Phycoremediation and adsorption isotherms of cadmium and copper ions by Merismopedia tenuissima and their effect on growth and metabolism

• The highest Cd2+ and Cu2+ reduction at 0.06 mgL−1 and 0.12 mgL−1, respectively.
• qmax was found to be the highest for Cd2+ followed by Cu2+.
• The affinity constant of Cu2+ on the biomass of M.tenuissima was higher than Cd2+.
• M.tenuissima is more tolerant to Cd2+ phytotoxicity than Cu2+.
• High concentrations of Cd2+ and Cu2+ passively affected on growth of M. tenuissima.

The current study tends to investigate the removal of cadmium and copper ions by Merismopedia tenuissima, grown in different concentrations of cadmium and copper ions, as well to investigate their effects on growth and metabolism. Sorption isotherms of Langmuir and Freundlich were obtained for the quantitative description of cadmium and copper uptake by M. tenuissima. Langmuir model adequately to describe the data of biosorption for these metals. However, the Freundlich model could work well in case of Cu2+ only. M. tenuissima appears to be more efficient for removing Cd2+ ions than Cu2+. However, the affinity constant of Cu2+ on the biomass of M. tenuissima was higher than Cd2+ indicating that M. tenuissima is more tolerant to Cd2+ phytotoxicity than Cu2+. FTIR analysis of algae with and without biosorption revealed the presence of carboxyl, amino, amide and hydroxyl groups, which were responsible for biosorption of Cd+2 and Cu+2 ions.

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