TY - JOUR
T1 - Red mud-enhanced magnesium phosphate cement for remediation of Pb and As contaminated soil
AU - Wang, Lei
AU - Chen, Liang
AU - Guo, Binglin
AU - Tsang, Daniel C.W.
AU - Huang, Longbin
AU - Ok, Yong Sik
AU - Mechtcherine, Viktor
N1 - Funding Information:
The authors appreciate the financial support from the Hong Kong Research Grants Council (PolyU 15223517 ), and the Alexander von Humboldt Foundation (AvH) for this study. The authors also gratefully acknowledge the experimental assistance from Ms Simone Hempel for this study.
Publisher Copyright:
© 2020 Elsevier B.V.
PY - 2020/12/5
Y1 - 2020/12/5
N2 - Lead (Pb) and arsenic (As) contaminated soil poses severe threats to human health. This study proposes a novel approach for synchronous stabilisation/solidification (S/S) of Pb and As contaminated soil and explains the immobilisation mechanisms in red mud-modified magnesium phosphate cement (MPC). Experimental results show that incorporation of red mud in MPC binder retarded over-rapid reaction and enhanced compressive strength via the formation of (Al,Fe,K)PO4·nH2O compounds as indicated by X-ray diffractometer (XRD) and elemental mapping. The presence of Pb had a marginal effect on the MPC reaction; however, the presence of As suppressed the generation of MgKPO4·6H2O, leading to a significant delay of setting time and a reduction of compressive strength. Extended X-ray absorption fine structure (EXAFS) analysis proved that Pb2+ strongly coordinated with the PO43–, whereas AsO2– gently coordinated with K+. The MPC binder displayed an excellent immobilisation efficiency for Pb (99.9%), but was less effective for As. The use of red mud enhanced the As immobilisation efficacy to 80.5% due to strong complexation between AsO2– and Fe3+. The treated soils fulfilled requirements of metal(loid) leachability and mechanical strength for on-site reuse. Therefore, red mud-modified MPC can be an effective binder for sustainable remediation of Pb and As contaminated soil.
AB - Lead (Pb) and arsenic (As) contaminated soil poses severe threats to human health. This study proposes a novel approach for synchronous stabilisation/solidification (S/S) of Pb and As contaminated soil and explains the immobilisation mechanisms in red mud-modified magnesium phosphate cement (MPC). Experimental results show that incorporation of red mud in MPC binder retarded over-rapid reaction and enhanced compressive strength via the formation of (Al,Fe,K)PO4·nH2O compounds as indicated by X-ray diffractometer (XRD) and elemental mapping. The presence of Pb had a marginal effect on the MPC reaction; however, the presence of As suppressed the generation of MgKPO4·6H2O, leading to a significant delay of setting time and a reduction of compressive strength. Extended X-ray absorption fine structure (EXAFS) analysis proved that Pb2+ strongly coordinated with the PO43–, whereas AsO2– gently coordinated with K+. The MPC binder displayed an excellent immobilisation efficiency for Pb (99.9%), but was less effective for As. The use of red mud enhanced the As immobilisation efficacy to 80.5% due to strong complexation between AsO2– and Fe3+. The treated soils fulfilled requirements of metal(loid) leachability and mechanical strength for on-site reuse. Therefore, red mud-modified MPC can be an effective binder for sustainable remediation of Pb and As contaminated soil.
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U2 - 10.1016/j.jhazmat.2020.123317
DO - 10.1016/j.jhazmat.2020.123317
M3 - Article
C2 - 32947716
AN - SCOPUS:85087421320
SN - 0304-3894
VL - 400
JO - Journal of Hazardous Materials
JF - Journal of Hazardous Materials
M1 - 123317
ER -
