Functionalizing biochar by Co-pyrolysis shaddock peel with red mud for removing acid orange 7 from water. (15th April 2022)

• Record Type: Journal Article
• Authors: Zhang, Ming; Lin, Kun; Zhong, Yuchi; Zhang, Dong; Ahmad, Mahtab; Yu, Jie; Fu, Hailu; Xu, Liheng; Wu, Songlin; Huang, Longbin
• Is Part Of: Environmental pollution. Volume 299(2022)
• Publication Date: 2022-04-15
• Subjects: Red mud biochar -- Acid orange 7 -- Adsorption -- Degradation -- Fe-biochar; Pollution -- Periodicals; Pollution -- Environmental aspects -- Periodicals; Environmental Pollution -- Periodicals; Pollution -- Périodiques; Pollution -- Aspect de l'environnement -- Périodiques; Pollution -- Effets physiologiques -- Périodiques; Pollution; Pollution -- Environmental aspects; Periodicals; Electronic journals; 363.73
• DOI: 10.1016/j.envpol.2022.118893
• Languages: English
• ISSNs: 0269-7491

Abstract

Abstract: Biochar modification by metal/metal oxide is promising for improving its adsorption capability for contaminants, especially the anions. However, conventional chemical modifications are complicated and costly. In this study, novel Fe/Fe oxide loaded biochars (RMBCs) were synthesized from a one-step co-pyrolysis of red mud (RM) and shaddock peel (SP), and their potential application for removing anionic azo dye (acid orange 7, AO7) from the aqueous environment was evaluated. Fe from red mud was successfully loaded onto biochars pyrolyzed at 300–800 °C, which presented from oxidation form (Fe2 O3 ) to the reduction forms (FeO and Fe 0 ) with increasing pyrolysis temperature. The RMBC produced at 800 °C with RM:SP mass ratio of 1:1 (RMBC8001:1 ) exhibited the best capability for AO7 removal (∼32 mg/g), attributed to both adsorption and degradation. The higher surface area of RMBC8001:1 and its greater affinity for AO7 led to the higher adsorption. In addition, RMBC8001:1 -induced degradation of AO7 was another key mechanism for AO7 removal. The reduction forms of Fe (FeO or Fe 0 ) in RMBC8001:1 may provide electrons for breaking down the azo bond in AO7 molecules and result in degradation, which is further enhanced in acid conditions due to the participation of readily release of Fe 2+ and the available H + in AO7 degradation. Furthermore, RMBC8001:1 can be easily separated from the treated water by using magnetic field, which significantly benefits its separation in wastewater treatment. Graphical abstract: Image 1 Highlights: Fe in red mud was transformed into its reduction forms during co-pyrolysis. Red mud biochar removed AO7 effectively via adsorption and degradation. Acidic conditions favored AO7 degradation by RMBC8001:1 . RMBC8001:1 can be magnetically separated.