ISSN: 1003-6326
CN: 43-1239/TG

Vol. 27    No. 5    May 2017

Immobilization of Cd and Pb in soils by polymeric hydroxyl ferric phosphate
Yi-ning YUAN1,2, Li-yuan CHAI1,2, Zhi-hui YANG1,2, Rui-ping WU1,3, Hui LIU1,2, Li-fen LIANG1, Wei SHI1
(1. School of Metallurgy and Environment, Central South University, Changsha 410083, China;
2. Chinese National Engineering Research Center for Control and Treatment of Heavy Metal Pollution, Central South University, Changsha 410083, China;
3. China BlueStar Changsha Design and Research Institute, Changsha 410116, China
Abstract: A polymeric hydroxyl ferric phosphate (PHFP) was prepared by using a byproduct of titanium dioxide containing ferrous sulfate and phosphates under alkaline condition. The PHFP was used to immobilize lead (Pb) and cadmium (Cd) in soils. Fourier transform infrared spectra, X-ray diffraction were applied to revealing the characteristics of PHFP, and the modified Tessier sequential extraction and column leaching experiment with simulated acid rain were used to assess the effectiveness of immobilization of Cd and Pb in soils by PHFP. The results showed that PHFP was indeed a polymer with complicated OH—Fe—P structure and consisted of Fe6(OH)5(H2O)4(PO4)4(H2O)2 and Fe25(PO4)14(OH)24. Moreover, the removal rates of DTPA-extractable Cd and Pb in soils reached up to 33% and 45%, and the water-soluble Cd and Pb decreased by 56% and 58%, respectively, when PHFP was added in soils at 4% dosage. In addition, the immobilization of Cd and Pb contributed to transforming water soluble, exchangeable and carbonate-bonded fractions to Fe and Mn oxides-bonded, organic-bonded and residual fractions. Under leaching with simulated acid rain, Cd and Pb release amount in PHFP amended soil declined by 53% and 52%, respectively, as compared with non-treated soil. The result implied that PHFP had a potential application for the remediation of Cd- and Pb-contaminated soils.
Key words: soil; Cd; Pb; polymeric hydroxyl ferric phosphate; immobilization remediation
Superintended by The China Association for Science and Technology (CAST)
Sponsored by The Nonferrous Metals Society of China (NFSOC)
Managed by Central South University (CSU)