Cr (VI) removal from industrial wastewater by regenerable sulfureted maghemite (γ-Fe2O3): Magical activity self-promotion after regeneration and effective recovery of Cr resource

• Published in: Separation and purification technology 2024-02, Vol.330, p.125386, Article 125386
• Main Authors: Zheng, Qianxian, Zhang, Yuting, Yang, Xuanlin, Tian, Quan, Hou, Chuanbing, Mei, Jian, Yang, Shijian
• Format: Article
• Language: English
• Subjects: Adsorption; Hexavalent chromium [Cr (VI)]; Regeneration; Removal mechanism; Sulfureted maghemite (γ-Fe2O3)
• ISSN: 1383-5866; 1873-3794
• DOI: 10.1016/j.seppur.2023.125386

[Display omitted] •Sulfureted γ-Fe2O3 exhibits superior ability for Cr (VI) removal with a rate of 10.1 mg g−1 h−1 and capacity of 74.0 mg g−1.•The Cr (VI) removal activity of sulfureted γ-Fe2O3 is self-promoted after regeneration.•Cr (VI) is enriched on sulfureted γ-Fe2O3 as Cr(OH)3 through multiple adsorptions and then refine Cr with chromite.•The reductive species on sulfureted γ-Fe2O3 for Cr (VI) reduction are FeS and FeS2. The currentsorbents for Cr (VI) removal from industrial wastewater have some unsatisfactory performances in terms of activity, regeneration, and safe disposal of adsorbed Cr species. Herein, sulfureted maghemite (γ-Fe2O3) was developed as a regenerable sorbent to recover Cr (VI). Sulfureted γ-Fe2O3 exhibited superior ability for Cr (VI) removal with a rate of 10.1 mg g−1h−1 and capacity of 74.0 mg g−1. Cr (VI) removal by sulfureted γ-Fe2O3 depended on the quantities of FeS and FeS2, as well as the amounts of adsorbed Cr (VI) and H+. Although the quantities of FeS and FeS2 on sulfureted γ-Fe2O3 notably decreased after regeneration, the adsorption of Cr (VI) and H+ onto sulfureted γ-Fe2O3 were significantly promoted after regeneration due to the formation of Cr(OH)3 and Fe(OH)3. Hence, the Cr (VI) removal activity of sulfureted γ-Fe2O3 was notably promoted after regeneration. Cr (VI) in industrial wastewater was gradually enriched on sulfureted γ-Fe2O3 as Cr(OH)3 through multiple adsorptions, and it can be used as a raw material with chromite to refine Cr as the chemical component of spent sulfureted γ-Fe2O3 was similar to that of chromite. Therefore, sulfureted γ-Fe2O3 may be a promising sorbent for Cr (VI) removal from industrial wastewater.