水化硅酸钙形成过程中对Cd(Ⅱ)、Zn(Ⅱ)的俘获作用

Entrapment of Cd(Ⅱ),Zn(Ⅱ) by C-S-H during C-S-H Formation

利用分析纯CaO,H2SiO3和Cd(NO3)2·4H2O[或Zn(NO3)2]在液相中人工合成n(Ca)/n(Si)为1.6和0.7的2种含Cd(Ⅱ)或含Zn(Ⅱ)的水化硅酸钙(C-S-H),研究C-S-H在形成过程中对Cd(Ⅱ)或Zn(Ⅱ)的俘获情况。结果表明,2种n(Ca)/n(Si)的C-S-H在俘获Cd(Ⅱ)后,其XRD图谱均发生明显的变化,特别是在Ca2+量不足[n(Ca)/n(Si)=0.7]的情况下,其晶格参数的变化较大,其特征峰无论是峰值还是峰位均发生了明显改变,表明有Cd2+替代Ca2+进入了C-S-H晶体。2种n(Ca)/n(Si)比值的C-S-H在俘获Zn(Ⅱ)后,其XRD图谱变化很微弱,仅特征峰的峰值稍有改变,但是这也显示出Zn(Ⅱ)进入了C-S-H晶体。C-S-H均能对Cd(Ⅱ)、Zn(Ⅱ)予以化学俘获。

In order to investigate the entrapment of Cd （ Ⅱ ） or Zn （ Ⅱ）, calcium-silicate-hydrate （C-S-H）.C-S-H containing Cd（ Ⅱ ） at n （Ca）/n （Si）=-0.7 and 1.6 were synthesized using analytical reagent grade CaO,H2SiO3 and Cd（NO3）2·4H2O and C-S-H containing Zn（ H ） at n （Ca）/n （Si）=0.7 and 1.6 were made from reagent CaO,H2SiO3 and Zn（NO3）2. The synthesis experiments showed that the X-ray diffraction patterns of C-S-H at n （Ca）/n （Si）= 0.7 and 1.6 were both significantly changed after they doped with Cd（ R ）,especially when Ca2＋ is deficient. The X-ray diffraction patterns of C-S-H at n （Ca）/n （Si）= 0. 7 changed obviously,both in peak values and at peak position. Indicating that Cd（ Ⅱ ） had entered into C-S-H lattice in substitution for Ca2＋. The experiments also showed that the X-ray diffraction patterns of C-S-H at n （Ca）/n （Si）=-0. ？ and 1.6 changed after they accommodated Zn（ Ⅱ ）. Although the change was slight and only occurred to the peak value, which also indicated that some Zn（ Ⅱ ） had been captured into C-S-H lattice. This investigation verified that Cd （Ⅱ ）or Zn （Ⅱ ）could both be chemically entrapped by C-S-H.