Stabilization and strengthening of chromium(VI)-contaminated soil via magnesium ascorbyl phosphate (MAP) and phytase addition

Lijun Han; Jiangshan Li; Xunchang Fei; Mengqi Wang; Shiyu Liu; Xianwei Zhang; Qiang Xue

doi:10.1016/j.jhazmat.2023.130860

Stabilization and strengthening of chromium(VI)-contaminated soil via magnesium ascorbyl phosphate (MAP) and phytase addition

J Hazard Mater. 2023 Apr 15:448:130860. doi: 10.1016/j.jhazmat.2023.130860. Epub 2023 Jan 23.

Authors

Lijun Han¹, Jiangshan Li², Xunchang Fei³, Mengqi Wang⁴, Shiyu Liu⁴, Xianwei Zhang⁴, Qiang Xue⁵

Affiliations

¹ State Key Laboratory of Geomechanics and Geotechnical Engineering, Institute of Rock and Soil Mechanics, Chinese Academy of Sciences, Wuhan 430071, China; University of Chinese Academy of Science, Beijing 100049, China; School of Civil and Environmental Engineering, Nanyang Technological University, Nanyang Avenue, 639798, Singapore.
² State Key Laboratory of Geomechanics and Geotechnical Engineering, Institute of Rock and Soil Mechanics, Chinese Academy of Sciences, Wuhan 430071, China; IRSM-CAS/HK PolyU Joint Laboratory on Solid Waste Science, Wuhan 430071, China. Electronic address: jsli@whrsm.ac.cn.
³ State Key Laboratory of Geomechanics and Geotechnical Engineering, Institute of Rock and Soil Mechanics, Chinese Academy of Sciences, Wuhan 430071, China; School of Civil and Environmental Engineering, Nanyang Technological University, Nanyang Avenue, 639798, Singapore; Residues and Resource Reclamation Centre, Nanyang Environment and Water Research Institute, 1 Cleantech Loop, 637141, Singapore.
⁴ School of Urban Construction, Wuhan University of Science and Technology, Wuhan 430065, China.
⁵ State Key Laboratory of Geomechanics and Geotechnical Engineering, Institute of Rock and Soil Mechanics, Chinese Academy of Sciences, Wuhan 430071, China; IRSM-CAS/HK PolyU Joint Laboratory on Solid Waste Science, Wuhan 430071, China. Electronic address: qxue@whrsm.ac.cn.

PMID: 36709739
DOI: 10.1016/j.jhazmat.2023.130860

Abstract

Cr(VI) contamination of soil threatens the environment and reduces soil strength. Therefore, both Cr(VI) stabilization and soil reinforcement should be considered in site remediation for future construction. This study investigated a biochemical treatment process using magnesium ascorbyl phosphate (MAP) and phytase. MAP was hydrolyzed via phytase catalysis to produce ascorbic acid (AA) and MgHPO₄·3H₂O precipitation. The AA reduced Cr(VI) into low-toxic Cr(III), which precipitated as Cr(OH)₃ and CrPO₄. More than 90% of the 500 mg/kg Cr(VI) in soil was reduced by 5% MAP (wt% of soil) and 1% phytase (vol/vol of soil water) doses at the geotechnically optimal soil moisture content of 16.8%. The MgHPO₄·3H₂O precipitates filled soil pores and enhanced the unconfined compression strength of treated soil by more than two times. This research reports a novel and practical enzymatically induced phosphate precipitation process for the remediation of Cr(VI)-contaminated soil.

Keywords: Cr(VI) reduction; Magnesium ascorbyl phosphate (MAP); Phytase; Soil strengthening.