| In this study, using Chlamydomonas reinhardtii as the model organism, the impacts of chlamydomonas on the removal and distribution of nano metals were investigated to discuss the feasibility of the removal of nano copper oxide from aquatic environment by chlamydomonas.Chlamydomonas reinhardtii and nano copper oxide were characterized in many ways. The capacity and mechanism of adsorption of nano copper oxide by Chlamydomonas reinhardtii was studied in terms of influence factors of adsorption, adsorption isotherm, adsorption kinetics by batch adsorption experiments,. The influence of Chlamydomonas reinhardtii on the dispersion/aggregation of n Cu O, the adsorption and assimilation, and the distribution of n Cu O among the interface of cell and solution were investigated by using 96 h absorption experiments. The effects of n Cu O on the extracellular polymeric substances(EPS) produced by C. reinhardtii were also studied to discuss the interaction between the n Cu O and alga cells. The main findings of this work are as follows:(1)The result of FT-IR shows that there are many functional groups on the surface of cell wall such as, hydroxyl group, carboxyl group, amino group, which pocess a good affinity to bound metal ions. The BET results shows that the specific surface area of nano copper oxide is large, indicating a high adsorption capacity of n Cu O.. The analyze of Zata potential suggested that the n Cu O presents an unstable colloidal characteristic and is prone to be aggregated in solutions.(2) The absorption of nano copper oxide by Chlamydomonas reinhardtii was mainly based on the biological and chemical adsorption, and monolayer and multilayer adsorption is coexistent, with a maximum adsorption capacity of 128μg/106 cell.(3) The existence of C. reinhardtii will improve the release of Cu2+ from n Cu O nanoparticles, with a maximal increasing of 73.33% as compared to the control, which could greatly reduce the potential toxicity of n Cu O in water environment.(4) The existence of C. reinhardtii can promote the agglomeration of nanometer copper oxide, resulting in decrease of n Cu O content d of nanometer copper oxide, which would reduce the toxicity of n Cu O nanoparticles to aquatic environment.(5) The concentration of C. reinhardtii would pose a significant effects on the distribution of n Cu O among the solution, the extra-and internal cells of C. Reinhardtii, with a significant decreased proportion of Cu2+ in internal cells.(6) Nano copper oxide particles have a significant influence on the content and composition of the EPS of C.reinhardtii algae cell, with an increase at the intial stage and then followed a decrease in the content of EPS of algae cells, while the total contents are allmuch more than that of the control group.(7) The polysaccharide content in EPS of C. reinhardtii algae cell can be significantly influenced by the copper oxide nanoparticles. The polysaccharide can facilitate the agglomerate and settlement of n Cu O and then decrease the suspended content of n Cu O in solutions, resulting in a reducing in toxicity of n Cu O in aquatic environment. large particles of nano copper oxide can be easier removed from the water environment compared to small particles of nano copper oxide:(8) The protein content in EPS of C. reinhardtii algae cell showeda trend of increasing initially and then decreasing with the variations of n Cu O concentrations, indicating that high concentrations of n Cu O pose an obvious damage of C. reinhardtii, with increasing in the damage degree as the extension of time. This may be attributed to the fact that the n Cuo of high level inhibit the growth and metabolism of algal cell, and cause a decrease of EPS and protein production of cells. |
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