Solidification/stabilization of simulated cadmium-contaminated wastes with magnesium potassium phosphate cement

  • Su, Ying (College of Civil Engineering, YanCheng Institute of Technology) ;
  • Yang, Jianming (College of Civil Engineering, YanCheng Institute of Technology) ;
  • Liu, Debin (Institute of Water Science in Coastal Regions of Jiangsu Province) ;
  • Zhen, Shucong (College of Civil Engineering, YanCheng Institute of Technology) ;
  • Lin, Naixi (College of Environment, Hohai University) ;
  • Zhou, Yongxin (Institute of Civil Engineering, Suzhou University of Science and Technology)
  • Received : 2015.08.04
  • Accepted : 2015.11.20
  • Published : 2016.03.31


Magnesium potassium phosphate cement (MKPC) is an effective agent for solidification/stabilization (S/S) technology. To further explore the mechanism of the S/S by MKPC, two kinds of Cd including $Cd(NO_3)_2$ solution (L-Cd) and municipal solid waste incineration fly ash (MSWI FA) adsorbed Cd (S-Cd), were used to compare the effects of the form of heavy metal on S/S. The results showed that all the MKPC pastes had a high unconfined compressive strength (UCS) above 11 MPa. For L-Cd pastes, Cd leaching concentration increased with the increase of Cd content, and decreased with the increase of curing time. With the percentage of MSWI FA below 20%, S-Cd pastes exhibited similar Cd leaching concentrations as those of L-Cd pastes, while when the content of MSWI FA come up to 30%, the Cd leaching concentration increased significantly. To meet the standard GB5085.3-2007, the highest addition of S-Cd was 30% MSWI FA (6% Cd contained), with the Cd leaching concentration of 0.817 mg/L. The S/S of L-Cd is mainly due to chemical fixation, and the hydration compound of Cd was $NaCdPO_4$, while the S/S of S-Cd is due to physical encapsulation, which is dependent on the pore/crack size and porosity of the MKPC pastes.


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