摘要
以N i2+为例研究了凹凸棒石与重金属离子长期作用过程,探讨了重金属离子在凹凸棒石上的吸附反应动力学,并运用高分辨透射电镜揭示了凹凸棒石与重金属离子互相作用引起重金属离子水解沉淀、形成氢氧化物或层状双氢氧化物次生物相的现象。实验表明,凹凸棒石-N i2+水悬浮体系中,随着时间的延长溶液的pH值逐渐升高,N i2+浓度逐渐降低,并且长期作用后悬浮液的pH值和重金属离子浓度受到固/液比控制。N i2+在凹凸棒石和水两相中的分配在长达40 d的时间内都没有达到完全平衡,表明凹凸棒石-N i2+水悬浮体系中存在凹凸棒石与重金属离子长期互相作用。凹凸棒石与N i2+长期作用N i2+浓度变化可以用抛物线扩散方程、双常数方程、一级扩散方程、E lovich方程较好地拟合。凹凸棒石与重金属的长期作用反应机制可能是由于凹凸棒石纳米效应和反应活性,表面缓慢水化导致含重金属离子溶液pH值缓慢升高,诱导了N i2+在凹凸棒石表面沉淀,在凹凸棒石表面形成了氢氧化物或层状双氢氧化物。
The long-term interaction between palygorskite and nickel ions was studied and sorption kinetics of nickel ions on palygorskite was discussed. The hydrolytic precipitation of nickel ions on the surface of palygors- kite caused by the interaction between palygorskite and heavy metal ions and the formation of hydroxide and/or layer double hydroxide were investigated with TEM. The results showed that the pH of solution rose and Ni^2＋ con- centrations decreased with time in the suspended system of palygorskite-heavy metal ions. The pH value and Ni^2＋ concentrations of suspended solution were effected by the ratio of solid over liquid. The distribution ofNi^2＋ between the two phases （palygorskite and solution） was not in equilibrium with interaction after 40 days. The longterm interaction between heavy metal ions and palygorskite could be well fitted with parabola, two-constant, firstorder diffusion and Elovieh equations. Reaction mechanism of long-term interaction between palygorskite andNi^2＋solution is presumed that surface hydrolysis of palygorskite slowly cauces pH increase of solution, which induces the hydrolysis of Ni^2＋ and hydroxide or layer double hydroxide is formed on the surface of palygorskite.
出处
《矿物学报》
CAS
CSCD
北大核心
2009年第2期152-156,共5页
Acta Mineralogica Sinica
基金
国家自然科学基金项目(批准号:40472026
50774027)
863项目(2006AA03Z337)
关键词
凹凸棒石
重金属离子
吸附
长期作用
palygorskite
heavy metal ion
absorption
long-term reaction
