Studies On The Adsorption Of PCBs To Marine Microalgae

The adsorption of PCBs to two kinds of marine microalgar-Chlorella sp. and Nitzschia closterium has been studied. From morphology and adsorption kinetics, absorbability to PCBs of algae has been primary discussed. It is found that the adsorption of PCBs by marin microalgae is an effective technology for the treatment of seawater containing PCBs.From the study of algae's growth periods, it is found out that the exponential phase of algae-Chlorella sp. and Nitzschia closterium is all about four days. During the period, algae grows rapidly. So it is favorable for algae to adsorb PCBs.It is demonstrated that a small quantity of PCBs don't have obvious toxic effect on algae. Furthermore, the growth of algae is slight stimulated in 24 hours.In the study of adsorption, it is founded out that when 10-50μg/L PCBs are added, algae can adsorb them rapidly. Absorbability to Clophen A40 of algae is stronger than that to Clophen A50. Absorbability to PCBs of Nitzschia closterium is stronger than that of Chlorella sp.. The adsorption amount of Clophen A40 and Clophen A50 comes to the maximum after 48h and 72h, respectively. So microalgae be reclaimed after 48h and 72h respectively to purify the seawater.From morphology and adsorption kinetics, it has been primary discussed that absorbability to PCBs of algae is relative to surface area and properties of PCBs. One side, algae adsorb PCBs through physical adsorption on its surface. So absorbability to PCBs of algae-Nitzschia closterium is stronger than that of Chlorella sp. because of its larger surface area. On the other hand, algae adsorb PCBs by external aggradation, passivetransport and so on. The algae cell wall is the network structure constitution which forms by the cellulose micro-filament silk. In the cell wall has the very many cavities hole. So The molecular weight low matter can easily to pass through the cell wall to enter the organization and then it is very difficultly to be released or metabolized. So absorbability to Clophen A40 of algae is more stronger.