Abstract:[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.
