Effective immobilization of hexavalent chromium from drinking water by nano-FeOOH coating activated carbon: Adsorption and reduction. (1st January 2021)

• Record Type: Journal Article
• Authors: Li, Bing; Zhang, Li; Yin, Weizhao; Lv, Sihao; Li, Ping; Zheng, Xiangyu; Wu, Jinhua
• Is Part Of: Journal of environmental management. Volume 277(2021)
• Publication Date: 2021-01-01
• Subjects: FeOOH -- Iron oxide -- Chromium -- Activated carbon -- Immobilization; Environmental policy -- Periodicals; Environmental management -- Periodicals; Environment -- Periodicals; Ecology -- Periodicals; 363.705
• DOI: 10.1016/j.jenvman.2020.111386
• Languages: English
• ISSNs: 0301-4797

Abstract

Abstract: In this study, nano α-FeOOH (nFeOOH, 100–500 nm) was coated onto activated carbon (nFeOOH@AC) through a dipping means for enhanced Cr(VI) immobilization from drinking water. The nFeOOH@AC significantly improved the Cr(VI) removal from 19.9% (AC control) to 93.4%. XPS spectra and chromium speciation demonstrated that about 90% of adsorbed Cr(VI) was converted to Cr(III) by the nFeOOH@AC, accompanying with a reduction-oxidation of Fe 3+ /Fe 2+ in the nFeOOH matrix due to electrons delivering between AC and surface-bound Cr(VI). The resultant Cr(III) subsequently reacted with Fe(III) to generate stable (Crχ Fe1-χ )(OH)3 precipitates, leading to a much lower Cr(III) release of 7.5% back to solution by the nFeOOH@AC as compared to the AC control of 33.8%, indicating that the nFeOOH@AC had a prospective potential for Cr(VI) immobilization and decreased Cr residue in treated drinking water. Results from column experiment also showed that the nFeOOH@AC afforded a 3.5 times higher capacity for Cr(VI) immobilization and a 3.4 times longer life-span than the pristine AC. Besides, Cr(VI) immobilization by the nFeOOH@AC was a pH-dependent process and the adsorbed Cr on the nFeOOH@AC could be readily desorbed with acetic acid. The disabled nFeOOH@AC could be refreshed by recoating nFeOOH particles with the above dipping method after stripping all the iron oxides with hydrochloric acid. This study demonstrated that nFeOOH coating is an efficient approach to enhance Cr(VI) elimination by AC during drinking water treatments. Graphical abstract: Image 1 Highlights: Nano-FeOOH coating significantly improved Cr(VI) removal and reduced Cr residue by activated carbon (AC). Remarkable Cr(VI) immobilization and longer life-span were achieved in nFeOOH@AC column. Cr(VI) was eliminated via adsorption, reduction and coprecipitation in nFeOOH matrix.