新型钛酸钠填料对Cu2+、Pb2+、Zn2+和Cd2+的竞争吸附研究

以钛酸钠纳米纤维为原材料制备新型钛酸钠填料,对水体中常见的重金属(Cu~(2+)、Pb~(2+)、Zn~(2+)和Cd~(2+))进行竞争吸附实验研究,分析了四元、三元及双组分竞争吸附的选择性吸附特性,并探讨了4种金属离子在钛酸钠填料上的相互作用关系.结果显示,初始浓度较低时,4种离子之间的相互影响差异性不明显;随着初始浓度的升高,4种离子的竞争吸附分配系数都呈下降的趋势,竞争吸附系数大小顺序为:Pb~(2+)Cu~(2+)Zn~(2+)Cd~(2+),这与重金属离子的第一水解常数大小顺序一致.竞争吸附结果表明,水中存在Pb~(2+)时,其余3种离子的吸附都会被抑制,尤其对Zn~(2+)和Cd~(2+)的抑制更显著,即在钛酸钠填料上Pb~(2+)的竞争吸附能力最强,Cu~(2+)次之,而Zn~(2+)和Cd~(2+)的竞争吸附能力较弱,其吸附过程容易受到其他二价金属离子的抑制.

Competitive adsorption of Cu2+, Pb2+, Zn2+ and Cd2+ by new-sodium titanate filler

This study investigated the competitive adsorption of heavy metal ions (Cu²⁺, Pb²⁺, Zn²⁺ and Cd²⁺) on a new sodium titanate filler prepared with sodium titanate nanofibers as the raw material. The selective adsorption characteristics of quaternary, ternary and binary systems were analyzed to reveal the interaction among the four kinds of metal ions on the sodium titanate filler. The results showed that the interaction between the metal ions was not signification when the initial concentration was low. With the increase of initial concentration, the competitive adsorption distribution coefficients of metal ions showed a decreasing trend, and was in the order of Pb²⁺ > Cu²⁺ > Zn²⁺ > Cd²⁺, which was in accordance with the first hydrolysis constant of heavy metal ions. The results of competitive adsorption showed that the adsorption of the other three ions would be suppressed when there was Pb²⁺ in water, especially for Zn²⁺ and Cd²⁺. In conclusion, the competitive sorption capacity was the strongest for Pb²⁺, followed by Cu²⁺, and was the weakest for Zn²⁺ and Cd²⁺, which were easy to be suppressed by other divalent metal ions.