C-S-H凝胶对Cd^(2+)、Zn^(2+)和Cu^(2+)的吸附固化作用

Effect of absorption and binding of Cd^(2+)、Zn^(2+) and Cu^(2+) with C-S-H gel

以分析纯Ca(NO3)2.4H2O、Na2SiO3.9H2O和重金属硝酸盐为原料,通过溶液反应法分别制备钙硅比为0.8和1.8的纯净及含Cd2+、Zn2+和Cu2+的C-S-H凝胶,研究了C-S-H凝胶在形成过程中对三种重金属离子的吸附固化作用。结果表明,两种钙硅比的C-S-H凝胶均能吸附固化Cd2+、Zn2+和Cu2+,重金属离子较易进入低钙硅比C-S-H凝胶夹层结构中,可以置换高钙硅比C-S-H凝胶结构中的Ca2+,在水化液相中形成Ca(OH)2。C-S-H凝胶对Cd2+和Cu2+的固化能力好于对Zn2+的,低钙硅比C-S-H凝胶对Zn2+的吸附固化作用优于高钙硅比C-S-H凝胶。

Two kinds of pure C-S-H gel, which calcium-silicate ratio was 0.8 and 1.8, and also the same two kinds of C-S-H gel consisted of Cd^2＋,Zn^2＋ and Cu^2＋ repectively , were prepared by solution reaction using analytically pure Ca（NO3）2·4H2O, Na2SiO3.9H2O and nitrates of heavy metals as raw materials. The effect of absorption and bindingCd^2＋,Zn^2＋ and Cu^2＋ with C-S-H gel during its formation process were studied. The results showed that both C-S-H gel, which calcium-silicate ratio was 0.8 and 1.8, could absorb and bind Cd^2＋,Zn^2＋ and Cu^2＋. The heavy metal ions were easy to enter the sandwich structure of C-S-H gel with low calcium-silicate ratio. The heavy metal ions could replace Ca^2＋ that in C-S-H gel with high calcium- silicate ratio, and Ca（OH）2 formed in liquid phase. The C-S-H gel could bind Cd^2＋ and Cu^2＋ better than Zn^2＋. C-S-H gel with low calcium-silicate ratio could bind Zn^2＋ better than C-S-H gel with high calcium-silicate ratio.