TY - JOUR
T1 - Designing Magnesium Phosphate Cement for Stabilization/Solidification of Zn-Rich Electroplating Sludge
AU - Zhang, Yuying
AU - Wan, Zhonghao
AU - Wang, Lei
AU - Guo, Binglin
AU - Ma, Bin
AU - Chen, Liang
AU - Tsang, Daniel C.W.
N1 - Funding Information:
The authors gratefully acknowledge the financial support from the Open Project of State Key Laboratory of Clean Energy Utilization, Zhejiang University (ZJUCEU2022001), Alexander von Humboldt Foundation (AvH), KAKENHI Early Career Scientists (No. 21K14574) and Hong Kong Research Grants Council (PolyU 15222020) for this study. The authors also appreciate the support of the Kyushu University Beamline (SAGA-LS/BL06) for the EXAFS experiment (No. 2020IIIK003) and the University Research Facility on Chemical and Environmental Analysis (URFCE) of PolyU.
Publisher Copyright:
© 2022 American Chemical Society. All rights reserved.
PY - 2022/7/5
Y1 - 2022/7/5
N2 - Electroplating sludge is a hazardous waste due to its high potential to leach toxic elements into the natural environment. To alleviate this issue, we tailored magnesium phosphate cement (MPC) as a low-carbon material for stabilization/solidification (S/S) of Zn-rich electroplating sludge. The interaction between MPC and ZnO was investigated to clarify the precipitate chemistry, microstructure transition, and chemical environment of Zn species in the MPC-treated Zn sludge system. Comprehensive characterization (by X-ray diffraction (XRD), 31P nuclear magnetic resonance (NMR), and extended X-ray absorption fine structure spectroscopy (EXAFS)) and thermodynamic modeling results revealed that the incorporated ZnO preferentially reacted with phosphate to form Zn3(PO4)2·2H2O/Zn3(PO4)2·4H2O, changing the orthophosphate environment in the MPC system. Stronger chemical bonding between Zn and phosphate in comparison to the bonding between Mg and phosphate also resulted in the formation of amorphous Zn3(PO4)2·2H2O/Zn3(PO4)2·4H2O. Zn3(PO4)2·4H2O precipitate appears to predominate at high {K+}{H+}{HPO42-} values, and the formation of Zn3(PO4)2·2H2O/Zn3(PO4)2·4H2O competed for the Mg sites in the MPC system, leading to the inhibition of formation of Mg-phosphate precipitates. Overall, this work uncovers the precipitate chemistry and microstructure transition of Zn species in the MPC system, providing new insights into the sustainable S/S of Zn-contaminated wastes by adopting MPC.
AB - Electroplating sludge is a hazardous waste due to its high potential to leach toxic elements into the natural environment. To alleviate this issue, we tailored magnesium phosphate cement (MPC) as a low-carbon material for stabilization/solidification (S/S) of Zn-rich electroplating sludge. The interaction between MPC and ZnO was investigated to clarify the precipitate chemistry, microstructure transition, and chemical environment of Zn species in the MPC-treated Zn sludge system. Comprehensive characterization (by X-ray diffraction (XRD), 31P nuclear magnetic resonance (NMR), and extended X-ray absorption fine structure spectroscopy (EXAFS)) and thermodynamic modeling results revealed that the incorporated ZnO preferentially reacted with phosphate to form Zn3(PO4)2·2H2O/Zn3(PO4)2·4H2O, changing the orthophosphate environment in the MPC system. Stronger chemical bonding between Zn and phosphate in comparison to the bonding between Mg and phosphate also resulted in the formation of amorphous Zn3(PO4)2·2H2O/Zn3(PO4)2·4H2O. Zn3(PO4)2·4H2O precipitate appears to predominate at high {K+}{H+}{HPO42-} values, and the formation of Zn3(PO4)2·2H2O/Zn3(PO4)2·4H2O competed for the Mg sites in the MPC system, leading to the inhibition of formation of Mg-phosphate precipitates. Overall, this work uncovers the precipitate chemistry and microstructure transition of Zn species in the MPC system, providing new insights into the sustainable S/S of Zn-contaminated wastes by adopting MPC.
KW - industrial sludge treatment
KW - metal leaching
KW - stabilization/solidification
KW - sustainable waste management
UR - http://www.scopus.com/inward/record.url?scp=85134083536&partnerID=8YFLogxK
U2 - 10.1021/acs.est.2c01450
DO - 10.1021/acs.est.2c01450
M3 - Journal article
C2 - 35735903
AN - SCOPUS:85134083536
SN - 0013-936X
VL - 56
SP - 9398
EP - 9407
JO - Environmental Science & Technology
JF - Environmental Science & Technology
IS - 13
ER -