title: Heavy metal removal by GLDA washing: Optimization, redistribution, recycling, and changes in soil fertility.
abstract: Soil washing, an emerging method for treating soils contaminated by heavy metals, requires an evaluation of its efficiency in simultaneously removing different metals, the quality of the soil following remediation, and the reusability of the recycled washing agent. In this study, we employed N,N-bis (carboxymethyl)-l-glutamic acid (GLDA), a novel and readily biodegradable chelator to remove Cd, Pb, and Zn from polluted soils. We investigated the influence of washing conditions, including GLDA concentration, pH, and contact time on their removal efficiencies. The single factor experiments showed that Cd, Pb, and Zn removal efficiencies reached 70.62, 74.45, and 34.43% in mine soil at a GLDA concentration of 75mM, a pH of 4.0, and a contact time of 60min, and in polluted farmland soil, removal efficiencies were 69.12, 78.30, and 39.50%, respectively. We then employed response surface methodology to optimize the washing parameters. The optimization process showed that the removal efficiencies were 69.50, 88.09, and 40.45% in mine soil and 71.34, 81.02, and 50.95% in polluted farmland soil for Cd, Pb, and Zn, respectively. Moreover, the overall highly effective removal of Cd and Pb was connected mainly to their highly effective removal from the water-soluble, exchangeable, and carbonate fractions. GLDA-washing eliminated the same amount of metals as EDTA-washing, while simultaneously retaining most of the soil nutrients. Removal efficiencies of recycled GLDA were no >5% lower than those of the fresh GLDA. Therefore, GLDA could potentially be used for the rehabilitation of soil contaminated by heavy metals.
authors.affiliation: College of Environmental Science, Sichuan Agricultural University, Wenjiang, 611130, China.
authors.forename: Guiyin
authors.initials: G
authors.lastname: Wang
authors.affiliation: College of Environmental Science, Sichuan Agricultural University, Wenjiang, 611130, China. Electronic address: srzhang01@aliyun.com.
authors.forename: Shirong
authors.initials: S
authors.lastname: Zhang
authors.affiliation: College of Environmental Science, Sichuan Agricultural University, Wenjiang, 611130, China.
authors.forename: Xiaoxun
authors.initials: X
authors.lastname: Xu
authors.affiliation: College of Environmental Science, Sichuan Agricultural University, Wenjiang, 611130, China.
authors.forename: Qinmei
authors.initials: Q
authors.lastname: Zhong
authors.affiliation: College of Environmental Science, Sichuan Agricultural University, Wenjiang, 611130, China.
authors.forename: Chuer
authors.initials: C
authors.lastname: Zhang
authors.affiliation: College of Resources, Sichuan Agricultural University, Wenjiang, 611130, China.
authors.forename: Yongxia
authors.initials: Y
authors.lastname: Jia
authors.affiliation: College of Resources, Sichuan Agricultural University, Wenjiang, 611130, China.
authors.forename: Ting
authors.initials: T
authors.lastname: Li
authors.affiliation: College of Resources, Sichuan Agricultural University, Wenjiang, 611130, China.
authors.forename: Ouping
authors.initials: O
authors.lastname: Deng
authors.affiliation: College of Resources, Sichuan Agricultural University, Wenjiang, 611130, China.
authors.forename: Yun
authors.initials: Y
authors.lastname: Li
mesh_terms: D002614:Chelating Agents / Q000737:chemistry*; D002681:China; D052918:Environmental Restoration and Remediation / Q000379:methods*; D005971:Glutamates / Q000737:chemistry*; D005998:Glycine / Q000031:analogs & derivatives* / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D008670:Metals / Q000737:chemistry*; D059027:Recycling; D012987:Soil / Q000737:chemistry*; D012989:Soil Pollutants / Q000737:chemistry*; D013997:Time Factors
chemical_list: D002614:Chelating Agents; D005971:Glutamates; D008670:Metals; C000605118:N,N-bis(carboxymethyl)glutamic acid; D012987:Soil; D012989:Soil Pollutants; D005998:Glycine
keywords: Chelate recovery; N,N-bis (carboxymethyl)-l-glutamic acid; Optimization; Soil fertility; Soil washing