Enhanced Cr(VI) stabilization in soil by carboxymethyl cellulose-stabilized nanosized Fe0 (CMC-nFe0) and mixed anaerobic microorganisms

作者：Su, Mei; Yin, Weizhao; Liu, Li; Li, Ping; Fang, Zhanqiang; Fang, Yili; Chiang, Penchi; Wu, Jinhua^*

来源：Journal of Environmental Management, 2020, 257: 109951.

DOI：10.1016/j.jenvman.2019.109951

• Zero-valent iron
• Carboxymethyl cellulose
• Green rust
• Chromium
• Bacteria

A collaborative system of carboxymethyl cellulose stabilized nanosized zero-valent iron (CMC-nFe(0)) and microorganisms was set up to enhance the stabilization of Cr(VI) in soil. In comparison with an aqueous-bound Cr (VI) removal of 18.9% in the nFe(0) system, a higher Cr(VI) removal of 68.9% was achieved in the nFe(0) and microorganisms system after 14 d remediation because the microorganisms on the nFe(0) surface promoted nFe(0) corrosion and enhanced abiotic and biotic Cr(VI) stabilization by generating highly active minerals such as magnetite, lepidocrocite and green rust on the nFe(0) surface. As a stabilizing agent for nFe(0) and an organic substrate for microorganisms, CMC on the nFe surface not only enhanced the dispersion of nFe(0), but also boosted the activity of microorganisms, resulting in a promotion of 0.9 and 0.5 times higher aqueous-bound Cr (VI) removal via the improvement of nFe and microorganisms respectively, thus a total 4 times higher aqueousbound Cr(VI) removal of 95.3% was achieved in the CMC-nFe(0) and microorganisms system as compared to the nFe system. After 14 d remediation, easily available species of Cr(VI) and Cr-total, such as water soluble (WS), exchangeable (EX) and bounded to carbonates (CB), were mainly transformed to less available Fe Mn oxidesbounded (OX) and residual (RS) species because of the production of ferrochrome precipitates (CrxFe1-xOOH or CrxFe1-x(OH)(3)). Besides, the stabilization of Cr(VI) in the CMC-nFe(0) and microorganisms system was pH-dependent and it increased with CMC-nFe(0) dosage. Due to excellent Cr(VI) stabilization and Cr immobilization, coupled CMC-nFe(0) and anaerobic microorganisms process is of great potential in remediating Cr(VI)-containing soil.