; Wei, Kun; Liu, Xiaoqing; Fang, De
• Is Part Of: Journal of environmental chemical engineering. Volume 10:Issue 4(2022)
• Publication Date: 2022-08
• Subjects: Nano carbon powder -- Hexavalent chromium [Cr(VI)] detoxification -- Chromium carbide -- Particle size -- sp2 hybrid orbital; Chemical engineering -- Environmental aspects -- Periodicals; Environmental engineering -- Periodicals; Chemical engineering -- Environmental aspects; Environmental engineering; Periodicals; 660.0286
• DOI: 10.1016/j.jece.2022.108091
• Languages: English
• ISSNs: 2213-2929

Abstract

Abstract: Carbon powders were used to detoxify [Cr(VI)] in metallurgical solid waste was investigated, since the presence of [Cr(VI)] had a very serious impact on the environment. Five types of carbon powders were selected as carbon sources and soluble CrO3 was used as a hexavalent chromium source in metallurgical solid waste. Ultra-fine Cr3 C2 powders (about 80 nm) were synthesized by carbothermal reduction reaction to achieve the detoxification of [Cr(VI)]. The temperature plays a crucial role in the synthesis of Cr3 C2 according the experimental and thermodynamic results, illustrating that the synthesis temperature was in the range of 900 ℃–1200 ℃. Surface area, morphology, and surface chemistry of carbon powders were investigated to analyze the effect of carbon type on the mechanism of detoxification of hexavalent chromium [Cr(VI)] and the formation of chromium carbide. The results show that nano carbon powder with finer particle size (30–50 nm), higher specific surface area (101.5 m 2 /g) and fewer chemical bonds with carbon atoms formed by sp 2 orbital hybridization are more suitable as a carbon source for carbothermal reduction of [Cr(VI)]. Therefore, nano Cr3 C2 powder was achieved at the lowest synthesis temperature (900 ℃), when nano carbon powder was selected as the carbon source. Graphical Abstract: Nano carbon powder shows better reduction ability to detoxify [Cr(VI)] by carbothermal reduction reaction, since the smaller particle size, the higher specific surface area as well as the lower oxygen content and proportion of sp 2 hybrid orbitals on the surface make it easier to carbonize Cr2 O3 and form Cr3 C2 . ga1 Highlights: Nano carbon powders can detoxify [Cr(VI)] by carbothermal reduction efficiently. Lower oxygen content and sp 2 hybrid orbitals on surfaces promote Cr3 C2 formation. Smaller particle size of carbon source favors the carbonization of Cr2 O3 .