The geopolymer,prepared from fly ash and sludge ash as raw materials by alkali activated,is used for solidification of Pb2+or Zn2+.The influence of Pb2+or Zn2+content on Pb2+or Zn2+leaching rate and compres-sive strength of solidified geopolymer are investigated.The apparent morphology is observed using scanning electron microscopy (SEM).The chemical structure analysis of the geopolymers by fourier transform infrared spectrometer (FT-IR) and X-ray diffraction (XRD) are tested.Combined with leaching kinetics simulation of Pb2+or Zn2+in the 3 leaching solution,respectively,the leaching mechanism is initially explored.The results show that fly ash/sludge ash based solidifie geopolymers have good fixing effect on Pb2+or Zn2+.When Pb2+or Zn2+content is 0.25％,the maximum compressive strength of the solidified geopolymers after 28 days can reach 56.1 MPa and 62.2 MPa,respectively.The fixation rate of Pb2+or Zn2+is mostly above 99％ in the three leaching solutions.The microscopic analysis shows that Pb2+or Zn2+is physically encapsulated in the internal structure of the geopolymer in the form of hydroxyl metal complex ions.The leaching process of Pb2+is consis-tent with the sphere diffusion model,and the apparent activation energy is 18.81 kJ/mol.The leaching process of Zn2+is controlled by interfacial diffusion and interfacial reaction,and the apparent activation energy is 30.95 kJ/mol.A new way for harmless treatment and resource utilization of bulk solid wastes such as coal gasification slag and sludge is developed.
关键词
循环流化床/粉煤灰/污泥灰/地聚物/协同固化/抗压强度/重金属固定率
Key words
CFB/fly ash/sludge ash/geopolymer/synergistic solidification/compressive strength/fixation rate of heavy metal
万方数据