活体微藻吸附水体中Cd2+的性能特征

【目的】藻类对重金属吸附和吸收是重金属进入食物链的重要渠道之一。研究活体微藻对水体中Cd~(2+)的吸附性能和吸附机理,旨在为Cd~(2+)等重金属离子进入水体后的去向及去除提供理论依据。【方法】选取地表水普遍存在的4种微藻:钝顶螺旋藻(Spirulina platensis)、铜绿微囊藻(Microcystis aeruginosa)、四尾栅藻(Scenedesmus quadricauda)和小球衣藻(Chlamydomonas microsphaera)作为试验材料,通过室内模拟实验,利用Langmuir、Freundlich和Dubinin-Radushkevich(D-R)3种等温吸附模型,研究4种活体微藻对Cd~(2+)的吸附规律及吸附参数。【结果】4种微藻对水体Cd~(2+)吸附均可以用Langmuir、Freundlich和D-R模型描述,其中用Langmuir模型拟合钝顶螺旋藻、Freundlich模型拟合小球衣藻、D-R模型拟合铜绿微囊藻和四尾栅藻的吸附效果最佳。四尾栅藻对Cd~(2+)的吸附量最高,而钝顶螺旋藻对Cd~(2+)的吸附量最低,但与Cd~(2+)的亲和力最强,4种微藻吸附Cd~(2+)主要是以离子代换为主的化学吸附。【结论】微藻对Cd~(2+)均有较强的吸附能力,会引起以微藻为食的水生动物Cd~(2+)富集;微藻也是去除水体Cd~(2+)的潜在吸附剂原料。

Adsorption of Cd2+ in water by living microalgae

Objective] It is one way of heavy metals into the food chain by algae adsorption. In order to study the fates of Cd2+ in water, the adsorption mechanisms of Cd2+ by living microalgae was studied. Methods] Four microalgae species, including Spirulina platensis, Microcystis aeruginosa, Scenedesmus quadricauda and Chlamydomonas microsphaera, which are commonly found in surface water, were selected as experiment materials. After simulation experiments, Langmuir, Freundlich and Dubinin-Radushkevich (D-R) models were applied to describe the biosorption isotherm of Cd2+ by four organisms. Results] The results indicated that biosorption isotherm was better fitted by the Langmuir model comparing with the other models in explaining the biosorption of Cd2+ by Spirulina platensis. Freundlich was the best one to describe Chlamydomonas microsphaera, and D-R was the best isotherm when describing the biosorption of Cd2+ by Microcystis aeruginosa and Scenedesmus quadricauda. The adsorption capacity of Scenedesmus quadricauda was the largest, whereas Spirulina platensis was the lowest with the strongest absorbability. It also showed that the biosorption of Cd2+ by the four microalgae was taken place by chemisorption. Conclusion] There exists large adsorption capacity of living microalgae to Cd2+, which may induce the enrichment of Cd2+ in aquatic animals by eating them. On the other hand, living microalgae can be used as a kind of adsorbent material to remove Cd2+ from wastewater.